TRExp

Stag, 2500 & 2000 Forum

Stag main bearings

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mollysdad Simon Hutchings
Penzance, UK   GBR
Hi,

a friend has just bought a 1974 Stag with the triumph V8 and the oil pressure light comes on at idle after a long run. I just wondered if it was possible to drop the sump and replace the main and big ends as a temp measure to get him through the summer?

Cheers

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
There's a procedure for it in the workshop manual (12.60.44), but I've not tried it myself.
https://drive.google.com/file/d/0B2H2NJt34OffYWY3M2RjYTQtNzFiOS00ZDYxLWJkNmMtMzQ4ZjU3YzczMjQ4/view?usp=sharing



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

sagreenwoo Stuart Greenwood
San Diego, California, USA   USA
Well before changing the bearings it would be best to check the oil pressure by installing a gauge. It could easily be the oil pressure transmitter that is not working correctly.
If the light only comes on at idle after a long run it is probably not serious enough to replace the bearings
You need to see 40 psi at 3000 rpm and 10 psi at idle
I am right now just in the process of changing my big end and main bearings with the engine in the car.
The ROM gives and adequate description of what you have to do. Basically you need to remove the front exhaust pipes and the cross member that that lower suspension arm attaches to. Then you can get the sump off and all the bearings can them be removed.
It took me about half a day to get everything off .
At the moment I am waiting for new shells to come.
If the shells you remove have no markings on them to indicate the size then you will have to measure the crank. You can easily measure the big end journals but not the mains. But when a crank is reground both mains and big ends are done at the same time so they should be undersize the same amount.
Before you start work check the crankshaft end float. Easy to do just follow the ROM. If it is too great then you should change the thrust bearings as well.
Stuart

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1354539 by sagreenwoo But when a crank is reground both mains and big ends are done at the same time so they should be undersize the same amount.
I wouldn't want to bet on that. Many shops will only grind the rod journals if the mains are OK (and vice versa). But if the shells are not marked, chances are very good that they are standard size. Regardless, it's wise to double-check the installed clearance (with plastigage).

BTW, just using thicker oil might get your friend through the summer without the light coming on. I don't know how easy it is to buy 60 weight oil in the UK, but you can always start with 50 and then add some STP or equivalent.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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