95 850 NA Burning oil after rebuild

fredt2 · Post by **fredt2** » 29 May 2025, 15:41

Greetings,
as per previous posts, i rebuilt my 95 850 NA engine after a blown head gasket, in this job i replaced the head gasket, hone and rering and replaced the worn rod bearings. one thing i missed out were the valve stem seals, which i regretably cheaped out on, already having bust my bank on the other stuff.
So, after putting everything together, cars starts normally, but all of a sudden a cloud of smoke started to come out of the exhaust.
After a little digging, i stuck a bore cam inside the cylinders and found some oil resting on top of the cylinders and on the cylinder head and valves, and when i put the camera inside the fuel injector ports, voila, a literal PUDDLE of oil resting on top of a closed valve.
Since theyre the only thing left untouched, i'm quite sure is the stem seals.
Now, i've already taken the cam cover, cams, lifters and stuffed #1 with rope, as per tutorial.
My question is, could it be something else that i royally screwed up doing rebuild? piston rings were all clocked at 120º

And yes, my back and i definetly know that i should've done that when the head was off, gettin' Mike Tyson'd would hurt less

Post by **wizechatmgr** » 29 May 2025, 16:55

How much over spec did you hone the cylinders? Did you order oversized rings as a result? Rings should be staggered during installation.

Did you have the head rebuilt because it sounds like crap valve to seat mating and thus leaking. The valve stem seal is likely just showing you the result of that when we're talking this much oil. Were the rings installed in the correct order? Specifically the oil control ring?

If it were valve stem seals most of the time you'll only notice a puff of smoke at startup.

fredt2 · Post by **fredt2** » 29 May 2025, 17:09

I didn't rebore the cylinders, just honed them because the walls were mirror polished, and replaced the rings because I already had the pistons out, so I did it.

Don't think it's the valve seats, probably would be losing a lot of compression if it were that. The car never had any misfire prior to the gasket blowing either, so i really doubt it, even if it was the valve seating, that doesn't explain the oil on top of the valve

fredt2 · Post by **fredt2** » 29 May 2025, 17:10

And yes, i staggered the rings before putting them back

fredt2 · Post by **fredt2** » 30 May 2025, 15:58

Here's an update:
After removing the lifters, disassembling 3 valve heads with the rope method, i took the seals off and all of them look very worn down, with the hole about ~1mm wider than the new ones, having no proper seal with the valve stem, here are some pics of the old one vs new and new stem seal installed.

Old one/New one

Also, to make the keeper job easier, i bought a pack of 10 2x6mm neodymium magnets, which i had one on the tip of a flat screwdriver, pic below

i then used this screwdriver/magnet to hold the keeper while i maneuvered it around the valve head without the risk of it falling somewhere.

with the keeper on place, with the magnet still attached, i slowly released pressure on the spring, letting it rest on the keeper, then did the same thing on the other side

still gonna come back with updates after i change them all

fredt2 · Post by **fredt2** » 02 Jun 2025, 04:25

Welp,
Changed the seals, pieced everything together, and... Still the same cloud of smoke on the exhaust
Now I'm at a complete loss, the engine idles smoothly, no stalling nor misfire
All that oil doesn't seem to come from the head, but there's very little blowby on the PCV system, much less than before I rebuilt the engine
Maybe it's just the new rings seating on the honing?

Post by **misha** » 02 Jun 2025, 07:54

What oil viscosity is in the engine?

Post by **misha** » 02 Jun 2025, 08:00

fredt2 wrote: ↑29 May 2025, 15:41 piston rings were all clocked at 120º

I hope that you meant...120⁰ apart.

fredt2 · Post by **fredt2** » 02 Jun 2025, 09:02

Yeap, I forgot to add "in relation to each other" at the end XD

Post by **misha** » 02 Jun 2025, 09:49

What oil viscosity is in the engine?

Did it burnt oil before rebuilt?

How about valve guides?

Did the ring had out of spec gap when you put it into a sleeve and leveled with a cylinder....before putting it onto a cylinder?

Was pcv system cleaned or replaced during this job?Could be clogged...also flame trap could be clogged.