namasgt

Did you do an intake refresh on this car? Almost looks like a little bit of sand got in there.
Either that or it starved oil causing the marks.

ammonman

The car had an intake "refresh" of some sort before my purchase. I say "refresh" as I have re-done/cleaned up a lot of sloppy work during my stewardship. Seems the last mechanic just replaced obviously failed things rather than doing any of the WYAIT's. Consequently I don't know how much care was taken to pre-clean the intake-to-head area with compressed air prior to taking the manifold off. The car was a Florida car when I bought it so it very well could have had some sand get into the cylinders during some service. I have since done a proper intake refresh.

Mike

Mrmerlin

leak down and or compression test is needed
#8 does not look good it almost looks like there are metal shavings at the bottom on top of the piston

ammonman

Those do look like metal flakes in the bottom of #8. However, the chips don't stay bright white as the camera moves. They may be bits of carbon covered in oil. You can see from a couple of the photos there is still quite a bit of oil in the cylinders.

Agreed that the next step is a leak down check. I'm going to do an initial check tonight on a cold engine and see if any gross failure shows up. If the results indicate there might be life left in the engine I'll get a new t-belt and crank seal installed, then warm up the engine and do a hot leak down test.

Mike

BC

There are not normally that many streaks when looking through the camera bore scope. Something is amiss. I am sure someone can show what a bore normally looks like with the borescope cameras.

Hai gebissen

I am patiently waiting for Greg Brown to comment on the condition of those cylinders.

GregBBRD

The only time I've seen cylinders like that is when silicon beads get left in the intake and work their way down the intake valves and into the combustion chamber.

The resulting "sanding" is quite frankly, completely unbelievable. The stems of the intake valves wear to such a huge degree that you can virtually break a fingernail on the resulting ridge. The rings get completely sanded away. The beads then travel through the oil return holes, destroy the wrist pins and the pin bushings, on the way to the oil pan. Once there, they "increase" the clearances in the oil pump significantly and are generally stopped by the oil filter. Bearing damage is generally minor, although slight scratches on the bearings do occur.

It's really ugly. I've seen way too many.

ammonman

That very well may have happened prior to my ownership. The intake had been painted at some point so it may have been blasted as well. I had the manifold blasted about a year ago and spent the best part of two days washing, scrubbing, and cleaning inside with picks and scrapers to get the thing spotless before reassembly and installation. Since this car spent some part of it's life in Florida it may have ingested sand at some point while being "repaired" by a PO's "mechanic". I put a leak down tester on the cylinders last night to look for gross failures. All the cylinders showed leakdown percentages in the mid-teens at both TDC and BDC with the exception of #6 and #7. These both indicated 20% traced back to leaking exhaust valves. While not great numbers they are in the realm of what I would expect from an engine with 200K and obviously marginal care for some pat of its life prior to my ownership. I think it's it is worth putting a seal and cam belt back on it and starting the engine to see what happens. Since I have no "before" to compare to it may run no differently than it did before the incident. At the very least it will be motive under it's own power while I decide next moves.

Mike

Mrmerlin

I would pull the engine and consider swapping in another one,
don't waste any more time with this coffee table

ammonman

IT LIVES!!!!! I fired it up to day after putting a new front seal, timing belt and plugs in along with a fresh oil change. I also mopped about 1/2 a pint of oil out of the intake. It took a big gulp while on the track. It smoked like a train upon start-up but eventually cleared. I just took it for a spin and it doesn't knock or miss but it is definitely still clearing out the cobwebs. I'll drive it for a week or two before I declare it sufficient until I can source less abused engine. Hopefully 928 Intl. will run their 1/2 off sale this year and will still have the engine Tom mentioned when I emailed last week.

I think I'll bite the bullet this winter and by a dedicated track car to finish my quest for a racing license instead of taking the 928 on the track any more. Once I outgrow a Spec 944, 914, or spec Boxster and can afford to run a proper 928 racer I'll have one on the track again. If I'd have been ready when the Coca-Cola car came on the market I'd have jumped. Oh well, there will be others.

Now to go clean all the grime off the car with a nice hot wash.

Mike

BC

While I also like the idea of a spec car, driving a 928 and having the same car as a track car seems Prudent

Mrmerlin

Mike glad you got it running , it might be interesting to reshoot the bores after it clears up some

ammonman

Thanks Stan. I added some Marvel's to the fresh oil to help dissolve/clean up any carbon or other sludge I knocked loose. I plan to commute it all week and if there are no indications anything is amiss I'll take a bit longer run this weekend. Once I have run it about two weeks I'll pull the plugs and camera the cylinders again.

I had considered keeping with one model to stock parts and work on as both track and daily driver BC. However, 944 Spec racers already built with log book are about 1/2 what I figure it would take refresh and turn a 5 speed 928 into a racer. Plus there are more opportunities to race the 944 Spec. A single car can be built to run NASA, PCA, and SCCA rule books as they all run some kind of 944 Spec series in my neck of the woods. I have 11 tracks in 8.5 hours and 15 if I stretch to 12.5 hours travel time.

Thanks for the encouragement and support all. 928 owners are the best.

Mike