Another dead 306 engine

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Thu 13 Jan 2005 20:39
Another dead 306 engine - jonny scrap-it
Hello to you all. Just before xmas my 96 306 D Turbo with 69000 miles on the clock decided to give up the ghost. I was doing 20 mph at the time under no load when cylinder number 3 stopped working, just like that. For 2 days before this happened I started to get a whistle on boost, kind of like an air leak noise rather than mechanical which I put down to a split in a pipe.
On examination I managed to get it to run again but only on 3 and a half cylinders and a compression test revealed 425 psi on 1,2,4 and less than 100 psi on 3. The links below show the glow plug on number 3. The first 2 are of the one that was in the engine, it appears to have been hit repeatedly by something small, hammering it flat and bending it up. The last picture shows a replacement plug that I installed and ran for about 5 mins before removing it to have a look. That one too has started to bend up but the markings look to me alomost like evidence of pinking, like you would see on the valves of a badly set up petrol engine of yesteryear. It is also worth noting that the marks are only on the lower half of the plug, ie piston side.
Any ideas what the problem might be before I commit myself to yet another weekend in the garage?
www.muchos.co.uk/members/jonboy/CGItemp66771105569...g
www.muchos.co.uk/members/jonboy/CGItemp65321105569...g
www.muchos.co.uk/members/jonboy/CGItemp67101105569...g
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Thu 13 Jan 2005 23:44
Another dead 306 engine - mjm
Something is broken inside this cylinder. It may be a piece of piston or a piece of valve or other debris. Whatever it is, it is not a pinking problem. Diesel engines permanently pink as opposed to petrol engines which only pink due to secondary unplanned ignition. The low compression pressure is the major clue. It looks like the only way to be find out what has happened is to remove the cylinder head. There is an outside chance that something may have broken/detached itself from the inlet tract, bolt, washer, screw or similar, damaged the inlet or exhaust valve(hence the low compression) and is now bouncing around in the cylinder. Whether you continue to run the engine is up to you but be aware that if it is a piece of metal from the above locations it may jam up somewhere(between the piston and cylinder wall?) and cause extensive terminal damage.
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