rad temps and hot days

[MikeJones]

I'm having second thoughts about cooling problems. Last year, I ran with a closed system and had no problems - oil temps and water temps matched and no overflow issues. Switched to an open system and when the engine is hot, it burps small amounts of air fairly continuously. I have always maintained enough fluid in the overflow tank and don't lose liquid, the overflow tank doesn't overflow but where is all the air coming from? No other leaks, oil is fine, no steam, etc.

I'd expected the system to be liquid only after initial purging and burping, and I expected the oil/water temperatures to basically match. Running at highway speeds for an hour, oil temp is 230° and water temp is 170°.

What should I be worried about?

Regards, Mike

[turbodon]

Interesting. The only time I have seen constant air burping is with a bad seal to the burp tank and the water will not return to the cooling system as it cools and it sucks in air. The other causes are bad head or head gasket.

Where are measuring oil temp? I measure in oil pan. On freeway, water 170 ish, oil is 160 ish about 10 deg cooler than water. When I come to a stop at a light in traffic after the freeway oil will climb and match the water. The water will climb to meet to about 200 ish.

If I understand the terms open and closed system, I run an open system and have no air after initial burp. I do have a Victor intake and have plumbed the back 2 water jackets into the system. They are normally blocked off by the intake. This can be a source of trapped air.

[MikeJones]

One possibility could be that I am using the kit filler "T" and had to try three different rad caps before one would seal properly. The first two would break seal when cooling under vacuum, sucking in air and not recovering fluid out of the overflow tank. I'm wondering if maybe the seal isnt perfect and lets in air.

I measure oil temp at the drivers side of the pan close to the dip.

How do I check if it is the head gasket?

Thanks, Mike

[turbodon]

If it is a head gasket with cylinder pressure into the water chamber, a carbon dioxide test kit for about $17 will test your water for a combustion leak.

If the system is full of fluid and at operating temp, when you rev the engine then let it settle back down, you may see bubbles flowing into tank (sign of combustion leak).

It sound like you may have just a rad cap seal issue.

[MikeJones]

I'm still having trouble with air bubbling through my overflow bottle whenever the engine is hot, plus my oil temps are higher than I would like, and the water temps are too low.

I checked the compression - all between 130 and 150psi (average about 142) so that rules out the head gasket (thank goodness). Spark plugs are tan and dry, and all look the same. Engine runs very well and idles well, as I would expect it to run rough if it was the head gasket.

Don, you'd mentioned that you plumbed the rear two water jackets. I was wondering if you had any photos as I only understand generally how to do this.

I bought a new filler T and new cap from Breeze, put in a new thermostat and a new rad air bleeder. Also replaced the hose to the overflow tank and all of the rad hose clamps, most of which are now double-clamped. Filler T is higher than the engine and the rad. I've tried purging with the front on jack stands and with the front right wheel elevated a couple of inches to help the air to the filler T, all of which has not changed the problem.

I'm now thinking about replacing the burp tank or adding a header tank as I seem to build up an air pocket in the top of the rad.

I'm supposing that air getting into the system would also appear as a leak when the system is pressurized, however, I dont have any apparent leaks (or steam).

I've been chasing this all summer and have probably spent 50 hours on this. Any other suggestions?? Thanks, Mike

[1cobra]

Hi,
If your heater hoses are highest point of your water system then then you will never get the air out in a non sealed system.
In my sealed system I installed a prestone back flush T in the top heater hose line as that is the highest point and simply open that cap and fill the system, no air pockets to worry about.
Perry.

[allbite]

Hey Mike, how high of pressure cap did you buy? I was having a similar problem and replaced the kit cap with a 20lb cap (I think kit was 12lb) upon a forum recommendation, and everything ran perfectly.

I couldn't believe it was such a simple solution as I was also having quite a hard time of it as well.

Andrew

[MikeJones]

Hi - my filler T is the highest point in the system, although there is the possibility of an air lock in the top of the rad (above the bleeder valve and the rad hoses).

I have a 16lb rad cap, but I'll try a 20lb cap. That would certainly be an easy solution.

Thanks, Mike