Recently my 1970 E-Type will fire up as normal and show round 60 PSI oil pressure, but within a minute or less, pressure drops to somewhere between 0 and 5 PSI. Sometimes it will read closer to 5 or 10, but usually its just a hair off the lowest marker on the gauge. If I let the car warm up, shut her off, and then restart say in 15 or so minutes, the gauge will read a more normal 45 PSI - but again drop off quickly to the same low reading as when cold. The car used to have great oil pressure, and nothing has happened that I am aware of to change anything - in fact I doubt there has been more than 30 miles between reading 25 - 40 PSI warm and what its doing now.
I plan to change the oil, install an auxiliary gauge, and convert to a spin-on oil filter (Cool Cat unit) but I figured now would be the time to address a faulty pressure valve, and or isn’t there another bypass valve too? Does the issue I am having point to a faulty by-pass or pressure release valve? Are they serviceable? I don’t currently have either a new pressure release valve or bypass, so if I had to order them that would really set back my planned schedule.
Most likely, it’s the oil pressure relief valve: you can determine this by pinching off the bypass return line with a pair of clamp pliers, and see if it brings the pressure up. This is precisely what happened to my car, and as soon as I put a new valve in, all was well.
“you can determine this by pinching off the bypass return line with a pair of clamp pliers” - Not to be a dunce here, but I assume that the bypass return line is the short length of hose running vertically from the oil filter housing down into the pan…yes?
Is the relief valve serviceable - so if I take everything apart tomorrow can I clean it up, or out etc? Or is this a replacement-only sort of situation?
The valve should open with 12lb of force on it. The spring should be 2.00 inches long and compress 1" with 9.5lb force on it.
Personally I’d ensure that you have identified and fixed the low pressure problem before changing to the spin on filter. Then you only have a single source of errors rather than 2.
The other valve is a bypass valve that is there if your filter gets completely clogged.
Could it be the sender that is at fault?
Say, an electric issue such as decreasing voltage, increasing resistance in the circuit, that arises and increases when the circuit is closed…
It is interesting that the OPR valve would be intermitant but try Wiggles test immediately and that will give you valuable info as to how to proceed. At least on my 63 FHC, the OPRV is part of the casting that fits between the oil filter and the engine block. It is definately servicable, although all there is to “service” is to check that the plunger is not stuck and to replace the spring. You will need a new paper gasket.
My next step would be the mechanical gauge. I cannot think of any scenario where the type of filter (OEM vs. spin on) would be the culpret.
Hoever, if it has something stuck in it holding it open (as mine did), it can be removed, cleaned and replaced. As far as I know, replacements are not available from the usuals.
I’ve ordered the new spring and valve - FYI that S.N.G lists the spring and valve for my 1970 2+2 versus the single piece valve, but I guess we’ll see . If I can ever find the brass adapter I ordered a few years ago, I’ll also have a second oil pressure gauge to compare to the one on the dash.
Changing to a spin-on was a plan before this issue arose, I just never got around to making the swap - so I don’t expect that the filter or anything is the issue, I just happen to have the changeover kit, and will make the change while I’m covered in oil anyway.
I guess that your car must have an older engine then. SNGB shows the changeover at engine number 7R.35583, and engines numbers in that range were fitted to early S2 cars built late in 1968. Hence my assumption you’d have the later oil filter housing. A photo of the underside of the housing would identify it.
I couldn’t speak to the year of the engine - it is original to the car though. I just bought the part S.N.G indicated for a Series II 2+2. I do see the part you have pictured (special order only) , but S.N.G calls that the Oil FILTER relief valve, whereas the part I bought is the PRESSURE relief valve Its not clear to me if they are in fact supposed to be the same thing for different engine years, but I am guessing they are both correct, as the filter relief valve is there to operate if the filter gets plugged up and so allows oil to bypass the filter, meanwhile the pressure relief valve operates on pressure only, and doesn’t care if the filter is blocked or not - so perhaps both parts are correct.
I can understand why you would think so, but unless your engine number is earlier than 7R.35583 (or is fitted with an oil filter housing from such an engine), you have ordered the wrong part. From the SNG web site:
Items 17&18 are the Pressure Relief Valve which routes oil back to the sump if oil pressure exceeds 60psi or so. Item 15 is the Balance Valve (which SNG also refer to as the Oil Filter Relief Valve) which bypasses the oil filter if the pressure differential across the filter exceeds 10psi or so (indicating it is clogged). Item 15 does look very similar to the Pressure Relief Valve for the later Oil Filter Housing, which is confusing…
Back to the SNGB web site:
Oil Filter fitted from engine #s from 7R.35583
The Oil Pressure Relief Valve is item#13 (as per the photo I posted earlier). It does look very similar to the Bypass Valve for the earlier version, but it isn’t the same part. If you remove the nipple #16 from the oil filter housing you won’t find any oil filter relief valve and spring (which are there in the earlier version). For this later oil filter housing, the Bypass Valve (which bypasses if the filter is clogged), is a behive spring valve that is part of the housing itself:
Here’s hoping that you do in fact have the earlier oil filter housing. If not, you can still unscrew the Pressure Relief Valve (as per my earlier photo) and hopfully you will find that some debris is trapped in it which can be removed. Good luck.
Well, if it is indeed the wrong part, it won’t be the first time. The part you reference is not available anymore from SNG - so I guess regardless of right or wrong, I wasn’t getting the other part anyway As you say - with any luck I’ll find something obviously stuck, and easy to remedy.
It will be annoying though - I’ve actually been mostly disappointed in the parts knowledge from other suppliers lately, which is why I went SNG this time - sigh.
Check with Welshent. Awhile back they advertised they had some NOS ones. I purchased one ( not sure how to tell if it is NOS) but have not installed it yet. An SII PRV is not serviceable.
Mine did the same type of thing. Check to make sure your sending unit is tight. Mine was a little loose but didnt leak much. A little oil in the threads made it loose a good ground connection.
I use the XJ6 filter blocks. You just have to be aware that at least the later ones have a 60 psi spring in the pressure relief valve, so depending on the condition of your engine you may have to change the oil pressure gauge to a 100 psi gauge.
WOW…just wow…I learned so much, thank you
…you all may be “barking up the wrong tree”… I have added this to my knowledge…and kept quiet
Mitch
Oh…we need to Honor our suppliers of these parts…over on the Triumph side, talk like above and we lost Victoria British (Becky sellls classic truck parts now…L&M…much better…people fix trucks…and maybe appreciate her effort?). Then we lost the Roadster Factory…
Keep them on the road…sure thing
Mitch
Triumph cars not motorcycles
. If I can ever find the brass adapter I ordered a few years ago, I’ll also have a second oil pressure gauge to compare to the one on the dash.
