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MG TD TF 1500 - LateTD XPAG

Helping a mate rebuild a late TD engine (integral oil filter).
I noticed that the oil port in the block has a reduction plug fitted. This is the port where the filter bypass oil enters the engine on separate oil filter pumps.
The hole in the plug is the same size as the one in the oil pump body so no restriction.
I have never seen this before and wonder why. The engine has run happily for the last 40 years so it must be OK.
Ray TF 2884
Ray Lee

Not 100% sure which hole you're talking of Ray but the one just above the driven gear support shaft in the block is for filter bypass oil return and normally if that plug in there is removed there is a ball, seat and spring in there that acts as the filter bypass relief valve-They're a bit of a pain to remove, some are quite tight but if you start to tap a thread into the hole, some just pull out using the tap as a handle, others are tighter and need pulling using your new thread and a puller bolt
William Revit

It is in the block where the oil pump mounts.
WSM fig A2 shows the hole where the by-pass valve goes on early engines. On late engines this is the main supply to the oil gallery and the by-pass is built into the oil filter housing on the pump see fig A36.
The only advantage is that it will give a better joint face at a high pressure point
As I said, it has worked for years,just curious to know why.
Ray TF 2884
Ray Lee

Thinking about it, I wouldn't mind betting the block is machined the same as the early type and without the relief valve they've had to fit that plug to reduce the hole dia. for somewhere for the gasket to seal.
maybe
willy
William Revit

yes,the blocks are machines the same except to fit the early pump to a late block you have to drill the oil supply tapping near the oil pressure takeoff. You also have to fit a new bypass valve in the large hole beneath the pump.
To fit a late pump on an early block the bypass valve is removed and the old oil supply tapping is plugged.
This is the only block I have seen with this mod.
Ray TF2884
Ray Lee

Hmm, interesting, I've only ever done early ones by the looks of it, as they've always had the bypass valve-
It sounds like this later setup is what carried through into EPEG 1500 blocks.
Cheers Ray
Merry Christmas
willy
William Revit

this engine needed a rebuild as an incorrectly drilled billet crank grenaded and destroyed it.
Lost parts, crank, 1 con rod and piston, camshaft,oil pump,oil pickup,baffle plate,sump and the tail of number 3 bore (broken off just below oil scraper ring on non thrust side now bored and sleeved).
Some bought and some donated parts will have it back on the road early January.
Ray TF 2884
Ray Lee

Hi Ray. Just guessing, but think a previous owner probably wanted a broader surface for the gasket, as Willy suggested. I guess there is a very small chance that the first integrated-filter blocks were like that until the factory realised it was unnecessary.
All the early "separate oil filter" blocks I have seen have had the bronze ball-seat internally threaded so they can be removed using an 8mm bolt with 1mm thread.
I know of a case where a late pump was fitted to an early block without the early bypass being removed! I believe it caused an issue with priming, but then the engine ran for decades without any ill-effects. It was only after a recent rebuild, that repeated difficulty in priming revealed the issue! I suppose it lowered the oil pressure a bit.
Merry Christmas!
Bob
Bob Schapel

This thread was discussed between 22/12/2022 and 24/12/2022

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