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MC's M96.01 strip down and rebuild

If it can't be saved, it may be possible have value as an exchange engine with Porsche for you or someone else, obviously that's a short motor and it still leaves the issue of the state of the heads.

It would be interesting to have comments from a regular re-builder (Hartec perhaps?) to see how typical/unusual this engine is.
 
Took out the tappets and placed them so I know which one is which.
Undid the 15 bolts around the valve tappet guide and then removed it.



The oil baffle was removed with the single bolt.



Then the four screws around chain box. The instructions say that these are pan head with captive washers but mine were allen bolts, three with washers, one without.

The bolt for the guide was then removed, again it looks like somebody has been here before me...



The sprocket for the cam drive was removed and then the head bolts all undone, working from the outside inwards. A few taps with a plastic mallet and the head was off.

Chain guides are well past it:


The combustion chambers look pretty clean:


The bores also look good. I cleaned one up a bit and it looked good.




All parts for this side stored and on to the other half.





I wonder if I was have some camshafts made if it would be possible to have larger journals put on the camshafts and have the head line bored for the larger bearings???

MC
 
Yes that maybe an option if it's not prohibitively expensive (ie more than a used head and cams). The call will come once you know how bad the guides, seats and valves are as that will really push the costs up.

Personally I'd ditch the cam followers as you can buy a set INA ones (they are the OEM supplier) for about £120, not from Porsche though!

:thumb:
 
I personally wouldn't write off those heads because of the cam bearing scoring. The damage will have been caused by particles making their way through the oilways to the bearings, and it's the source of those particles that I would look for.
The cam bearings are oil fed and not subject to serious loads, so because of that I wouldn't be concerned about them getting worse with further use if the rest of the (particle generating) issues in the engine are addressed.

That said, really want to know what Baz from Hartech would have to say on the subject, and the stuff the OP is finding as he progresses.
 
As said the cam bearing faces have been scored because of the swarf in the oil system, whoever ran it possibly ran it low on oil which tore up the crank bearings sending swarf around the engine, they also may have topped up the oil (it was already too far gone) making the damage worse by driving it for longer with what was contaminated in the oil.

If anything can be salvaged I would be tempted to get the cams and head cam faces welded up and machined to standard sizes, this shouldn't cost too much and then at least you are back to just needing a crank and bearings as you had already planned for.
 
It's never a good sign to see chewed up bolt heads and wrong bolts fitted.

It means a bodge-merchant has been there before you.

Goodness knows what has been done.

Flog the decent bits and forget about it.
 
PeterS said:
It's never a good sign to see chewed up bolt heads and wrong bolts fitted.

It means a bodge-merchant has been there before you.

Goodness knows what has been done.

Flog the decent bits and forget about it.

Where is the fun in that :) It will be interesting to see what I find when I get to the source of the damage, and if I can do the job properly and get it back to being a great engine then it will be all the more satisfying for it. As I will be stripping and inspecting the entire engine there will be no unknowns left with a bit of luck.

MC
 
Fascinating read dude, I love a bit of detective work too...

I can't imagine a professional outfit will have tried to rebuild this engine before, it looks like a DIYer's first attempt :what:

Whilst I think you'll easily find the source of the metal particles (shells being my guess, and lets hope the crank isn't beyond repair), I doubt you'll ever find the cause of the problem because that will have been removed at the previous rebuild, unlike all the $hit floating round in the engine!
 
You have metal particles in the oil that have circulated and caused the damage to the cams and pretty much everything else thats oil fed imho .

Crank and shells probably wont be pretty .

See what the damage is when you get it totally stripped .

A total guess but atm it kinda looks like a failed IMS bearing thats been replaced without cleaning out all the metal .

Good pictures and detail though .. its like being at work in the evening for me .. not sure thats a good thing though .

My hat off to you :)
 
The wind was keeping me awake so I thought I would get up early and get a bit more done before I start work.

Moving on to the 4-6 head I basically repeated the same procedure as for the other head, except I couldn't set the engine to TDC on the correct stroke due to other head being off and the chain not wanting to turn. The damage on this head and camshafts does not look as bad, although there are clear signs that it has been off before. The head bolts were not very tight either, I measured them at around 25 lb/ft to break them. The chain tensioner was also not in very tight.

Camshaft holder fitted:


Tensioner removed:


Scavenge pump removed and solenoid cover removed, note the marker pen from a previous visitor:


All bolts undone ready to remove the cover:


Cover off:


Timing chain sprocket unbolted. Tensioner bolts and the bearing covers removed so that the camshafts can be removed, camshafts and timing adjuster removed:


Tappets removed as before, then the carrier was unbolted and removed, the tappets were put back in the correct places. They most likely won't be ever used again, but it is just a habit of trying to keep things where they came from.

Again the bores look to be in decent shape, and the head looks clean:





Now that the heads are off all of the parts have been put on one side for further work later:


The next job is to split the crankcase. The manual calls for a special tool to hold the flywheel pulley still whilst the nut is undone. I don't have one, but I do have a similar tool made many years ago for the same job on another car:


After the puller was removed the crankshaft to IMS tensioner is removed, to get to this I had to remove a water pipe:


IMS cover and centre nut is removed next. The centre nut needs to be undone whilst using a screwdriver to hold the middle still. This calls for another Porsche special tool, I guess deep ring spanners are not part of the German tool kit?


This elbow was then removed, followed by the water gallery which also holds the oil pump:




Guide rails and sump gubbins next I think, either later today or tomorrow.

Although I haven't got a proper bore measuring micrometer, I could have a go at measuring the bores with digital calipers. I assume the problem with bore ovality requires measuring the tops of the bores?

MC
 
Very interesting and educational.

Thanks for taking the time to post these pictures and commentaries. :thumb:
 
Chain guide bolts are removed next:


Three of them came out easily and there wasn't a lot of wear on the guides. The last one has a chewed up head and will need to have an extractor on it at some point. This is the one with the very worn guide. Clearly had a 'partial' rebuild at some point:


Next up the two air/oil separators and the oil pickup are removed:


Then turn the engine over to get the at the two bolts which hold cylinder 1-3 crank case to the bearing carrier.


Then flip the engine over again and undo the single long bolt in the other crank case. Then after undoing the 24 short bolts which hold the two crank case halves together the top half can be simply lifted off. I noted some damage on one face where somebody looks like they have tried to prise apart the two crank cases:


There we have it, some pistons:


The bores do look pretty good, I will have to get them properly measured:


I also noted that two bolts have damaged heads on the oil cooler, that is why it is still on the block. Another job for the extractors.

Next job is to get the pistons off and then the con rods, getting towards the really interesting bits.

MC
 

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