Strange Oil pressure

[bigblackcaddy]

The symptoms:
I've got a rebuilt engine (MF block, new AAZ head from boraparts) that cannot seem to make oil pressure when hot. At cold startup the gauge goes up to 7 bar, pretty quickly dropping down to 4 bar. The warmer the engine gets, the lower the pressure gets, until at hot idle it's reading not quite zero, but 1/4 bar maybe, with the oil light on. Worse yet, once it's hot, at idle at traffic lights and such it makes this metal squealing noise like wear indicators on brake pads. I cringe imagining the turbo machining itself... I've been feathering the throttle to bring the idle (and pressure) up and the noise stops.  Driving when hot, the oil pressure is 1~1.5 bar. If I really get on it it will go up near 2 bar but that's about as high as I can get it.

What I've tried:
Hooked up a friend's mechanical pressure gauge to the head in place of the VDO sender. It read ~80 psi quasi warm. It had been sitting for half an hour or so. I couldn't really leave it it on to get a reading while driving.

Replaced oil seal inside vac pump gear, checked for end play, leaks.

Pulled oil pump (new meyle 36mm) and inspected it for clogs/debris, of which there were none. Checked oil pump bushings to make sure they were replaced when engine was rebuilt.

Checked rebuild reciept for intermediate shaft bushings... If they werent replaced, I sure did pay for them!

Put a thermocouple on my Volvo oil cooler to tell when the sandwich plate starts to allow flow. It does not seem to correlate with the low pressure.

I'm running 15w-40. Puralator pure one filter. Oil pan windage tray, and plastic baffle that snaps onto the pump pickup.


Possible fixes/problems left:
Replace VDO sender (and gauge just to be safe).  The squealy noise at hot idle tends to make me think it's not lying tho.

Turbo leaking oil? I ran it with just a half finished down pipe for the first couple of trips around the block on the engine and it did blow oil all over the steering rack.. I figured it was the new rings that hadn't sealed yet. It's been about 60 miles now and I'm not getting oil out the tailpipe, so I figure that has stopped.

The engine sat for a year or so in my attached garage after the rebuild, but it stays dry in there. Slight chance of bearings rusting or something? I doubt it tho.

Sorry for the long post, but I'm pretty stumped at this point and wanted to explain where I'm at. Any other ideas are welcome.
 

[burn_your_money]

I seem to recall reading somewhere that a Puralator oil filter caused a guys low oil pressure problems. Might be worth checking.
Is your MF hydro or solid lifter?

[bigblackcaddy]

Thanks for the response.

The MF block is hydro... It's got the bump on the front for the head oil passageway.

+2 points for Napa. They were open till 6 on Sunday, and they have Mann oil filters. I also picked up a napa gold (wix) and it is huge compared to the Mann. Figured I'd give it a try as well and see if either helps.

I threw the Mann on and drove around the block. Coolant temp started at 120f and got up to 185f. Oil Pressure was ~2 bar when I started it up and was nearly zero when I stopped about 3 min later. It was idling kinda rough too... I'm getting paranoid that it's gonna explode or something.

I noticed a funny behavior just after I started it up that I'd never seen before. I would blip the throttle just a bit to watch the oil pressure jump, and it was actually doing the opposite. The pressure would fall about half a bar each time I revved it, and it would recover when the revs fell.

[CRSMP5]

your killing your engine... unless its got abt 18psi at 2200rpm its way too low on oil pressure..

time to pull the pan.. and look at all your bearings.. sadly no way to check the intermediate shaft ones.. unless you pull the shaft..

[bigblackcaddy]

 The "nearly zero/one quarter bar" I mention is at idle. I'm getting around 1 bar at 2200 i'd guess (no tach). Still way too low though, I agree, which is why the only driving im doing is to see if my changes make any difference.

I did pull the pan, this morning, to look at the pump and it's bearings. They're new. Intermediate shaft bearings should be new as well, but at this point i'm wondering if the builder forgot them. Not sure what other bearings I can check out without breaking down the engine.

[vanbcguy]

My GUESS is your timing belt is slipping on the IM pulley...  Check your timing belt, STAT!  The question of WHY it is slipping is a whole other thing.

[rodpaslow]

In my early building engine days I forgot to put sealant between the block and piston oil cooler bodies.  I got relatively the same thing you are describing.  I'd get 80 psi cold, but close to 0 hot.  Once I added sealant- no problem. Might be something to check.

[bigblackcaddy]

Thanks for ideas everyone. I'll be happy to come on here and report when I find the problem, but for now, just an update... I ordered a new VDO mechanical oil pressure gauge to do away with the question of the 30yr old electronics. Got it installed today and went on a short test drive. Engine didn't warm up totally, but enough to know that my old electronic gauge was correct. I was getting 7 psi at idle and 13~16 driving around gently by the time I shut it off. *sigh*

I checked my timing belt tension to see if IM pulley could be slipping. I could turn it about 45 degrees like the bentley calls out. Wasn't oily or anything. What else could cause slippage?

Can the oil squirters be removed/reinstalled without removing the crank? What type of sealant should I use if there is none?

[81 vw pu]

Check the oil pump for a stuck (open) pressure relief valve. If stuck open most of the oil pumped will bypass back to the oil pan.

[gnavs]

this sounds identical to the problem I'm having.  I'll be listening for what you come up with.  good luck!

[R.O.R-2.0]

MF motors are supposed to be solid lifter engines.. the ME is the hydro motor..

i ran my 1.5TD with just enough oil pressure to bring the gauge off the peg, and it ran great for a long time.

maybe your IM shaft bearings are messed up some how?

[VTPSD]

did you ever get this solved? sounds similar to my issues.

[tyb525]

An oil hole in the head that is or isn't blocked when it should be?

[bajacalal]

MF motors are supposed to be solid lifter engines.. the ME is the hydro motor..

i ran my 1.5TD with just enough oil pressure to bring the gauge off the peg, and it ran great for a long time.

maybe your IM shaft bearings are messed up some how?

I thought MF was turbo mechanical and ME was non-turbo mechanical. I don't know what the hydraulic one is... But where are the "engine codes" on our engines anyway?

[theman53]

MF motors are supposed to be solid lifter engines.. the ME is the hydro motor..

i ran my 1.5TD with just enough oil pressure to bring the gauge off the peg, and it ran great for a long time.

maybe your IM shaft bearings are messed up some how?

I thought MF was turbo mechanical and ME was non-turbo mechanical. I don't know what the hydraulic one is... But where are the "engine codes" on our engines anyway?

Engine codes are on the block between #3 and #4 IIRC. For the most part they mean something but the MF is a tough one. It is always a stock turbo engine, but I have had mechanical and most I have heard are hydro engines. The ME could be the same way, I have only had them as hydro, but IIRC they are non turbo from the factory. They do have machined flats for oil squirters but don't have squirters.

VW with their casting marks are kind of random. Most cylinder heads have all the same number but different letters. For the most part I have found you never know what you are getting until it is there in your hands. The numbers and letters mean nothing compared to a chevy or something that you know exactly what you are getting.