high oil pressure. aw11 20v turbo, no oil cooler

[adamaw11]

I've noticed my oil pressure is getting much higher now according to the standard aw11 guage. (it sits around where I have the red line marked in the photo cruising at 3000rpm)

Previously it used to sit between lines 2 and 3 in the pic when cruising at freeway speeds, and somewhere between 1 and 2 while idling.
This was with the basically standard blacktop 20v, with the aw11 oil pressure sender screwed into the block. It was running an oil cooler off a sandwich plate underneath the oil filter.

Now with the turbo setup, its getting up above line 3 when cruising at only 3000rpm - its near the top of the guage now.
The oil supply for the turbo is coming from a T-piece which is now between the oil pressure sender and the block, and I had removed the oil cooler for simplicity.

After some sustained spirited driving using revs up to 8000rpm and ~6psi it has developed an oil leak - I havn't established where from yet, but possibly from around the T-piece, or the fitting that feeds the turbo.

-could the pressure be high due to high oil TEMPs? from running no oil cooler? even though its very high cruising on the freeway.
-can anyone estimate from the aw11 guage how high is too high with oil pressure.
-could it be that it was actually lower than it should be previously when I had the oil-cooler-sandwich plate setup, and now its actually where it should be for a blacktop 20v and just looks high on the aw11 guage.

If anything, the engine sounds LESS rattly than it did before at idle

[fixeruperer]

oil pressure will decrease with temp.

get a mechanical gauge in psi, and screw it in and check the pressure with that gauge.
could be faulty sender unit or gauge.

[trdee]

As above. Another thought here is if you are getting more blowby than your breather can cope with then it can increase the crankcase pressure. Which may show up on the gauge.

[adamaw11]

alright, I'll have to get another oil pressure guage, where would you normally screw it into? same spot as factory oil pressure sender? in this case the t-piece coming off the block?

if its more blow-by, would that still occur under light throttle - light load cruising - steady speed? or only under some load?

My crankcase breather filter isn't soaked with oil yet. I realised the PCV valve on the crank case is only a one way valve, allows air to be sucked out of the crankcase, but blocks up when pressure is against it the other way, so I wouldn't expect my 6psi boost to be a problem there.

[dnegative]

Sendor or the gauge is probably a little fucked.
Put a mechanical gauge on

[trdee]

yes can tee into the same spot. and no if it's happening at idle etc then it obviously wouldnt be from boost.

[YOGI8U]

Have you changed the oil and you are now running a thicker oil?

[73GTV]

compression and leak-down test required to insure that blow-by is not from worn rings. Any restrictions in your oil supply to that sender will result in a high pressure, coking from the oil return from the turbo, dirty oil filter. That will cover all of the possibilities.

[adamaw11]

I found out the main cause of the oil leak. The broken thread bit was screwed into the block.


Guessing the: sender-tpiece-block setup couldn't handle the vibrations etc.

Since its a only a 1 wire oil pressure sender, I guess it earths through the thread in the block.
Adding this t-piece was one of the changes from before-after, so perhaps the t-piece and thread tape cause more resistance in the circuit and caused the reading to be higher.

I just temporarily have the turbo oil feed screwed straight into the block with no leaks, but I'll have to work out a better setup.

Will maybe look at doing the oil filter relocation and tee-ing off those lines for turbo oil feed, and plumb in an oil cooler while I'm at it.

[SHEPPO3930]

make sure you use 1/8 BSP fittings, not 1/8 NPT. common mistake for 4age owners. looking at your pic, it looks like only a couple threads of that adapter have screwed into the block, this is normally the case when you screw in a 1/8 NPT fitting into a 1/8 BSP tapped hole.

you can keep using the set up you have pictured if you add a braided line from the t-piece to the oil pressure sender. mount the oil pressure sender to the block somewhere using a p-clip, or even onto the chassis if the line is long enough.

[adamaw11]

make sure you use 1/8 BSP fittings, not 1/8 NPT. common mistake for 4age owners. looking at your pic, it looks like only a couple threads of that adapter have screwed into the block, this is normally the case when you screw in a 1/8 NPT fitting into a 1/8 BSP tapped hole.

you can keep using the set up you have pictured if you add a braided line from the t-piece to the oil pressure sender. mount the oil pressure sender to the block somewhere using a p-clip, or even onto the chassis if the line is long enough.

Thats interesting, and appears that may have been the problem all along. I knew it didn't screw very far in to the block, but figured it was mainly from it being a tapered thread.

Now I'll need to look at getting some 1/8 BSP fittings, maybe I can get a 1/8 BSP to 1/8 NPT joiner and still use the same T-Piece.

I'll also look at remote-mounting the sender as you've suggested.

[trdee]

yep this has happened to a few people. you need a 1/8 BSPT thread into the engine block. And it is preferable to either brace the T piece or mount it remotely, as the extra leverage snaps them. has happened to a few people already as mentioned.

also yes the oil pressure sensor grounds through the block so a change in resistance will cause a change in the reading. you should also use sensor safe threadlocker.

[allencr]

Yes, the electric circuit goes through the sending unit to the block, but if there was actually extra resistance from tape/whatever(there ain't), then the gauge would be showing a lower reading, cause when it has zero resistance is when the display will be high/pegged.

[trdee]

the aw11 pressure gauge is funny. the test in the manual does not specify a high/low resistance. the test for it is to wire a test light in series with the power to the sender and it should then flash variably with reference to engine speed. thats what the bgb says anyway.

[dnegative]

make sure you use 1/8 BSP fittings, not 1/8 NPT. common mistake for 4age owners.

One will go into the other ok but not really the other way around.
Although if you use a brass fitting (and because pipe threads work essentially by cross threading) you will get away with it 9/10 and never have a issue.