Thread: TD5 BIG-END BEARING FAILURE

For just one bearing to fail points to bent or twisted con rod, incorrect clearance, if original my money would be on something not right with the con rod, big end cap, bolts.
Is the bearing original, get the rod tested for out of round in big end bore, refit the cap and torque up only one bolt and check clearance, a machine shop should be able to tell you if the rod is the cause, Good luck, Regards Frank.

You didn't mention the oil pump bolt so its probably still tight. However if its loose enough the oil pump wont turn causing bottom end failure, a known problem if the bolt was one that didn't get any/enough thread locker and has not been replaced.

Originally Posted by Tank

For just one bearing to fail points to bent or twisted con rod, incorrect clearance, if original my money would be on something not right with the con rod, big end cap, bolts.
Is the bearing original, get the rod tested for out of round in big end bore, refit the cap and torque up only one bolt and check clearance, a machine shop should be able to tell you if the rod is the cause, Good luck, Regards Frank.

Or bad bearing. ..

my 98 300tdi ate a big end that ate the crank. And its not the only 98 vintage 300tdi to do so....

Oil pump bolt loose. The only thing that will stop a TD5 like this.
While a faulty shell may be possible I'd put money on the bolt.
Number3 is usually the first to go. If it was caught early you might save the crank with metal spray on that journal.
It's engine out job. 2nd hand crank in good condition with new bearings would be my choice and a little ringing around should see you with a good crank and new shells around the 500 - 600 mark plus the labour which is going to come up to tidy sum.

Was the engine oil correct viscosity?

Thanks Strangy, Graeme, Uninformed and Tank for your thoughts.
Mention by Graeme and Strangy of (loose?) oil-pump bolt seems like it might be on the mark. I have had a replacement short engine put in the vehicle, and was shown the old block with the crankshaft facing up. The workshop also showed me the old oil-pump rotors, pointing out circular score-marks on them. For my education, where is the oil-pump bolt located: is it accessible to be checked and tightened from the outside of the engine?

Now, in the day or two before the bearing failure, I noticed and was puzzled by a sound a bit like what you hear when you have a hose running and you kink it. This "cavitation" sound happened a few times while I was driving, and only lasted a short time each time. I didn't know what it was, but I had never heard it from the vehicle before and I didn't like it. Maybe this sound was coming from the oil pump?

Concerning the oil viscosity used: when I changed engine oil, I used Castrol Magnatec 10W-40. About 2 months later, I had the oil-cooler/warmer modified and the engine oil was replaced by the workshop, which told me that I should have used 5W-40. So I presume that at the time of the B-EB failure, and for the month before, the oil was 5W-40 (the workshop specified Penrite).

Something else that I didn't mention before: the workshop told me that the timing chain bottom sprocket from the old engine showed evidence of having had some movement on the keyway.

I did see the piston that came out of the No. 3 cylinder, and to me the con-rod did not look bent. But I'm not a mechanic, and I don't know how much out of true really matters - can you tell me something about this?

Thanks, Andrew

The problematic oil pump bolt is the one that holds the sprocket to the pump, accessible only with the sump removed.

Hi Graeme,
So, is the oil pump driven by the timing chain, and would it be correct that some movement of the lower timing-chain sprocket and scoring on the oil-pump rotors are directly related?
Andrew

If the inside of the oil pump had score marks they could have been caused by the bearing failure (did they show you the bearing shell, if so how about a pic) with metal getting into oil pump, though that seems remote.
Or the pump could have caused the bearing failure through lack of oil pressure.
But why only #3 big end bearing, I still think the culprit is the con-rod, either twisted or out of round.
If it was oil pressure related you would find bearing damage throughout the engine along with cam lobe damage, what's happening with your old engine, Regards Frank.