Hi guys,

Got a strange one which I'm investigating so though I'd ask for suggestions.

Had a 1.9tdi 1999 that had the worst polymerised/gunky oil I have seen in a long time, 20 years to be precise. BUT, it ran and had oil pressure. It didn't die and the cam was in good nick when I replaced the tappets. Anyhow got the top end cleaned up and flushed out the sump as best as I could 3 times then filled with flushing oil before starting the engine.

Engine starts and sounds okay but the tappets didn't pump up, then the engine warning no oil pressure came on.

Take the oil filter out - it wasn't even wet with oil, still dry and new. Oh dear.

I then removed the blanking plug by the oil pressure switch and started teh engine. A fair amout of oil pours out.

I'm thinking either a) the oil pickup is blocked, but I can't see why it would be suddenly and also that doesn't explain the oil that runs out when I remove the blanking plug by the oil pressure switch and run the engine.

Or that somehow the oil is draining back into the sump, by something like a wedged open pressure relief valve. I cannot remove it because it's blocked by the oil dipstick housing tube which appears to be welded into the engine block....

So any thoughts?

Any ideas how to get the dipstick out so I can check the relief valve out?

Funny thing is when I first started it, I'm sure the oil pressure came up because the tappets went quiet, then they went noisy and the light came on. So a bit of something may have 'stuck' in the oil pressure relief valve and stuck it open? Or more likely a load of crud has blocked the oil pump pickup tube...

Greg.

You dont take the dipstick tube out, you take the oil filter housing off the block, four bolts.

Thanks - I did see that but due to the amount of crud on the block it's going to be a pain to get it back on cleanly, hence I wanted to simply unscrew the relief valve but the dipstick tube is in the way.

I guess if no-one knows how to remove it I'll have to presume it's hard pressed in and you can't, and do as you suggest and pull the housing.

Greg.

Why not clean off the outside of the block first? These are normally pretty clean engines (helped by the standard undertrays) and a clean motor is more pleasant (and easier, as you clearly realise) to work with.

Also, I could be wrong here, but doesn't the oil pressure relief valve bypass the filter when it gets clogged, rather than bypass the top end feeds?

Personally, from your symptoms and when they appeared, I suspect that the problem is that the capilary in the oil pressure warning switch is blocked. I've seen this happen before, usually associated with a recent oil change.

BTW sorry to ressurect an old thread, but turned out to be a blocked oil pump strainer pickup from a sump FULL of crud. Like cornflakes set in chocolate. Due to him running on vegoil for 20k with no oil changes (we advise 5k max, vegoil polymerises engine oil in short order after that).

Anyhow, no oil pressure was down to that reason.

Greg.