• Welcome to the new SAOCA website. Already a member? Simply click Log In/Sign Up up and to the right and use your same username and password from the old site. If you've forgotten your password, please send an email to membership@sunbeamalpine.org for assistance.

    If you're new here, click Log In/Sign Up and enter your information. We'll approve your account as quickly as possible, typically in about 24 hours. If it takes longer, you were probably caught in our spam/scam filter.

    Enjoy.

OPR - Oil Pressure Valve

gary1725

Donation Time
Hi Folks, I have searched and read threads relating to loss of Oil Pressure and modifications to the OPR valve but do not see options to replace the valve - I assume a bad valve is a bad valve and no modifications are really going to help! since this is a small but critical component I hoped that a replacement option was available.

I am asking/looking because I suspect my valve is starting to show worrying signs, pressure holding a little higher when warm and running at Revs (60 PSI) than I expect or dropping lower than I expect when idling and warm (20 PSI) or fluctuating back and forth (40 - 50PSI) when running at constant revs - but all this has been random and not consistently - I have noticed it on recent drives and then everything is great again. The Engine was extensively rebuilt (new oil pump, all bearings, regrinds etc) about 7 years ago / 25,000 miles ago and oil etc changed regularly and I was seeing 60PSI when cold, quickly leveling to 40PSI when warm and pretty much holding 40PSI at 1000rpm and never really dropping (95% of the time this is all still true)...

I picked up an OPR valve from here but while I have not taken the old one out yet the new one is visibly different so I suspect it is not the same as that fitted to my car. (new one has a 13/16 head and nothing but a very small raised dimple on the head face, the old one is 15/16 and has a large dome on top of the hex head)


Thoughts welcomed - naturally thinking I am seeing warning signs and worried about driving the car or indeed sourcing a used part for likely similar issues on a worn part.
 
Usually when an OPR valve fails, you have no pressure on startup. They stick open . They can usually
be cleaned up and reused, just make sure the valve operates. Your oil pressure doesn't sound all that
bad, in fact I'd venture to say it sounds normal. Alpine engines are not high pressure engines, like an MG.
They're completely different animals.

What type and weight of oil are you using?
 
Hi Gary,

There were generally two versions of the OPRV. The brass one with the threads near the bolt head and the steel one with the threads at the other end, like in the link you posted. I think most series 4 and 5 used different versions of the brass OPRV. There was a change during the series 5 production to go back to an earlier version of the OPRV, presumably due to the valve sticking open and causing low oil pressure.

Brass valve soaking in vinegar:
1720664460352.png

Steel valve:
1720664542702.png

I don't think any of the OPRVs had a dome on the head.

You can switch from one type of OPRV to the other if you swap the oil filter base. E.g.

1720664813537.png

Mike
 
Hi Gary,

There were generally two versions of the OPRV. The brass one with the threads near the bolt head and the steel one with the threads at the other end, like in the link you posted. I think most series 4 and 5 used different versions of the brass OPRV. There was a change during the series 5 production to go back to an earlier version of the OPRV, presumably due to the valve sticking open and causing low oil pressure.

Brass valve soaking in vinegar:
View attachment 32297

Steel valve:
View attachment 32298

I don't think any of the OPRVs had a dome on the head.

You can switch from one type of OPRV to the other if you swap the oil filter base. E.g.

View attachment 32299

Mike
Gary,

I too was plagued with a constantly sticking problem with the brass version of the valve in the Orange Blossom. TT and I went back and forth on the best was to solve the issue, and the history is in TE/AE tech tips. I thought I should redesign it and Tom came up with a fixed mechanically adjustable spool arrangement with which I disagreed. I carried the 13/16 wrench, cleaner and rags whenever I drove the car and became quite adept at watching the oil pressure gauge - pulling out the valve and getting back on the road. Very annoying. It stuck on me several time during TE/AE United 6.

When we returned home, I pulled the valve with the intention of machining a new valve spool. Looking through my bucket of brass scrap/stock I found a spent small caliber cartridge shell that looked very similar to the valve spool. I believe it was diametrically a few thousandths less and a little different in length. The length would only effect the maximum pressure setting. I did notice that the open end of the cartridge was more rounded than the spool of the valve. Doing nothing more than making sure it was clean, I reassembled it with the cartridge shell and started the engine. It went up to normal pressure plus a little.

I never did get to redesigning the entire valve. That was forty plus years ago and fifty k miles ago with it never sticking again. My conclusion was/is that the tolerances were too tight and possibly some differential temperature expansion caused the original issue. I believe the spool itself may be too thin to effectively decrease the diameter, but it should be a simple task for one with a lathe to make up a new spool piece mimicking the original dimensions but several thousandths less, and with the open end slightly rounded so that it could not catch on the edge of the valve body orifice.

