Pulled my heads today (pics)
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From: Boulder Creek, CA
Those scratches look like normal tooling marks from when the head was planed in a shop. The gasket looks almost new, the plugs are too white, no sign of coolant entering the cylinder or else the combustion chamber and the piston top would look brand new (steam cleaned). The head nuts found have been loose.
Can you provide similar marks on a properly machined head?
Drifting
Joined: May 2010
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From: Northern Virginia
Those scratches look like normal tooling marks from when the head was planed in a shop. The gasket looks almost new, the plugs are too white, no sign of coolant entering the cylinder or else the combustion chamber and the piston top would look brand new (steam cleaned). The head nuts found have been loose.
Three Wheelin'
Joined: Apr 2010
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From: Sacramento, Ca.
Scratches look like someone used a strip of emery cloth wrapped over a file to clean the old gasket material off. Get them clean & checked with a proper straight edge for straight or however the machine shop does it.
Quick check of the valve job: put the head flat, chamber side up, plug installed. Put some diluted dish soap in the chamber. Then blow compressed air in the ports. Leaky valves will make bubbles in the chamber from air passing them.
With the compression numbers you were getting, might only be a gasket issue.
Quick check of the valve job: put the head flat, chamber side up, plug installed. Put some diluted dish soap in the chamber. Then blow compressed air in the ports. Leaky valves will make bubbles in the chamber from air passing them.
With the compression numbers you were getting, might only be a gasket issue.
Last edited by Jim Devine; Apr 5, 2016 at 06:00 AM.
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From: Anaheim
I can't tell you if the heads have never been off or if the head gaskets are original....
However, given the amount of corrosion on the two end upper studs in the picture, it's been a very long time since these heads were removed.
The lack of corrosion /pitting on the head surface is impressive. Whoever owned this car apparently changed the coolant on a regular basis.
The area on the pistons that is clean is interesting. The lack of carbon build-up is a result of oil being present in high enough quantities to not allow the carbon to stick. Normally, I would associate this with rings that are not properly sealing, however with 51K on this engine, that would be very difficult to understand. Perhaps the oil is coming down the intake valve guides due to failing stem seals? There is some evidence to support this idea, in some of the combustion chambers.....but not all.
Engine problems/engine repairs are not always cut and dry.
However, given the amount of corrosion on the two end upper studs in the picture, it's been a very long time since these heads were removed.
The lack of corrosion /pitting on the head surface is impressive. Whoever owned this car apparently changed the coolant on a regular basis.
The area on the pistons that is clean is interesting. The lack of carbon build-up is a result of oil being present in high enough quantities to not allow the carbon to stick. Normally, I would associate this with rings that are not properly sealing, however with 51K on this engine, that would be very difficult to understand. Perhaps the oil is coming down the intake valve guides due to failing stem seals? There is some evidence to support this idea, in some of the combustion chambers.....but not all.
Engine problems/engine repairs are not always cut and dry.
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From: saratoga, ca
it all looks pretty good. with greg on this one, there might be some oil dripping down via the valve guides.. any smoke when running? decel?
what about those scratches on the head.. i didnt notice anything unusual there. what are you seeing ?
what about those scratches on the head.. i didnt notice anything unusual there. what are you seeing ?
Official Bay Area Patriot
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Fuse 24 Assassin
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Greg, wouldn't a coolant leak into the cylinders also cause that 'clean look'? I had a 944 that had 2 'steam-cleaned' cylinders and the pistons looked pretty. The head gasket had failed on it. Although, the center of the dish appears to be built up with carbon still, so the oil leak from valve guides is very possible.
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From: Anaheim
Greg, wouldn't a coolant leak into the cylinders also cause that 'clean look'? I had a 944 that had 2 'steam-cleaned' cylinders and the pistons looked pretty. The head gasket had failed on it. Although, the center of the dish appears to be built up with carbon still, so the oil leak from valve guides is very possible.
Although he only showed one side of the engine, that one side has very similar looking pistons and I could not think of a scenario where all cylinders would be getting the same amount of coolant. (In my experience with a leaking head gasket, one cylinder (or two if the gasket blows between the cylinders) is always much cleaner than the others.)
Captain Obvious
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From: Cambridge, Ontario, Canada
Greg, wouldn't a coolant leak into the cylinders also cause that 'clean look'? I had a 944 that had 2 'steam-cleaned' cylinders and the pistons looked pretty. The head gasket had failed on it. Although, the center of the dish appears to be built up with carbon still, so the oil leak from valve guides is very possible.
Also, on the pic that shows the "scratches" shows signs of clean up after the head came off. Look at the carbon build up in the bottom left and the scratches that a wire brush would leave in the carbon.
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From: Anaheim
Highlighted the "not cut and dry" problem in blue.
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From: saratoga, ca
yep... agreed on that count too!
much of the best chance conclusions might be found at the time the head is pulled from the gasket to see any thing that might show coolant flow or hot spots. once the "crime scene" is disturbed, its tough to put the pieces back together as to what really is going on.
much of the best chance conclusions might be found at the time the head is pulled from the gasket to see any thing that might show coolant flow or hot spots. once the "crime scene" is disturbed, its tough to put the pieces back together as to what really is going on.
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From: saratoga, ca
Those scratches look like normal tooling marks from when the head was planed in a shop. The gasket looks almost new, the plugs are too white, no sign of coolant entering the cylinder or else the combustion chamber and the piston top would look brand new (steam cleaned). The head nuts found have been loose.
Former Vendor
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From: Anaheim
im looking at the scratches on the head that seem to be like someone used a scotch brite pad to remove some of the carbon , to see how thick it was or something (that close up pic). there is a TON of carbon in the combustion chamber. maybe it was running a little fat, and some of that clean area at the bottom of the piston was caused by raw unburnt fuel cutting through any carbon. the cylinderwalls look really nice though..... i think this is a quickie head skim job at the shop, valve sealing check, maybe new valve guides, and a new head gasket and reassemble, no?
My attitude is that it is simply too much effort to ge the engine in and out, get the heads on and off, to not just hand the heads to a machine shop and have them "kiss" the valves and the seats. And if a guide is replaced, the seat will have to be re-cut regardless....guides are not concentric enough, nor go squarely enough in the holes to keep the exact same center line.
Last edited by GregBBRD; Apr 5, 2016 at 09:55 PM.
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From: Norcal
heads are going to Greg tomorrow for rebuilding. you know, while your in there.
Bottom end should be ok, with the mileage I have. I will pop the pan and maybe a rod cap or too, to have a look.
recommendations for cleaning the tops of the pistons, with them still in the block?
tonight Ill post up pics of the pistons. they all do look the same with regards to the clean spot near the bottom.
I never noticed and exhaust smoke, but I do burn some oil between changes. Keep in mind I dont drive this car much. maybe 2000 mile a year. Neither did the previous owner.
Bottom end should be ok, with the mileage I have. I will pop the pan and maybe a rod cap or too, to have a look.
recommendations for cleaning the tops of the pistons, with them still in the block?
tonight Ill post up pics of the pistons. they all do look the same with regards to the clean spot near the bottom.
I never noticed and exhaust smoke, but I do burn some oil between changes. Keep in mind I dont drive this car much. maybe 2000 mile a year. Neither did the previous owner.