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I have a 1951 chevy 235 and I just did a valve job and replaced my copper head gasket with a Fel-Pro Composite head gasket. I did a three stage torque (with correct bolt sequence), ran it and brought it to temp, then let it cool and did a re-torque. The head and block were decked and all surfaces were very clean. I discovered this morning a seep leak along the entire spark plug side of the gasket. What can I do????? Should I torque again? I installed it dry (no sealant) as instructed. Any tips would help...

Adam

It's possible the leak will self-seal after a few more heat/cool cycles. You could also try a hot retorque, by bringing the engine up to running temp and loosening the head bolts one at a time and retightening while the engine is still hot. Last resort, treat the cooling system with a solution of sodium silicate (water glass) and running the engine for several miles before letting it cool down. That's an old trick we used to use to cure seep leaks after radiator repairs, but it also works on gasket leaks that don't involve sealing compression pressure.
Jerry

What is leaking. Compression, coolant, or oil. Is it possoble something is leaking from the water outlet or side cover & running across. It doesn't sound right to be leaking the intire length of the head gasket. I use Bars Leaks for coolant leaks like that.

Thanks for the responses, guys. It's coolant for sure. I can see it seep from the head gasket line on the spark plug side and the composite gasket looks saturated. It's by no means dripping. When I run the engine, it stops completely until the engine cools, then it seeps out again. I'll try the hot re-torque and see what happens. Any other suggestions? I'm a little nervous about putting any additives in the water system to stop the leak...

For years Cadillac used a product in their cooling systems to help make sure there wasn't any leaks. Think they still do in the Northstar engines.

But you shouldn't have to retorque the headgasket, but it won't hurt to do so and may solve your problem.

Good luck

I am guessing that you have a problem with either the head or block. Maybe the decking process exposed a crack.

Oh man, I hope it's not a crack!!! I'll give it a few more days of heating and cooling cycles and see what happens. I'll keep you guys updated and if there's any other suggestions, keep them coming...

Adam

Adam, I don't read that you specifically cleaned the threads in the bolt hole and bolts themselves.
It is common for material built up in this area to make your fastener torquing process inaccurate and clamping force on the joint inadequate.
If this cleaning is in order I would remove the bolts one at a time after draining the coolant and then re-tighten the assembly using an anti-sieze lubricant on the threads and under the bolt head.When using the anti-sieze use the lower figure for the bolt tightening specification because of the superior lubrication.

The locating pins in the block had to be removed to 'deck' the surface. If the pin/pins bottom out, this could cause the gasket leak. The Fel-Pro compos gasket is a great design and the compression of the gasket is key to 'no-leaks'. The 'water glass' was a method used on a few of my Ford flathead cracked valve seats. It does work great on cracks and small leaks, but it can also restrict radiator and heater core passages. If you have no luck with some of the suggestions you have, I will suggest checking head and block surfaces.Check the locating pins.

235's do not have locating pins.
Depending on how much was taken of the head and block, the head bolts could be bottoming out.

Thanks for all the excellent advice, fellas. I did not clean the bolt holes thoroughly, or use anti-seize lube on the bolts, so I'm beginning to think this may be the problem. I'm going to take it off again, check everything (including any cracks or if the bolts may be too long now after everything was decked) and see what happens. After many heat and cool cycles and another retorque, it's still seeping.

Adam

Debris in the threads can prevent the bolt from getting the stretch it needs for a good gasket seal due to thread drag. Remember to run a chaser into the block threads, either one designed for the job, or a slightly dull tap. You don't want to enlarge the thread, just clean up what's there.
Jerry

Thanks, Jerry. I will do that for sure. Do you guys suggest anti-seize on the threads, lube, or sealant? I've heard any and all could be used, but I don't know if the head bolts need sealant or not.

Adam

It's possible for coolant to crawl up the threads and end up leaking from under the bolt head if it doesn't seal to the head surface well. A little dab of brush-on Permatex gasket sealer will lubricate the thread during assembly, then help seal against coolant leaks on holes that go through into the coolant passages. I use Never-Seez on the threads and a small amount under the bolt head so all the torque goes to tightening the bolt, not to overcome drag, and it seems to seal well also. If you use anything other than motor oil for thread lube, stay toward the low end of the torque specifications.
Jerry

While you have it off put a straitedge on it sideways. Ive seen guys use these table with a grinding wheel & get it curved.

Once again, thanks for all the great advice. I'll take my time with the next head gasket and definitely keep you guys updated with the outcome...

Adam