Head gasket suggestions

jcode68 · Nov 19, 2006

Well, my new CHP 347 appears to have a bad head gasket on the drivers side. I have oil leaking between the head and the block in the very rear of the head. Leaked down onto the header and now the nice ceramic coat is burn brown color . The pisser is this is a brand new engine with less than 50 miles on it. I called CHP and they said often times the heads need to be re-tourqued after a couple of heat cycles. Ok, this sounds legit since the block is iron and the heads are aluminum. I tourqued them to 75lbs, but they were already fully toruqued and still leak. The passenger side seems fine. The gaskets they used are a graphite type. So now I need to replace the gasket and want to do this once with the best gasket. Can you guys give me a suggestion? As I said, the block is a stroked 347 and running AFR 185 aluminum heads. BTW, my warranty is just slightly out from CHP since I have been taking my time with my drivetrain project. Although I haven't called them back since they suggested re-tourqing, I know they will just replace the gasket (parts only) and don't want to necessarily use the same gasket. Anyone else ever experience this type of problem?

10secgoal · Nov 19, 2006

If you are only going to do one side, them re-use the same. That's what I would do. Maybe the engine installer didn't do something right, or it's a fluke in the HG. If it does it again, and you follow all the correct torque sequences and still have the same problem, then look elsewhere.

jcode68 · Nov 19, 2006

Well, I would prefer to leave the other side alone since it doesn't have a problem. I guess it makes sense to have them match. I never replaced head gaskets before, so don't know why a gasket would fail in this way. Anyone else ever have a problem like this? If so, what was the cause of the failure?

D.Hearne · Nov 19, 2006

I'd be more inclined to suspect your oil leak is from the valve cover. There's no oil passage between the head and block. I've got the same leaks with my small block valve covers at the rear. Two sets of covers and they both leak. I think the top end gets too much oil, much the same as the FE's which are easily remedied with restrictors.

10secgoal · Nov 20, 2006

How does the top of the motor drain back into the pan ?

302 coupe · Nov 20, 2006

oil does in fact run from the heads down into the block. The big holes at the bottom corners of the heads are for oil drainback.

thehueypilot · Nov 20, 2006

Wow that sucks.....I have had a lot of issues with CHP in that area. A good quality gasket should not need retorqued even with aluminum heads. I would really check to make sure the leak is coming from under the head before tearing it apart. Like mentioned above it could be a leaking valve cover. The head torque seems a little low but I have a 351W with AFR225 heads and my torque is 100 ft/lbs for the outside "short" bolts and 110 for the longer bolts as per AFR specs. I also use the graphite paste to lesson the unwanted friction during the tightening sequence. I would think CHP would use good quality gaskets and graphite paste when they assemble their longblocks, but maybe they took a shortcut that day. Good Luck.

D.Hearne · Nov 20, 2006

302 coupe said:
oil does in fact run from the heads down into the block. The big holes at the bottom corners of the heads are for oil drainback.

OK, there is a drainback passage, but this oil isn't under pressure and it's unlikely to leak, unless there's something wrong with the gasket. I'd still suspect the valve cover gasket, the outer bottom corners have no bolt to tighten it against the head, I know mine are leaking there.

10secgoal · Nov 20, 2006

Just clean that bad boy all up. Then let it idle until leak is found.

jcode68 · Nov 21, 2006

Thanks for all the respnses.
Huey - CHP gave me the tourque specs when I spoke with the. I didn't verify this against what AFR specs, but will check their website and tourque accordingly. I was also told by my mechanic that heads shouldn't need to be retourqued as a general rule of thumb.

