Coolant reservoir: How does it bleed air?

[Hindsight]

My understanding is that the coolant reservoir allows air to be "automatically" bled/purged from the system. At least, I'm 90% certain that's how it works on other cars I have owned. But on the Subie, I'm not quite "getting" it... there are way more lines going to the reservoir than I'm used to seeing and not all of them originate from the highest point in the system so I'm a little confused.

The way I understand it, you want the reservoir to be higher than the radiator/engine, and you want a coolant line going from the next highest place (engine or radiator) to the top of the reservoir. Then you have a "drain" line back into the system somewhere. I see like 3 or 4 lines going into the top of the reservoir on my 2007 donor.

The other thing that confuses me is that there is a radiator cap. I'm used to having a reservoir and no radiator cap. Since the reservoir is higher than the radiator, and the reservoir is supposed to have coolant in it, opening the radiator cap (which is lower than the reservoir) should always result in coolant pouring out... unless I'm missing something here too?

[Goldwing]

The air works its way there being the highest point then gets pushed out past the cap through to the coolant bottle. On the 818, many are tapping the engine coolant outlet line and running that to the line next to the one mentioned above (not through the cap). I also added a burp line at the top of the radiator and ran that to the same spot through a tee. Burping the system was a complete non-issue.

[Hindsight]

Thanks Rich. I'm not sure I 100% understand you though. You said many are tapping the engine coolant outlet line (this being one of the LARGE diameter lines right?) and running that line "next to the one mentioned above"... which one, and why next to? Are you saying they are tapping the engine coolant outlet line and running the tapped hose into the reservoir?

RE your burp line on the top of the rad... we both have an 07 donor - mine looks like it has a burp line (on the top passenger's side)..... doesn't yours have one as well? I was assuming I was going to have to run that line all the way back to the reservoir mounted in the engine compartment, but doing so would mess up the dynamics of it because it would have to dip down below the radiator which would defeat the purpose.

[Goldwing]

Sorry, I got cut short and didn't get to expound. I worried about the dip as well, but it worked flawlessly. I tied the radiator burp and a tee at the radiator inlet (highest point due to the lean of the radiator in the 818, but probably overkill) together and ran it back to the engine mounted coolant bottle. As soon as hot water got to the radiator, the burp line warmed up too. Being at the top it gathers the bubbles, being a small hose, the bubbles are pushed right through. Yes, tapping that large outlet. I sourced a tee from a VW vr6 engine rather than tapping since my engine was already in and difficult to reach. You can see what I did in my build, or check Wayne Pressley's. Some are putting overflow bottles at front and back, but the concern there was whether the two bottle setup would work. With my luck, the front would let fluid out, but then only draw fluid back in from the rear bottle, running dry in back and overflowing in front. Tying the burp lines was an experiment, that so far seems to work fine.

My build, post 88 on page 3:
http://thefactoryfiveforum.com/showthread.php?13026-Goldwing-s-818-Street-The-Phoenix

Wayne's build post 281 mentions it. (http://thefactoryfiveforum.com/showthread.php?10525-Wayne-Presley-VeryCoolParts-Build-Thread-H6-power/page8)

[Goldwing]

The line on the left at the top of the tank brings the burp lines in. The line exiting the cap on the right goes to overflow. Bubbles get pushed out there, but the first few starts, after cool down, opening it and topping it off finishes the fill of the system.

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[Goldwing]

I just capped the outlet after the radiator cap on the radiator itself.

[Wayne Presley]

I do the cooling system mod which you tap the water outlet and run a line to the rear degas tank. I use one coolant recover tank in the back and put a higher pressure cap on the radiator than the degas tank.

[Hindsight]

Thanks very much for the replies!

Wayne, is the water outlet you tap the aluminum one that comes off the upper engine (normally then connecting to the upper radiator), or something else?

My donor has a higher pressure cap on the radiator vs the degas tank and it confused me..... why is this? What does it do for you?

Thanks in advance!

[Goldwing]

Yes, tap the upper one on the engine. And yes, goes to the upper radiator port too

I'm not sure why the caps are different regularly, but if you run only one overflow bottle in the 818 like I did, you want the lower pressure cap feeding the bottle. I'm not sure about how those caps differ in letting coolant back in after cooling off, so I capped the line leaving the radiator cap to be sure it doesn't draw air in.

[Wayne Presley]

Thanks very much for the replies!

