Head gasket or more?

[Oliver S.]

The numbers matching engine of my ‘65 300hp was overhauled in 2004/5 - not sure, because under previous owner ship. Meanwhile around 15.000 mls have been added. Until last year oil consumption was minimal. By the end of 2019 I obseved a slightly increased consumption. This year I’ve added 150 mls and the consumption was apparently as high as in the 800 mls before - based on the decrease of the oil level on the dipstick, which I wrote down. So I decded to chech the spark plugs. After removing the one of #6 cylinder the plug was wet - not fuel but coolant. However the coolant level hasn’t decreased considerably since the last check. The engine ran great, not misfiring etc..
The big question to me is if this points more to a blown head gasket or is there any known cylinder head issue possible? If this has anything to do with the oil consumption - I don’t know.

Oliver

[Joe L.]

Re: Head gasket or more?

The numbers matching engine of my ‘65 300hp was overhauled in 2004/5 - not sure, because under previous owner ship. Meanwhile around 15.000 mls have been added. Until last year oil consumption was minimal. By the end of 2019 I obseved a slightly increased consumption. This year I’ve added 150 mls and the consumption was apparently as high as in the 800 mls before - based on the decrease of the oil level on the dipstick, which I wrote down. So I decded to chech the spark plugs. After removing the one of #6 cylinder the plug was wet - not fuel but coolant. However the coolant level hasn’t decreased considerably since the last check. The engine ran great, not misfiring etc..
The big question to me is if this points more to a blown head gasket or is there any known cylinder head issue possible? If this has anything to do with the oil consumption - I don’t know.

Oliver

Oliver------


There are basically only 3 ways for coolant to get into the combustion chamber. The first (and most common) one you've identified: a failed head gasket between a coolant passage and the combustion chamber.

The second is a cracked block or head.

The third involves a failure of the intake manifold gasket allowing coolant to leak from a coolant passage into the intake port and, thence, into the combustion chamber.

I don't see how such a problem could be associated with an oil consumption problem.

[Mark E.]

Re: Head gasket or more?

Oliver------


There are basically only 3 ways for coolant to get into the combustion chamber. The first (and most common) one you've identified: a failed head gasket between a coolant passage and the combustion chamber.

The second is a cracked block or head.

The third involves a failure of the intake manifold gasket allowing coolant to leak from a coolant passage into the intake port and, thence, into the combustion chamber.

I don't see how such a problem could be associated with an oil consumption problem.

Are the plugs oil fouled, or just have coolant on them? If no oil on the plugs, do you have an external oil leak? Look on the backside of the cylinder heads and the bellhousing for oil. A black light is helpful.

If oil is getting into the cylinders, the question is: Are the oil and coolant issues from a common problem? Or separate?

If common, what are the possible causes? Maybe an intake gasket leaking from the oil galley and coolant passage? I can't think of another.

Otherwise, you have two separate problems.

[Oliver S.]

Re: Head gasket or more?

The oil issue was the reason to check the plugs. Actually, I stopped after checking 3 of them and seeing this, because now a professional has to take over. Without the water I would have driven the car and further observed the oil consumption, i.e. check for more smoke etc.. But first the water leak has to be addressed. Would it be ok to drive another 5mls to the garage? At least I could check for white smoke during start up to get an impression on the severity of the leak itself.

Oliver

[Joe L.]

Re: Head gasket or more?

The oil issue was the reason to check the plugs. Actually, I stopped after checking 3 of them and seeing this, because now a professional has to take over. Without the water I would have driven the car and further observed the oil consumption, i.e. check for more smoke etc.. But first the water leak has to be addressed. Would it be ok to drive another 5mls to the garage? At least I could check for white smoke during start up to get an impression on the severity of the leak itself.

Oliver

Oliver-------


I think you can easily drive it for 5 miles to the shop without having any problem. As a matter of fact, you probably drove it a lot further than that with the coolant issue before you even discovered it. It's just that now you know about it.

[Ray K.]

Re: Head gasket or more?

Oliver,
I would check all of the intake manifold bolts for tightness and re - torque them to spec. You might also consider as a temporary measure a coolant sealer and drive it for a few miles to see if it cures the problem. My guess, as stated, would be a head gasket issue. At any rate, driving it for 5 miles or so is not a problem, as Joe has pointed out.

Ray

[Oliver S.]

Re: Head gasket or more?

