losing coolant

[egchewy79]

A couple of times now, I've noticed that the coolant level in my overflow tank is low and need to top it off. Car's got around 1800 mi on it now and this is twice now that the coolant level was low (below the lower pipe/nipple in my overflow tank). After the first time, I resealed/tightened up the temp sender on the intake which did have a slow weep.
Can't see any wet spots on the intake or water pump. No excess coolant puked on the garage floor.

Also for a while I noticed that there's a "different" odor when I pull the car into the garage. I initially assumed it was the smell of engine paint/header coating burning off, but am wondering if it's coolant boiling off.
I've smelled boiling/smoking antifreeze before and this isn't it.
I was also wondering if high zinc oil smells different coming out of the exhaust pipes w/o cats.

I've checked the oil which doesn't look like chocolate milk and no white smoke coming from the exhaust, so I'm pretty sure I don't have a head gasket problem.

[Nigel Allen]

A cooling system pressure test will identify any leaks.
Not sure which coolant reservoir you have, but others have reported that the FFR supplied unit is a little undersized. As your car has been on the road for a while now and this is a new problem then it is more likely a leak.


Here's hoping it is a simple fix.

Cheers, Nige

[chjort]

Chewy, I have the BPE 347 and I had a slow, but persistent leak from the thermostat housing. I similarly noted coolant low a few times. Replaced it with the Dorman part from Autozone and no more leaks and the system has been working fine. Do you see coolant residue, looks like white salt stains, anywhere? At least changing the thermostat housing is a cheap and easy fix. Hope that helps!

[egchewy79]

Nigel
I noticed it during maybe the first 1000mi, and tightened up the temp sender in the intake that did fix a visible leak. I have an aftermarket 1qt "moroso-style" tank that I got off amazon. Pressure testing might be the next thing.

Chjort, I'll wipe down the intake/motor to see if I can identify any coolant residue.

In the meantime, I don't mind topping off the coolant every 1000 mi or so.

[Norm B]

The other place it could be leaking is the intake manifold. It can leak from the crossover in the intake into the intake ports in the head. If you can’t find an external leak, pull the spark plugs and check for an unusually clean plug at the 1,4,5 or 8 position.

Norm

[egchewy79]

The other place it could be leaking is the intake manifold. It can leak from the crossover in the intake into the intake ports in the head. If you can’t find an external leak, pull the spark plugs and check for an unusually clean plug at the 1,4,5 or 8 position.

Norm

Would I expect to see white smoke from the exhaust if this were the case?

[Norm B]

Would I expect to see white smoke from the exhaust if this were the case?

Depends on the size of the leak. A small leak won’t cause enough steam/smoke to be noticeable but the exhaust will smell “funny”

[Norm B]

These leaks aren’t the kind that fix themselves and it will get worse over time.

[Ted G]

I am following this as I have seen similar loss of coolant with mine. Check your radiator too for those signs of leaks. My radiator seems to have developed a very small streak of this chalky residue near the upper inlet. Also, I have always noticed what seems to be a little too much water vapor in the sidepipes.... enough to make my concrete wet.

[egchewy79]

Depends on the size of the leak. A small leak won’t cause enough steam/smoke to be noticeable but the exhaust will smell “funny”

I do recall putting a smear of RTV on the gaskets prior to installing them around the coolants ports for this exact reason.
Hopefully for my sake, I'll find something external leaking w/ a pressure test.
Would I necessarily hear a leak if it was in this location? or simply just notice that the system won't hold pressure over time?

[Jeff Kleiner]

Never a drop on the floor or signs of an external leak while it was with me.

Jeff

[Ted G]

I have also noticed that my expansion tank (Canton 2 Qt) is releasing a bit of coolant from the overflow.... but my expansion tank has never been more than half full. Wondering what would cause this; maybe you are having the same issue.

Ted

[Its Bruce]

A couple of times now, I've noticed that the coolant level in my overflow tank is low and need to top it off. Car's got around 1800 mi on it now and this is twice now that the coolant level was low (below the lower pipe/nipple in my overflow tank). After the first time, I resealed/tightened up the temp sender on the intake which did have a slow weep.
Can't see any wet spots on the intake or water pump. No excess coolant puked on the garage floor.


