Thread: TD5 Engine bearings- have I stuffed up?

With the 2 sets of mains the good news is you have a 50/50 chance of getting right - so try fitting each of the caps in the respective position and see if you can feel a lip or examine the machining marks and look for a perfect match. You may need to get a magnifying glass to view to make sure the cross markings match and line up, and there should be no lip felt with the finger.

Once you have what you think is a match, then get a bore micrometer and check they are all perfectly round and they should be the same.

If you are lucky the two sets have enough of a difference in diameter that it is obvious which cap went with which block.

Matching the connecting rod caps is going to be trickier - especially if you have two sets all mixed up and no number markings. You may be able to match by the split markings and seeing what fits together if the break marks are rough. Again if you can visually match - then when bolted up should be no lip, check cross markings match, check for roundness and internal diameter.

Hopefully someone else will chime in. Good luck!

You've got a bit of a problem, the block is line-bored with the journals in place which makes the journal an individual match for that particular location on that particular block. Likewise with the conrods, they are bored with the journal bolted together. With some precision measuring equipment you will probably be able to determine which main journal fits where; e.g. for position 1 on a block you will have two journals marked 1 and you should be able to determine which of the two gives a perfectly round bore at that location, and work your way down the block. More difficult for the conrods though as you will have 8 potential matches for each rod, unlikely to end up with 8 correct matches I would think.

Originally Posted by POD

You've got a bit of a problem, the block is line-bored with the journals in place which makes the journal an individual match for that particular location on that particular block. Likewise with the conrods, they are bored with the journal bolted together. With some precision measuring equipment you will probably be able to determine which main journal fits where; e.g. for position 1 on a block you will have two journals marked 1 and you should be able to determine which of the two gives a perfectly round bore at that location, and work your way down the block. More difficult for the conrods though as you will have 8 potential matches for each rod, unlikely to end up with 8 correct matches I would think.

Its half as bad as that, as I have the known 5 conrod journals for the engine I want to use - the one with the overheat, I assume from the replies its pretty critical each one is matched up?
Actually, one is known so its down to 4

Do-able then with a bore gauge. Perhaps even visually by matching the hone marks.

Originally Posted by DeeJay

Its half as bad as that, as I have the known 5 conrod journals for the engine I want to use - the one with the overheat, I assume from the replies its pretty critical each one is matched up?
Actually, one is known so its down to 4

Absolutely need to match. When they fracture split the con rods unless you match the cap to the rod, you will get varying clearances. Even bolting on and torquing up with the wrong cap will damage the mating surfaces and you will never get a good seating cap.

But because they do manufacture as one piece and then fracture split the big end cap from the rod, each will have a unique finger print.

A specialist engine machine shop may be able to help, and resize the rods.
And yes, it's critical they are matched.......maybe marking before disassembly would have been a good idea.

Originally Posted by DiscoDB

Absolutely need to match. When they fracture split the con rods unless you match the cap to the rod, you will get varying clearances. Even bolting on and torquing up with the wrong cap will damage the mating surfaces and you will never get a good seating cap.

But because they do manufacture as one piece and then fracture split the big end cap from the rod, each will have a unique finger print.

Could you expand on what the process is to “fracture split” for my education please.

Phil

Originally Posted by Phil 850

Could you expand on what the process is to “fracture split” for my education please.

Phil

From the LR training info on the D2 TD5:



https://discovery2a.com/Resources/Di...gine%20TD5.pdf

These are caps from a TD5 - you can see when they split it leaves a very unique pattern on each cap. No two caps would be identical.



Must admit I did not realise the fracture was so rough on the TD5 - have seen others which were a lot finer. So should make matching easier.