Club 80-90 Forums

Hi Fellow mechanical horse whisperers,

Working to diagnose the sudden and complete lack of oil pressure in my engine and would appreciate some input from someone more learned than me.

First, some background: The problem occurred after the van had been parked for almost 2 months while I replaced the water pump, on first startup there was no oil pressure. Before being parked up the oil pressure warning light did not activate, except occasionally on long motorway runs.

Things I've checked/done:

1- Changed oil pressure sensor and checked wiring.
2- Cranked engine and tried to observe if there was any oil flow from the sensor hole: there was no flow at all!
3- Changed oil filter and oil: I opened up the old filter and while the oil was definitely dirty (quite black) there was no sludge.

Things I suspect based on reading done so far and where I'm going to troubleshoot next:

A) Oil pressure relief valve seized open? Have replacement valve and spring ready.
B) Oil pump failure?
C) Blocked oil sump pickup screen?

Based on the background so far what would anyone suggest focusing on? My inclination is to go by order of simplicity so A) then B).

As for C), Not sure what I'd do to check a blocked sump screen (apart from opening up the engine). Has anyone had experience with crankcase cleaning solvents? I know they're a divisive issue. One alternative idea I had is to try to suck/hoover up any sludgy residue in the crankcase by introducing a suction tube through one of the hydraulic lifter holes.

Grateful for any insights,
Mohammed

first off you need to confirm you have no pressure with a gauge, cranking and looking for oil at the oil pressure switch is not conclusive as there is little flow until the engine is running especially if it's all drained down which it will after 2 months.

It's more likely just an electrical failure.

If you confirm with a gauge no pressure then ...

Worth checking valve as it's quite easy but I doubt it.

Oil pumps don't usually fail like that, oil pickups don't usually block to give no flow.

check if there is any oil in the coolant?, there is a plug in the gallery that can rot through, then oil flows into water system.

https://www.ebay.co.uk/itm/12pc-ENGINE- ... 3192254380" onclick="window.open(this.href);return false;

Thanks for the gauge link and the advice Mr Itchy!

When it comes to checking oil pressure with gauge while running engine, how long would you suggest I run the engine for? I'm naturally jittery about the potential to cause damage or does the fact that the engine will be run at quite low load mean it's an acceptable risk?

Have you actually run the engine yet?
If so how long for?

With a gauge you will see pressure in under 5 seconds after starting, if you don't then shut it off

Run it 2 or 3 times for about 30 seconds at a time after the oil change.

Well you could run it a few seconds with no oil pressure switch to confirm oil is flowing but I strongly recommend a gauge, noting like 100% clarification.

Everybody with a WBX should have one and check it periodically.

Compression tester too

I should add 30 seconds twice with genuinely no oil pressure your tappets would be rattling badly, are they?

It seems like the oil pump isn't self-priming. Once the oil has drained back into the sump and the pump is full of air, it doesn't have enough "suck" to draw oil up from the sump. I had this problem when starting a DF after a rebuild. In my case the problem was that the oil pump cover gasket supplied with the gasket kit (from Brickwerks) was much too thick, resulting in too much clearance within the pump. The cure was to fit the correct thickness gasket. (about 4 thou IIRC). A badly worn oil pump might produce the same symptoms.

^^^but he hasn't changed the pump or gasket so why would this change after 2 months? far more likely a red herring.

Easy stuff first

- I'm assuming it's an early case DG so only one oil pressure switch, no DOPS system.

Do the electrical test first.

1. Ignition on, wire connected to switch, engine not running - warning light should be on
2. Ignition on, wire removed from switch, engine not running - warning light should be off.

Once the electrics are confirmed OK, then you can continue with Itchyfeets advice

One more thought, did you fill the filter with oil when you changed it, if not you will probably never pull oil through by cranking.

I had one engine once do a similar thing after some work (can't remember what). It was drained of oil for some time, a week or two. Once it was all fixed and refilled with oil and a new (primed) filter, I turned it over without firing (coil disconnected) for quite some seconds, oil light stayed on. I repeated a few minutes later, still on. Ok, I thought, I'll start it up - that'll do it. Nope, like you I ran it for what seemed like waaaay too long with no oil pressure (from 5 to maybe 20 seconds). The damn thing would not go out. So I eventually backed off the oil filter to let any air out, and started her up - GUSH! 2 seconds was all it took, stopped engine instantly, retightened filter, cleaned up, restarted, light went straight out every time from then on. It was weird, but the filter had somehow airlocked even though I'd primed it. So try that...

Sent from my ONEPLUS A3003 using Tapatalk

Thanks for all the excellent advice.

1- turns out my faith in my electrical reconnection was sub par. Systematic troubleshooting as advised revealed incorrect wiring, and not one, but two fault pressure senders. Seeking replacements and will report back.

2- I will follow the advice on priming the filter (I had filled it, but will fill more) and the air lock issues advised and see how it goes.

HOpe ALL having a good weekend and by good I mean camping rather than wratching and wrenching! But wait who are we kidding we love it really.. ha!

Thanks for coming back with an update and glad it seems to be electrical, it's the easiest fix.

Given the description I'm a bit surprised that your van has DOPS, but never mind. Have a look at the page below, make sure that you have the right logic when testing around the switches being normally open / normally closed and which one does which. The "blue" one between the pushrod tubes is the basic / original oil pressure switch. Having two faults switches would seem to be particularly bad luck

https://www.brickwerks.co.uk/brickwerks ... -switches/

ps - they are switches, not senders, just thought I would get that in before Andrew (ajsimmo) steps in, it's one of his favourites