Engine cooling issue

cholstrom

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Sep 22, 2012
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I recently replaced the heads and intake on my 400m. Everything seemed right, and it started on the first crank. Running down the road all guages look fine, but when I stop after a 15 minute or longer drive the engine coolent thumps. I don't know how else to describe it. At first I thought the engine was still running so I got out and opened the hood and I could watch the upper radiator hose jump with each thump. It went on for a few minutes about as fast as it would take you to read thump, thump, thump, thump. No loss of fluid but I did notice when I turned the ignition back on the temp guage was pegged. As soon as I started the engine it dropped back down to normal. The engine and radiator do not feel unusually hot. I have no water in the oil, no apparent loss of coolant, just this thump thing. Anyone ever heard of this?

 

Rons beast

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Hey Chol. Welcome.

Ditto Bully on this. Check the T-stadt. If not put in backwards, most have a small air bleed that requires the T-stadt be put in with the bleed at the 12-oclock position.

The "thump...thump" was definetly air in the system. More specifically in the top end of the engine, working it's self out.

Good Luck

 

cholstrom

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Sep 22, 2012
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Pulled the thermostat, not upside down. Put in a new thermostat and tryed it again. Same issue. Does not seem to do it when the engine is running, only just after you turn it off for a couple of minutes.

 

Bully Bob

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Hi cholstrom..,

Don't have any info. on you (experience, etc.) but assume you saw the marking on the 'stat "this side toward rad."

Another check is to run the eng to temp. with the rad. cap lose, or off.

THIS is dangerous if there's air in the system, it may shoot out bringing hot water with it..!!!

This must be done in an open area & could be messy. No one near the vehicle.

I know fr. experience. When I was 16, I did this. I got a nice hot water face wash..!

Removing the t-stat B4 doing this "burping" may be even safer.

Other than "air", It's by me what is doing that... :unsure: :unsure:

AFTER RE-READING..,

"I recently replaced the heads and intake on my 400m."

Were these items meant to.., & in fact, match up to the block..?

Including correct head & intake gaskets...?

 
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Gon_Phishin

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Oct 19, 2012
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1
My 400m was running relatively hot and did some forum searches and found this T-stat.

http://www.summitracing.com/parts/BRA-333-180/

After I swapped it out it dropped the running temp down to normal.

But the make sure you burp the cooling system good.

Also I added an aftermarket overflow tank so it would stop dumping on the ground.

 

cholstrom

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Sep 22, 2012
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Ended up pulling the right head and sure enough, the head gasket was on backwards. Put on a new one, (with the embossed "Front" toward the front of the engine) and all is well with the world now. Thanks everyone for the suggestions.

 

Blueblooded

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Sep 22, 2004
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Pulled the thermostat, not upside down. Put in a new thermostat and tryed it again. Same issue. Does not seem to do it when the engine is running, only just after you turn it off for a couple of minutes.
sounds like the head gasket was put in wrong seen this before on the 400 modifeid
 

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