Low oil pressure on a low mileage engine

[rabbitman]

On the '92 golf.

I hooked up a pressure guage and with no tach (when I did this test) 

@ idle or slightly revved with COLD oil it was 60-70psi, not nearly as high as my rabbit.
@ 3000-3500rpm with HOT oil I get 30-35psi
@ idle (700-900rpm) with HOT oil it was 10 psi at the most and I think I can hear a rattle that shouldn't be there, more like a thudthudthud noise in time with the rpm.

I checked the intermediate shaft bearing before I had the engine back together and it was perfect.

The other possibles are mains, rods, oil pump shaft bearing, lifter bores and cam bearings.

I've seen the cam bearings and lifter bores, cam surfaces are good but the lifter bores weren't perfect though I think they're good enough.

How common is it for the pressure relief to stick open? That would be a nice easy (cheap) fix.....if it's fixable.

[ORCoaster]

Did you install the gauge at the side of the head where the oil pressure sender is located?  Or are you taking readings off the oil flange fitting holes by the filter.  I have a gauge on the head and I get 30-35 at idle when hot.  80-100 lbs at cold startup.  Running hot it generally ranges from 65-70 I would say.

I think your pump might be shot.  That might be rebuildable.   

[rabbitman]

Did you install the gauge at the side of the head where the oil pressure sender is located?  Or are you taking readings off the oil flange fitting holes by the filter.  I have a gauge on the head and I get 30-35 at idle when hot.  80-100 lbs at cold startup.  Running hot it generally ranges from 65-70 I would say.

I think your pump might be shot.  That might be rebuildable.   

Taken from the head. It could be the pump, I've never heard of these oil pumps wearing out but I have heard of the relief sticking shut causing way high pressure. IDK if they ever stick open though.

[rallydiesel]

Did you replace the main/rod bearings? Did you mic the crank before to check if it was undersized?

[rabbitman]

I didn't have the bottom end apart at all, never even took the oil pan off. Currently I'm timing it with a gauge so it'll start without making a huge blue cloud and then when I get more time I'll pull the pan and take a look at the oil pump.

Anyone heard of these pumps relief valve sticking open?

[rallydiesel]

I suppose in theory but I have not heard of it actually happening in reality.

[rabbitman]

Bringin' this back up, took the oil pan off and removed/disassemble the oil pump and it has 30mm gears .

[damac]

On my 85 jetta td I put the oil gauge in the same spot as you because I thought I had read you want to know whats going on up there with oil flow and that the oil pressures are lower than at the filter flange.  Now I am wondering is that true?

If I compared my specs to yours, we are similar.  I have not got less than 15 at the hottest idle, and we are close to the same at rpms I might read just a tad bit more.

I also refreshed my setup a bit because I got the car used at close to 200,000 miles, unknown engine parts.  I replaced seals, main because I was down there, intermediate bearings,  vacuum pump, etc.  Didn't tear into head or lower end internals.

I don't know what kind of oil pump I have but I cleaned out the screen and just put it back in.  If that later bigger 36mm pump is better what kind of numbers are people getting with it and is it a must to prolong worn engines?

My high pressure buzzer also has been going off sometimes after I replaced both sensors.  But it was so random I disconnected it for now and assumed I have a wiring problem from it to the dash because It took 3 tries with the books test and the buzzer finally went off on driveway.  But then it doesn't stop literally sometimes no matter what the rpm, or it will keep going until you stab the throttle, etc.

My car has been running so good, good mileage and all of that so I wanted to drive it another year or two before rebuilding but now you have me wondering what could happen with this oil pressure thing.

[rabbitman]

I have a 36mm pump on my rabbit NA and a mech head (stock was 26mm pump) and I get 10-15psi at hot idle (800-850rpm) and 30psi hot @ 2000 rpm. I can rev to 3500rpm hot and get around 55psi which I consider plenty good.

You're car would probably have a 30mm pump.

Idle pressure to me isn't as important as high rpm pressure, at idle there isn't nearly as much force as at 4000rpm.

[R.O.R-2.0]

my old 1.5d used to have JUST ENOUGH PRESSURE to bring the needle off the peg on my auto-meter oil pressure gauge.

i figure it had about 6psi oil pressure when it was warm, idling.. and that engine did just fine till the day i cracked the block to hell..

had a 30mm turbo oil pump in it even.

so, if my engine was fine with basically NO oil pressure, then you guys should be golden.

[rabbitman]

Well I looked high and low and finally found this:
http://catalog.importrp.com/item.wws?sku=VWW080906&itempk=141006&mfr=Meyle&weight=3.000

Part # is 068 115 105ANMY but I had to call to find that part #......The "MY" at the end is to show that it's a meyle pump instead of Febi.

I'll confirm gear length when it gets here. Dirt cheap if you ask me..........and notice at the top it says "customer service IN THE USA", I could actually understand the guy!!!!!

Auto Parts Discount also has the same pump for 10 bucks more.

[nathan_b]

my old 1.5d used to have JUST ENOUGH PRESSURE to bring the needle off the peg on my auto-meter oil pressure gauge.

i figure it had about 6psi oil pressure when it was warm, idling.. and that engine did just fine till the day i cracked the block to hell..

had a 30mm turbo oil pump in it even.

so, if my engine was fine with basically NO oil pressure, then you guys should be golden.

6psi is a car cry from 0, just saying. I had an old bug that had 2lbs hot idle, you could move the crank around in the bearings, but it stayed together. It is all about how the bearings got worn. Are they shaving from overheating and oil starvation? beat up from too high rpms (in beetle motors), or worn from 400kmiles.

[guy plain]

dang the big old 6-71 and 8-71 detriot deisels have only 3 ro 4 pisi at an idle...and they last for ever.....

[rabbitman]

Idle oil pressure is not much of an issue for me, I have enough there anyways.

But what about at 5000rpm (which I will almost never do) when there are lots of forces at work trying to make the rods blast through the block?

[theman53]

Found a thread that might be of some use.
http://forums.vwvortex.com/showthread.php?5129625-Diesel-Vacuum-pump-rotary-vane-type&highlight=diesel+vacuum+pump

called the dealer and all parts are NLA. Bushings can be made though. This finally answered my question as to what the heck that rivot was under my vac pump.