nosnow

I am trying to decide on my best course of action. I have an 89 S4 that has been gone through, interior is close to perfect, new suspension, new brakes, intake refresh, A/C, steering rack and so on. This is a car that I plan on keeping and have owned for 6 years but I am not sure how to manage this situation. The engine has extremely high chrome readings indicating rings are wearing and the number 8 cylinder is down about 15 psi from the rest of the bank so not much and could be carbon. The engine also runs warm never over heating but runs close to the top of the gauge verified with infrared temp gauge. The engine has ~200K miles and goes through a quart of oil ~4K miles so it isn’t burning a lot.

My decision is whether to pull it and rebuild it now or drive it till it pops and keep my eye out for a hen’s tooth used engine which would still need to be rebuilt. The only reason why I am considering holding out for a used engine is due to the 3rd tab on the timing belt bracket being snapped off. I think an aluminum welder might be able to fix the issue but not sure, the block is not cracked and this appears to be the only defect but I have heard not many people have the skill to fix. I am not sure if any additional work would be needed on the heads.

I was debating about trying my hand at rebuilding but quite frankly would be interested in finding a shop/builder to do the rebuild. I'm not interested in doing a built engine the standard Porsche stuff is good enough. I’ll pull it as I want to paint and detail the engine bay while the engine is out.

Thoughts?

FredR

As a rule of thumb a 10% spread of compression test values is generally considered acceptable and in that context `15 psi is neither here nor there- just the kind of number that causes that causes many enthusiasts to fret.

You might want to consider carrying out a leak down test to see if indicates excessive ring blowdown on No 8. I tend to view oil analysis results as being of interest but how much stock one should put in the doom and gloom scenario remains to be seen.

If you have other interests in removing the motor then as I am concerned changing out the head gaskets is a sufficent driver for pulling the motor just to see what is going on corrosion wise. With the motor out and the heads off pulling the pistons is only a matter of minutes worth of extra work assuming the sump gasket would be a routine replacement item. On a 200k mile motor that is over 30 years old the rings do not owe you anything. You then get to see the condition of the big end shells and then you are well and truly down the rabbit hole.

Keeping the original motor is also a big plus in my opinion- I have to live with that consequence but then I had little in the way of choice after I lost my 90S4 some 17 years ago.

Petza914

I'd drive it until it needs rebuilding due to head gasket failure or compression on #8 falling far enough to cause misfires. 1 qt of oil every 4k miles isn't bad at all.

buccicone

Drive it. 4K miles on a quart? That’s not oil consumption.

Kevin in Atlanta

Excuse my ignorance, but what is the 3rd tab on the timing belt bracket?

nosnow

If you are looking at the front of the engine it is the farthest most bolt hole from the center of the engine. It is a little protrusion on the block and the outer most portion is broken off, been gone for years. It holds the timing belt tensioner bracket.

nosnow

Thank you all seems I am a bit paranoid. I am concerned about running hot but will watch it like I have for the last few years.

Kevin in Atlanta

Gotcha.

GregBBRD

1. 200,000 miles and 34 years is way beyond intended Porsche design use.
2. Deteriorated head gaskets/main bearings/rod bearings are common.
3. Very likely that your 'running hot" issue is deteriorated head gaskets, which allows the coolant to "short circuit", before cooling the rear cylinders. (#4 and #8.)
4. 1989 was the first year of the updated cylinder head design and very desirable. '87 and '88 engines have a cylinder head issue, which allows the heads to crack.
5. Finding a good used 89+ donor, which you can just "bolt in" is, indeed, like looking for the Holy Grail. '87 and '88 engines seem to be more plentiful, however, they have the "weak" cylinder head issue mentioned above.
6. Buying a donor engine usually means that you are just buying some else's problem.
7. If the donor engine has been sitting for any period of time, it will need to come apart, regardless. (Cylinder head, engine block, head gasket damage from corrosion.)
8. Oversize pistons from Porsche (the only viable option for repairing damaged bores) are equally difficult to find, once the original bores are damaged beyond use. The last new set I bought (Porsche doesn't have them) cost me a small fortune, but I was thrilled to get them.
9. The Alusil block can be repaired....repairing an "outer edge flaw" (tab broken off) is not terrible to do (although it does require some special skills.) Repairing a crack/hole in the interior portion of the block (away from an edge) is extremely difficult/not likely to work.
10. "Properly" rebuilding one of these engines (so they will last another 100,000 miles) is not cheap....regardless of where you start.
11. Take it out, take it apart, and see what you realistically have to work with. If it is terminal (not likely, at this point) then deal with finding/buying a suitable "core" to disassemble and rebuild. (I have several of these.)

nosnow

Between Greg's write-up and my wife telling me she renewed the 928 as non-op I am going to pull the bandaid off. I was already planning about 6K in parts and another 6K in labor and machine work. I'll probably start gathering parts now and pull the engine in spring when I can work reasonably outside as my garage ceiling is too low to pull an engine so I'll need to do it on the side yard.

jschiller

This caught my eye. Just how low is the ceiling, the more or less standard 8' ?
I will be pulling mine in the near future to change head gaskets and I hadn't given any thought to the ceiling height. I know there are issues in getting the legs of most Harbor Freight type of inexpensive hoists under the car from the front so most folks seem to go in from the side but are there ceiling clearance problems with the boom out far enough to center over the engine?

Has anyone here pulled an engine while under an 8' ceiling?

nosnow

I have a house built in the early 50s with a very low garage door and ceiling. If the car is on jack stands you may have a problem getting the engine out, especially if you are doing it under the garage door.... don't ask me how I know...

Speedtoys

Take it off stands to pull it. You dont need under the car at that point.

Kevin in Atlanta

If you were ever interested in converting your Auto to a five speed I have an '89 with 42k miles with a salvage title.

karl ruiter

Since you have a realistic budget and you are in CA, I would consider going to Greg. I don't know what he charges, or what his current wait time is, but I think you might be in the correct ball park. If you do it in your side yard, it can probably be much less than what you are currently thinking, but my '88 engine has been sitting completed for 6 months or a year and waiting to be dropped back in. Partly because I am getting older and the thought of wrestling it back in the hole is that that attractive, and part because I know there is always a chance I have screwed something up and I just don't want to know.

Basically, right now you know you need head gaskets, because all 928s need head gaskets right now. Obviously, while you are in there, you will do bearings, rings, valve guides, etc. However, realistically, there is gonna be a bunch of other stuff that crops up too. If you have Greg do it, he will just handle the surprises (and charge you for it ), but if you are doing it yourself you can really bog down.