Took off the head, need advice on how to proceed

[yoramw]

My 86 Turbo had some smoking and was consuming about a qt of oil for every 700 miles.
Trying to diagnose I did a home compression test which gave me decent results I think (150,149,149,145).
I also had the turbo replaced with a Lindsey rebuilt very recently.

Since I also saw some minor oil leaks from the crank pulley area I decided to do a front reseal and also do the head gasket preventive replacement and value stem seals replacement.

Today, finally the head is off, but now I am not sure if the smoke and oil consumption will be taken care off by the head refreshment and need your help on how to know the condition of my rings...

A friend suggested to put all pistons at the same height and top with diesel fuel and see if the level change in any of the cylinders over 8-10 hours.

Is this a recommended approach or is there another procedure I can try to help me decide how to proceed?

Some photos:

[rufrob]

Since you've gone this far, replace the valve seals, get the head checked and cleaned. Do the crank bearing and rings.


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[yoramw]

To move on to rings and crank bearings, do I "just" support the block, take off the cross member, oil pan and remove the pistons from below with the block still in the car?

This is the first time I went so far into the engine. The car is on jack stands in my garage.

Any insights on the process will be much appreciated.

[djnolan]

Did you have one of the plugs fouling/cylinder missing? You may have a bad valve guide seal. This could cause the oil consumption you are seeing. The bad valve guide seal could be caused by a broken inner valve spring. So get the head checked out first.

In fact, I would bet lunch number one cylinder has a bad valve guide seal from the looks of the carbon buildup. (especially if your compression test was even. and if you had a good leakdown test then i would bet dinner too that it is a valve guide seal versus a cracked ring. And since you ahve the head off then you would be able to see scouring so it is almost certainly a valve guide seal.)

[yoramw]

I am not sure if any plugs were fouling. I did not notice any misfires.

Here are a few more photos:




Do these marks/scratches on the top of the cylinder wall a cause for concern?
Do these plugs tell any story?

[djnolan]

I was thinking the piston to the left (either 1 or 4?) and the first valve picture showed a lot of carbon buildup.

I had an oil consumption and fouling problem with an 85.5 N/A and it turned out to be a valve guide seal that was caused by a broken inner valve spring.

[yoramw]

I believe it is called number 4 (the closest to the firewall).
This is also the cylinder which had the lowest number in the compression test I did.

I hope it is a broken valve spring or seal/guide.

[9FF]

Originally Posted by yoramw

To move on to rings and crank bearings, do I "just" support the block, take off the cross member, oil pan and remove the pistons from below with the block still in the car?

This is the first time I went so far into the engine. The car is on jack stands in my garage.

Any insights on the process will be much appreciated.

So, at this point you know the compression wear is quite even but you are burning some oil. You might as well take the pistons out (from the top), check the bores and if they don't have any marks or scratches that catch your fingernail simply replace the piston oil control rings. Also gives you the opportunity to do your rod bearings. As for the head, it just needs to be cleaned, checked over and the valve stem oil seals replaced. Your oil consumption isn't really that bad, it's within spec.

[northern_aqs]

The compression results are really quite even, I wouldn't worry about the rings at this point unless you were going to do a full rebuild. Based on the carbon build up, I agree dollars to donuts that its valve seals and or a broken valve spring. I would replace the rods bearings, clean the piston tops and avoid disturbing the bores too much. Assemble with a rebuilt head and you could probably run it successfully until you wanted to pull it completely and rebuild properly. Having new rings (even just oil control) seat on worn bores is not always 100%.