Big End bearings

JCP123 · Friday at 18:19

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?

lynall · Friday at 19:32

What make was the oil pump?

JCP123 · Friday at 19:43

Allmakes

freelance · Friday at 20:22

Did you oil the shells at fitting, and did you prime the pump before assembly? Are the crankshaft journals in tolerance?

JCP123 · Saturday at 04:07

Yes, yes and yes.

lynall · Saturday at 06:08

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.

JCP123 · Saturday at 07:29

Yes, yes and yes

JCP123 · Saturday at 07:41

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.

Phill · Saturday at 10:30

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.

JCP123 · Saturday at 12:15

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.

freelance · Saturday at 17:54

Wrong thickness head gasket?

JCP123 · Saturday at 18:01

Nope! 3 hole Elring came off and a 3 hole Elring went on.

resto_d1 · Saturday at 20:00

Did you plastigauge or measure journal/ big end tolerance to ensure you didn’t need above standard?

lynall · Saturday at 20:00

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.

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?

JCP123 · Saturday at 21:32

resto_d1 said:
Did you plastigauge or measure journal/ big end tolerance to ensure you didn’t need above standard?

The journals all measured as standard.

JCP123 · Saturday at 21:37

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?

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.

freelance · Saturday at 23:10

What condition are the main bearings? Are/were both thrust washers in place ?

JCP123 · Sunday at 10:11

Mains were perfect and the thrust washers were in place.

lynall · Sunday at 10:15

Oil is like water and electricity, if there is an easy route it will take it.

freelance · Sunday at 20:59

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.

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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