The terms are often used erroneously, so I'm going to ask... is your overflow tank vented to atmosphere or is it pressured within the coolant system? If it's vented to atmosphere, how big is it or what are the dimensions?

[rthomas98]

Get some UV coolant dye and a black light. Put it in and run it for a bit then go and look for the justin Pollock painting under the car. I would do this before doing anything else.

[egchewy79]

Never a drop on the floor or signs of an external leak while it was with me.

Jeff

Nor for me. That's why I was guessing it was evaporating off the intake or somewhere else before hitting the floor.


I have also noticed that my expansion tank (Canton 2 Qt) is releasing a bit of coolant from the overflow.... but my expansion tank has never been more than half full. Wondering what would cause this; maybe you are having the same issue.

Ted


The terms are often used erroneously, so I'm going to ask... is your overflow tank vented to atmosphere or is it pressured within the coolant system? If it's vented to atmosphere, how big is it or what are the dimensions?

Here's the tank from amazon.
https://www.amazon.com/EVIL-ENERGY-Reservoir-Expansion-Universal/dp/B0B4NP6K1X/ref=sr_1_8?crid=618U8IEM6YBQ&keywords=overflow+tank&qid=1698680830&sprefix=overflow+tank%2Caps%2C80&sr=8-8
1Qt size, vented to atmosphere, half full
Twice now in 1800mi I've noticed that the fluid is below the lower nipple/bung that connects to the T-piece/filler neck, meaning it's sucking in air when the engine cools. I've refilled it each time, but need to track down the site of loss.

[JohnK]

Do you have any silicone hoses in your cooling system? Silicone hoses are more permeable than rubber hoses and will cause coolant loss over time.

[egchewy79]

Do you have any silicone hoses in your cooling system? Silicone hoses are more permeable than rubber hoses and will cause coolant loss over time.

yes, all my hoses are silicone (upper and lower radiator, heater in/out). hadn't thought of this scenario.

found this post. maybe that's the source of my loss.
https://motoiq.com/silicone-radiator-hoses-not-for-the-street/

I'll pull #1,4,5,8 plugs and pass a borescope to make sure it doesn't look like the cylinder walls have been steam cleaned.
anyone else out here experiencing this issue w/ silicone? also explains the slight odor I'm smelling if it's seeping through the pores of the hose.

[Its Bruce]

Here's the tank from amazon.
https://www.amazon.com/EVIL-ENERGY-Reservoir-Expansion-Universal/dp/B0B4NP6K1X/ref=sr_1_8?crid=618U8IEM6YBQ&keywords=overflow+tank&qid=1698680830&sprefix=overflow+tank%2Caps%2C80&sr=8-8
1Qt size, vented to atmosphere, half full
Twice now in 1800mi I've noticed that the fluid is below the lower nipple/bung that connects to the T-piece/filler neck, meaning it's sucking in air when the engine cools. I've refilled it each time, but need to track down the site of loss.

It's only 1 qt. There is a scenario here that your coolant overflow tank simply isn't big enough. Ie, your coolant expands by more than a quart and you'll be left with nothing in the tank.

Do you happen to know the volume of your coolant system (engine + radiator + hoses + etc.)?

Edit: I'm looking at that tank, trying to figure out how it would be plumbed as an overflow tank. I assume you're using one of the upper ports as an inlet and the other upper port dumps to the ground?

[rich grsc]

A 1qt tank is too small. jmo

[egchewy79]

It's only 1 qt. There is a scenario here that your coolant overflow tank simply isn't big enough. Ie, your coolant expands by more than a quart and you'll be left with nothing in the tank.

Do you happen to know the volume of your coolant system (engine + radiator + hoses + etc.)?

Edit: I'm looking at that tank, trying to figure out how it would be plumbed as an overflow tank. I assume you're using one of the upper ports as an inlet and the other upper port dumps to the ground?