Wayne, is the water outlet you tap the aluminum one that comes off the upper engine (normally then connecting to the upper radiator), or something else?

My donor has a higher pressure cap on the radiator vs the degas tank and it confused me..... why is this? What does it do for you?

Thanks in advance!

That is correct Hindsight. I run the higher pressure on the radiator to make the system push water out the degas tank first and plug the radiators cap outlet so it doesn't suck air when the system cools off.

[Hindsight]

Nice, thanks guys. Makes perfect sense.

[Wayne Presley]

http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod1_zpsf770980b.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod1_zpsf770980b.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod2_zps9688ed12.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod2_zps9688ed12.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod3_zps1a200d9d.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod3_zps1a200d9d.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod4_zps8b009e73.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod4_zps8b009e73.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod6_zps9877251c.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod6_zps9877251c.jpg.html)

[Wayne Presley]

http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod7_zps4d48a7a4.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod7_zps4d48a7a4.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod8_zps5181d2f6.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod8_zps5181d2f6.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod9_zpsb714c699.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod9_zpsb714c699.jpg.html)
http://i213.photobucket.com/albums/cc175/vcpinjectionpb/coolmod/mod10_zps09ecaafa.jpg (http://s213.photobucket.com/user/vcpinjectionpb/media/coolmod/mod10_zps09ecaafa.jpg.html)

[Hindsight]

Wow, a picture tutorial even. Thanks Wayne!!

[Harley818]

Wayne, Hindsight, or someone who has done this.......How thick is the aluminum where you are drilling and tapping?
I have a 2002, and it looks 1/8 in or less.

I'm ready to go.. just a bit nervous. The one in Waynes picture tutorial looks thicker, but its hard to tell.

[Wayne Presley]

There is plenty to support the 1/8 NPT fitting.

[Buzz Skyline]

Wayne, Hindsight, or someone who has done this.......How thick is the aluminum where you are drilling and tapping?
I have a 2002, and it looks 1/8 in or less.

I'm ready to go.. just a bit nervous. The one in Waynes picture tutorial looks thicker, but its hard to tell.

I have a 2002 donor motor too, and the pipe seemed robust enough to take the pipe tap. I haven't run it a lot, but it's been up to temperature and pressure several times without a problem.

I drilled and tapped it with the pipe attached and the motor installed. It was a bit tight, but totally doable. It's also nice to do it with everything attached because you can confirm there are no interference problems.

[C.Plavan]

That is correct Hindsight. I run the higher pressure on the radiator to make the system push water out the degas tank first and plug the radiators cap outlet so it doesn't suck air when the system cools off.

Wayne- I have a 1.3 bar (19 pounds) cap on the radiator (mishimoto aluminum radiator)- but my degas tank cap has no markings or numbers. Its a stock cap. Anyone know what the Bar is on the degas tank?

What pressure cap did you use on radiator vs degas tank? I'm guessing 1.3 bar on radiator and 1.1 bar on Evap tank?

[Bob_n_Cincy]

Wayne- I have a 1.3 bar (19 pounds) cap on the radiator (mishimoto aluminum radiator)- but my degas tank cap has no markings or numbers. Its a stock cap. Anyone know what the Bar is on the degas tank?

What pressure cap did you use on radiator vs degas tank? I'm guessing 1.3 bar on radiator and 1.1 bar on Evap tank?
Hi Chad
Below is out of the 06 service manual:
Degas tank cap 16psi +/- 2
Radiator cap 20psi +/- 2.1
Bob

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[C.Plavan]

Hi Chad
Below is out of the 06 service manual:
Degas tank cap 16psi +/- 2
Radiator cap 20psi +/- 2.1
Bob

35585

Thanks Bob. So essentially I can cap off the radiator and just use the rear degas for expansion like Wayne said. Then I still can use the front expansion tank for Waynes AWIC heat exchanger.

[Bob_n_Cincy]

Thanks Bob. So essentially I can cap off the radiator and just use the rear degas for expansion like Wayne said. Then I still can use the front expansion tank for Waynes AWIC heat exchanger.

Chad,
On the 818R you have an advantage.
I would run small hose from the radiator gas exit port (usually to right top of radiator) back to the degas tank. You must keep this high (do not dip down).
This will prevent any gas pockets forming in the top of the radiator. It will also allow you to fill the cooling systems without any convoluted methods.

Unfortunately we can't do that on the 818S. That is the main reason I have my radiator in the back.
The picture below shows my hose.