I will clean everyting up real good and see if I can 100% isolate the leak. I had the valve cover off this weekend and didn't notice any failure in the gasked, but anything is possible. I sure would rather replace a valve cover gasket than get into replacing the head gasket. I actually had a head gasket failure with my 2000 GT. Drove it off the lot and smelled oil burning smell, which turned out to be a leak from the head gasket. I know it's competely different engine etc, but shows it can happen even if the oil is not under pressure.

truck90278 · Nov 21, 2006

lyou will probably have to find a shop to do this for you, but the cost is minimal. For finding leaks, a dye which reacts to a black light can be added to the oil, drive it until the leak returns. A black light will show the actual leak location

jcode68 · Jun 22, 2007

I'm dusting off this older post to give an update and ask for more opinions. I took a break from my 68 for a few months and am now getting back to this problem. Per D. Hearne's suggestion, I replaced the valve cover gaskets with the best I could find, these Moroso bad boys and I canot see that they are leaking anywhere. However, I still have a leak. I took a couple of pics of the leak:

These shots are taken from underneath on the drivers side. It looks to me like it is leaking directly under the header tube, down the head onto the block and then streams down onto header. This makes no sense to me I checked the valve cover above this header tube and it's not leaking. Unless this is a head gasket problem and it's just blowing up the head in that one spot, I have no other ideas. I don't want to pull the head unless I'm very certain it's a gasket issue. Appreciate any insight and guidance.

RUSTYNUT · Jun 23, 2007

I would do a compression test befor pulling head. My money would be on a leaking intake manifold. The oil is brought to the valvetrain in your push rods. It drains back to the pan by openings around your push rods. Your heads don't have oil under pressure in the castings themselves. I would look realy hard for leaks in pvc, bent valve cover flange etc. The only things I can think of to have oil leaking out of head gasket will show up on a compression test, but you would already notice how bad the engine was running. Get one of those little mirrors on a telescoping handle and look on the back side of the intake.

dennis112 · Jun 23, 2007

Try cleaning the engine, thoroughly dry it off, then liberally spread some talcum powder on it. Be sure to put the powder on the front and rear of the head and where the intake mets the block. Start the engine and watch where the oil comes from.

The powder may look like crap, but it will wash off easily.

65fastbackresto · Jun 23, 2007

Prob dumb question

FYI, my new Edelbrock heads say to retorque after 2 to 3 hours of engine time, and I wouldn`t beleive a mechanic, I have a feeling that Edelbrock and AFR know much more about this issue then a mechanic.

You ever sean a shop with a R & D department?

My engine builder happily agreed to retorque mine when its ready, that is if I can ever get it all running....LOL

jcode68 · Jun 24, 2007

Thanks for the suggestions guys. I didn't get a chance to trace the leak this weekend, but will try the talcum powder idea. If that fails, will pick up some dye and blacklight. Based on where I see the oil on the head in the picture, not sure how this could be a manifild leak, but I am determined to find it wherever it is. I would rather it be a manifold gasket replacement than a head gasket!

HookandLadder · Jun 24, 2007

What intake are you using? And what block is it? Had the same problem with an RPM performer air gap leak. It was in the rear, but the way the oil runs down it sure looked like it was the head gasket.

SoCalCruising · Jun 25, 2007

Where is the dipstick and, if it's in the front cover, did CHP use a roller block, but not seal up the in-block dipstick hole? It is on the driver's side near the pan rail and will spit oil up onto your header, especially when you rev it.

If this turns out to be your problem, do a search for this topic as there was a recent thread about how to plug that hole with the engine installed.

jcode68 · Jun 26, 2007

SoCalCruising - really good question. I am using a front cover dipstick. Not sure if the block is/was a roller block, but it does have a roller valvetrain now. I know blocks can be converted, so I don't want to assume. I will definately check for this, just can't believe I would have missed this while I had the engine on the stand. Thanks for the tip

HookandLadder - I am using an Air Gap. I checked the rear and it seems dry, but will go over it again. Thanks for the suggestion.

SoCalCruising · Jun 26, 2007

If you were able to use a stock-style roller lifter (not a link-bar lifter), dog bones and spider, then the block was a roller originally.

Head gasket suggestions

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