I have the radiator T piece running to the bottom of the tank. One of the top bungs has a nipple w/ hose going to ground. I blocked off the clear tube holes as it was leaking and couldn't find a good way to tighten around the clear tubing, so those bungs got sealed using large metric bolts.
I'd argue that 1qt is large enough. I've been through many heat/cool cycles w/o issues. Fluid only found to be low on 2 occasions.
If the overflow was too small, I'd expect it to puke everytime it got hot and sucked dry when it cooled off. This has not been the case in the past where no fluid is seen on the garage floor after parking and multiple occasions w/ fluid level fine when engine is cooled off.
FYI, SBF w/ just under 4 gallons of total coolant for block, hoses, heater and radiator.

[JohnK]

If you have 4 gallons (16 quarts) of coolant in your cooling system then a 1 qt. expansion tank is not large enough.

https://blog.cantonracingproducts.com/blog/calculating-expansion-tank-size-requirements

"The general rule of thumb for proper capacity of expansion is 12% of total coolant volume for draw down and 6% of the total volume for thermal expansion."

So a 16 qt. system would need 1.92 qt. for expansion and 0.96 qt for draw down, or 2.88 qt. total capacity.

[egchewy79]

If you have 4 gallons (16 quarts) of coolant in your cooling system then a 1 qt. expansion tank is not large enough.

https://blog.cantonracingproducts.com/blog/calculating-expansion-tank-size-requirements

"The general rule of thumb for proper capacity of expansion is 12% of total coolant volume for draw down and 6% of the total volume for thermal expansion."

So a 16 qt. system would need 1.92 qt. for expansion and 0.96 qt for draw down, or 2.88 qt. total capacity.

this is a calculation for expansion tanks, not overflow tanks.
the FFR provided overflow tank is what, 500ml? and consider a bit too small?
I've not seen any overflow tanks in the range of 3-4L/Qts in size. Most commercial overflow tanks are in the range of 16oz-2L.

[rich grsc]

Yes, 2 qt, double what you have. Don't think anyone is saying 4 qt?

[egchewy79]

Yes, 2 qt, double what you have. Don't think anyone is saying 4 qt?

John K was mentioning 2.88qt volume for an EXPANSION tank.
If my tank were too small, wouldn't I notice fluid draining from the puke tubing every time I got it up to temp? and wouldn't the fluid level be below the lower bung/nipple each time it cooled off?
again, I've checked multiple times in the past and have only found it to be low twice, leading me to believe this is a slow loss of fluid. Like I said, I'll pull the cross over plugs to see if they are excessively clean compared to the central plugs, but am starting to wonder if the silicone tubes are contributing to some of this.

[Dave Tabor]

re-torque the intake bolts and see of that helps

[CraigS]

re-torque the intake bolts and see of that helps
I agree. When I do an intake I run the engine through a couple of heat cool cycles w/o driving it and torque the bolts after each cool down. Then I torque them again before each drive until they stop moving. This often takes 5-6 cycles until every bolt stays in position. Also go over every hose clamp. I am not sure about silicone hose but clamps seem to compress standard hose slightly so they need another 1/2 turn or so on the screw. BTW if you get a bore scope you want to look at the top of the pistons or at the combustion chamber.

[egchewy79]

I did the retorquing procedure during the first 500mi break in period. I guess I can retorque again if needed.
haven't had a lot of time recently but will report back when I do get a chance.
I already have a borescope that attaches to my cell phone and will look at spark plugs and cylinder walls and pistons that look "too clean" .

[Railroad]

Just re tq the intake for now. Might not need to do the heads.

[Mark Reynolds]

I'm not seeing where the tank is vented to atmosphere.
Maybe the system is just purging air and replacing with coolant and your level will stabilize soon?

[egchewy79]

I'm not seeing where the tank is vented to atmosphere.
Maybe the system is just purging air and replacing with coolant and your level will stabilize soon?

just to be clear, there's no concern about how the system is plumbed. the canister is hooked up correctly, vented to atmosphere with one of the upper bungs/nipples. fluid is coming/going from a nipple on the bottom of the canister.
Then question is why am I slowly losing a small amount of fluid over time. Is is getting into the heads from a leaky gasket? Is it an external leak (less likely)? or is it due to the use of silicone racing hoses instead of rubber?

I don't think the overflow canister is too small (never had any fluid dripping out of the puke line after multiple heat cycles) so I believe the loss to be a slow evaporation/consumption of the fluid somewhere else.

[Dave Tabor]

Go out to the car right now and put a wrench on the intake bolts - are they tight?

