gregg reese

what is the allowable crankshaft end float on a 2000 boxter s? Anyone know the specs?

Thanks folks.

Gregg

Macster

AFAIK Porsche doesn't publish that info.

I would expect the play to be pretty much the same as for other engines. From when I worked on a few engines, the allowable play at the time of assembly was in the neighborhood of 0.002–0.006 inch.

An engine that had been in service as a daily driver may see this climb to 0.010 inch without problems. Not sure how high this can go before there would be trouble. A good sign the clearance is too much would be if a manual transmission equipped car manifests a deep low volume knocking sound at hot idle. A automatic can just manifest a clunk once in a while as the car transitions from stationary to moving or when coming off the throttle once moving.

What is the end play?

Did you have a chance to look at the crank's thrust face for signs of wear? Are the buttons which the face spins against in good condition?

gregg reese

Thanks Macster, I think your allowable play estimate is a good one.

The end thrust on my original engine was off the chart. This is because the the thrust bearing had, in fact, failed. On dismantle, I found part of it in the oil return pump and part of it in the casing half. Yes, the crank's thrust face was worn badly and there was wear/damage on the bearing housing and debris in the oil pan.. For any of you who have not experienced this, it is a major problem. Nary a bolt was left unturned in getting to the bottom of this.

I have decided that it is preferable and possibly cheaper to replace this engine with another used engine. (there was also a tiny crack in the cylinder head.)
So the reason for my question was to make sure I did not buy an engine with significant wear on the thrust bearing.

It seems this mode of failure is relatively rare. The car was new to me, but had about 150,000 km on a 6 spd manual engine. I am unsure how it was treated before I got it, but I suspect it had a hard life.
Thanks again.
Gregg

PTEC

There used to a spec for this but I cannot remember it. We used to remove the rear main seal and measure the crankshaft to the case in four places and check the measurements. We replaced A LOT of engines under warranty due to the measurements being out of spec. In the end Porsche created a "go/no go" tool that was a basically a cnc'ed billet rear main seal on a handle that you attempted to insert between the crank and the assembled case halves. If it fit, it was OK, if it didn't it needed an engine. After this tool was released the number of engines we replaced dropped significantly lol.

Macster

We were talking about end play of the crank how much movement the crank can have in a axial direction.

Maybe the fault is my reading comprehension but I believe what you are referring to is the radial play/position of the crank journal around which the RMS fits with the cavity in the crankcase. In some few engines the crank cradle would shift out of position and the early warning sign was a leaking RMS. But a new one would not last long. The memory is faint now but I seem to recall the engine would not run long enough to try a 3rd RMS but would develop serious internal problems from the shift in position.

Back in 2002 when I had my 2002 in for a leaking RMS I don't recall how I knew about this possible shift of the crank but I mentioned it to the service manager. He got in touch with the factory and sure enough the factory confirmed that it was a concern. The factory I guess provided some guidance and the tech measured the position of the crank in my car's engine and found it to within spec and the new RMS was installed -- along with the improved IMS bearing end plate with the improved seal -- and the engine was fine and the RMS and IMS bearing end plate both remained leak free from then (the work done at around 25K miles) to when I sold the car with 317K miles on it.

Later I read/learned at any rate Porsche had a "go no go" gauge made for techs to use. If the gauge could be slipped over the crank journal and into the crankcase cavity where the RMS was pressed the crank shaft position was ok.

PTEC

You're right he could be asking about end play or axial movement in the crankshaft, I did not think of that. The term end float could mean a few different things i suppose. And yes I was talking about radial play which as you found out first hand was a big problem.