1000 miles on rebuilt engine leaking head gaskets WHY?
 

My 389 was rebuilt from a engine shop here in Tn, He used the Felpro gasket set to rebuild the engine the head gaskets were not the race ones. I believe they are the no retorque ones perma. Is that really true? Dont all head gaskets need to be retorque after they get hot then cold? Here are a few pics, you can see its near every bolt. I do not have anti freeze in my oil, the egine never 0ver heated. Will the retorquing the head bolts do the trick? Please any comments would be appriciated. I have $5,000 in the engine and its leaking anti freeze. The shop charged me $1,800 to do the break down and reassemble, I bought all the parts rods TRW Pistons cam lifters so forth,They did the start up and break in on a stand. Heads have been milled to clean them up. Runs great no smoke coming out tail pipe. Passenger side looks worse than driver side.

You should retorque the heads after a few heat cycles.

I agree, re-torque as is and my bet is that all will be fine with the details provided above (never over heated, milled surfaces), etc... I always add anti seeze under the heads of bolts, washers, etc... for a more accurate torque to eliminate any un-necessary friction between the two surfaces.

Tim john---

its always a good idea to re torque the hardware.

also a good ides to run a block sealing formula through the block until everything stabalise's.

a competent machine shop will know what industrial standard of roughness resurfaced heads and decked block should have. anything else will cause head gasket problems

I've had to use bars leak on a sbc build before. Not the warm fuzzy feeling we look for after dropping 5 large...... I am with the others, re torque and add sealer....

Did you ever wonder why we don't re-torque bolts on new cars? They don't even use sealer on the head gaskets--and very seldom develop leaks.

The block was checked with straight edge not decked, they said it didnt need it. I will retorque the heads. back off 1/4 than go to 100 lbs.

Do NOT back the head bolts off prior to torquing. That will disturb the preload already on the system and make things move around. Torque to spec and leave it.

could it be something else, maybe an intake leak, or freeze plug on the head???

I would re torque it and see what it does. Do it cold and don't loosen and re-torque. Just torque it from where it is.

Torque to 100 ft/lbs cold.

If it still leaks you have a problem with level somewhere or gaskets and heads need to be pulled. Period.

Thank all you guys for your input I really do appriciate your comments to help. So do I back off a 1/4 turn then retorque? or just retorque where the bolt is at? I here different opinions back off? or dont?

I,ve never re-torqued any of my head bolts ever, on pontiac, ford , chevy, mopar. notta.

Contrary to what others have posted, you must back off the bolt to properly re-torque them. What you have to do is one at a time. Back it off a 1/2 turn and then torque to 100 ft lbs in one motion. If you just try to torque them when they are tight, the breakaway torque is much more than the actual torque value. It wont be accurate.

Those are leaking pretty heavily. Not sure a re-torque will fix it. I wonder if the head bolts are bottomed out and keeping the gaskets from sealing. I'd have to agree with an earlier post. Heads need to come off and see what the issue is.

Serious damage will occur if a cylinder fills with coolant and you try to start the engine. Broken pistons and bent rods. Not worth the risk in my opinion to just torque the head bolts again.

These pictures are recent from a cold week or two sitting. I noticed anti freeze on the ground. The cold temp seem to really make it leak.

Like Bruce said.

I deck all blocks we build. Even though they check flat with a straight edge, you would be amazed at how much they are off. I have seen Pontiac blocks with a factory deck job that sloped off at one corner and took .015 to clean it up all the way across. You can't pick these things up with a straight edge, only low spots. If it's a gradual slope, especially off to one corner, they will check pretty flat. I have many pictures of messed up decks that the customer thought was good. Hopefully re-torquing and stop leak will fix it. Otherwise, you'll need to tear it down.

Here are pics of a Pontiac deck that checked pretty flat. This block took about .010" to clean it up. This is a typical factory deck job, and this is exactly why we deck anything we are going to build. If it leaks, we have to take it apart to fix it. It's just not worth it.

also, there is a specific roughness to the finish after decking the block that you need for the head gasket to seal....also, i think the finish is different for aluminum blocks/heads as well due the expansion. a good machine shop knows what those surface finishes should be.

I'm in this camp. Why build an engine and go without decking the block? Not only is it a chance, but as previously stated, the finish is also an issue. Makes me wonder what other areas/tasks were skipped/short-cutted.

IMO, if it's leaked, the gasket needs to be replaced, at minimum. Once a leak-path has developed, you need to take appropriate steps to ensure it doesn't leak further.

You might be able to get away with replacing the head gasket and cleaning up the surfaces, if amount of work is a concern, you can try that first.

And yes, any and every head gasket needs to be re-torqued after a few heat cycles.

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This is correct, for the most part.

Any more, with all gaskets, smoother is better. Especially so with aluminum heads and cast iron block. The heads will expand more than the block so it is very important to have a very smooth surface with aluminum. The head needs to be able to slide across the gasket as it expands. Otherwise, if the surface is rough, when the head expands, it pulls on the head gasket and after time, tears the coating on the head gasket. Other times, it rips the sealing ring around the cylinder, apart. Smooth works best for MLS as well as fiber gaskets. MLS has to have a smooth surface. Fiber can get away with a little rougher if cast iron heads are used.

As for us, we deck smooth for any gasket. We don't have head gasket issues either. The old wife's tale of "you need a rough surface to BITE the gasket" has been invalid for many years now, though some shops still follow this philosophy.