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Torque value for heat exchanger?

C

Cruisers Man

New member
The engine in question is a 1994 GM 7.4L with the closed cooling system. The end caps to the heat exchanger are bronze with a single bolt thru the center. What I need to know is the proper torque value for this. The install prior to my repairs had cracked the end caps slightly, I really don't want the same results. Thanks in advance.
 
Book (2003) says "Clean the gasket surfaces on the end plates and the heat exchanger. Apply PerfectSeal to both sides of the new gaskets. Install the end plates and the new gaskets onto the heat exchanger. Install the bolts and tighten securely." So I guess the answer is "tighten securely".
 
My 1992's have a full plate cover (3/32" approx. thick ) rubber gasket. I've never used anything on the gaskets and tighten the center bolt to about 15 lbs. As John says...securely...I have had these caps off every year to clean the core of the exchangers and I have never had a problem. Then again, it is 11 years difference between the two.
 
knuckle47 said:
My 1992's have a full plate cover (3/32" approx. thick ) rubber gasket. I've never used anything on the gaskets and tighten the center bolt to about 15 lbs. As John says...securely...I have had these caps off every year to clean the core of the exchangers and I have never had a problem. Then again, it is 11 years difference between the two.
Click to expand...

I do the same thing with my 1981 vintage heat exchangers. I had the caps off a few weeks back to check and just put new rubber gaskets and no sealant.
 
I have never used any sealant on these end plate rubber gaskets, and I have never had a leak.
If you plan to re-use the rubber gaskets, note that they have taken a "set". So keep them indexed the same, and keep them end-to-end the same.
Easy way to do this: Mark the H/E shell, mark the gasket, and mark the cover plate before removing them......... otherwise, install new rubber gaskets.

BTW, the center bolts take the metal cover plates down tightly against the gasket and H/E shell.
What's causing the end plates to crack, is more likely just good ole Father Time.

Perhaps keep a NEW spare gasket and cover plate on board!


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On my HX end caps there is a small (approx 3/4") non-metalic washer sandwiched between the gasket and the end cap. If that gasket is missing the end cap may get pulled in too close and cause it to crack (just my theory), so make sure it is in place when reinstalling the end cap.
 
Like erich, mine have the nylon washer, too. that said, I did put mercruiser kits on mine when we lost the first OEM HX (whole kit was cheaper, to me, than the OEM HX). FWIW, the black one has a 3 -6 ft *lb torque spec.
 
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