I also think it's an advantage to mount the degas tank higher.
Bob
http://thefactoryfiveforum.com/attachment.php?attachmentid=35586&d=1415642628

[C.Plavan]

Thanks Bob. All my ports on the rear expansion tank are taken. Which spigot do you having it goto? I guess I could run a line down the pass side on the roll cage door bar.

I would guess you just fill the whole system from the rear then once the front radiator is full.

[FFRSpec72]

Thanks Bob. All my ports on the rear expansion tank are taken. Which spigot do you having it goto? I guess I could run a line down the pass side on the roll cage door bar.

I would guess you just fill the whole system from the rear then once the front radiator is full.

In talking to everyone last week at SEMA it seemed that the best thing to do is to block off the front radiator nipple (passenger side) and just have the overflow tank in the front and use the degas tank in the rear to bleed (with the mod that Wayne did).

[Bob_n_Cincy]

Thanks Bob. All my ports on the rear expansion tank are taken. Which spigot do you having it goto? I guess I could run a line down the pass side on the roll cage door bar.

I would guess you just fill the whole system from the rear then once the front radiator is full.

Hi Chad
Combine with the hose from Wayne's port hose at the tank.
You will be able to fill the whole system from the rear without ever opening the front radiator cap.
My radiator doesn't even have a cap.
You might still have to circulate the water to get any air out of the humps in the main radiator hoses. (like where it goes over the steering box)
Bob

[FFRSpec72]

You might still have to circulate the water to get any air out of the humps in the main radiator hoses. (like where it goes over the steering box)
Bob

The FFR R car added a front pump to help the circulation, it runs all the time, seems they also used to help get the air out of the system as they did not use Wayne's mod

[Bob_n_Cincy]

I agree with the circulation pump FFR added. I would have mounted it lower. That sill doesn't get rid on any gas that accumulates in the top of the radiator.

I've got about 75 hard autocross runs on mine. (1 min run, 5 min idle) I need to get the body on and get it out to a track day to do some hard endurance runs to verify my system.
Bob

[metalmaker12]

The FFR R car added a front pump to help the circulation, it runs all the time, seems they also used to help get the air out of the system as they did not use Wayne's mod

The pump was for the awic

[FFRSpec72]

The pump was for the awic

They might have one for that but they have a radiator pump mounted off the bottom radiator return, as we discussed this at length with Jim at SEMA

[metalmaker12]

As much as I want to think or believe gas or air bubbles are forming in the system I can not fully agree. I feel once bleed correctly you won't have any bubbles or pockets of air. In all my previous builds I have never had that happen ( lotus Elise, subarus, Chevys and fords, even a gt 40 I had to change over coolant. My coolant issue was a leak, I ran really low not knowing and pushed it really hard with body on. My iats got way up there and on top of that my coolant was way low and sucking in air. Result was a blown set of head gaskets, and my #4 piston and bore got damage. I think oem pump is more than strong enough to circulate the coolant ( especially the flat style pump)

Bob what might be a prob and a second bennifit to your rear mounted setup is the front mount system may in fact be to good at cooling under load and bring the coolant temp to low so the thermo closes again. It's called thermo shock and the fiero was plagued by it.

I will be up again soon so I can see what really going on.

[Bob_n_Cincy]

The pump was for the awic
They had a boost pump in the blue car at vir
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[metalmaker12]

They might have one for that but they have a radiator pump mounted off the bottom radiator return, as we discussed this at length with Jim at SEMA

Ok cool so something new, or I did not see yet. We will see if they think it's needed

[metalmaker12]

It looks like a Stuart pump, nascar uses them, there like 400 and work awesome

[Hindsight]

VW uses the same Bosch pump commonly used for AWICs, to run coolant through the engine cooling system after the vehicle is shut off. I have one on my 1993 Eurovan. They are about $150 or so.

[Bob_n_Cincy]

Bob what might be a prob and a second bennifit to your rear mounted setup is the front mount system may in fact be to good at cooling under load and bring the coolant temp to low so the thermo closes again. It's called thermo shock and the fiero was plagued by it. I will be up again soon so I can see what really going on.

I agree with the thermal shock issue. When the Subaru thermostat opens, it lets a rush of cold water in. But that also immediately closes the thermostat. I feel the thermostat in a Subaru works much harder than normal cars.

The temperature gauge in a Subaru (in crossover log) is one of the steadiest I've see in any car. (I have not verified with a data log.)

