OK... so I have a '98 V70 T5 with 228k miles on it. Back in the spring, the car managed to burn an intake valve in both cyls 1 and 2. I thought it had a blown head gasket. When we took the head off, it was clear what the problem was. We had the head dipped, magna-fluxed, etc. and had 2 valves installed. The head was verified to be straight and true. About a month ago, the engine finally got reassembled... with new head bolts, new gaskets, 2 new valves, new plugs, new belts (both serpentine and timing). The car runs great... but when I get on it pretty good and then let off, out comes a pretty decent blue-ish cloud of smoke. It doesn't smoke at all while I've got my foot into the accelerator... only after I've let up and the engine is letting off.

I've heard (too late, unfortunately) that if you do a head job without also doing a ring job, that you'll wind up with blow-by. I'm thinking that's what I'm seeing... in that when I really wind up the engine, it's allowing pressure to blow past the rings... thereby pressurizing the crankcase. Then... when I let up, the pressurized crankcase lets oil blow past the rings to equalize the pressure... which results in burned oil and the cloud of blue-ish smoke I'm seeing.

Is this a reasonably accurate description of what I'm seeing, or is there some other explanation? Is there anything - short of disassembling the engine again and re-ringing the engine - that I can do to correct the problem... or is this just gonna be one of those "live with it" conditions? I'm wondering if changing the type of oil or perhaps running an oil additive or maybe Slick50 or something along those lines might seal things up sufficiently to address the problem. Or... if it might be something else... I'd sure like to know as I'm not quite sure what to do at this point (and really have no desire to repeat the exercise just to ring the pistons).

Help

 

I have never heard that about the rings.
Did you clean/replace the vent system when doing the head?
It could be a clogged vent system or a turbo going bad.

 

Sounds like bad turbo is more likely. When you let up the tension on the compressor shaft changes, that, along with more vacuum is sucking in oil.

Remove the OTE charge pipe and check for oil residue. If there is a little coating that is normal, if it's wet you've got a dying turbo.

 

I have very little experience on the newer Volvo engines, but lots on the 20F. These engines could pull oil through a worn valve seal under high vacuum conditions, such as downshifting at high speed. When you touch the throttle after this one would see a nice puff of blue smoke. After an extend idle (red light), hitting the gas could also produce a puff, but not as extensive.

I don't see much discussion of worn valve seals ever mentioned, it this just because this doesn't happen any longer due to a better design? I'd like that answer!

Jerry

 

The valve seals very rarely leak on the newer Aluminum motors.

 

My old V70R was doing that at 230,000Kms, figures it was stem seals or turbo, both expensive, sold it and bought a T5 2001, which frankly is a far better car.

put some thick oil in it, flog it an buy an 01 or later T5, never looked back, goes harder than the R and no AWD nightmares
Karl