1725 oil pressure relief valve

[SIVAllan]

The S IV (with S V motor) shows about zero oil pressure at idle. Haven't really let it warm up yet, but with a small rev the pressure goes up to 40 pounds or so.

I removed the oil pressure relief valve, and it is soaking in a paraffin bubble tank, along with the base unit.

It did not want to come out, and had to knock the base unit on a table a bit before it fell out. Hopefully that was the source of the low reading.

Question:
The OPR valve is (I'm guessing) an early one. It has round ends. I think it was superceeded maybe twice, for valves with hex ends, and I'd think different base units to match the hex ends.

Searching the forum I found this link to the old forum:
http://www.team.net/www/rootes/rsb/66_06.html

Now I wonder whether to try and swap out for a later OPR and base unit.

Has anyone had a problem with the SV round end OPR valve?

 

[RootesRacer]

I dont think this is the oil pressure relief valve.

My guess (since Ive never taken one apart) is that its the oil cooler diverter valve.

None of the alpine relief valves ever looked like this.

 

[SIVAllan]

I dont think this is the oil pressure relief valve.

My guess (since Ive never taken one apart) is that its the oil cooler diverter valve.

None of the alpine relief valves ever looked like this.

Thanks RootesRacer,

I thought that the other choice was for an oil filter drain .

"Contestant #2" looks like the pic attached, and is now also soaking in the bubble tank.

Allan

 

[RootesRacer]

Thanks RootesRacer,

I thought that the other choice was for an oil filter drain .

"Contestant #2" looks like the pic attached, and is now also soaking in the bubble tank.

Allan

Contestant #2 is the winner.

I often see burs in the inside of the pipe where the relief piston resides.
You get the burs from many years and cycles of the piston hanging just slightly open.
This along with the obvious sludge is what hangs the piston fully open on some unfortunate day.

You should make sure the piston is fully free as it closes else look for a better less worn valve.

 

[Nickodell]

Allan: had the same problem on my SV a few years ago. Examination of the PRV showed a deposit buildup on the inside of the valve which was causing the piston to stick.

You can't remove this with paraffin/kerosene. This is a lighter hydrocarbon similar to the oil the deposit came from. You need a much more aggressive solvent. This is the procedure I used successfully:

1) Empty any paraffin out, then soak the valve in lacquer thinner overnight.
2) Exercize the piston (I used a rod chucked into my drill press) a dozen times with the valve submerged in thinner.
3) Empty valve and repeat 2 half a dozen times.
4) Empty and then submerge valve in engine oil. Exercize piston.
5) Repeat 4.

However, if there is a serious step worn into the cylinder, it might hang up again.

 

[SIVAllan]

Thanks guys,

I dried off the valve and took a closer look based on your comment.

The piston has dried residue on it around some of the edges of the doorways to each side. The piston also is lightly striated, which may be normal wear, or could indicate tiny burs inside the barrel and beneath the piston, where I can't see.

I can see at least the upper part of the barrel's inside surface, and don't see a bur visible through a 7x loop. I do see a hunk of goo a few mm from the top of the inside of the barrel. It is large, a few mm long, and a third as wide.

I understand there is a spring beneath the piston. I can just see the end of it looking through the small hole at the bottom of the barrell.

I also see a lip around the inside of the top of the barrell.

Is "victory" defined as a freely moving piston up to that lip?

I'll pick up some lacquer thinner tomorrow. I take it that mineral spirits are too weak, acetone too strong?

Thanks again,

Allan

 

[Bill Blue]

Acetone is one of the many solvents that makes up the brew known as lacquer thinner. Sometimes the slow drying stuff is pure acetone.

Bill

 

[SIVAllan]

...soaking...

 

[Nickodell]

Allan: I'm probably preaching to the converted, but use lacquer thinner the same way as other highly-flammable solvents with harmful vapors - outdoors if possible, or indoors with plenty of ventilation and far from any ignition source.

 

[SIVAllan]

Thanks Nick, always wise to mention the danger of such flammables. Don't wanna blow/burn up the workbench - or my self either .