If I can get enough cooling air through the rear mounted radiator. It is the closest to the factory plumbing design.
Bob

[Harley818]

So following Waynes mod outlined above to drill and tap into the coolant passage, I did the mod last night.
If you check my build thread you will see pictures similar to Waynes tutorial above but I did check the thickness and the wall thickness of the aluminum is about 1/4 inch. Lots of meat for the 1/8 NPT thread. Worked out really well and now ready to bleed up to my turbo coolant tank.

[dougkirkbride]

I have read multiple versions of this mod and was trying to understand it fully before I do it. I was having problems understanding what hoses go from what to what once the tap is completed in the motor outlet alluminum tube. different versions stated different places. I created this schematic to better understand it. i have a 2006 wrx donar, and running stock setup for engine, no heat exchanger, etc. the fact that the caps of the radiator and fill tank are different psi help to understand it. At any rate hopefully this looks correct to people and helps others to better understand it. If something looks out of place please comment.

coolant routing schematics:
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35676
35677

overflow tank
35678

turbo coolant expansion / fill tank
35679

radiator and turbo coolant fill tank caps
3568035681

[wleehendrick]

I have read multiple versions of this mod and was trying to understand it fully before I do it. I was having problems understanding what hoses go from what to what once the tap is completed in the motor outlet alluminum tube. different versions stated different places. I created this schematic to better understand it. i have a 2006 wrx donar, and running stock setup for engine, no heat exchanger, etc. the fact that the caps of the radiator and fill tank are different psi help to understand it. At any rate hopefully this looks correct to people and helps others to better understand it. If something looks out of place please comment.

Doug, thanks for posting that; I'm in the same position as you and would like confirmation this is correct.

[EODTech87]

Doug if you labeled your first picture with the same numbers as the 5th picture then you have number 2 and number 3 switched. The line that goes to the cap should go to the overflow tank that is moved from the radiator to the back of the car. The line that's next to the turbo coolant line is the one that should be connected to the fitting that is installed as per Wayne's instructions.

[Goldwing]

it appears you plumbed it correctly on the car (5th pic) with the line coming from the reservoir cap going to the overflow. The first pic/drawing shows it wrong, with 1 and 2 swapped. With 3 being the turbo return if memory serves me right. The burp lines from Wayne's mod go in next to the turbo return. That line used to come from the radiator as a burp line. In my build, I maintained the radiator burp feature, and simply tee'd the two burp lines together. Both lines going to the tee warmed up in the proper sequence demonstrating good flow from both lines.

[dougkirkbride]

Doug if you labeled your first picture with the same numbers as the 5th picture then you have number 2 and number 3 switched. The line that goes to the cap should go to the overflow tank that is moved from the radiator to the back of the car. The line that's next to the turbo coolant line is the one that should be connected to the fitting that is installed as per Wayne's instructions.

Yes i tried to keep all the numbers in the pics consistent, i still may be backwards thou, the #2 in my schematic is the engine overflow (part number 27 in the subaru schematic) this goes to the cap on the turbo coolant fill tank. it does make sense that this hose should go to the overflow reservior pulled from the radiator and relocated to the back. Then the #1 line in my schematic is the engine air breather (part number 28 in the subaru schematic) this is the line that ties to wayne's burp line mod on the outlet from the motor.

Those who did'nt bring a breather line from the radiator.....did you just cap off the two open radiator ports?

[dougkirkbride]

it appears you plumbed it correctly on the car (5th pic) with the line coming from the reservoir cap going to the overflow. The first pic/drawing shows it wrong, with 1 and 2 swapped. With 3 being the turbo return if memory serves me right. The burp lines from Wayne's mod go in next to the turbo return. That line used to come from the radiator as a burp line. In my build, I maintained the radiator burp feature, and simply tee'd the two burp lines together. Both lines going to the tee warmed up in the proper sequence demonstrating good flow from both lines.

Rich,
that 5th picture is a cut and paste from a prior forum pic, it just showed what my turbo fill/coolant tank looks like. i couldnt tell where they had #1 and #2 plumbed to. I am trying to avoid another line going from the rad to the back........ your's should definatly be fail safe.

[Harley818]

My understanding is that Wayne's mod works to bleed up to the coolant tank. You just cap off both rad ports, and make sure they can't suck air in, then top up the coolant at the turbo coolant tank.
I have yet to try it, but others have tried with good success.

