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Discussion Starter · #1 ·
My tragic tale:

My 1982 SIII's engine was totally wrecked when I got it (clouds of both blue and black smoke, using a sumpful of oil in a week). A rebuilt injector pump and cleaned injectors solved the black smoke, but the blue smoke needed a full re-build. This involved a re-bore, new pistons, new bearings and a re-ground crankshaft. The head was skimmed (0.006 thou.) and had 4 new pre-combustion chambers fitted. The valve gear was showing its age but was working fine. Being on a limited budget (and still with a gearbox to re-build) I left it.

3 weeks ago the engine (having only done 6,230 miles since the re-build) began to make a horrible clonking noise and running roughly. It cut out and I bumped to a stop at the side of the road. Couldn't see anything wrong, so I started it up again. No noise- just the sweet tuktuktuktuktuktuk of a diesel idling when warm. I pulled away gently and noticed in the wing-mirror that a huge cloud of black smoke was now following me about.

I re-set the tappet clearances, which didn't do anything. A diesel specialist re-timed the injector pump and said the injectors were worn (having seen them on a test-rig, I'm amazed the thing ran as well as it did), so I got a new set. Didn't help. A compression test revealed that No.3 cylinder was 50 p/si down on the others.

This evening I took off the head to see what on earth was going on, and found that THREE OF THE PRE-COMBUSTION CHAMBERS HAD FALLEN OUT!
and that the one that had stayed in only stayed in because it had melted itself to the cylinder head! And that was No.3 cylinder- the one with low compression. The melted parts of PCC had obviously rained onto the piston and completely deformed the piston crown and the very important V-cut out for the valves.

The other pistons were OK, but now had an interesting circular depression on them from the PCC when it came loose from the head. Luckily the bores are fine (no scratching or scoring), so a new set of pistons and a new head are 'all' that is needed- expensive but better than another re-bore.

I'll let the pictures tell the rest:
 

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oh dear

common problem after head skims they need to be centre popped in as the chambers are inserted before the skim the deformation that hold em in gets removed during the skim so it has to be redone after the skim
 

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This is what my engine did too! Only one PCC though but buggered the head and block faces. I had access to another engine and have just got it in and so far so good, it runs.

Amazing thing is, I literally dug this engine up out of a half buried SIII on my in-laws farm. After five years in the mud the thing fired up first (ish) turn of the key :clap:

Check the piston crowns have not crimped the rings on your motor.

Gripper.
 

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Discussion Starter · #5 ·
Yep, same thought occured to me. I dropped all the pistons and checked them, and decided that only one was needed as a replacement. Sent the head off to be checked for cracks/warping etc. and if it was sound to have new PCCs fitted. I had them buy over-size ones and individually machine each one to fit its particular slot. It turned out both valves on No.3 were bent as well (probably once the cut-out in the piston melted), which can't have helped compression, so that was more expense!

Anyway, it's all back together now, and with the new injectors it sounds brilliant- as it should after spending about £430 on it! It seems to have about twice the power as well- I can hold 40mph up hills!

Jack
 
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