In order to get a better impression regarding the extend of the damage I took some photos with a USB smartphone camera after having engaged the starter 2x without plug #8 and #6 and no main ignition cable to the distributor. Not really much water poured out of the hole during these actions. There seems to be coolant in the piston pockets as can be seen, too.
However, I have to wait 4 weeks until my garage has ot time. The owner will reply after having seen the pics to tell me if I should pick up a conservation spray used in marine boat engines to preserve the cylinder walls.
What is your guess on the presence of this issue? New or there for a while?

Oliver

[Joe L.]

Re: Head gasket or more?

Oliver,
I would check all of the intake manifold bolts for tightness and re - torque them to spec. You might also consider as a temporary measure a coolant sealer and drive it for a few miles to see if it cures the problem. My guess, as stated, would be a head gasket issue. At any rate, driving it for 5 miles or so is not a problem, as Joe has pointed out.

Ray

Ray------


Yes, that's a good point. Oliver should check all the intake manifold bolts for proper torque. If any are found to be especially loose, that could be the whole problem by allowing coolant to leak by the gaskets from the head's coolant passages to the intake ports.

[Oliver S.]

Re: Head gasket or more?

Thanks for this tip. I’ll check the bolts and let you know.

Oliver

[Edward D.]

Re: Head gasket or more?

Easy way to check for blown head gasket is to remove the water pump belt, remove the thermostat cover & thermostat. Check that water level is at least 1/2" below surface of intake where thermostat was. Start engine and rev a couple times to about 3K. While you are dong that look for bubbles in the water. Shut down engine before it gets to hot. Bubbles indicate head gasket blown between cylinders and water jackets. No bubbles and you likely have an intake manifold gasket problem. This is common and why we put a bead of sealant around water jackets in head when installing a gasket and manifold. Hopefully you have an intake manifold gasket problem, this is a lot easier and cheaper to fix than a head gasket.

[Joe L.]

Re: Head gasket or more?

Easy way to check for blown head gasket is to remove the water pump belt, remove the thermostat cover & thermostat. Check that water level is at least 1/2" below surface of intake where thermostat was. Start engine and rev a couple times to about 3K. While you are dong that look for bubbles in the water. Shut down engine before it gets to hot. Bubbles indicate head gasket blown between cylinders and water jackets. No bubbles and you likely have an intake manifold gasket problem. This is common and why we put a bead of sealant around water jackets in head when installing a gasket and manifold. Hopefully you have an intake manifold gasket problem, this is a lot easier and cheaper to fix than a head gasket.

Edward------


.... even easier (and better), use one of these:


DSCN3696.jpgDSCN3697.jpg

[Richard G.]

Re: Head gasket or more?

Years ago, I was offered a HP block for sale.
It had been rebuilt but also suffered a blown head gasket, the reason it was pulled. I have the foresight to check the bores with a micrometer before I purchased it. All the cylinders were within .002 except one. It was .014 oversized. I assumed the coolant caused the oil to be washed/watered down and this resulted in the wear. Could have been a lot of things like steam but I avoided a personal disaster that time.
Could it be cylinder wear has caused the higher than normal oil consumption?

One more story;
A friend was having issues with his 250HP 327. We did a compression check and all was well except one had a compression reading significantly higher than the rest. We did it again and it was even higher the second time. Figured it out when we removed the gauge and rolled the motor over. Shot water clear across the shop.
I am glad you identified the issue. If it was mine, I would put a head gasket in it unless the leak was obvious the intake. Typically, difficult to prove an intake leak from a visual inspection. Replace the head gasket and be sure to look for a mismatch between the intake and the heads. So many heads have been shaved over the years I would confirm the fitment. And be sure to mike the bores while you are there. The top of the piston, in the leaking cylinder(s) will be clean if it has had a coolant leak for long.

[Oliver S.]

Re: Head gasket or more?

Richard,

picture no. 3 shows the top of the piston:
https://www.forums.ncrs.org/showthre...197#post872197
The increased oil consumption occurred over a period of 1.000 mls - after 12.000 mls without any real oil issues. Ever since I have the car I haven't had to refill coolant. Even now I haven't noticed any obviously bigger loss in the coolant overflow tank.

Oliver

[Oliver S.]

Re: Head gasket or more?

I had a call with the garage. They told me that - in case of a intake manifold leak - cylinder #8 should also have water, because it is closer to the coolant passage. However, this is not the case as I also checked with the endoscope. All other spark plugs on this side look good, too. So apparently only cylinder #6 is concerned.

[Oliver S.]

Re: Head gasket or more?

I decided not to start the car before driving to the garage. However, I pressurized the coolant system to 14-15psi and took more pictures. Based from the attached picture I would guess it is the gasket because there are no coolant drops above the separating line between block and head.

Oliver

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