Oil Pres

[kc7bur]

Hello all,
82 1.6D 5spd Rabbit
Lately the oil light and buzzer has been coming on at idle after its warmed up. The dipstick says full and I can see oil being splashed around when I open the oil fill on the valve cover at idle. Oil pump? or faulty sensor?
Thanks, Jay

[QuickTD]

The sensors have been known to fail. These engines also like fairly heavy oil (15W40 is good).

 The light might also be right, oil pressure may be a bit low if the engine has some miles on it. Most common cause of low oil pressure in these engines is worn intermediate shaft bearings. I would suspect this to be the case if the engine has more than 150K miles on it. Nothing in an engine has an easier life than the oil pump, its just 2 steel gears spinning in an oil bath, doubtful that its the problem.

[Northboundtrain]

Well, Quick TD may be right about worn intermediate shaft bearings.  In my recent rebuild, my intermediate shaft bearings are a tad bit tight and my pressure is pretty high -- 100+ psi when the engine is cold and I give it some fuel.  Have to take it easy until the engine warms up, or else I'm afraid I might blow a seal or something.  

How is it though that the tightness or looseness of these bearings affects oil pressure?  I can't seem to conceptualize the relationship.

[srivett]

RE:  How loose bearings affect oil pressure.

Consider squeezing a pop bottle without a cap on it.  The contents quickly jumps out of the bottle.  This is how worn out bearings behave.

Consider squeezing a pop bottle with a small hole drilled into the cap.  The contents comes out slowly and there is more resistance to squeezing the bottle.

Steve

[QuickTD]

The oil pump pumps a fixed volume of oil so oil pressure depends entirely on the amount of internal "leakage" that the engine has. The clearance of every engine bearing represents an internal leak. The more clearance the bearing has, the more oil escapes between the bearing and the shaft and the lower the oil pressure.

 The intermediate shaft bearings in VW diesels wear faster than the rod/main bearings, so they are usually the first thing to affect the oil pressure.

[935racer]

Theya ren't really bearings, they are races, they have a plating on them that likes to flake off, and thus the oil escapes fromt he sides of the races instead of going through the designated hole.

[QuickTD]

If these bearings are plated, someone better tell my machinist, as new I-shaft bearings are reamed-to-fit after insertion.

 I shaft bearings are plated, same as any other plain bearing. They have a steel backing with an aluminum overlay. The VW bearings have quite a thick overlay that allows reaming/honing after installation. The clevite bearings are pre-sized and do not require sizing after installation, they may have a bit thinner overlay. The fracturing that most people experience is the result of the overlay coming off the bearing. The steel shell usually remains intact.

[kc7bur]

I could disconnect the buzzer and put a piece of tape over the light.

[Rat407]

I could disconnect the buzzer and put a piece of tape over the light.

Since mine still has low pressure and I replaced all the bearings, yes intermediate shaft ones as well. I just unpluged the small one wire terminal from the alternator. That took care of my light/buzzer.

[935racer]

You can get durabond races that are plated on both sides, you want thos eones. THey install fairly easily if you have th correct tool. Yes there is only one hole and it is crucial that the hole on the race is prefectly lined up to the oil gallery. for the one on the tranny side of the engine take the oil cooler off and you can see down there and properly align the race, the one on the t belt side is easy to see from the intermediate shaft opening.

[Baxter]

Have you thought about checking/having the oil pressure checked with a gauge?
All this conflab, could be this, could be that, but unless you get the pressure checked you may be pissing in the wind.
At least if you have it checked you know where to start, at could be as simple as a faulty oil pressure switch, as as started it could be big ends/ mains/ intermediate shaft bearings.

[Baxter]

Also, VW's DOP (Dynamic Oil Pressure) system could be at fault, the connection between the multi plug and the circuit board of the rear of the instruments are known for high resistances causing false alarm of the buzzer of doom.
I know your "Westmoreland" ones have a different dash, dunno if thats what yours is, Im in the UK so unsure of US systems, should imagine that they are the same though.
The buzzer shouldn't operate below 2000 rpm, thats why there is a engine speed signal to the rear of the instruments, so the DOP system knows how fast the engine is going.
Also remember that one oil pressure switch is a normally closed type and one a normally open type.

Started writing this for European T3's, never got around to finishing it of, may be of some use..
http://194.242.159.246/brickyard/info/dop.htm

[kc7bur]

It only buzzes at idle after its been warmed up. It just started doing it.
I only paid $400 for it with the intention of putting it on Ebay, but I don't want to sell until I know its not going to be a problem.

[Baxter]

If the pressure drops when the engine is above 2000 rpm then the buzzer will come on.
It will only go off if the ignition is turned off.
So, if you have pressure problems, drive it around under 2000 rpm and the buzzer will stay off.
Disconnect the speed signal for the buzzer of doom from the W terminal from the back of the alternator, that should shut it up in the meantime till you check your pressure and switches.

[ejust]

sounds like my engine needs some lovin'

warmed up i get maybe 10psi at idle, about 25psi at 2k, makin my lifters tick like hell