odd oil pressure !

[rustjunkie]

I am having a issue with the oil pressure on a 2.5 s engine ,its been recently rebuilt approx. 9500 miles ago .oil pressure on start up from cold is 100psi and almost off the gauge until hot then it drops back to 60 to 80 psi at about 2000 to 3500 rpm and around 40psi at idle .this seems a little on the high side to me ? No nasty leaks from engine oil seals and pressure relief valve not sticking as far as I can tell ,taken it apart all seems ok .
now it gets odd when the engine is warm on starting I am getting the triumph knock from bottom end, it doesn't do it every time its started and if it does its about 30mins after switching off . knocking continues until warning light goes out normally within 5 to 6 sec of start up, oil pressure as shown on gauge is straight up to 60 psi .engine has spin on filter conversion Chris Witor filters used, the gauge has been checked and passed ok .I have dropped the sump and checked main and big ends they are unmarked and at 30 mains and 40 big ends undersize. oil pump is new and within tolerance. The engine uses next to no oil .next I am going to replace 0 rings on filter to engine block in case its bypassing the filter but as the filter is down stream of pump and relief valve I cant see this as the problem. Any thoughts on this gratefully received.

[atom]

First thought when I read your summary goes to some restriction in the oil gallery?

[Alan Chatterton]

First thought, is your oil pressure gauge telling the truth? Pop another one on and check. The 100psi plus is not right.
If that is ok, remove a gallery plug towards the front of the block (under alternator) and see what you are getting at the front bearings.
Rocker shaft wet?
Seals in the spin on part of the filter can cause problems, do you have the new style one with a moveable centre or the old fixed one? There were two different sized seals for that one and you may have the wrong one.
Knocking is bad, suggests a bearing gone, did you check all of them, knocking is big ends, are you sure one of them isn't gone?


Alan Chatterton
Chairman
Triumph 2000/2500/2.5 Register

Sent from my iPhone using Tapatalk

[rustjunkie]

Thanks for the information. The filter housing is the older type with two thin rubber rings as opposed to having one thin ring around the edge and a rubber washer in the centre if that makes sense. Plenty of oil at rockers it did have a external oil feed now removed as i didn't think it would be helping matters.l have checked all big ends and all still look brand new .if they were incorrect it would knock all the time ? I am puzzled as to why it doesn't knock from cold as oil will have drained down over night but i have never had a problem from cold . Will dig out a spare gauge check out the gallery then report back.

[Alan Chatterton]

The oil filter stops the start up knock. With the filter full, bottom end gets oil instantly rather than filling the old style oil filter first. It might be the centre o ring on the filter housing, but that still doesn't explain the knock.
Puzzling.
Carry on with your checks and see what develops.


Alan Chatterton
Chairman
Triumph 2000/2500/2.5 Register

Sent from my iPhone using Tapatalk

[Clifford Pope]

Could it be something wrong with the oil pressure relief valve? If it were sometimes stuck closed and sometimes open, would that explain the erratic pressure? Gunged up so that it either gave too much pressure or sometimes none?
Wrong spring, broken spring, damaged seating/plunger?

The old-style spin on conversion needs careful fitting. You need to do the plasticine squeeze test, and then get an appropriate O-ring.

[racer]

when the engine was rebuilt where the gallery plugs removed, front, side and rear? a "must" on possibly a 40+ year old engine, i would go for, like the others, a semi blocked gallery, i now always put my oil pres. gauge and switch into the tapping at the very front of the engine, after having the main gallery blocked by machining swarf, which i think was from having cam bearings fitted but found on washing thru.

[pete lewis]

Before you get carried away I reckon you need to work out
why it knocks with no pressure untill your warning light is
extiguished but the in car gauge appears to show you have pressure
one of them is wrong

As your knock stops when the lights out you have drain back

even the best filters can still drain of its a very crude rubber flap
not rocket science

and when hot oil drains quicker than cold.

just avthought

pete

[rustjunkie]

as yet not had a chance to take a look .but thanks for the reply's. I hope to get on to it this weekend I have found another pressure gauge and got hold of new o rings . also have a new relief valve on order. knock appears to be coming from rear bearing nearest the bulkhead don't know if that's significant or not ? have a feeling I might be dropping the sump again !

[pete lewis]

Just an odd thought after a rebuild a loose flywheel can give
very strange and random knocking

pete