Update: MC engine - low oil pressure

EBavely veetesse at hotmail.com
Thu Nov 21 09:04:23 EST 2002


Hello all...

First, thanks to those who wrote me with suggestions from the initial post.
Just an update to the continuing investigation of this engine that appears
to have low oil pressure.

Before dropping the oil pan, I decided to switch oil filters since I had put
an el-cheapo type filter on for initial break-in.  After switching to the
Mann oil filter, to my surprise, the oil pressure when cold shot up to
around 75 psi (was around 30-35 psi before).  To my dismay, however, the oil
pressure went down to its previous levels as soon as the car got
warm...around 10-15 psi at idle and about 30 psi or so when driving below 4k
rpm.  Both the gauge and the warning buzzer confirm this.  Crap.

Although that confirms what so many have claimed about quality filters, I
still wanted to find out why this newly rebuilt engine isn't showing high
oil pressure on the gauge like it should when warm.  Last night, I dropped
the pan and did the following (per list suggestions):

1.  Checked that all piston oil squirters are in place and tight

2.  Verified all crank plugs are indeed in the galleys in each crank throw

3.  Inspected oil pickup tube... seems to be in good shape, gasket was in
good shape and tube appeared to be tight on the oil pump flange. Fluid
appears to flow just fine through pickup tube.

4.  Verified that the 5kt oil pickup tube was indeed compatible with the 4kq
oil pan (used in swap).  The numbers are the same in Et_ka.

5.  Removed oil tempostat from oil filter/cooler flange and inspected.
Everything seems to be in good order and free from obstructions.

So...I still have not found the answer to this problem.  At this point,
tonight I think I'm going to try plasti-gauging the bearing clearances
although I doubt that this is the problem.  The crank was checked by a
reputable shop and everything "felt" fine when the bottom end went together,
plus I don't hear any expensive clunks when the engine runs.

I guess the next step after checking the clearances is to replace the oil
pump with a known good unit.  I checked Et_ka and found that basically all 5
cyl oil pumps are the same, so I should have a spare.  I'm also thinking of
bypassing the oil cooler to see if possibly the lines and cooler are
contributing to the low pressure.

I was really hoping it'd be something obvious... like a squirter laying in
the oil pan, but no luck.  This all seems odd to me as I hear that oil
pressure is almost never a problem with these engines....

As always, I'm open to any other suggestions anyone might have...even
longshots.

One positive note though... I did solve the overboost problem by replacing
the WG diaphragm (thanks SJM).  The engine is now seeing the stock boost
level and not spiking, cutting out like before.

Elliott Bavely

86 4ktq
83 CGT
81 Coupe ITB
88 80 Fwd
Bunch of other VAG orphans



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