[Goldwing]

Then, just to be sure, the first two pics have the line coming off the radiator cap going to Wayne's bleed mod. This is not correct. The bleed mod tapped line needs to plumb in the top of the tank (labeled 1) next to the turbo return line which both empty coolant into the reservoir bottle. The line past the cap is unpressurized and should drain to the unpressurized overflow bottle or draw coolant back in after cooling off.

The 5th pic correctly shows the hose coming off the cap heading across to the driver's side where the overflow bottle is located (well, FFR's plan anyway). The other line going to the top of the reservoir bottle appears to come from the passenger side likely the front of the engine where the bleed mod would be. Not near the bottle.

I hope that helps.

Ya, if you aren't using the radiator ports, just cap them off. After getting the air out initially, it likely won't give you any trouble. But worth an occasional peek, perhaps?

[Mechie3]

turbo coolant expansion / fill tank
35679


I make a bracket that offsets the coolant tank so the cap isn't stuck directly underneath a frame rail. ;) Or, if you have the resources, you can make your own. Makes it so you don't have to unbolt the tank everything you want to fill it or burp it.

[dougkirkbride]

I make a bracket that offsets the coolant tank so the cap isn't stuck directly underneath a frame rail. ;) Or, if you have the resources, you can make your own. Makes it so you don't have to unbolt the tank everything you want to fill it or burp it.

Craig, i have your bracket, just have not installed it yet, hopefully soon.

[SixStar]

What's the solution for people that followed the (complete lack) of build instructions and have a running and driving car already? Pull the intake manifold and remove the crossover pipe so they can tap it?

[dougkirkbride]

All, Thanks for setting me straight on this.......These should be the CORRECTED schematics and other information.

3572235723357243572535726

[Wayne Presley]

What's the solution for people that followed the (complete lack) of build instructions and have a running and driving car already? Pull the intake manifold and remove the crossover pipe so they can tap it?

Drain a portion of coolant, remove upper rad hose from motor, drill hole with shop vac next to bit, grease tap to hold cuttings, install barb and hose, refill coolant.

[Hindsight]

I love this forum.

That is all.

[Goldwing]

All, Thanks for setting me straight on this.......These should be the CORRECTED schematics and other information.

3572235723357243572535726

Yep, more better now! :)

[SixStar]

Drain a portion of coolant, remove upper rad hose from motor, drill hole with shop vac next to bit, grease tap to hold cuttings, install barb and hose, refill coolant.

You missed a step, remove intake manifold. The entire crossover pipe is located under the intake and turbo inlet.

[Wayne Presley]

You missed a step, remove intake manifold. The entire crossover pipe is located under the intake and turbo inlet.
No I didn't, I did it on my 818 with the motor in the car.

[Mechie3]

Me too. :)

[SixStar]

What a useless argument. The turbo inlet sits ON the crossover. You can't fit a finger between them let alone a drill and tap. Magic tools! :D

[Mechie3]

I have a silicone inlet so it's easy to come off. I also cut it in half and extended it 3" so even easier to remove the front half. Yes, that needs to come off. Manifold, no (at least not for me).

From my build thread:
http://i.imgur.com/GNQa0F6.jpg?1

There is a boss on the engine crossover pipe on the front where I drilled and tapped. It's a square and says "G" on it (at least mine did). I drilled an 1/8" hole in the center then drilled it larger (Q size) and tapped it with an 1/8-27 NPT. I just happened to have an 1/8" NPT right angle fitting lying around too. The only bad thing is you need to be careful that you tigthen the fitting enough but not too much so that you crack it. With the 90 degree fitting you have to angle it correctly too so it becomes a game of "do I go around again, or stop here and hope it's tight?". The wall is a little thin and it's a cast part. I have a spare so was willing to try it out. Worst case I'd just machine a fitting up and weld it to the tube.

[Harley818]

Six star.... like Wayne said.
I did exactly that a few days ago with the engine in the car. Go check the pics on my build. Disconnect the inlet and hose like Wayne says... push it out of the way.... drill and tap with grease and ducttape.....etc.
With engine in the car......

[C.Plavan]

What a useless argument. The turbo inlet sits ON the crossover. You can't fit a finger between them let alone a drill and tap. Magic tools! :D

I'm guessing you make alot of friends :confused:? Why not try looking at other peoples build threads? I have done Wayne's mod also. I did not have to remove anything (firewall was already off). I clocked the fitting to the 1 o'clock position. Drilled, tapped, hooked up hose, done. Simple as that.

