gnosis

If anyone is interested in following along with my 968 engine rebuild, I'm documenting it on a website, complete with photos of the steps along the way. Feel free to browse the site and leave your comments, especially if you have any tips or suggestions as I go. I'm trying to update the site daily, but the frequency and quantity of material will vary depending on how much I get done.

I'm also waiting for parts to be delivered in order to complete the job, and have hit a snag with my new lightweight flywheel. It appears to be the wrong one.

Anyway, read more on my site if you like.

Clayton

BruceWard

Wow, great information!

I look forward to reading further installments and hope to see lots of pictures.

If you need server space or bandwidth please let me know.

Apex

gnosis - Interesting read - thanks for going to the effort with sharing that.

Slightly off topic - here did you get the engine brace? I could use one of those! thanks...

gnosis

I'll post here whenever I update the site. I should be able to add an installment about engine disassembly before the end of the week. I've hit a bit of a snag with the flywheel issue. The supplier has confirmed that it's the wrong item, so it has to be shipped back to the US and then a replacement shipped to me. This will take weeks. I may have to rebuild and reinstall the engine with the original flywheel and clutch for the time being.

Apex, regarding the engine brace, I got it from a local auto parts supplier. I expect most places like that would stock something similar. I can't tell you the names of any vendors in your area since I'm in Australia.

Apex

Thanks gnosis - google has taught me much in the last hour about engine supports... several are available from on-line vendors... ebay also (but of course!)

gnosis

I guess they come in different sizes. You might want to check the width of any you find to make sure they can adjust to the right size for our cars. The one I bought only just fitted into the right spot when adjusted to its smallest possible width. Any wider and it wouldn't have worked without modification.

If you like, I can tell you how wide I think it should be to work properly.

Apex

You've read my mind - I'm going to measure both overall width between fender grooves AND distance from centerline to the engine hook just to make sure!

So no need to measure... but I appreciate the offer - and thanks for the head's up!

gnosis

I've just added more to the site. Info on my flywheel problem and a whole lot of photos of the engine disassembly so far.

I also found the cause of my overheating problem. The impeller on the water pump has separated from the shaft. It's barely spinning when the engine revs. I made a video of the damage. You can read the story and watch the video from this link or see the whole site here to read about earlier stuff including the flywheel story.

Sorry I can't post a link to the new photos. MSNSpaces doesn't seem to allow that. You'll have to go to the Photos tab manually to see the pictures in the Engine Disassembly Photo Album.

Clayton

RajDatta

Nice job there!
Good luck, will stop by to read every so often.
Raj

gnosis

Thanks Raj. I hope people who've never done this sort of thing before will have a look out of curiosity, and I also hope that people who have experience doing this will be able to preempt any mistakes I make, or add their two cents as I go.

And speaking of going, I've just added another update. The final installment of the engine disassembly process. The direct link is here.

Clayton

Miles968

Awesome pictures and details!
I'm glad you are doing it instead of me
It is great to be able to follow along with you!

gnosis

I've updated my site. Info on measuring the internals and a few photos of my power steering gear, which is going to be rebuilt too. Read more here.

Clayton

gnosis

Thanks Doug. It's been really enjoyable work so far, and taking the photos is easy. It also helps me with the reassembly work. Hopefully it will help others too.

The cams are out and cleaned. They look okay, but I haven't measured the lobes yet. The teeth are another matter, however. Lots of evidence that they'll break off at the point where the chain rubs them the wrong way once it's stretched and the plastic guides have worn. If anyone is interested I can take some more closeup photos of the teeth. I expect they'll simply show what my earlier photos (in the VarioCam Examination Photo Album on my site) show. That the metal starts to chip away and eventually the teeth break right at that point. I can now be sure that I don't have any broken teeth yet, but the wear marks are consistent around all the teeth of both cams, so it's inevitable that they'll break.

I was contacted directly recently by someone who's doing the remanufacture of the cams by adding metal teeth. I expect the same person may contact you directly since you've shown an interest in what's being done in that area.

Note that if you want to see any detailed photo in particular from my site, I can provide it. Note that I have high resolution versions of all the photos I've taken so far, and can email them to anyone who wants to see more detail.

Clayton

gnosis

I've updated the site with the results of my piston ring measuring activities. I've drawn some conclusions, but if anyone has any more information or theories about how worn my engine is, I'd like to hear them.

The big surprise was the sheer amount of wear on the top rings. The biggest gap is 1.7mm, and that's not a typo.

Here's the link to my site where you can find complete results in tabular form and my ramblings.

Clayton

gnosis

These blocks aren't coated. They're a metal matrix of aluminium and silicon, with the aluminium molecules etched away from the silicone molecules, leaving them standing slightly proud. The rings run only on the silicon. This makes for an immensely resilient surface because the silicon is such a hard substance. Consequently, it's extremely rare for these blocks to leave a ridge.

I expected the top rings to be worn. I just didn't expect three times the maximum limit. It doesn't make a lot of sense for engineers to design the rings such that the top one has a much shorter life than the others. With that in mind, I expected the wear to be similar with respect to each ring's maximum tolerance. This wasn't the case, as the top ring is 300% wider than maximum, compared to almost within spec 2nd rings.

One of the pistons did have some alignment of gaps. It wasn't the one I've been experiencing the lowest compression on, though, so I can be pretty certain the valves are to blame for that.

The upside is that new rings are going to give me a healthy injection of compression over the old ones.

Clayton