My 91 L98 (152k) pukes blue smoke when warm. On cold start, it doesn't spew any smoke at all. But once it's warmed up it will spew blue smoke when I rev it and it spewed smoke all through it's smog test today (failed). If I park it hot and restart after 10 minutes, it lets out a nice puff too.

I pulled the intake manifold and found what seems to be a gasket that was letting oil get sucked into the intact tract. The bolts weren't very tight either - I probably could have taken them off with a screwdriver.

In the second pic you can see my finger wet with oil - that's from just rubbing my finger along the walls of the intake runner.

 

 

I can't really see a problem

 

My finger is wet with engine oil from inside the intake runners of the TPI base.

 

Your gasket sealing areas look ok though. Some oily residue inside the intake is normal.

 

I realize that due to PCV, but there's one that's clearly worse than the others. That plug was a little "worse" than the others too. I guess I'll know once I get it back together.

 

I didn't really see a problem. Everyone I've taken off with 100k+ miles on it looks the same as that. Let us know how it comes out when you get it back together.

 

There was a TSB regarding warped TPI manifold bases.

I don't recall the exact wording of the TSB, but I do remember that "threading" in the manifold bolt holes near the front and rear water jackets is evidence of the manifold being warped.

I think the TSB came out in '88 or '89 and included a new manifold part number. I would think that your model year would have gotten the newer part number from the factory.

The manifold on my '87 was warped and sucking oil. I was also getting a light throttle ping.

When you get new gaskets, I'd recommend installing Fel-Pro Print-O-Seal gaskets and not the Perma-Torque.

BTW, what happened to the heat shield that's supposed to be on the bottom of your manifold?

 

$20 says it's valve seals. very common on our cars. the best of them do it. if the manifold gasket was leaking you will notice a surging or, hesitaion or high idle from a vacume leak. 152miles is alot

 

Couple things:

She never smoked on cold startup. It wasn't until warm that the smoking started, and only when I would rev it up or drive it.

If I let it idle for 10 minutes hot and revved it, a big puff would come out on the first 2 or 3 revs then stop smoking until I let it idle 10 min again.

When I took the intake manifold off, the passenger side bolts seemed rather loose. I could have taken them off by sticking the right side flat-head screwdriver into the TORX hole and turning it by hand.

 

I forgot about this one. I vote for this too. In fact, I looked back at my records and I too replaced the valve stem seals (both intake and exhaust) with positive-type seals.

In retrospect, I should have just left the umbrella seals on the exhaust valve stems.

It tough getting old....the memory is SHOT.