After a night of soaking in acetone, the valve is still stuck. Tried to exercise it gently with the end of a screwdriver but no luck. It is stuck pretty good.

Moved it over to a jar of motor oil, vibrating a little on top of an aquarium pump. Will again try to exercise it after some time goes by, then try a spray of brake parts cleaner, then into a vat of lacquer thinner to soak some more.

 

[SIVAllan]

Using Nick's prescription for curing sick OPR valves, the SIV's valve was restored to working order .

Unfortunately, oil pressure only rose (barely) to the first tick mark on the oil pressure gauge at fast idle. That's about 15 pounds of pressure, and is about 25 pounds short.

Pulled the OPR valve to recheck if it had stuck partially open again, but it was closed. (Will replace it anyway as I'm not sure it is to be trusted.)

What are the remaining options?

--fuel pump intake screen?
--fuel pump?

Possibly the oil pressure gauge?

Thanks.

Allan

 

[Bill Blue]

Not possibly the oil pressure gauge, definitely the oil pressure gauge. I knew a guy that spent over $250 addressing low oil pressure on his son's Fiat, all due to a bad gauge.

Bill

 

[Tom H]

Alan, I assume you mean :
Oil pump screen
Oil pump

Tom

 

[Nickodell]

Alan: how many miles on that engine? If it's well worn, 15 psi at idle is not really that bad if you're using regular 20W40 or 30W40 (that's engine and oil hot, of course), and you report that it reaches 40 or more at highway engine speeds, which is the stock PRV blow-off pressure. Seems the valve is performing properly again. I also assume that you recently changed oil and filter (a clogged filter will give low pressure). If it were my car I would drive it happily with those readings.

 

[SIVAllan]

Tom - right .

 

[SIVAllan]

I'll see about checking the oil gauge. The car has about 90k but who knows when the engine was replaced. It's full of new oil 30W with a new oil filter, leaks just a little at the front sump, no smoke issue so far.

 

[RootesRacer]

I'll see about checking the oil gauge. The car has about 90k but who knows when the engine was replaced. It's full of new oil 30W with a new oil filter, leaks just a little at the front sump, no smoke issue so far.

Question, prior to the valve sticking, did you ever have better pressure at idle than you now have?

If yes, your valve is probably still messed up, and the motor is probably not as worn as it looks based on the idle pressure.


Does it go to 40 or 45 PSI at 2500+ RPM?

 

[SIVAllan]

I've not run the engine long enough to let it warm fully so far, but believe it did run up past 25 psi anyway.

Today I let it warm up a bit, and at fast idle it holds around 15, with a rev it goes to 25, but it did not go past that. The tach is not working so I am guessing on the RPMs.

On slow idle, it's back to near zero.

Somehow this doen't quite make sense to me. The engine doesn't smoke, knock, or rattle and doesn't leak much, is full of oil. How could worn bearings make the pressure go so low and not rise to 40?

May be wishful thinking, but it seems like there must be another culprit either in the oil pump or oil gauge, or the OPR valve.

I will use another oil pressure gauge to rule that out over the next few days, and can replace the pump if that is worth the effort (would be nervous about yanking the distributor but the WSM has good instructions).

Your thoughts are most welcome!

Allan

 

[RootesRacer]

Having a fairly worn engine would NOT prevent the oil pressure from hitting the relief pressure, which should be 40 to 45 PSI. It would just do so at a higher RPM, where the engine is pumping more oil to overcome internal leakages and excessive clearances.

If the engine cannot produce the 40 to 45 PSI, then your relief valve is still somehow bypassing oil, OR your pressure gauge is NFG.

Now as far as idle oil pressure, Ive seen engines with fresh internals run with 10 to 15 PSI with a hot 700 RPM idle, this would not bother me on a street engine, juts so long as the engine makes 40+ PSI at or around 2500+ RPM. This says that the pump has capacity to provide an excess of oil to overcome the internal leaks in the RPM range where it matters.

 

[todd reid]

Oil Pressure Relief valve

Alan,
The same gunk that was in your pressure relief valve could also be in the line running to your guage. You might want to check this out while you are swapping out guages. It may be possible to clean and/or blow out the line while you have the guage off.