Desperate help, no oil pressure on 1.9 dg engine.

AMBROSIA · Post by **AMBROSIA** » Sat Jan 05, 2008 5:48 am

I am having serious problems with my t25 1.9 water cooled engine.
Everything thing was fine until 2 weeks ago.
One morning I started the engine and there was no oil pressure:eek:
I quickly switch off, checked the engine oil level etc, got back in car, started it and everything was fine.
I have fitted a vdo gauge and sender using a small brake pipe as an adapter.
This kept happening but not always.
Then yesterday morning it started with high oil pressure (4 bar not the usual 3 bar) and when warm returned to normal. About 1 mile from work it suddenly dropped from 2 bar to 1 bar. I dropped a gear expecting it to increase but it stuck at 1 bar.
When I got to work and stopped the car I again checked the oil level, restarted the car and there was no oil pressure:mad:
I came back 1 hour later, started the car and it was fine again.
Today I have changed the oil and filter and confirmed there are no metal bits or water/fuel in it. I also removed and checked the oil relief valve for dirt or being the wrong way round but it was fine.

To be sure I removed the oil pressure sender pipe in case the vdo sender was lying or air locked, kept turning the engine over and no oil came out

I removed the oil pump cover to see if there was any oil.
Oil did start to ooze out but I would have expected to see it more full.
I checked the pump and although there are marks on the cover where the oil gears touch it looks fine.

I am completely stumped by these weird events and have no idea what to do next?

Judging by the lack of oil in the pump all I can think off is:

1. The pump is too worn and unable to suck.
2. The oilway to the pump is blocked.
3. The pickup tube filter is blocked.
4. The pickup tube is not sealing properly and sucking in air.

Before I start stripping the engine down again can anyone advise?

Many thanks,

Iain.

Piper · Post by **Piper** » Sat Jan 05, 2008 8:57 pm

I had an old Chevy do that once, and I advise you to NOT do what I did, which is ignore it, and keep driving, (ah the stupid things we do as young people). Good luck, I hope it works out, I do love the Vanagons!

tencentlife · Post by **tencentlife** » Mon Jan 07, 2008 9:36 am

So you had the pump cover off, looked at all those things, but didn't pull out the gears? I think your problem is a slipping driven gear. I've seen a few other folks with this problem. The top gear is slipping on its shaft. It gets worse as things warm up. Pull it out and if you can make that gear move one iota on the shaft it is NFG. The pressed-on gears that are stock are crap. I've had enough reports of this that I only use the CB Maxipump I. Their pumps have keyed driven gears.

If yours is slipping and you want to get back on the road, spot weld the gear to the shaft within the recess on the outer end. Make sure the spots are ground flat across the gear face. But if you're this far in, the hardest work is done, a wise man would put in a new, better quality pump.

AMBROSIA · Post by **AMBROSIA** » Tue Jan 08, 2008 2:32 am

I think your problem is a slipping driven gear

Yep, thats the conclusion I have come to also.
I could not get the main drive wheel out as the water pipe was in the way but a slipping gear fits the pattern of events I have been having.
A new oil pump is coming but the quality is questionable.

Thanks for the help people.

AMBROSIA · Post by **AMBROSIA** » Sat Jan 12, 2008 1:42 pm

Well, changed the pump today and it's still not right.
Too ages to pump any oil through to the sender hole but got oil pressure eventually.
I started the car and the oil pressure gradually rose to 3 bar and stayed their until I decided to go for a drive.
After about 3 miles of steady driving it dropped to just over 1 bar and their it stayed regardless of what rev's I did.
After about 20 mins of driving it was still about 1 bar and the engine sounded fine.
There are no rattles from the engine at all.
Here are a couple of vids, one whilst driving and one when I got back:
http://s9.photobucket.com/albums/a64/dj ... V00092.flv
http://s9.photobucket.com/albums/a64/dj ... V00093.flv
The last things I can think of are that the pressure relief value spring is too weak, there is oil leaking with little resistance somewhere is the pressure circuit or oil starvation on the pickup side.
If it was worn bearings I would have thought you would hear some knocking by now?

tencentlife · Post by **tencentlife** » Sat Jan 12, 2008 2:28 pm

If you could hear bearing noises you'd be way too late. They don't start making noise until they're ready to fail.

Weak pressure relief springs are pretty common. Start there with a fresh spring and piston. Adding a 1.5mm washer under the spring seat is good for a little boost in hot pressure, so long as it's not too much when cold.

Bad suction would cause intermittent pressure fluctuations, I would think. The overpressure looping design in the wbx case has always been something that bugs the hell out of me, though. I modify my cases to eliminate it, but I don't have any hard evidence to blame that for OP problems.

AMBROSIA · Post by **AMBROSIA** » Sun Jan 13, 2008 11:45 am

Thanks tencentlife, I am beginning to suspect the main bearings are the culprit.
Here's a vid just after startup showing whats going on with gauge.
http://s9.photobucket.com/albums/a64/dj ... V00094.flv

Joe vw · Post by **Joe vw** » Sun Jan 13, 2008 5:46 pm

If the main bearings were bad the problem would be constant, not intermittent. I would not trust an Electric guage for testing. Screw a mechanical guage in at the engine. Remove and inspect the relief valves.

If Silicone was ever used as a sealant like valve covers ect. it's possable the pickup is clogged, that would cause an intermittant problem. No sump plate makes it hard to determine, but pressurizing the pickup from the oil pump hole could dislodge it out the oil fill hole at the sump, along with flushing with oil- if this is determined to be the problem.

Always coat new oil pump gears with vasaline to start a prime when taken apart. Once together the prime holds in the pickup and gears.

You may have added to your problem though with a new pump unless it was o-ringed. New pumps are out of tolerence on the OD., they are aways .003- .004 too small, this allow them to loose prime and suck air. Even Berg O-rings their pumps as there are none manufactured correctly unless it's a high dollar special pump.

AMBROSIA · Post by **AMBROSIA** » Mon Jan 14, 2008 12:59 am

Well, just driven to work and the engine vibration at 2k is getting worse, so an engine strip down it is

Thanks for all the advice.

Iain.

AMBROSIA · Post by **AMBROSIA** » Sun Jan 27, 2008 1:49 pm

Got to the bottom of the problem.

The pickup tube was blocked with loads of crud, dirt and slime.
The bearing shells have been scored but no major damage to the crank:D

I'm getting all the new parts together now to start the rebuild.
Anyone know where I can source a decent hydro cam in the UK?
Seems rude not to use a more suitable cam with my dell 40's.

tencentlife · Post by **tencentlife** » Sun Jan 27, 2008 8:43 pm

yuck.