zogster

So I'm troubleshooting an intermittent low oil pressure warning - more here - and want to a) replace the oil pressure sensor, and b) check and service/replace the oil pressure relief valve (hopefully service if it comes to it, as WOWSAH those babies are expensive).

Needless to say, I'm having trouble with both.

Removing the sensor is proving tricky as there's so little space around there, and I couldn't get hold of a 24mm spanner to fit in that space. I managed to get enough of a grip on the sensor body to turn it, but rather than remove the sensor itself as I'd hoped, it's turning the top body part of the sensor relative to the part that screws into the block. So I'm not sure whether to try a bit harder to get a short 24mm spanner, or use brute force to get the top part off then remove the lower part with a 24mm socket (as the sensor is being replaced anyway, it doesn't mater if it's damaged coming off.) The first option is clearly better, but the hammer option is tempting right now.

More importantly, re. the relief valve: I removed it fairly easily, but I'm not sure about checking and servicing. (It's the late type valve, btw).

The inner piston appears to move in and out freely, and spring pressure feels OK as far as I can tell - I'm using a small piece of wood to press it in. From what I've read, failing valves tend to stick open or closed, so this seems OK. I've read up a little on the dismantling and service of these valves, but can't actually see how to pull it apart, and I don't want to do that if it is actually working.

Can anyone give good advice on checking and servicing these?

John_AZ

FYI:





The '87 OPRV has 2 "O" rings that have to be replaced
You must get a new aluminum crush washer or it will drip, drip ,drip...

GL
J_AZ

zogster

Thanks John - I just needed to pull harder on the body of the valve, as it turned out.

Having got it opened, all the internal parts seem OK, and the O-ring (#5) which it says to replace even seems good. So I might just reassemble as is - it looks like I'd have to break the o-ring off to replace it, and I'd be picking a new one from a generic set of rubber o-rings so maybe best to keep what's there.

Edit: actually the O-ring was slightly cracked, and broke when I was taking a closer look. Have the part number for the replacement O-ring so I'll pick one up and finish the job properly

VirginiaF1

Howdy...
While you are at it, any need/plans to replace those crucial oil cooler gaskets?

zogster

And on the oil pressure sender, I'm wondering whether a 24mm crow's foot head on a socket extension would get in there. Seem easier to find than short 24mm spanners - not sure whether the sender body's a bit too wide though...

John_AZ

Just to be clear, both "O" rings should be replaced with the OEM #.
Pelican sells them for a few dollars a pair.
I have also gotten them from the Porsche dealer.
These are not the off the shelf black ACE hardware quality.

It will only take a gentle compression to put together---use a lot of lube oil on the "O" rings.

IF you decide to replace the oil cooler housing gaskets as mentioned above, removing the oil cooler and housing requires the LATE "OPRV Alignment tool" ($50) to prevent binding.

The 24mm Crows should work. I have a basic old thin (ground down) open end that works for me.

GL
J_AZ

951Saga

Yes, though I had to cut the wrench width down with a dremel to fit.

gtroth

FWIW, the Martin 1224MM fits on the oil pressure sender (short enough and thin enough). If the sender's torqued too tight, though, it still may not work for you.

divil

For the sender unit, drop the sway bar to get more clearance, then use a normal 24mm spanner (wrench) from underneath. I have removed mine a few times in this way.

zogster

Dropping the sway bar is looking like a good idea - it's another one of those engine bay spots where you can't really get good access without taking apart a lot of other stuff.

ANyway, ordered the O-rings and crush washer - £0.70 and £0.37, just about the cheapest 944 bits I've ever found!

I think I'm going to leave the cooler gaskets for now - as they're not leaking enough for it to show, I'm doing as little as possible.

zogster

OK, so... (after delays for being a bit sick, waiting for parts or tools, and some rather cold days)...

Changed the oil pressure sender, and replaced the OPRV with its new O-rings.

Started it up, and found pressure reading off the scale, AND the low-pressure warning light. So I swapped the leads on the two terminals on the sender (wasn't being *completely• stupid... they're the other way around on this particular sender), and now I have a healthy oil pressure reading, and no warning light. Yippee!

Conclusions:
• A 24mm crow's foot wrench is the way to go for sender removal. Gets in there without the need to drop sway bars etc, though it is still a bit fiddly.
• The late OPRV is easily pulled apart and reassembled - a good thing, as it's clearly got mixed up with 'DeLorean Flux Capacitor' in the spares pricing regime.
• And I really need to get some new fasteners for the belly pan and aluminium undertray.