If the engine abuse was poor oil change intervals, the rings may be sticking in their piston grooves due to sludge and varnish deposits. I have had reasonably good luck cleaning the engine rings with Rislone. This is a slow acting cleaner which won't cause a flood of loose gunk in the engine.

The Rislone is basically a strong oil detergent. You use a quart of the stuff in place of one quart of regular oil at the time you change oil. Then just drive normally until the next oil change. I have had good improvement in oil consumption and crankcase pressure in a '78 Chev V-6 and an '86 Volvo 240.

It won't work miracles though. If the problem is worn rings or cylinders, it won't make much difference. At least the Rislone treatment is inexpensive.

If this system is like that on our late '98 V90,check the small vacuum hose from flame trap to in take manifold. Ours had turned to goo internally (outside felt fine) and was plugged,resulting in some excess pressure at idle.


sredwine I now have a '94 940T and a '95 945T-195K and 162K respectively

I'm not sure what type of breather box this 6 cyl engine has, but with the B230 engines ( I have a 940 that has the same 4 cyl block as the 740 and 240's) the breather box CAN get very clogged with oily fumes drying and building up over the years - so that no ventilation is going to/from the intake manifold, where the fumes are sent to be combusted further.

So, this breather box, if clogged can act like a closed valve, sealing in the combustion by-products and building up pressure in the lower block. It's the only "avenue" with which the bypass, past the rings can get to the intake manifold. You can sometimes stick screwdrivers in them and knock them about to break apart the crust inside, or you can replace it. To test it you can blow in one of the openings and sense for air blowing out the other openings. Also, there is a tube under the breather box that allows oil to drip back down into the pan - that could get clogged as well.

So, if this breather box is not replaced/cleared you'll start pushing out the main seals, front and back; and any other seals under pressure. You may want to leave the oil dip stick NOT CAPPED FULLY to allow to vent the pressure off in the meantime. Oil should not creep up so far, and out.

But I would say you need to look at this engines' breather box equivalent - it must have something similar to the 4 cyl block.

Best of Luck

I doubt the rings are bad, these are very durable engines. Some blowby is normal and if there is a sudden release of pressure when you pull the dipstick as you imply then the crankcase vent is surely blocked somewhere. Even if the rings where shot and blowby was present it would never build up pressure on a properly vented crankcase. I am assuming that after the intial whoosh at the dipstick the pressure is released and does not continue to blowout.
--
David Hunter

Bob's post is right on, I would also add, make sure the engine in hot, and the throttle plate is held wide open.

How is the oil consumption? After an oil change, does the oil remain clean for a while?
My old engine, about a tank of gas and the oil was dark, 4 tanks and it was black. Now on the new engine, it has to have 2,000 miles before I don't need my eye glasses to even see it on the dip stick.

I swapped out my engine when having to put in a quart of oil per every tank of gas. Upon examination of the old engine, which by the way never acheived higher that a quart of oil to 1,500 miles of driving when new. The old engine, the rings were badly worn, and the cylinders were worn near the upper most area, the most critical, but the lower parts of the cylinders still had their cross hatching marks from the factory hone. In '95 volvo change there thickness to the rings to something a little more robust.

I don't think you will want to re ring this engine, it is not an easy project, some work would need to be done to the block, that expense alone is enough to think about a swap. You could upgrade to a longer timing belt interval in the process.


DanR '94 964 332,000 miles (98,000 on the new engine)
--
DanR

This is a 960 Inline 6 6304

Pull the plugs and look at them. Are they dry? Sooty? Wet? gray ashey?

Then run a compression test, at least twice to be certain. Save the readings.

INto each cylinder squirt maybe a tablespoonful of engine oil. Wait a few minutes while it runs around and down to the rings. Run another compression test.

If that second test gives results significantly higher than the first, the problem is the rings. If not, the problem is in the PCV system.

Good Luck,

Bob

:>)

PS: Your post is not clear as to which engine you are dealing with. My guess is that if a broken timing belt ruined the head, you have a B6304 I-6 AL engine.

Did you check the PCV?

I am having the same issue with my B20. I would like to stay tuned so I can see what is the problem.