Cooling system help---please read

[swb85]

I'd love some insight here, please read the whole thing. My cooling system consists of aluminum high flow water pump, 180* stat, stock brass radiator, 16" electric fan with shroud. Everything was perfect last summer and my cooling system worked great. It ran right at 180* on the highway with the fan off. In traffic, my fan kicked on at 195* and brought the temp down to 175* within a minute or two. I could sit in traffic on a 100* day with the a/c on high and never see north of 195*. The cooling system actually worked so well that during cold months, it struggled to warm up on my morning commute.

Two months ago I had a head gasket leaking coolant (externally) all over my motor, so I changed from a Mr. Gasket 5800 to a Felpro 1014. Immediately following the swap, I noticed that it didn't struggle to warm up in the cold like it used to. Now that the weather is starting to break I'm getting worried. It's only 50* outside, and it's running way hotter now. After 5 minutes of highway driving, the temp is all the way up to 195* and climbing. As soon as I get off the highway and kick my fan on manually, it brings the temp back down to 180*, although it takes longer to do so than it used to. I've tried replacing the thermostat as well as adding a bottle of Water Wetter to the system......absolutely no change.

The ONLY thing that has changed in the system is the head gaskets, and although I'm baffled as to why, that has to be the reason my cooling system is struggling now. I REALLY REALLY don't want to have to change head gaskets again. I'm running hot on the highway when I've got tons of airflow going through the radiator, but in traffic with a single fan running it's staying cool. I just don't get it. Any thoughts/suggestions are appreciated. For comparison, here's the picture of the original head gasket:


And here's a picture of the gasket that's in there now:


The cooling holes are slightly different.....enough to make this big of a change in system performance?????

[James McClure]

SWB: you've answered your own question. Change back to the other gaskets OR, get the right ones from GM. New gaskets may be thinner pushing compression up a little bit also, which would drive temp up, but I don't really think that is an issue here. Different valve adjustment will make a difference as will A-F mixture and timing, just an after thought. Jim

[swb85]

Thanks for the reply James. My static compression actually went DOWN a tiny bit with the gasket swap (4.2" bore X .039" thick compared to the original 4.15" bore X .038" thick). Valves are adjusted the same as before, zero lash + .5 turn. Carb jetting is the same as well. I've just never heard of a cooling system being choked because of a head gasket!! I could understand if I somehow got the wrong gasket, but any gasket for a SBC should work fine for my app right? I've used a 1014 before on a 350 and never had issues. My truck hates me.

[blu87]

Sometimes your engine needs to burp after you've drained coolant and refilled. In other words it gets an air pocket that can slow internal flow. I've never had it, but have followed the adventures of many others here and on classic chevy web sites. One of the "fixes" was to run the car/truck on a set of ramps with the rad cap off. Shortly it would burp itself and the problem went away. Sounds unlikely but many swear by it.

[us111]

have had air in system twice,2 different vehichles
both same results ,slightly overheating .both times
was able to open raditor cap just ofter thermostat
opening (soon as heat started blowing)with someone
reving the engine a little,both times was able to add
almost 1/2 gallon of fluid 2 radiator,no further problems.
sure you know just be carefull opening cap.

[wedgemon]

Just curious. Did you hold the new gasket up to the old one and compare all the various journals? The bottome pic looks a bit restrictive on some.

- Dave

[89 crew]

Is it possible a bit of gasket sealant is limiting the thermostat? Maybe stopping it from opening all the way, and limiting the amount that normally flows through a closed thermostat. Extra rtv is hell on radiators.