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Last year I took our 1994 Defender 110 CSW down to Rome over the alps. At the end of the long pull up hill the oil warning light flickered on. Once the engine had cooled it went off and we had no problems on the return journey to the UK (apparent from a cooked alternator!). Ihad no problems at all for the rest of the year until the warning light came on permanently preceded by a small clunk.

I immediately stopped and check the oil level which was fine but appeared at the bottom of the dip stick i.e. not plasetered all over it. After stripping the engine down found that the oil pump had suffered a catastrophic failure with the outer ring failing completely and the broken remanants jamming in the timing belt case.

The case is split and needs replacing and I need to check for damage to the bores etc but what I'd really like to know is what is likely to have caused total failure? Is it simply a case of it being old and worn beyond tolerance causing the teeth in the rotors to jam?

Has anyone else suffered a similar problem with their 300tdi?

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When you find out please tell me.

Mine had the gear loose its internal fingers in Feb 2011. All I did was ft new big end shells and a new oil pump. The crank front is damaged but all seems well at this date. I didn't bother about pistons. Just concentrated on the crank.

One of my local indy dealers had this happen on a customer car. He just cleaned the journals and fitted new shells, the car is still running

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What sort of mileage had these vehicles done?

I just wonder whether it is an issue which is related to age or mileage.

At one stage I was running a couple of 300 110s each with over 300,000 miles on them and no such failures. Then again I reduced the oil change interval to 5,000 miles once they got to 100,000 miles just to keep the sums simple and always used Miller's fully synthetic oil.

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Neil without looking it up about 240,000 miles in my case. I too use Millers XFE changed at 6,000 miles.

In my case there is a wonder ?? The front of the crank is rounded off instead of being squared....The wondering is Was it sold to me in that condition 124,000 before it went again.

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The case is split and needs replacing and I need to check for damage to the bores etc but what I'd really like to know is what is likely to have caused total failure? Is it simply a case of it being old and worn beyond tolerance causing the teeth in the rotors to jam?

Has anyone else suffered a similar problem with their 300tdi?

Could you post some pictures? The outer rings in oil pumps of many engines crack between the teeth - it's probably the most common failure mode for that type of pump - but continue to run for some time like this, though with reduced oil pressure (and often not low enough to trigger the light).. It does wear the soft casings quickly, and once this start happening the rest is inevitable. I suspect this may have been the case with yours.

As has been said, the most parts most vulnerable to low oil pressure are the crank journals and the bearings that run on them. It's very unlikely the bores will have suffered much, but pay close attention to the big end journals particularly.

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Sorry for the delay in responding and thanks for the interest. The vehicle has 194,000 on the clock but the block is a genuine LR replacement of indeterminate age. Assuming just the block was changed then the pump is probably original but who can tell. I've attached a couple fo photos and will put the 'in-situ' ones up next week. One of the teeth of the outer ring jammed in the case and I guess at this point the flats on the pump were ripped off by the crank. There doesn't seem to be much damage to the crank nose.

Having taken the head off I see that faintly stamped on the top of the block is .040 - it would be good to know what this means as I intend to fit new rings but don't know what size to use - I suspect over size by .040" is what I need but I really have no idea at the moment. Any other ideas how I might work it out? The bores look pretty good with very little if any step at the top.

The cam lobes - particlarly the one for the vacuum pump were pretty worn.

300tdi oil pump 2

300tdi oil pump 1

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Ouch. A decent set out vernier calipers should be good enough to tell you what's going on with the bores.

Have you checked the big end bearings yet?

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Haven't got that far yet but hoping to get No. 1 piston out this weekend to see what they're like. I'll post an update with more information in due course.

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Decent and vernier are 2 words that you never see in the same sentence. You would be better taking it to.a local engineering firm to ask if they can drop a bore mic in there or even some telescopics to measure the hole properly.

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Fair point, but even on the worst set of verniers, you can read whether it's 40 thou over standard size! I have telescopic bore gauges and micrometers going up to 6" (for this very thing), but not the kind of stuff most people have lying around in the garage...

Agreed that if in doubt it's best to take it to a competent machine shop, though.

Fingers crossed for you.

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Picture of the oil pump failed in the timing case and the wear to the upper big end bearing on Nr.1 piston. The pistons are 40 thou over sized and given the stamp on the block I believe the cylinders were bored out to accomodate. I've ordered a 40 thou oversize KS piston ring to try in the bore and check the ring gap in the bore. As noted before the existing big end bearings are marked with 010 so I'm presuming that these are 10 thou oversized so next step, assuming the rings fit the bore OK, will be to order a set and check the clearance with a bit of plastigauge. I'm presuming that I'll need to hone the bores before rebuilding - something I've never done before so any advice welcome! The Nr. 1 cylinder seems to have very clear hone marks still and no lip at the top or bottom so it seems in pretty good condition.

Failed oil pump in situ in timing case

Upper big end bearing Nr. 1

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I'd get some advice from good machine shop, but they'll probably recommend a light hone. It is easy enough to do yourself, but won't cost you a lot to get the the shop to do.

Get the crank journals checked and maybe polished too, if they have survived without any scoring.

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