overheating

[rbodell]

I am looking for some input as to what to look for and where.

I have a video camera on the engine so I caught the temperature guage raising in time to shut down the engine. I narrowed down the problem to the thermostat sticking. Ironic that it is one of the few American made part in the engine isn't it.

The temperature got up to 230 degrees. My opinion is that that was not enough to break any castings.

The Radiator showes some bubbles when I first start it up and they drcrease as the engine warms up. I still get a few bubbles though.

The head gasket is also american made which me think the head gasket may not be the problem, but if so, what would be the problem.

I have a head gasket ordered and am going to try that anyhow as I think it is the most probable answer to the bubbles.

I was wondering is any body else has has any overheating and what the damages were. Especially where you caught it before it got too hot.

[mkdutchman]

you probably didn't damage anything..........still good to check

FWIW, this thread is from when my 6/1 overheated.........and I wasn't fortunate enough to catch it in time

http://listerengine.com/smf/index.php?topic=2062.msg26018#msg26018

[ronmar]

The bubbles are probably from the head gasket. How much have you run it since the overheat and thermostat replacement?  Do you have a resovoir on the top?  That is the advantage of a clear/opaque overflow resovoir.  Any head gasket leaking into the cooling will show up as bubbles, but it also brings oil/carbon contamination to the cooling loop which floats to the top of the resovoir and creates a "bathtub ring" in the resovoir...  No oil scum in the resovoir?  you may just be purging out small amounts of trapped air in the head.  Do you have a weep hole in your thermostat? This helps to purge the trapped air.

Ron

[rbodell]

you probably didn't damage anything..........still good to check

If you got off that easy, I am surprised that the head gasket failed. I asume it is the head gasket anyhow. I will check the head though while it is off anyhow. I wanted to see what the top of the piston looks like anyhow after running WMO in it. Thanks for the reasurance.

[rbodell]

The bubbles are probably from the head gasket. How much have you run it since the overheat and thermostat replacement?  Do you have a resovoir on the top?  That is the advantage of a clear/opaque overflow resovoir.  Any head gasket leaking into the cooling will show up as bubbles, but it also brings oil/carbon contamination to the cooling loop which floats to the top of the resovoir and creates a "bathtub ring" in the resovoir...  No oil scum in the resovoir?  you may just be purging out small amounts of trapped air in the head.  Do you have a weep hole in your thermostat? This helps to purge the trapped air.

Ron

I have run it alltogether, probably 1.5 to 2 hours. I haven't replaced the thermostst yet, I now have it hooked up to a geo metro radiator because the overflow hose has a clear line and I can see the bubbles raising to the overflow tank. I haven't seen any soot or oil in the tank. I removed the inner seal on the radiator cap so it will not build up preassure. That way any air bubbles have a clear path.

As the engine warms up and the bubbles decrease, the size of the bubbles decrease too. Some are as small as about 3/8 diameter so they don't get trapped anyplace.

[rbodell]

By the way, I started the engine up and warmed it up twice. Both times there were a lot of bubbles when it started and decreased as ti warmed up. I think that pretty much rules out air in the block working their way out.

[mkdutchman]

By the way, I started the engine up and warmed it up twice. Both times there were a lot of bubbles when it started and decreased as ti warmed up. I think that pretty much rules out air in the block working their way out.

I wouldn't count on it ..... I get a lot of air after I do a cooling system purge nd refill and it continues for a long time. Occasional bubbles show up after several hours ....

I seriously doubt that there was any damage whatsoever especially if the engine was still running when you shut it down.

Jens

Considering that my block temperature was over 400F, and damage relatively minor I'd be inclined to agree. You do run at 195 to 200, do you not? 30 more degrees probably wouldn't do anything, would it? Does anyone know at what temp the liner o-rings start cooking?

[cujet]

Remember that combustion gasses leaking into the cooling system pressurize it to extreme levels. A big leak will blow the rad cap off in a few seconds. A small leak will take a minute.

Chris

[rbodell]

Remember that combustion gasses leaking into the cooling system pressurize it to extreme levels. A big leak will blow the rad cap off in a few seconds. A small leak will take a minute.

Chris

I removed the inner seal from the rad cap foor air to escape and coolant to remain full

[Doug]

I like the idea of a low presure rad cap....

You can take a 5 pound rad cap and heat the spring with a mini torch to soften it a little more

[rbodell]

Considering that my block temperature was over 400F, and damage relatively minor I'd be inclined to agree. You do run at 195 to 200, do you not? 30 more degrees probably wouldn't do anything, would it? Does anyone know at what temp the liner o-rings start cooking?
[/quot]

It normally runs at 180 to 190 depending on wether it is on a tank or radiator

[dkwflight]

Hi
Nobody mentioned drilling a small hole in the t-stat
to alow some air and water to pass by.
With the stock t-stat in the circuit there will be now flow untill the head and water in the area of the t-stsat is hot enough to open. This usually means the engine is over heated to some extent before the t-stat opens.
Search the site for t-stat messages.
Dennis

[mobile_bob]

hd truck engines of various manufactures incorporate the little bleed hole in the t/stat in on form or another
otherwise you trap an airpocket and make for erratic temp before the stat opens, sometimes getting an overheat condition

on the engine's that we work on that don't come with the hole i drill an 1/8" hole and then insert a 3/32 cotter pin, spread and clip off short
the reason for the pin is to keep corrosion or other crap from plugging the hole,,, it will sit in there and wiggle keeping the hole open.

it doesn't take much of a hole, the 1/8" is probably too large, but with the cotter pin the effective opening is quite small but large enough to
purge the air pocket quite well.

bob g

[clytle374]

On some systems the hole is vital.  The air trapped under the T-stat means you have to have a a lot of steam hitting it to open it. 

I had a '70 351C, 4V if your wondering.  Without the hole it would heat up and blow half the water out when the T-stat opened. 


 

[Quinnf]

If you've got a leaky head gasket, combustion gas might have filled the head up with gas, displacing coolant.  T'stat then is sitting in a bubble of gas and not in direct contact with the hot cylinder head.  That shouldn't have happened.  Every new t'stat I've seen in recent years either has a small hole, a hole with a loose rivet that wiggles around like Mobile Bob (who actually lives in Tacoma - go figure!) and keeps the hold open, or the base of the t'stat is held off the water outlet flange by three little dimples punched into the corresponding flange on the t-stat.  If yours is like the latter, then it's clear that the dimples didn't do what they were supposed to.  3/32" hole in the t'stat should do the trick.

230 degrees is nothing to worry about in a cast iron engine with a cast iron piston.  Aluminum piston is another story.

Quinn