Oil Pump Losing Prime

[rs899]

I have an 82 Rabbit Pickup , 1.6NA with about 180K on the last rebuild.

I have a mechanical oil pressure gauge on it. It has good oil pressure- 20+ lbs at hot idle and 70 at speed.  However, the oil pump likes to lose prime, especially when it has been sitting.  I didn't start it for a week and it took about 15-20 seconds for it to build pressure.  This seems to happen even overnight, but then it may only take 5 seconds to start to pressurize.  It seems to help if I blip the throttle.

The oil pump is fairly new- about 2 years old and with about 30K miles on it.

Any ideas why it may be reluctant to begin picking up oil?

Rick

[maxfax]

Since you are in Florida I guess we can rule out -10 degree weather.....  Now to start hitting you back with some questions  ..

Do you have the gauge connected to the head or the oil filter housing?  Is this something that came on gradually, all of a sudden, always done it?    Have you recently changed oil.. (Maybe a goofey filter?)

On all of my VW's I've noticed a slight delay in the oil pressure at startup..  Comes right up with a blip of the throttle..  Can;t say that I've paid attention as to how long it takes though..  Probably not more than a few seconds though..  Definitely worse on cold days, or on the rare occasion that it sits for a few days... I always chalked it up to having the gauge connected to the head which is the very end of the oiling system...

[rs899]

The gauge is connected to the head ( I also have the factory idiot light connected with a "T").  It kind of comes and goes.  I haven't noticed it in awhile.  No, I haven't changed oil lately ( actually, it's draining now) and I usually use a Purolator  or STP (Autozoo brand of Champion labs).

As I said, the oil is draining...I have half a mind to pull the pan and take a look at the pump...but what to look for?  Obviously, factory clearances, but any other ideas?  This was happening even when the pump was almost new.

Rick

[Rabbit on Roids]

is it leaking at all around the filter flange? mine would leak there and take longer to prime.

[wolf_walker]

5 sec at the head isn't unreasonable with some age on it.  What weight oil?
I'd use Mahle or Mann filter, see what that does.

[rs899]

Five seconds wouldn't bother me, but then it turns into ten,then fifteen ...then....when do I shut it off and start walking?

IIRC it would do it when I used Mann filters too, sometimes....

I'll take a look at the bolts on the filter flange....

It's still draining...I haven't torn into it yet.  (playing with the '91 Jetta that I am resurrecting).

Rick

[Vincent Waldon]

I'd be inclined to pull the pan and have a look... sludge in the filter screen, housing bolts that have worked loose, mounting bolts that have worked loose, excessive wear on one or both gears (Bentley has the feeler gauge spec on wear limits).

[wolf_walker]

3/4 of us here could have the same problem and never know it, most of us drive em too often.

[rs899]

I pretty much drive this one every day, but I have been off work for a week.  I think I will pull the pan and take a look tomorrow, if I can stand the cold

[rs899]

Just to finish this thread off, I pulled the pan and didn't see anything odd- clean as a whistle there.  I replaced the oil pump with a new one I had bought from Rock Auto for $22 and the problem has gone away.  This pump doesn't seem to deliver as much at speed when hot "only " 60 psi, but who cares- the oil light goes right out when it starts.  The replacement pump is a made in USA, probably Melling, all cast iron.  I hope it lasts...

It's all good.

Rick

[Vincent Waldon]

Thanks for posting back... always important for us to learn what the final outcome was, and really helpful when people search for answers.

[rs899]

Oh -and I took the old pump apart.  It did not look particularly worn and seemed to be in spec when I tried to measure the gears.  But something was obviosly wrong with it.

[burn_your_money]

I also have a mechanical gauge hooked up to my head on my 1.6TD and with the temps at or below freezing it usually takes 5 seconds to register 20 psi on the gauge. I'm running Rotella 5W40 (or 30, I forget) Synthetic. With it cold I see peak pressures of 60 psi at idle.

[Rabbit on Roids]

i get over 100 psi very often at idle when its cold. i dont even like driving it cold just because of the really high pressures. then when it warms up, it idles at about 15 psi.