33 replies to this topic

[Cooperman]

I had exactly that on a 1275 'S' and it ws DGS (Dirt, grit & s***) in th pressure relief valve. That was despite a thorough clean of everything before final assembly.

That needs to be the first thing to check.

[Cooperman]

I had exactly that on a 1275 'S' and it ws DGS (Dirt, grit & s***) under the pressure relief valve seat. That was despite a thorough clean of everything before final assembly.

That needs to be the first thing to check.

[84sprite]

If Changing the oil filter, I use Mann or Framm filters, I'd then check for flow to the head

Cal844
It’s a brand new MG Rover one that I fitted on rebuild

[84sprite]

I had exactly that on a 1275 'S' and it ws DGS (Dirt, grit & s***) under the pressure relief valve seat. That was despite a thorough clean of everything before final assembly.

That needs to be the first thing to check.

Cooperman 

yeah I think this will be the first check this evening - I really don’t want to pull the engine unless i really have no other option

[Cooperman]

If you initially had pressure it is unlikely to be a build issue. The rubber ring is not easy to distort and even withour the ring, it is unlikely the pressure would go to zero.

The symptons are exactly what you would expect with a stuck relief valve. When mine happened it was on the first rally after building the engine. At normal tickover when hot it was reading virtually zero, but when revved over 4000 rpm it climbed to 50+ psi and at 6000 rpm it was 75 psi. On removing the plunger, which was hard to get out as it was partly jammed by a small piece of swarf, it was obvious that it had stuck in the open position. Cleaned up the bore and seat for the plunger, polished the plunger with 1500 wet & dry, then with 'Brasso' and it was fine. I also put a small washer under the spring to slightly increase the spring load.

I'm fairly sure that is your problem. I guess you were only using quite low revs at the time.

Good luck with it.

[84sprite]

If you initially had pressure it is unlikely to be a build issue. The rubber ring is not easy to distort and even withour the ring, it is unlikely the pressure would go to zero.

The symptons are exactly what you would expect with a stuck relief valve. When mine happened it was on the first rally after building the engine. At normal tickover when hot it was reading virtually zero, but when revved over 4000 rpm it climbed to 50+ psi and at 6000 rpm it was 75 psi. On removing the plunger, which was hard to get out as it was partly jammed by a small piece of swarf, it was obvious that it had stuck in the open position. Cleaned up the bore and seat for the plunger, polished the plunger with 1500 wet & dry, then with 'Brasso' and it was fine. I also put a small washer under the spring to slightly increase the spring load.

I'm fairly sure that is your problem. I guess you were only using quite low revs at the time.

Good luck with it.

Thanks cooperman 

yeah It was only running to first set the ignition timing - it dropped to about 20psi during this .... then out the gate up the road so was running at low revs for 10 mins then upto about 3000 rpm to check gear changes that’s when I noticed it had dropped to 0

[Cooperman]

Alternatively it could simply be the gauge. Do you have a low-pressure warning light as well as a gauge. Either fit a low-press warning light, or check the gauge on another vehicle. That's after removing the plunger and checking for DGS in the bore/seat.

[84sprite]

Alternatively it could simply be the gauge. Do you have a low-pressure warning light as well as a gauge. Either fit a low-press warning light, or check the gauge on another vehicle. That's after removing the plunger and checking for DGS in the bore/seat.

I had the low pressure light wired while testing the engine out of the vehicle .. but since fitting the engine I didn’t wire it up because I had other wiring that needed doing to start from key and thought I could rely on the gauge.. it’s only a couple of wires so will wire it up 

[84sprite]

Ok all ... I took the relief valve out ... all looked clean and good ... connected the pressure light and reseated the valve .. took out plugs and ran on starter still no pressure so I took the pipe off the back of the gauge and tuned her over again ... a bit of spluttering from the pipe and then a steady stream of oil and the light went out ... reconnected the pipe to the gauge and 60ish psi ... so all I can put it down to was a blockage in the pipe

Light on no pressure before starting on starter motor
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Light off turning over on starter motor
 EF1EA995-9DCF-42D8-B99F-CFADCF8149B0.jpeg   38.4K   4 downloads

Edited by 84sprite, 06 May 2021 - 10:42 PM.

[cal844]

Air in the pipe preventing it reading. Was there oil flow to the rocker assembly?

[nicklouse]

Air in the pipe preventing it reading. Was there oil flow to the rocker assembly?

Air in the pipe makes no difference to the pressure read. A blockage would.

[cal844]

Air in the pipe preventing it reading. Was there oil flow to the rocker assembly?

Air in the pipe makes no difference to the pressure read. A blockage would.

That's true, my apologies.

[Cooperman]

Well done, problem sorted with no need to do anything serious.

[burchy35]

That's excellent news. I was about to ask if you had used any of the dreaded blue roll while building up the motor to temporary block up any openings.
But panic over, carry on and enjoy 👍

[sledgehammer]

I'm thinking of fitting a low oil pressure buzzer -

 

when driving , the oil light isn't really that noticeable , I tend to look for pot holes now a days & other cars

a buzzer would let me know instantly that something is wrong , either that or a fog light oil light