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Help me confirm 300tdi smoke on startup reason


piper109
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Repaired 300tdi engine. Recent rebore and new AMC cylinder head about 20k miles ago. Engine was bought used. Repair was done in a shop somewhere in Shropshire. Car is 99 SD Disco, last of the D1's

When I start up from cold in the morning, I sometimes get a fair bit of blue smoke. When it smokes, the engine does not rev cleanly but rather "8 strokes".

The smoke clears up after 100 yds or so and oil consumption is very little, almost negligible.

A rebuilt turbo was supposedly fitted, with larger impellor.

I think it is bad valve stem seals (probably poor quality when fitted) as the 8 stroking I believe tells me that oil is messing with the combustion whereas a turbo leak would not do that.

I live in 2 places, one is in the lowlands about 300 hundred feet above sea level. The other is at 3200 ft above sea level and it smokes much worse at the high altitude. My neighbours are contemptuous of my smoky old Land Rover as it fogs the neighbourhood.

Any opinions? Am I on the right track thinking its valve stem seals? Anything else to check before I replace them?

I plan on doing them with the head on as the engine runs great otherwise and it seems a shame to lift the head just for that.

Thanks for your help.

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It looks like good old fashioned oil burning blue to me...a bit whitish.

If you have ever heard a 2 stroke engine that's too rich,on choke,it sounds like its firing every other stroke. While its putting out smoke it sounds like that, that's why I said it was 8 stroking.

A while back when I replaced all 4 glow plugs, 2 of them were wet with oil. I'm not sure how they can get oil on them unless oil is dripping off a valve in open position and I cant guess whether its inlet or exhaust. If its getting burnt its probably inlet but I'm assuming they might all be bad.

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I had similar happen; it was the seals, but they had just liftd off the top of the guides - there has been some discussion on this in recent threads.

Nigel

Thanks, What did you do. Did you manage to push them down through the springs somehow. Any tricks you used?

Can you home me in on the recent discussion?

Thanks again,

Steve

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I have removed the valve cover and looked at the valve stem seals. They are very hard to see, buried inside the valve springs.

I removed the rocker shaft to improve visibility.

I believe they are all in place. I had to spray some WD-40 in there to see them clearer. These seals are yellow whereas the ones I have seen on the internet are blue.

It must be very tricky to push down those seals with the springs in place. I'm intrigued to know how you did it, what tool you used and how did you achieve visibility?

I also removed the breather pipe and it was slightly wet with oil but only a little. Same with the intercooler pipe.

I ran the engine with the intercooler disconnected from the intake manifold and no oil seemed to be coming out, just air, even at higher revs. I suppose if there is sufficient oil in the intake manifold, some can run in through an open valve. Oil consumption of this engine is not really high, about 1/2 litre in 5000 miles.

I suppose I'm a bit suspicious of the stem seal quality as there seems to be so much "aftermarket" stuff around of dubious quality and reputation. Are the OEM seals blue?

Steve

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