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Author Topic: Oil pressure lost  (Read 3806 times)

February 06, 2019, 12:54:48 am

ORCoaster

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Oil pressure lost
« on: February 06, 2019, 12:54:48 am »
I thought I had this problem figured out the other day but it happened to me again tonight on the way home.
As I leave work I drive slowly through a puddle of water that is about 3 inches deep.  I know there is a place where there is a crack or a hole that causes the front end to drop a few inches so I don't want to be racing through and do damage to the car.  But what happens as the front end does that quick drop is that I then loose oil pressure.

If I continue the few feet around the corner and turn the engine off then back on I can generally get the pressure to come back up again.  Trying to figure out what is going on here.

I removed the vane style vacuum pump last weekend and shimmed it up so that the gear would not jump back up about a half an inch.  I am wondering if the oil pump itself is loose from the block and dropping out of the vane pump.  I did get a pair of vise grips on the shaft and pushed and pulled on it from above and didn't get any movement. 

Just wondering if removing the pan and checking for a loose pump is worth laying in the rain in the driveway.  I have other vehicles to drive but this needs to be fixed as I am looking to sell it in the spring. 

Let me know if you have had this same problem and what the fix was that made it go away. 

Thanks



Reply #1February 06, 2019, 11:10:35 pm

fatmobile

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Re: Oil pressure lost
« Reply #1 on: February 06, 2019, 11:10:35 pm »
Maybe the oil is splashing and your plastic oil pump baffle has broken and allows air to be pulled in.
 Oil level OK?
Got the right dipstick?
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block

Reply #2February 07, 2019, 11:37:26 pm

ORCoaster

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Re: Oil pressure lost
« Reply #2 on: February 07, 2019, 11:37:26 pm »
The first time this happened I did pull the dipstick, it is the stock one, and it was a qt low so I added that much from the emergency bottle in the trunk.  That stopped it from popping the light on, but I think it was more about the vac pump engaging with the oil shaft.  I have the older diaphragm pump style vac pump on the engine.  It is all in tip top shape as I just tore it apart to figure out why it was detaching from the oil pump drive shaft.

We are scheduled for rain for the next 3 to 4 days so laying on the driveway might be out unless I get on it first thing in the morning. I would have been able to do it today but swapped my work day from Sat to today so I didn't have to dig holes in the rain or lay on my back under a mobile home in the rain.  Good that the Rabbit only needs to go a short distance to get me to work.  The Caddy has brake issues so I am holding off on driving that for a bit.  Need a new proportioning valve. 

I think I will pull the pan and see if the pump is loose.  That is the most direct route.  It pumps good pressure as it gives me close to 100 psi on start up and about 40 at idle hot.  I think I have adjusted the valve in the bottom of the pump in the past. 

Reply #3February 08, 2019, 09:48:14 pm

wdkingery

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Re: Oil pressure lost
« Reply #3 on: February 08, 2019, 09:48:14 pm »
Cannot belive this is still going!

Reply #4February 09, 2019, 07:39:05 pm

ORCoaster

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Re: Oil pressure lost
« Reply #4 on: February 09, 2019, 07:39:05 pm »
What the car or the problem?

Reply #5February 09, 2019, 09:53:31 pm

libbydiesel

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Re: Oil pressure lost
« Reply #5 on: February 09, 2019, 09:53:31 pm »
Any chance that the issue is wiring?  I could see how a chafed wire in the sender circuit could ground out on a bump and give the symptom you describe. 

Reply #6February 10, 2019, 07:43:20 am

zuhandenheit

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Re: Oil pressure lost
« Reply #6 on: February 10, 2019, 07:43:20 am »
I had some very worrying oil light behavior 1000+ miles from home during my first post-AAZ road trip, which turned out to be a loose/damaged wire from the sender. It was intermittent but seemed RPM-dependent -- I was afraid to even hope that it was an electrical fault.

Reply #7February 10, 2019, 02:21:20 pm

ORCoaster

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Re: Oil pressure lost
« Reply #7 on: February 10, 2019, 02:21:20 pm »
I wish I could slap my forehead and go, Yah, that's it.  But the oil pressure gauge at the top of the head is confirming the light on the dash.  Gauge drops to zero as the red dot glows.


Reply #8February 10, 2019, 08:43:05 pm

libbydiesel

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Re: Oil pressure lost
« Reply #8 on: February 10, 2019, 08:43:05 pm »
Is the gauge mechanical or electrical?

Reply #9February 10, 2019, 10:20:53 pm

ORCoaster

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Re: Oil pressure lost
« Reply #9 on: February 10, 2019, 10:20:53 pm »
Mechanical, comes off a tee at the same place as the pressure switch, @ the head.

Reply #10February 10, 2019, 11:28:00 pm

libbydiesel

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Re: Oil pressure lost
« Reply #10 on: February 10, 2019, 11:28:00 pm »
Well, that's definitive then.  In that position I'd pull the pan and see if I could see any issue with the pump or pickup tube. 

Reply #11February 11, 2019, 10:41:28 pm

ORCoaster

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Re: Oil pressure lost
« Reply #11 on: February 11, 2019, 10:41:28 pm »
That's the plan, pull the pan.  But with gusting winds of near 45 mph and rain being driven into the windows and down my neck right now I think I will hold off for a few days and let this storm track ride on by.  I will update after I find something.  Good or bad.

Reply #12February 18, 2019, 01:13:44 am

ORCoaster

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Re: Oil pressure lost
« Reply #12 on: February 18, 2019, 01:13:44 am »
Finally, an afternoon with sun and warmth enough to get under the car and pull the pan.  After doing so I grabbed the oil pump and expected it to wiggle some.  But no, nada, solid as a rock.  I pulled on the pick up tube and the same thing.  No movement at all.

I looked up under the pickup tube with a bright flashlight and there was nothing on the screen, nothing in the oil pan either that might have sucked up there then let go later.  I looked in the little port for the high pressure relief and found nothing.
 
But that got me thinking, what if the pressure went up past the limit and then the little release mechanism didn't release?  Would that allow the pressure to drop to zero?  I can't understand why I would have lost oil pressure twice at nearly the same point in my route home. 


The conditions would have been similar. cold engine, cold oil, same length of running time and same hard bump in the road.

Offer your theory if you care to do so.  I am going to run it as it is and hope for the best.

 

Reply #13February 18, 2019, 02:09:10 pm

fatmobile

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Re: Oil pressure lost
« Reply #13 on: February 18, 2019, 02:09:10 pm »
Maybe the low oil caused it to lose prime.
  Try spinning the oil pump with a drill,
 by removing the vacuum pump.
 I've had to prime them when starting a fresh engine.
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block

Reply #14February 18, 2019, 10:09:07 pm

ORCoaster

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Re: Oil pressure lost
« Reply #14 on: February 18, 2019, 10:09:07 pm »
It lost pressure after about a two minute idle and slow crawl down an ally.  Did it twice same place.  I have a mech gauge that showed 0 pressure when that happened.  Once I shut the engine off it came right back.  I have removed the vac pump, rotary style, and it is bolted up tight to the block.  So I am not sure where it could disconnect between the two pumps. 

I was down a quart the first time it happened but was on level ground all the while it idled up.  Just going to watch the gauge a little bit more I guess.


 

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