Months of repair, few weeks problem free, now low oil pressure. Ugh.

[JD159]

Been gone for a long time getting my engine sorted out. Some of my previous posts include a lifter with a hole in it, then I thought I was going to part the engine, finally my shop managed to get things back together.

Long story short, re-ground the cams, all new lifters, and all high spots from the head removed, it was re-assembled. As for contamination, a few flushes and hoping for the best. Yes, a full rebuild cleaning every part is the best procedure, but that is not in the budget, so it was either part it or take a bit of a gamble. My mechanic, pretty well known in the Toronto area, reassured me that everything would be fine. After a long year, a few oil leaks, a couple thousand, I had it back on the road and the engine was as smooth as ever.

HOWEVER, this morning, it took a few extra seconds, longer than usual to build pressure to 5 bar. I figured hey, could just be the weather. Drove great on the highway, lots of power, 5 bar driving, idle at 3, perfect oil pressure. Leaving for work, took a little bit longer then this morning to gain pressure, that concerned me a little, after about 10 seconds it got back up to 5 bar. This was after it sat for a few hours, so it is not going to idle at 3 just yet. This evening, I fire it up about to head out, and its at about 1 to 1.5 bar, with the red indicator below the pressure gauge on. I'm waiting, and waiting, to long for me to feel comfortable at low pressure so I turned it off. Now I'm worried.

On the ride home from work, once it got pressure, car drove great, engine felt strong, stable, just perfect.

What do you think?

I'm almost 99% sure I torqued the crank bolt to 155. Could of it worked loose a little? I'm going to double check that tomorrow, maybe crank it to 156 or 157 to give it a bit more.

So far I've gathered that it could be the oil pressure sender, OPRV, maybe a clogged oil filter, crank bolt, or a broken pick up tube (hopefully not…)

Also, I've got about 350 miles on a new WP and belts.

From the conditions I've described, does it seem like any of these stand out in particular?

[SolReaver]

Don't panic just yet. Check your sender connections and lines to the instrument cluster. If possible see if you can swap out the sender or get a mechanical OP gauge in there. Clogged filter is not likely IMHO.

You can check the crank bolt but don't strong arm it.

[JD159]

Going to check the sender connections tomorrow. Took off the rubber boot and got some pictures, I'll upload those shortly. The sender unit and wires look TERRIBLE, so i'd hope its that. Will also try mechanical OP gauge tomorrow.

Where will I be attaching that? Any idea what the fitting is off the top of your head??

[SolReaver]

I would say that where the sender threads in would be your best bet. That way you see what the sender sees. You might be able to check the OP using the current sender and a multimeter just to see if the sender is within specs and if the gauge in the cluster is reading correctly.

Again, don't panic, get some solid connections, take some measurements with a few test leads and go from there. IF you were having oil starvation difficulties your engine would complain dramatically.

Oh, and check to see if the connections to the sender weren't accidentally swapped as sometimes happens.

[Gawernator]

If they were swapped the gauge would be reading max pegged past 5 BAR, that isn't it. Try cleaning the contacts with contact cleaner or an eraser and pop them back on. I'm not so sure that's the issue because even when my contacts were corroded and covered in oil they were reading normally lol. Cleaning my instrument cluster didn't change the oil pressure readings either, but YMMV. Clean the grounds under dash just to be safe. Also.. higher resistance would make the gauge indicate a higher pressure rather than lower...

[John_AZ]

Basics. Are you using a Mahle, OEM Porsche or K&N oil filter?

High end oil pressure sender mod:

951 no oil pressure - Page 3 - Rennlist Discussion Forums

If your oil pressure sender is old----or a cheap URO (do not use), buy an OEM VDO most accurate or at least FAE:

Pelican Parts - Automotive Parts and Accessories - Porsche & BMW

If the suggestions here or above are not helpful, then you may have a crack in the oil pickup tube, a bad "O" ring on the oil pickup tube or an oil pump problem.

J_AZ

[JD159]

Thanks guys,

Mahle filter.

Probably running the stock sender unit lol.

Will grab a gauge today. Hopefully I can get one that threads in.

If it was the tube, wouldnt I of gotten strange/low oil pressure on the drive home?

[mytrplseven]

I'm thinking that John_AZ may be on to something, since this is getting progressively worse. An additional question: What weight oil are you running? Also, did they put all the seals in when they re-assembled the oil pump sleeve behind the crankshaft pulley? If they aren't all there then you're looking at possible degredation of the function of the oil pump drive. Check under the engine front end and check to see if there's evidence of oil leaking from behind the crankshaft pulley. BTW over-torquing the Crankshaft pulley is not a good idea. All you'll do is exacerbate an existing problem.

