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Author Topic: Rebuilt 1.9 AAZ, low oil pressure  (Read 1486 times)

June 23, 2020, 07:31:08 pm

Vandoka

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Rebuilt 1.9 AAZ, low oil pressure
« on: June 23, 2020, 07:31:08 pm »
I have a rebuilt AAZ 1.9 td swapped into a 1987 syncro doka. The original motor was the 1.6 td. During the swap I added a larger oil cooler used in a passat I believe (not sure how to add a pic here, sorry) I had seen it on some other builds and thought I would give it a try. During some test drives the oil buzzer would go off when rpms reached over 2k. The oil pressure sensor in the oil filter flange was from the old 1.6. I added a vdo electrical oil pressure gauge to make sure I knew what oil pressure values I had. And grounded out my oil pressure sensor to eliminate the buzzing. I am using Rotella 15w-40 diesel oil for the time being as the motor gets broken in. Upon start up the oil pressure measured at the oil filter flange is close to 60 psi. Then while driving at 2500-3200 rpm it comes down to around 30 psi. Today, after a short trip (less than 1.5 miles) after the engine was completely warm and the rad fan cycled thru I was sitting in the driveway and had almost no oil pressure on the gauge. If i ran the engine up to 2000 rpm the oil pressure gauge barely moved. It was about 80 degrees out and the truck had been idling for about 15 min prior.

I was curious if this cooler may have something to do with  my lower oil pressure. I have read several other threads about low oil pressure on the AAZ. In  my case the engine is supposedly totally rebuilt, and it came from Quality German in CA. I used the oil pickup from the original 1.6 fitted to a new oil pump, int. shaft, int. shaft pulley, timing belt etc. No oil is coming out anywhere, like from the turbo lines etc.

So would the cooler be the cause? Anyone running this setup?

Thanks!



Reply #1June 23, 2020, 10:47:45 pm

ORCoaster

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #1 on: June 23, 2020, 10:47:45 pm »
Wow, a NEW oil pump and no pressure!  As I read your post I was thinking, bad pump. But to not have any pressure at the lines is a bad thing. 

How about deleting the oil cooler and measuring what you have with the gauge?  Is the Passat one like the others I have seen where it fits between the flange and the oil filter?  A quick removal of that and leave the hoses for the water attached.  Just go back to the smaller internal pipe that you took off the flange to add the cooler.


Reply #2June 23, 2020, 11:50:29 pm

fatmobile

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #2 on: June 23, 2020, 11:50:29 pm »
 I suspect the I-shaft bearings.
 Did you put new ones in?
If so:
 What brand?
 How hard did the I-shaft turn by hand.
 It should turn kind of hard when first installed.
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block

Reply #3June 24, 2020, 01:03:41 am

libbydiesel

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #3 on: June 24, 2020, 01:03:41 am »
The large passat oil cooler would help increase and stabilize oil pressure. 

Reply #4June 24, 2020, 09:35:56 am

Vandoka

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #4 on: June 24, 2020, 09:35:56 am »
Thanks for the info. guys. The cooler is very similar to what was on the 1.6, only slightly taller. So there is no oil line that I can tap outside of the ports on the oil filter flange. I can check with the supplier to see if the engine had new intermediate shaft bearings when it was rebuilt. As far as turning the Intermediate shaft, it turned pretty easily by hand when I installed the AAZ specific Int. shaft.

Reply #5June 24, 2020, 11:47:51 am

Vandoka

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #5 on: June 24, 2020, 11:47:51 am »
The other thought/question I have is on the original 1.6 oil filter flange there are two ports, one for the turbo feed line and one for the oil pressure sensor. On the aaz  oil filter flange there are three ports. With my setup the port closest to the flywheel holds the factory oil pressure sensor. The middle port holds the oil feed line for the turbo, and the port closer to the injection pump side of things has my VDO pressure sender. Would this port have different pressure than the oil pressure sensor port? I installed the VDO sensor in this space because it fit pretty easily and assumed that all three holes were exposed to the same pressures during operation.

Reply #6June 24, 2020, 07:14:25 pm

libbydiesel

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Re: Rebuilt 1.9 AAZ, low oil pressure
« Reply #6 on: June 24, 2020, 07:14:25 pm »
I haven't tested the three ports or even examined the flange but I don't think it matters significantly.  One might be before the filter media but the difference would be negligible.  I would use a mechanical gauge to confirm low oil pressure.  Electronic oil pressure gauges are notoriously inaccurate.  The fact that your warning buzzer is going off makes the oil pressure issue likely, though.