A bit worrying.

[Lebro]

Just been out for a quick 10 mile round trip in the TR. all going very well, but 3 miles form home noticed oil pressure was very low - about 40 LB down on where it should be. worrying, have checked oil level - ok, no leaks that I can see, oil is on the rockers, no knocking from engine. 1st guess is the pressure relief valve got something holding it slightly open, will check when engine cooled down.

Can't think what else it could be. pressure was very good up till now.

Bob.

[ianc]

Back in the early 1960s, my old TR2's oil pressure would drop to about 40 psi when cruising, and to almost zero at tickover following a blast down the M!.

It rattled like nobody's business when started on a sub-zero morning, but the old heap was amazingly quick when wound up (acceleration with a standard TR2 is not very rapid) and would cruise the M! at 100mph.

You had oil flow, Bob, and that's what really mattered, so no damage should have occurred.

Ian Cornish

[Rob Salisbury]

Oil pump rotor spinning on the shaft as the engine get warm, maybe?

 

Cheers Rob

[Tony_C]

Could the oil pump drive have sheared Bob?.....(perhaps not if you have plenty of oil up on the rockers!)........ Sure you will sort it, not something so simple as faulty gauge?

 

Cheers 

Tony (and happy to help if you need someone to hold and pass the spanner’s)

[BlueTR3A-5EKT]

Yes strip the oprv and wash out any crud.   
I have had exactly that problem and a wash out fixed it.

Part of the problem is the spring binding in its hollow adjuster.   
some one once posted a mod with a pin down the middle of the spring to hold it central in the adjuster tube.

Certainly scares you on a rebuilt engine when the oil pressure drops 

Peter W

Edited May 19, 2021 by BlueTR3A-5EKT

[Lebro]

It certainly does !!!

Well, I let it cool down for an hour or so, went back to it, disconnected a few things to give me better access to the filter housing, then I thought, I would just spin it over to see if there was any sign of pressure. There was - lots ! put it all back together, & it's all back to normal. Been for a spin , all 100 % 75 PSI at 2000 RPM, & 40 PSI at tickover.  whew !  Somehow letting the pressure go to zero must have closed it right up. will keep a careful eye on it form now on.

Bob

[Hamish]

fingers are crossed for  you bob.

hopefully just a self rectified anomaly

[Lebro]

I,m sure it was the prv, anything else would have been catastrophic.

Bob.

[BlueTR3A-5EKT]

2 minutes ago, Lebro said:

I,m sure it was the prv, anything else would have been catastrophic.

Bob.

+1

[Waldi]

Hi Bob,

never a dull moment.

Luckily it “resolved” itself, so damage to the engine is unlikely.

I would remove the PRV for inspection, my new plunger had a very tight fit in the existing body. Bore was not scored/worn, so I sanded the plunger a bit to reduce the diameter of the valve (stem clearance felt ok). It worked ok.

Does your oil filter have a by-pass valve that (also) dumps to the sump? As you have a 4-cylinder, I’m not familiar with those engines.

Cheers,

Waldi

[ntc]

First thing you should do is drain the oil and examine it closely 

[Lebro]

Yes, I think an oil (running in oil at present) & filter change would be a good idea, I was going to wait till I got to 500 miles (only 290 so far).

Another run  out tonight to local group meeting (1st in quite some time) pressures still normal.

Bob.

[jpmf]

My oil pressure gauge reads about 50% of the actual pressure (tested with an independent pressure gauge) when oil is hot, it's fine when the oil is cold.

I wouldn't trust the gauge too much. If you could test the pressure with another gauge screwed into where the oil warning light sensor is, just to be sure.

[Lebro]

I'm guessing the TR6 gauge is electric ?  The mechanical (Bowden tube) TR3 one really can't do that. It may not be accurate, but it won't change by 40 PSI, then go back again. But thanks for the thought.

Bob.

 

[Waldi]

TR6 gauge is hydraulic too Bob.
Good idea to change oil and filter.

[RogerH]

1 hour ago, Waldi said:

TR6 gauge is hydraulic too Bob.
Good idea to change oil and filter.

That is correct  -     see     item #40      Gauge

 

Roger

[Lebro]

Oil & filter now changed. Nothing nasty found in the old running in oil, now filled with Penrite classic light. (20W60).

Bob

[Hamish]

you'll be right mate

 

it was just a blip to keep you on your toes

 

H

 

[MilesA]

These cars do like to keep us on our toes. Great that it was just a momentary blip though...

Miles

[brenda]

Bob the last holiday we had last year my newly rebuilt engine dumped most of its oil, no damage done we are away again this week and have done 800 miles so far but I think I have looked at my oil pressure gauge and oil pressure light more than my Speedo this week and checked the engine every night and morning before we set off. Difficult not to keep looking.

Mike Redrose group