Big End bearings

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J

JCP123

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I’m missing something obvious here but I’m running out of potential culprits! I just rebuilt a 10p TD5 and after 600 miles the Big Ends are Goosed!

At rebuild I changed the oil pump, shells, rings and oil obviously. Everything was like for like and it had no problems or wear before I stripped it.

No, I didn’t check oil pressure on start u as it was fine before and I’d fitted a new pump so assumed 🙄 it would still be good.

What could have caused this?
 
I think you need to start from the basics was the oil pump somehow managing to pull up air up via the seal between the pump and the block?
Is the pressure relief valve working?
Were the main bearing shells different between top and bottom shelles ie drillings?
Is there some sort of restrictor at the top of the block for the oil feed to the cylinder head?
if it was okay before it'll be something simple that you have done or forgotten.
 
Lynall. Unfortunately it has to be something simple as you say; it not a complicated engine. The oil pump gasket was obviously renewed but that doesn’t mean it wasn’t to blame somehow but I can’t see how really; it’s not complicated. There are no restrictions anywhere as far as I know; all oil ways were blown through thoroughly. I must admit that I didn’t think to check the relief valve as, like I said, everything was fine beforehand and I didn’t disturb it.

I ran it on 15W40 and someone has suggested that is not a good idea. Even so, would it throw out big ends after 600 miles? I’m not convinced. I’m not sure if it was synthetic or not but I’ll find out.
 

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15w40 is fine. Doesn't matter what oil you used there's always a knowall handy to say you're doing it wrong. Did you change it at 100 miles and again at 500 miles. They're not solid rules for breaking in, but pretty good practice, certainly the 500 miles change.

That's some pretty deep scouring in a short amount of time, so if I had to put my pay-packet on it then I'd say lubrication issue.
 
I changed the oil after about 80 miles then again at about 2-300 miles. I was just about to do it again at 600 when I discovered the problem. I just can’t understand why it isn’t lubricating. I will check the new oil pump against the old one on Monday just to rule that out but there’s really not much else that it could be.

Incidentally, after cleaning tae pistons I noticed an almost invisible exhaust valve imprint on 3, 4 and 5. You have to hold it to a light to see it and you can’t feel it. I’m wondering if oil pressure will affect the operation of hydraulic tappets enough to cause this. It wasn’t there before so it makes sense that the problem might be related.
 
JCP123 said:
Lynall. Unfortunately it has to be something simple as you say; it not a complicated engine. The oil pump gasket was obviously renewed but that doesn’t mean it wasn’t to blame somehow but I can’t see how really; it’s not complicated. There are no restrictions anywhere as far as I know; all oil ways were blown through thoroughly. I must admit that I didn’t think to check the relief valve as, like I said, everything was fine beforehand and I didn’t disturb it.

I ran it on 15W40 and someone has suggested that is not a good idea. Even so, would it throw out big ends after 600 miles? I’m not convinced. I’m not sure if it was synthetic or not but I’ll find out.
Click to expand...
TBH even of you ran it on 20/50 it should not be an issue in the miles you have done.
There is an old saying that goes, any oil is better than no oil.
I have ran motorbikes for thousands of miles on 15/40 as I could get that from work and I could not afford the proper stuff.

I recently took apart a truck engine that had somewhere around 2 millions kms on the tacho, and the shells were better than yours!

I know little about the td5, but do check as some engines have a restrictor to limit the amount of oil going to the valve gear, and if this was missing it could be an easy route for the oil to take rather than via the crankshaft, might even be the size of the oil hole in the cylinder head gasket?
 
lynall said:
TBH even of you ran it on 20/50 it should not be an issue in the miles you have done.
There is an old saying that goes, any oil is better than no oil.
I have ran motorbikes for thousands of miles on 15/40 as I could get that from work and I could not afford the proper stuff.

I recently took apart a truck engine that had somewhere around 2 millions kms on the tacho, and the shells were better than yours!

I know little about the td5, but do check as some engines have a restrictor to limit the amount of oil going to the valve gear, and if this was missing it could be an easy route for the oil to take rather than via the crankshaft, might even be the size of the oil hole in the cylinder head gasket?
Click to expand...
Restrictor? I can’t say that I’ve seen anything like that. I had no bits left over so I assume it’s still in there if it has one. The head gasket was exactly the same as the one which came off; same make and thickness with no additional or missing holes.
 
Oil is like water and electricity, if there is an easy route it will take it.
 
JCP123 said:
Lynall. Unfortunately it has to be something simple as you say; it not a complicated engine. The oil pump gasket was obviously renewed but that doesn’t mean it wasn’t to blame somehow but I can’t see how really; it’s not complicated. There are no restrictions anywhere as far as I know; all oil ways were blown through thoroughly. I must admit that I didn’t think to check the relief valve as, like I said, everything was fine beforehand and I didn’t disturb it.

I ran it on 15W40 and someone has suggested that is not a good idea. Even so, would it throw out big ends after 600 miles? I’m not convinced. I’m not sure if it was synthetic or not but I’ll find out.
Click to expand...
The big end cap looks terribly hammered in the pic, were the bolts loose when you dismantled, or is it a poor photo?
 
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