1966 300 cid engine / oil loss at headgasket after rebuild

[Guest stefan66skylark]

Hallo all,

my freshly rebuild 300 cid V8 has developed leaks at three edges of the cylinder heads, close to the exhaust headers, towards the very front/rear of the engine.

As far as I remember the oil lines for the rocker shafts are located in that area.

It's not that bad, but she marks my otherwise clean driveway.

I have used Fel-Pro head gaskets, block and head surfaces were ultra smooth and clean.

The heads were tightend in the correct sequence and torque.

General question: Is it advisable to retorque the headbolts on this engine after a few warm/cold cycles? What's the right technique; loosening and retorque or just retorque?

Specific question: Will this rectify the oil loss?

I have read somewhere in the www that Fel-Pro head gaskets are prone to leak on nailhead engines. Should I have used another brand of gasket?

Please share your wisdom...

Stefan

[ol' yeller]

Stefan, are you sure that is where you are leaking? A much more common point for leaks are at where the intake manifold contacts the heads. There is are 2 rubber strip gaskets that run along the front and rear of the block but the corners at the heads need to have a small drop of sealant or they will leak. Is it possible that they are leaking at that point and dripping to where you are seeing it? An oil leak from a head gasket is pretty unlikely on the newer version of the 300 with cast iron heads.

[Guest stefan66skylark]

Dear Greg,

thanks for your reply.

Please have a look at the attached pictures taken this morning.

The show the joint head/block at the front and read edge.

I double checked that it isn't drippimg down from the valve covers and it can't be traced to the intake.

And regarding my initial question; do you know wether it is advisable to retorque these heads?

Thanks

Stefan

[ol' yeller]

Stefan, that is very odd. There is an oil passage in the head that runs up to the rockers at the front and rear of the head. I see no harm in re-torquing the head but I doubt it will make a difference. I wouldn't loosen them but just make sure they are snugged up to the recommended torque. Was the block decked or the heads shaved? That may make your head bolts too long and have them bottom out before they seal correctly but I would assume that you would also have a pretty massive coolant leak as well. The only other possibility is a crack in the head. I have never seen this problem before.

Greg

[60FlatTop]

The gasket should be good for 40 to 60 PSIG at those passages under normal conditions. And you shouldn't leave oil in the driveway, that's for sure. If it was in my garage I would run a compression check and a leakdown test just to be sure cylinder pressure wasn't forcing the oil out for some odd reason. Pressurizing the cooling system both cold and warm it not hard and might add some insight. Be sure you don't see a little oil in the coolant.

Anything you find that might make you suspicious is going to lead you to pull the heads. When you do it the tests may help you pinpoint the problem. Try to remove them as gently as possible without disturbing much.

We had low pressure on my Park Ave after installing a new long block. Although it is really hard to work up the willingness to take stuff apart again we found the engine rebuilder supplied the wrong timing chain cover gasket; could have lost the new engine.

"The level of perfection one can achieve is directly proportional to the number of times they are willing to do things over." Can you translate that to German?

Bernie

[Guest stefan66skylark]

Greg and Bernie,

thanks for your assistance!

During overhaul the top of the crankcase has been honed, just to create a smooth surface.

The heads have not been shaved, just cleaned.

Oil is reaching both rocker shafts.

Checked headbolt torque, head bolts don't move at max torque of 110 Nm (81 ft/lbf).

(I know about friction coefficients, but at least bolts are tight)

Checked compression, all fine.

No oil in water, no water in oil.

A bit more pressure in the cooling system then it used to be, but not too much (radiator cap 15 psi and thermostat 180° both new).

I will check both oil level/condition and coolant level/condition before each cold start during the next months and see how things develop.

Also I place a big piece of cardboard underneath the car, so leaks may be traced more easily and the garage stays clean.

Would prefer to remove the heads again in fall, I'd like to drive the car now. Weather is beautiful over here right now!

As for the translation, that would be something like:

"Der vom Einzelnen zu erreichende Grad an Perfektion ist direkt proportional zur Anzahl der Wiederholungen."

And there's a lot of truth in it!

Thanks much, yours

Stefan

[60FlatTop]

Drive it like you stole it and if it breaks fix it.

Hold the beer mug high and say :

"Der vom Einzelnen zu erreichende Grad an Perfektion ist direkt proportional zur Anzahl der Wiederholungen."

I've had one head off my '60 twice and taken the body off the Riviera frame twice.

I took German as a language in High School. The only thing I remember after 50 years is "einen reifenpanne". I guess that shows where my priorities were.

Bernie