Leaking Case Halves?

I'm posting this here too because the engines I believe are the same here. My 2000 Boxster S just had a new IMS bearing, new RMS, new spark plug tubes, actuator seals, new cam chain tensioners and oil separator. It has 160,000 miles. Brought it home and it's leaking oil too much. The shop believes it is a leak from the case itself. They are totally behind the work, I trust them, and I'm bringing it back. I just like to know what I can about this. Is this a known issue? Is there something else that could be going wrong here? The car was leaking a lot of oil when I brought it in. The thought was that was caused by the other issues that were addressed. So either there was still something else that was causing the leak (like the case itself) or something was not put on right (which I think is unlikely).

Unlikely. The correct way to locate oil leaks of any magnitude (rather than throw parts at it) is to first clean the engine and its bay of all residual oil; then add a Uview oil dye to the engine oil and run the car as normal for a day. A UV light source will cause the leak source to light up like it was Christmas.

Thanks Jeff. I thought the explanation sounded unlikely as well.

Hmm. I also posted this on another board, and someone there said they thought that the early 2000 S engines had an issue with case bolts. That made me remember that the shop said they did try to tighten some bolt up because of the leaking. Of course this other person said he thought it was addressed on the 986forum. I went there, and found one post that mentioned case bolts. Who posted it? JFP in PA. Ha. So wondering what details there are about that.

Ah, found Jeff's comment elsewhere: If you are referring to the bolts that hold the case halves together, if they are weeping at all, they should be replaced with new microencapsulated replacement bolts and then torqued to spec before moving to the next one. A lot of M96 engines came with bolts that had no sealant on them, and over time they start to weep, even though they are correctly torqued to spec. Tightening them will not stop the problem, replacing them with the correct new bolts will. This is something we always look for when doing an IMS bearing, the RMS, or doing a new clutch.

Those case bolts are directly above and below the rear main seal opening and are really obvious when they are leaking. If your shop did the RMS and did not notice the bolts seeping, they owe you an explanation.

The only defense I can give, is that they said the RMS was leaking a lot. So they may not have realized there were two sources of leaks there.

I just got the car back. Without asking me, they said they fixed the leak by cutting a little channel and filling it with epoxy. I'm not sure what to think about them at this point.

Quotes source post: 12265782

I do, run away..................there is only one word for that: Butchery

Yes, I just emailed them how disappointed I was. I pointed out that this would be completely unacceptable in my 911 or 912. And clearly I've spent a ton of money on this car for the long run. Not sure why this should be any different.

A question though. Putting aside all of the other things, why would a 24 year old Boxster case leak at this point? They insisted that they do change the case bolts as a matter of course when they do a RMS - but I will say on the original invoice they do not list new bolts. Do cases just warp over time? Or because the bolts get lose? Or some external damage? On a rebuild, do the case halves need to be resurfaced, or just rebolted and torqued?

The reason for the case bolt leaks is realted to the fact that the wrong bolts were installed at the factory on some M96 engines. The correct bolts are micro encapsulated, meaning they have a special coating on the threads, which you can see as a distinct blue/green sealing material on the threads and under the bolthead flange: Bolts without this coating simply allow leaks and tend to become loose. Porsche had a TSB about this problem years ago.

Is there any other reason the case halves would be leaking? I suspect they failed to follow their normal rule of putting in new bolts. And they didn't want to admit it, because it meant pulling the transmission out to replace them. And they would rather slap on glue. But I'm wondering if even with replacing the bolts, the halves can still leak.

When these engine cases are assembled, a very fine bead of a special sealant is put around the lip of the cases where they join. The small number of these special bolts then hold the case sides together. Once a leak begins, it usually starts at the bolts, and if the case sections become loose enough, the bead of seal can fail; but that only happens in extremely rare situations. Normally, the leaks are confined around the bolts themselves. Porosity leaks, literally oil coming right thru the case metal can happen but are very, very rare, and cannot be fixed. In all my years working on these cars, I have never seen one myself, but I have also seen several engines with the bolt problems.

Is there a way to tell from the outside if the case bolts that can be seen are the new ones? The invoice did not show a charge for these case bolts. So I told the shop that, and that I suspect they just didn't do it. The shop just told me that they spoke with the mechanic that did it, and he said he did it, and the bolts come with the IMS kit. I just looked online. I don't see a single IMS kit that comes with those bolts and LN doesn't even sell them. So I just told the shop I think their mechanic is lying to them to cover up that he blew it. I'm wondering then if I could even prove from the outside of the engine that the bolts are not new ones. Although I will say that whatever he put epoxy on, it is not leaking at all now. If the problem was near the bolts inside the transaxle, there is nothing he could have put epoxy on outside of the transaxle that would stop that leak.

Your problem trying to see the bolts is that most of them are inside the bellhousing: And if they did not bill you for the bolts, which are about $5-7 each, you didn't get them. And I have never seen an IMS retrofit that included them, the bolts that come with the new IMS bearing are for the IMS flange cover.

For what it is worth, I spoke at length with the owner today. He said that the leak was coming from the spot marked with the yellow paint below. He said it was first thought to be the bolt to the right, but they confirmed it was not. He believes it was perhaps a flaw from the factory that just lasted until now.