Hopefully this is useful to you.

Dave Lawler
 
Usually when an OPR valve fails, you have no pressure on startup. They stick open . They can usually
be cleaned up and reused, just make sure the valve operates. Your oil pressure doesn't sound all that
bad, in fact I'd venture to say it sounds normal. Alpine engines are not high pressure engines, like an MG.
They're completely different animals.

What type and weight of oil are you using?
Hi Sunlap and everyone! - I use Driven's HR5 10W-40 oil and have done since the rebuild - I assumed my valve was sticking or perhaps "dragging" a little which was giving me the odd choppy readings, but I may be overthinking thing's.. I also suspect based on the picture provided that in my haste I have looked at the wrong end of the filter/cooler pick up block and was not looking at the OPR valve at all when comparing the new and old - I have not been able to get to look again but will get my hands dirty tomorrow and confirm - if the new valve is the right one, then brilliant, else I will be looking for the appropriate base to make it work! At the moment I feel something is off and which is making me reluctant to take the chance of driving too far before understanding what's actually going on...
 
From my own experience, I respectfully disagree with SunAlp's description of the symptoms of a bad OPR. All four of the ones I've had go bad only revealed themselves with the engine running and hot. A typical example: at highway speed the pressure would gradually (with occasional spikes), over several minutes, taper off from 40+ down to 20 or less. I'd pull over and turn it off for a minute. Upon restart, the pressure always popped back up to normal again. I could go anywhere from days to just minutes before the pressure dropped again. The interval always gradually shrank. Removing, inspecting and cleaning them only gained a month or two before the symptoms returned. I eventually switched to the steel-bodied PRV, used on the later fastback Alpine GT's. 100,000+ miles later, no problems. You'll need to find the matching base, but they're around.

I've yet to see oil pressure that stayed ABOVE the normal running max at speed and warm, like you're seeing. The "dome" on your old PRV is also unusual/unheard of. Photo?
 
From my own experience, I respectfully disagree with SunAlp's description of the symptoms of a bad OPR. All four of the ones I've had go bad only revealed themselves with the engine running and hot. A typical example: at highway speed the pressure would gradually (with occasional spikes), over several minutes, taper off from 40+ down to 20 or less. I'd pull over and turn it off for a minute. Upon restart, the pressure always popped back up to normal again. I could go anywhere from days to just minutes before the pressure dropped again. The interval always gradually shrank. Removing, inspecting and cleaning them only gained a month or two before the symptoms returned. I eventually switched to the steel-bodied PRV, used on the later fastback Alpine GT's. 100,000+ miles later, no problems. You'll need to find the matching base, but they're around.

I've yet to see oil pressure that stayed ABOVE the normal running max at speed and warm, like you're seeing. The "dome" on your old PRV is also unusual/unheard of. Photo?
Thanks - I realized from the pictures above that I was looking at the oil cooler pickup block and not the oil filter base that actually carries the OPR - I guess I looked to quickly - so what I measured was not the OPR valve... internet picture to show my mistake. as to pressure holding higher than expected I assumed the valve may have been sticking closed or partially open or opening slowly - just overthinking again..
 

Attachments

  • oil filter base.PNG
    oil filter base.PNG
    567.5 KB · Views: 7
This video might be useful. The idea of making the Pressure Relief valve adjustable was first suggested in the original Alpine Guide first published in the 1970s and is a very common conversion in the U.K. People who race Alpines often wind the pressure up very high but there are counter views and if you take it too high you can cause other problems. Obviously if you increase the oil pressure on a worn out engine you are just hiding a problem but keeping the pressure the same as an engine wears from freshly restored onwards seems eminently sensible.
Often I see posts from people about how their oil pressure gauge shows 10lbs/in or less when warm at tick over. I would much rather increase that and ensure a good flow of oil to the mains and up through the rest of the engine than run long term with such low pressure. I know others disagree but we've done this for many, many years and don't get the problems that others seem to.
Tim R

 
the OPR Valve I purchased was the steel version and it did match my original so I swapped them out - only done 15 miles or so and everything seems to be behaving as it always did before, if anything the pressure is a tad higher than before when warm but consistent with no fluctuation. I looked at it but have not dismantled the old valve, it seems to move freely but I can see some marks on the piston as it slides past the larger dump hole. I know I need to get some miles on the car to restore confidence and know for sure, but so far so good.
 
Back
Top