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Oil pressure relief valve...take 15!!

Alpineracer8

Alpineracer8

Donation Time
Hey, all:

A long while back, we were discussing erratic oil pressure and the general concensus was that the usual culprit is the oil pressure relief valve in the oil filter housing. The problem appeared to be that the brass piston sticks in the brass tube, creating erratic gauge readings. If memory serves, the ultimate fix was the replacement of the brass unit with a late Series V unit made out of steel.

So, here's the $64,000.00 question...does anyone out there have one of these babies that they would want to part with? I had my brass one gone through and we thought we had it taken care of but, on my last trip to the track, I noticed during my last session that my oil pressure gauge would sometimes shoot up to 100 psi with the engine hot. Typically, I see it at around 60 psi while I'm on the track. Naturally, when I came off the track, it dropped to around 15 psi when it normally only would come down to approximately 35 psi. We could go through the valve again but, at this point, I'm losing confidence in our ability to work our magic on the brass unit and make it work. I'd rather not risk my racing powerplant to this "on again, off again" brass POS...can anyone help save a racing engine by selling me a steel oil pressure relief valve???

Thanks much,
 
Its more than that you need a steel relief valve, you need the appropriate base that goes with it.

Making a valve out of brass with a brass piston is plain dumb, you NEVER use the same metals for stuff like that, always one hard and one soft.

Consider disassembling the valve, cleaning the bore in the housing then having a steel piston made.
 
The steel PRV's come up on eBay periodically, NOS, from a particular seller whose name escapes me. They usually go for $40-$50. Most fastback Alpines used this PRV, so that's the best source for the base.

I don't recall the steel PRV being an official part for Series V's. The factory service bulletin that came out somewhere around early-to-mid Series V production said to switch back to using the earlier PRV from the Series IV.
 
Andy- You may want to read the caution Sam gives on this forum (in the "Alpine Cars and Parts Wanted" section, listed as "Need Oil Pressure Relief Valve"). It may require extreme caution to remove the OPV apart from the base, if you decide to go that route. Is it possible to clean the valve while it's still in the base (removed from the car, of course)?

I've not removed an OPV but it has the same kind of hollow bolt setup as that confounded intake manifold coolant hose, and I've busted two of those. Very frustrating.
 
If you've got a sealed container you can try soaking it in carberator cleaner overnight. Sealed to keep it from evaporating of course.
 
I had this problem in my series II, and a local mechanic (William at Corte Madera British & European in Corte Madera, CA) disassembled the valve and replaced the little brass piston with an appropriately sized steel ball bearing. I haven't had any PRV-related problems since.
Rootes Post Vintage Spares also has NOS series V PRVs. I bought one, but I wound up cutting the spring out so that I could use it in the other valve. I think the best idea would be to drill a hole in the bottom of the relief valve and tap it for a small bolt, then replace the brass piston with a steel ball, then use the bolt in the bottom of the PRV to adjust the oil pressure. Using heat to de-solder the old brass valves can warp the brass tubing and weaken the spring.
 
Armand4 said:
I had this problem in my series II, and a local mechanic (William at Corte Madera British & European in Corte Madera, CA) disassembled the valve and replaced the little brass piston with an appropriately sized steel ball bearing. I haven't had any PRV-related problems since.
Rootes Post Vintage Spares also has NOS series V PRVs. I bought one, but I wound up cutting the spring out so that I could use it in the other valve. I think the best idea would be to drill a hole in the bottom of the relief valve and tap it for a small bolt, then replace the brass piston with a steel ball, then use the bolt in the bottom of the PRV to adjust the oil pressure. Using heat to de-solder the old brass valves can warp the brass tubing and weaken the spring.
Click to expand...

http://www.team.net/www/rootes/sunbeam/alpine/mk1-5/techtips/prvalve.html
 
I believe that was Tiger Tom's modification.

A word of caution. The original design was for the PRV to control the system pressure to around 45psi. Except for racing, or to restore pressure with a worn engine, there is no benefit to be realised from raising the pressure over stock and there are several dangers, chief among which are blowing out part of the system, particularly flexible lines to the oil cooler, where fitted.

Someone on the forum related a couple of years ago exactly that happening, after tampering with the PRV.

Oil flow is as important, if not more so, than pressure, since the oil carries away a considerable percentage of the engine's heat. It is second only to the cooling system in this.
 
Nickodell said:
I believe that was Tiger Tom's modification.
Click to expand...

Actually its mine from about 15 or 16 years ago.

Perhaps he did something similar.

I performed this modification to enhance the pressure for a modified 1725 which I ground slots in the sides of the rods for extra rod bearing oil flow and spray to the bottom of the pistons.

The reason I posted the link was to provide a safe way to disassemble the valve for purpose to get to and replace the piston with a superior material.

On my pre-modified valve the regulated pressure was a tad above 40, which in my opinion was not up to par. I would not hesitate setting the pressure to 50psi on a stocker, and in my own case 65psi for added bearing cooling.

As for damaging stuff, yeah if you preset the spring too high you will blow the aneroid in the pressure gauge. The key is to set the tension low, then adjust on a running engine upward till it meets your needs. The instructions even tell you thats what to do.
 
