Thread: Can anyone identify this tapping noise?

Originally Posted by 350RRC

Did you get a torque reading while undoing the bearing cap bolts by any chance?

No I didn't.

I started to try get an estimate on the mains (mainly because the manual doesn't specify a tightening torque) but I gave up after having issues with my torque wrench.

Originally Posted by DiscoDB

Pretty sure if the shell had spun you would see score markings - so sounds like this is not like the failures seen on the 2.7 but something different has happened.

What spec oil were you running?

I suspect you won’t land on a definitive reason why it failed, can only speculate now.

You can see in the photo that there is 'some' score/friction marks there on the adjacent main. I'll take a measurement when I get home tonight and see if there's any wear. I doubt there will be much. But again, symptom or cause?

Penrite 5W30. Although I had it at an indi recently (3-4 months back) for a oil cooler/rear timing belt change and I'm not sure what they put in it.

Originally Posted by martinfrench

You can see in the photo that there is 'some' score/friction marks there on the adjacent main. I'll take a measurement when I get home tonight and see if there's any wear. I doubt there will be much. But again, symptom or cause?

Penrite 5W30. Although I had it at an indi recently (3-4 months back) for a oil cooler/rear timing belt change and I'm not sure what they put in it.

You will be looking for scoring on the back of the main bearing shell and the housing. This will tell you if it has rotated at any stage and blocked the oil flow to the big ends.

Can they rotate and return to the correct position? - possible but unlikely and now speculating. If the main had rotated I would have expected you would have found this during the strip down.

There are so many unknowns - including if you are not the original owner what it’s prior history was. Damage could have been done some time ago and only now worn enough to fail.

Could also be a manufacturing / assembly defect - such as wrong size bearings fitted to the big ends with too much clearance, again shortening life and only now failing.

I guess the real question now is - so what is next? Does this D4 get to run again?

Originally Posted by martinfrench

The "good" journals measure 62.94, the worn one is 62.62. So I'd need to go +0.5 if I was to get it ground.

0.5 = .020" which is ok but not "desirable" so to speak.
I've seen plenty of engines down to .020" on the mains and big ends, but in a perfect world I guess you'll go with a new crank?

Originally Posted by Discodicky

0.5 = .020" which is ok but not "desirable" so to speak.
I've seen plenty of engines down to .020" on the mains and big ends, but in a perfect world I guess you'll go with a new crank?

And you can get 0.5mm undersized main and big-end bearings for the TDV6.

If re-using, I would get the crankshaft crack tested as well to make sure there is not another pre-existing condition waiting to go snap!

LR Time has detailed data and parts info now after their YouTube rebuild. If you emailed them I’m sure they would share the info.

Originally Posted by Discodicky

0.5 = .020" which is ok but not "desirable" so to speak.
I've seen plenty of engines down to .020" on the mains and big ends, but in a perfect world I guess you'll go with a new crank?

The cranks are hardened to a certain depth from memory.

It's in the LR Time vids...........maybe #3 of the TDV6 rebuild.

He ended up using a different S/H crank anyway.

DL

20 years ago we’d stress relieve, weld up the journal, shotpeen/linish the non-machined areas, re-harden the journal and then nitride the whole thing for good measure. Jobs a good-un.

Edit : maybe 30 years… time slips by.