[Blitzboy54]

This is the 2L version. I like it. I need to move my FFR reservoir when I add a supercharger anyhow. I might switch to this as I think it would work better.


https://www.amazon.com/Reservoir-Universal-Monitoring-Rust-proof-Polished-Aluminum/dp/B0B4ZK7Z1J/ref=sr_1_3?crid=2JQBDLY0LG65U&keywords=overflow+tank+2l&qid=1699034403&sprefix=overflow+tank+2l%2Caps%2C223&sr=8-3

[egchewy79]

update:
had time tonight to remove my air cleaner and check intake bolts. all bolts are tight (18ft/lbs for aluminum intake). I removed all plugs. Pic is of plugs 1-4, with all looking the same. Borescope didn't show any differences in the cylinders. In fact, I was surprised how clean all the cylinders looked. No external signs of leak. Nothing wet from the puke tank.

Short of renting a pressure tester, is it safe to say the fluid loss might be from the silicone tubes? Not sure if anyone has real world experience on how much fluid loss is expected w/ upper/lower silicone tubes as well as silicone heater hoses.191887

[JJK]

I have read previously there was a study by Gates that found silicone hoses resulted in 20x the water loss per year compared to EPDM rubber.

https://motoiq.com/silicone-radiator-hoses-not-for-the-street/

[egchewy79]

I have read previously there was a study by Gates that found silicone hoses resulted in 20x the water loss per year compared to EPDM rubber.

https://motoiq.com/silicone-radiator-hoses-not-for-the-street/

same link i posted in post #17.
I read the comments too.
might explain the odor I'm smelling as well.

Next question: Should I replace the volume w/ just water or coolant? I'm assuming the hoses are permeable to both water the the contents of the coolant.

[JJK]

from a chemistry perspective, ethylene glycol is slightly denser than water and has a larger molecular structure than water, so more water should permeate through silicone than antifreeze. so, I suspect you should top off with mostly water. but if you also smell the antifreeze (ethylene glycol) then that means some antifreeze is also permeating, and some should be replaced.

[JohnK]

Next question: Should I replace the volume w/ just water or coolant? I'm assuming the hoses are permeable to both water the the contents of the coolant.

I have heard anecdotally that silicone hoses are permeable to steam specifically, which would imply that only the water content is lost and not the ethylene glycol so only water should be added to make up for the loss. Not sure I trust that source though. The safest bet is to pick up a coolant hydrometer like this (https://www.amazon.com/ABN-Deluxe-Antifreeze-Coolant-Hydrometer/dp/B00YEZILQC/ref=sr_1_1?keywords=antifreeze+hydrometer&qid=1699148999&refinements=p_72%3A1248861011&rnid=1248859011&s=automotive&sr=1-1) and test the ethylene glycol content of your coolant. This will tell you if you need to add water or coolant.

[egchewy79]

I have heard anecdotally that silicone hoses are permeable to steam specifically, which would imply that only the water content is lost and not the ethylene glycol so only water should be added to make up for the loss. Not sure I trust that source though. The safest bet is to pick up a coolant hydrometer like this (https://www.amazon.com/ABN-Deluxe-Antifreeze-Coolant-Hydrometer/dp/B00YEZILQC/ref=sr_1_1?keywords=antifreeze+hydrometer&qid=1699148999&refinements=p_72%3A1248861011&rnid=1248859011&s=automotive&sr=1-1) and test the ethylene glycol content of your coolant. This will tell you if you need to add water or coolant.

Brilliant. Added to my cart

[Hoooper]

How much silicone do you have in the system, and how long since it was first filled? If you have ALL silicone lines and theyve been filled for a few years its possible thats the source. If you only have elbows/couplers in silicone thats not where the issue is

[egchewy79]

How much silicone do you have in the system, and how long since it was first filled? If you have ALL silicone lines and theyve been filled for a few years its possible thats the source. If you only have elbows/couplers in silicone thats not where the issue is

both heater hoses (~3-4 ft?), upper radiator hose (~2-3ft?), and 2 elbows on the lower radiator tubing are silicone.
Had to top off the overflow tank twice in nearly 2000 miles, so let's just say once every 1000 miles. Each time, maybe 3-4oz added.