RootesRacer said:
Actually its mine from about 15 or 16 years ago.

Perhaps he did something similar.

I performed this modification to enhance the pressure for a modified 1725 which I ground slots in the sides of the rods for extra rod bearing oil flow and spray to the bottom of the pistons.
Click to expand...


My apologies. I certainly wasn't accusing you of plagiarism (!!) Tiger Tom's method is very similar. He posted it in several places some 20 years ago, including the great handbook The Sunbeam Survivor.

We are in agreement that upping the pressure is a good idea when there is extra bearing clearance, either because of wear or modification.
 
Hey, all of you "in the know" guys:

I took my OPRV out today and, sure enough, the steel piston that I had made for it last year was sticking inside the brass cylinder. In fact, the brass cylinder looks almost like it's got a very slight depression on one side of it close to the bolt head. I have no idea where that came from as I don't remember seeing that the last time we had it apart.

So, if I'm understanding you guys correctly, the Alpine Fastback model was the one that had the all steel OPRV in it, right? But, to use that on a two-seater Alpine, you have to put the matching oil filter base on with the steel valve. Am I following so far?? If that is the case, will these Alpine fastback oil filter bases fit on a 1600 roadster engine? I'm running a Series V spin-on filter base on my 1600 now so that I can run the oil cooler. Does the Alpine fastback oil filter base have the connections for the oil cooler? Is there anything else I need to know about trying to use a fastback oil filter base on a roadster motor? And, in case those aren't enough questions, just what the heck is the difference between the fastback and SV oil filter bases?

Thanks,
 
I believe you are correct that the OPR valve needs a matching base in order to screw in to the base properly.

But I thought that the all steel valve was introduced during one of the 2 or 3 OPR valve changes during SV production .. ??
 
The filter bases will fit all series alpines, only SV cars came with factory coolers but the factory cooler block will fit beneath any spin on filter and be compatible with any 3 or 5 main engine.

I have a much better way to cool your engine oil using a merkur/SVO oil filter adapter. This eliminates the cooler block, those old hoses and that marginally functional "hairy" copper cooler.

The merkur filter adapter puts the filter at a 90 degree angle which will prevent filter drainback and make oil changes less messy since you can direct where the filter oil goes.
 
Yesterday afternoon while going through my stash of parts, I found a block for an oil cooler that goes under a spin on oil filter base. This block, however, has a threaded hole in the front of it on the side facing the front of the car. I've looked in my factory parts manual but my manual only covers Series I-IV cars. I strongly suspect that this is a Series 5 unit but I don't know what the extra hole is for. My OPRV screws into the actual spin-on filter base so I wouldn't think the mystery hole would be for the OPRV. Any thoughts? Could this be the mystery part that I need to run the steel OPRV??

Wishing and hoping,
 
Alpineracer8 said:
Yesterday afternoon while going through my stash of parts, I found a block for an oil cooler that goes under a spin on oil filter base. This block, however, has a threaded hole in the front of it on the side facing the front of the car. I've looked in my factory parts manual but my manual only covers Series I-IV cars. I strongly suspect that this is a Series 5 unit but I don't know what the extra hole is for. My OPRV screws into the actual spin-on filter base so I wouldn't think the mystery hole would be for the OPRV. Any thoughts? Could this be the mystery part that I need to run the steel OPRV??

Wishing and hoping,
Click to expand...

No, the missing part you see the hole to is for a pressure balance valve which prevents full flow from going into the cooler. I think all it does is make sure there is some oil pressure developed befor it allows oil flow to the cooler which helps get oil pressure faster on startup.

Seriously skip all that stuff and go with the water cooled setup, you will not regret is.
 
How does the Merkur/SVO oil filter adapter provide extra cooling? Is it as effective as the stock oil cooler? The 1725 definitely needs the extra cooling, as the fastback Alpine designers found out when they tried to run without one on the prototypes (which is why the aluminum pan came about).


RootesRacer said:
The filter bases will fit all series alpines, only SV cars came with factory coolers but the factory cooler block will fit beneath any spin on filter and be compatible with any 3 or 5 main engine.

I have a much better way to cool your engine oil using a merkur/SVO oil filter adapter. This eliminates the cooler block, those old hoses and that marginally functional "hairy" copper cooler.

The merkur filter adapter puts the filter at a 90 degree angle which will prevent filter drainback and make oil changes less messy since you can direct where the filter oil goes.
Click to expand...
 
RootesRooter said:
How does the Merkur/SVO oil filter adapter provide extra cooling? Is it as effective as the stock oil cooler? The 1725 definitely needs the extra cooling, as the fastback Alpine designers found out when they tried to run without one on the prototypes (which is why the aluminum pan came about).
Click to expand...

IIRC Jarrid is probably talking about the oil/water cooler. it had the benifit of helping get oil to temp at start and cooling when running.. not to mention no PSI drop off.

As for the 1725 needing the extra cooling.. i have brought this up before.. but so many people upgrade their SI-IV alpines (and hot them up) with 1725's but do not add the oil cooler. Then you have the other rootes cars that ran the 1725 without the coolers... sometimes lower output.. but pulling heavier cars.. Are they that important in a non racing application?
 
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