[JD159]

BP 20W50

Seals behind the oil pump sleeve...

Not sure what those are. I only did the belts, not the rollers. Reason being, the belts and rollers were replaced about 15k miles ago, but it was some years ago. I felt as an easy precaution to change the belts fearing rubber deterioration and the WP due to the added stress of a new belt. I only removed the crank bolt and pulley. Put pulley back, torqued to 155. I will set my torque wrench to 155 and see if it has worked loose at all.

I'll make sure to check that area to see if its wet at all, but there are no leaks under the car, and my mechanic gave it a very thorough inspection when he timed the cams precisely, fixing a leak at the top end. All is dry up there now.

If those seals were missing would it of shown up earlier? I put on 350 trouble free miles with perfect oil pressure.

[SolReaver]

Originally Posted by SolReaver

If possible see if you can swap out the sender .

And John AZ is right, John is always right.

[strath44]

I'm so sure this will be relating to the crankshaft bolt being loose or the oil pump sleeve or seals not right.

[SolReaver]

Strath44: yes, it IS possible that the crank bolt or oil sleeve thingie could be wrong or that a seal has failed. IMHO, the sender may have just gone over to the dark side or wasn't that great to begin with. Both are valid hypothesis...er...hypothesisi?

We can't rule out some electrical connector strangeness either. Both of us are thousands of miles away and giving it out best guess based upon knowledge and experience.

I am leaning towards a bad connection and/or bad sender because the voices in my head are telling me so. I would bet a beer upon it.., just to be sociable. Of course, that is not such a good wager for you Because Scottish beer is sooo much tastier than the stuff around here.

[mytrplseven]

I only asked about the oil pump sleeve and seals because you mentioned the crankshaft pulley and bolt. Didn't know you didn't pulle the sleeve and seals while you were in there.

[JD159]

Not a problem! Now I know thats a spot to keep in mind, and something I can eliminate. I took a look around the pulley, on top and below, looks totally dry, no spots of oil anywhere under the car.

Getting a gauge tonight and will remove the sender.

1) Remove sender, connect gauge, check to see if pressure. If pressure, replace/repair sender. If no pressure…

2) Crank Bolt

3) OPRV

Thanks for the help so far.

[SolReaver]

Yep. Once we have a solid reading on the OP we can go from there.

I would suspect the OPRV over the crank bolt though, especially if you did the OC seals with all the work. The OC housing needs a special alignment tool when installing and if it is off by a fraction the OPRV will bind.

Did you do the OC seals?

[JD159]

Fixed it! Ill post a longer update soon, still under.

Oprv + possible old lifter piece = stuck valve.

Yes Im aware i have contamination issues, but a strip it down rebuild is not feasible. Will do another flush and filter change soon.

[SolReaver]

YA Forsooth! YOU HAVE EMERGED VICTORIOUS!

Details later though, Inquiring minds want to know and all that.

[JD159]

OK! So I started with the oil sender. Took that off, looked grimy, gave it a bit of a clean before I put it back on and I was about to check the pressure. Something told me I wasn't getting pressure anyway though, and then I realized the adapter I got wasn't the right fit! So I couldn't check the pressure anyway.

With the car jacked up, tools ready, and the will to do work, I figured hey, might as well pull that OPRV!

I knew something was up when I barely put any torque on the wrench and the bolt broke loose. Next, as I pull it out, I felt something sharp, like a staple! I pull the thing out, and going right through the valve, holding it open, is this!!!!



I look at it, confused, bewildered, then I remember, my lifters with the holes, before the rebuild. I'll bet its part of the spring from inside the lifter's when they exploded.

I put the sender back in, the OPRV back in, no alignment because I hadn't changed the cooler seals. The OPRV seemed to function nicely once the obstruction was removed, didn't look scored or scratched, maybe a little scuffed but nothing that looked bad. I used the same seals, for now, will order some new 0-rings at some point as a precaution but as for now pressure went back to normal. Does the OPRV have 1 or two o-rings? I saw a flat type one towards the end of the valve, and a metal washer at the head.

Thanks for the help from everyone, I've emerged victorious!

[mueller944s2]

944 repairs are never in the budget for me either, but you'll most likely because taking it apart again if it's not flushed.

[mytrplseven]

Nicely Done!