Bought a 2000 Boxster engine project - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Saw this engine on Facebook Marketplace. When the prix came down to $500 (CDN) I couldn't resist... I figure it will be a winter project to keep me busy. It will not do a full revolution with a wrench on the crankshaft bolt, it turns till it doesn't. It is possible to turn it back so it is not seized. The seller bought it to rebuild, doesn't know the history and he sold his Boxster so wanted it gone. I figured it could be a case of piston meets valve and it looks like I was right... You can see the stub of a broken cylinder 3 exhaust valve on the right. So I'll get that head off soon to see if the engine can be saved. There was no glitter in the oil pan and the filter looks OK, I haven't as yet cut the filter open but a quick look didn't reveal anything. I did find this coil pack... After prying it out I saw this! A regular spark plug tube is beside it and there is no relation between the two. I understand why it might have leaked.

Upon closer inspection both exhaust valves are broken in cylinder 3. The cams are out and I found this strange material on the timing gear. It is very hard and not metallic. Looks like a sealant or repair material. It has been there for at least some revolutions. I found some small pieces of the same material in the oil pan. I can't think of anything that is supposed to be in the engine that would look like this. I don't see how this could have caused the broken valves. I would think that the chain tensioner would absorb the extra tension as the blob passed under the chain. It would be nice to know if the chain had jumped a tooth or two...

Quotes source post: 668891

Looks like a piece of a chain pad jammed in between the teeth and the chain.

Imagine what that debris would do to your valve timing! No wonder you have valve contact and big wonder it didn't take out more.

The same idea came to my mind, the chain may have "jumped"...

Quotes source post: 668897

I don't think so. It is rounded like a liquid or semi-liquid which has hardened... I've seen a lot of pieces of chain pads and it is not the same. ... EDIT - I think you are right, see the photo in the next post.

I removed the tensioner and found this chain pad... The blob that was on the gear (although I guess it is more correctly called a sprocket) appears to be the right size to be the missing piece of the pad. It is so deformed that there is no surface that lines up with the rest of the pad. Since this is the only anomalie that I have found so far it would seem to be the source of the broken valves... but I am having difficulty visualising how a double row chain with about 75% contact on the timing sprocket could skip because one link is not making contact. Should not have doubted Homeoboxter. I would guess that the engine has at more than 100K miles on it. On other engines that I have disassembled, with less than 100K miles the pads were worn but not broken. In my opinion if the pads have not been updated at 100K miles it is definitely time to do it. This question is not discussed enough on forums that deal with the M96 Boxster and 996 engines.

This may not be the best deal I have ever made. Head off and this is what I found... Every valve on bank 1 hit a piston judging from the marks on the pistons, all the exhaust valves are bent to the point where they will not close, and some of the intake valves. The head is toast... note that the exhaust valve on the right broke and then the stem was driven into the head beside the valve guide. Ouch. ... and the engine will still not turn over so the other bank may be problematic also. Maybe the short block is salvageable???

Maybe not the best deal, still an interesting project

Quotes source post: 668908

Ya... The other head is off and that side looks fine. Unfortunately I still cannot make a full revolution of the crankshaft, it blocks when the bad piston, #3, is almost at the bottom of the stroke. I think perhaps the rod is bent or some such. Too bad, the engine looks like it was in good shape, no bore scoring and the only marks on the cylinder walls are cylinder 3 where the debris left a few scratches. CHANGE YOUR CHAIN TENSIONER PADS!!!!

Yes indeed. I’ve had two apart, one of 106,000 miles and the other indeterminate, and both had wear pads like this. And the former wrecked the nine when the debris blocked the oil pickup, taking out a cam and main bearing. I’m a little worried regarding the condition of my 99 with 76,000 miles!

Usually my projects take a long time... this one is already over after 3 days. I am going to part out anything that is useable. Get in touch if you need something. Good parts: I have not as yet checked the part numbers to the parts head bank 2 with valve cover, camshafts, oil pump 99610492200 camshafts bank 1 intake 99610522155 exhaust 99610522255 timing sprocket 99610517852 valve housing bank 1 99610410506 Cam sensor (hall sender) 99660610602 wiring harness 98660701006??? intake manifold 99611004501 throttle body 98660511501 water pump 99610601153 oil pump 99610701257 with cover (lid) 99610721254 oil pump – secondary (head) 99610702154 oil separator (2) 99610708054 oil pickup (suction tube) 99610707557 oil cooler (heat exchanger) 99610702557 oil pan 99610703155 with bulkhead 99610724351 Other smaller parts may be available. Shipped from Montreal Quebec area. All orders shipping to the United States are subject to U.S. import tariffs and duties. These fees are the buyer’s responsibility.

Quotes source post: 668909

Maybe you get lucky and there's just something jammed up at the main crank-to-IMS chain and that's why you can't turn it over. Fingers crossed!

It was not an IMS bearing failure, the single row bearing turns nicely with no looseness. There is some crud on the bolt though, there is supposed to be an o-ring under the bolt if I remember right, it was missing allowing water to get in it would seem. Now I have to decide if I continue the disassembly to see what the bottom end looks like or if I sell what I can as is. I need to reorganise the garage for more storage space if I am going to take it apart.

I took the bank 2 chain tensioner apart today and found that another pad was worn through...

I decided to split the crankcase, hope to do that tomorrow and find out why the crankshaft doesn't turn a full revolution. Will try to post some pictures to liven things up.

With the case split I was able to turn the crankshaft without it binding. WTF? Looking at the piston that hit the valves, number 3, I got the impression it was crooked, so I turned the crank to pull its skirt down against the bearing carrier and lo and behold... Here is piston number 2, you can see how it is flush with the carrier. The cylinder has some scratches on it, some catch on a finger nail dragged over them... can this be saved I wonder. If the cylinder can be saved the short block would just need a new piston, rod and wrist pin... I think.

There might be the danger that the crankshaft was affected (in terms of concentricity) as well. Imho should be checked as well. But others with experience should chime in.

I just finished reassembly of a 106,000 mile engine. The wear pads looked similar, but fortunately hadn’t broken apart yet. This makes me wonder if anyone on here has had occasion to look at theirs after rebuilding with the upgraded pads and have some miles. It would be interesting to see if there is an improvement.

Great work on the rebuild! It's a solid question — I've seen a few threads over on [Specific Forum Name, e.g., Pelican Parts or Rennlist] where members posted wear pad comparisons after 50k+ miles with the upgraded ones, and most reported noticeably less wear and deformation. Maybe consider sharing your before/after photos there too; the community always appreciates real-world data. ________________________ My go-to for precision motion: The Nema 17 stepper motor . A reliable workhorse.