[metalmaker12]

I'm guessing you make alot of friends :confused:? Why not try looking at other peoples build threads? I have done Wayne's mod also. I did not have to remove anything (firewall was already off). I clocked the fitting to the 1 o'clock position. Drilled, tapped, hooked up hose, done. Simple as that.

It took me like 30 mins tops. Ps if you have a solid inlet this might be a *****.


Remove intake, bend back inlet and zip tie out of the way.

Drill and tap (1/8 npt)coolant inlet

Place some thread sealant ( I used honda bond) on a 1/8 not 3/16 barb and screw in.

So what's the confusion

[Goldwing]

Or, if you don't have magic tools and do have the stock inlet like me, use a VW vr6 coolant y and plumb the tap in rather than tapping it in. My tapping it in would have been too much like Happy Gilmore. It just didn't appear worth the trouble after finding an $8 part that took care of it. See my build for more details.

[RM1SepEx]

I did mine in the car as well but before coolant. I stuck a shop rag into the inlet beyond the hole location. Drilled and tapped, dragged shop rag out pulling out all the drilling and tapping garbage. Plenty of room for my DeWalt 18V drill. Tapped it with the drill too... piece of cake. I used a straight brass hose barb from Ace. Had to repair my coolant tank with the same barbed fitting as it was broken off the plastic tank.

[Hindsight]

All:

I'm getting ready to do this finally and while cleaning up and removing things on the engine I no longer need like EVAP, TGV, throttle body coolant loop, etc, I found a port on that upper aluminum coolant pipe/manifold that looks like it would work really well as a bleeder. It comes off the same pipe that everyone is drilling and tapping into so I'm thinking, why not just put a bleeder hose onto this pipe? Originally this nipple was for one of the two hoses that goes to the throttle plate warmer but I'm not using it anymore and would just block it off.

Here is the nipple I'm talking about:
http://i.imgur.com/XVhcePN.jpg

So what do you think? Should I just run this up to the reservoir to act as the bleeder line?

[metalmaker12]

Where wanes bleeder line is the pass heed gets fluid directly prior. This port is prior to that do I am unsure if it will work the same. You could try it, just monitor the pass head temps compared to the drivers head. It seems like it would be fine, I just have never done this to the degas tank.

[ssssly]

I'm starting to wonder if people are having bleeding issues because they are mixing up their radiator and coolant expansion caps.

These caps are not interchangeable.

The water cooling system for the turbo requires a different config on the coolant expansion cap than a normal radiator cap.

I'm also starting to wonder how this change in plumbing may effect the water cooling for the turbo.

[Hindsight]

I think most people (that have discussed it), are using a higher pressure cap for the radiator, and lower pressure cap for the reservoir (which makes sense).

I'm still trying to figure out where I want to tap the degas line though. I like the idea of taking it off the upper side of that pipe but I'm not sure it would make that big of a difference. I'd rather use a nipple that exists already - if it would work well.

[ssssly]

Right, but the reservoir cap is not a regular radiator cap. If you use a regular radiator cap on the turbo reservoir it can cause several issues with the coolant and turbo water cooling systems.

[JeromeS13]

Right, but the reservoir cap is not a regular radiator cap. If you use a regular radiator cap on the turbo reservoir it can cause several issues with the coolant and turbo water cooling systems.

Tell me again how the reservoir cap isn't like a regular radiator cap? To my understanding, it's the only cap that IS like a regular radiator cap. The OEM radiator cap is the one that is different (it vents under pressure, but does NOT pull on vacuum). Also, the only other difference is opening pressure. The reservoir cap pushes at ~16 +/- 2psi (and pulls at -0.1 to -0.7 psi). The radiator cap ONLY pushes at 20 +/- 2.1 psi.

[ssssly]

The reservoir cap has a pressure and vacuum valve. On overpressure it diverts to the overflow tank. On cool down the vacuum opens to circulate turbo to radiator.

The cap on the radiator is a straight relief valve.

If you run the reservoir cap on the radiator it will cause overheating and air bubbles in the system.

Running the radiator cap on the reservoir will prevent cool down circulation and can result in superheated coolant. You can blow the plastic end tanks off of the stock radiators this way.

If you swap them you get both. Overheating and bubbles in the coolant while running and dangerous superheating on shutdown.

[ben1272]

I love this forum.

That is all.

What he said! The time this forum saves is astounding......should just call it a time machine.