Sudden loss of oil pressure...

[Giles_Paul]

Wonder if anyone can assist?

After a massive rebuild of pretty much the entire car, I finally got it back on the road this week. Its had all new sensors on the engine, and a full top end overhall, including head gasket and a load of other bits.
Ive used it all week to drive to and fro and confidence has slowly built in it behaving properly. I did an oil change on Wednesday evening after the initial runs were done, and changed the oil filter. Had a spirited drive home from the workshop on Weds night and arrived home all tickety boo with a grin on my face.
Went out to the car on Thursday morning, started perfectly but zero oil pressure and a very noisy top end?!? Immediately shut it off.
Ive spent today cleaning the OPRV and checking that, which has turned out to be fine, I need to check tightness of the crank pulley, but I doubt that would be the issue or suddenly loosen? Could it be a dodgy Mahle oil filter or priming issue? Im at a loss but wondered if anyone in the club has ever had a similar issue? Ive read several aricles but cant get a sensible answer.

Thanks in advance, as a recently joined Club member I look forward to your responses.

 

[944Turbo]

Usually is the bottom pulley in these instances, if it comes loose the drive to the oil pump is lost,
Tony

 

[Giles_Paul]

Usually is the bottom pulley in these instances, if it comes loose the drive to the oil pump is lost,
Tony

Thanks for the speedy response! Is there an easyish way to lock the flywheel? Im no where near my workshop and only have basic tools at home where its stranded.

 

[richardjjs1]

Get it trucked home
The Crank Pulley has an high torque setting

 

[944Turbo]

Usually is the bottom pulley in these instances, if it comes loose the drive to the oil pump is lost,
Tony

Thanks for the speedy response! Is there an easyish way to lock the flywheel? Im no where near my workshop and only have basic tools at home where its stranded.

Flywheel lock where the starter goes is the usual way, I guess you could put it in gear and get someone to push hard on the brakes, but as Richard says it is a high torque setting!
Tony

 

[Waylander]

It should be 150lbsft
very tight indeed

I have to ask has it been undone in your recent tinkerings, if not then time to look elsewhere

 

[Giles_Paul]

Wasnt touched in recent tinkerings no, everything but that. Hence my doubts about it coming loose.

Already tried in gear with brakes on, too much movement / twist in transmission to get a proper 150. Will have to get it to the workshop I think and investigate. Dont know where to look next? Lost prime in the pump, or cracked pick up. Clutch and Torque tube bearings were shot before so vabration might have caused issues?

 

[vitesse]

Has the sender failed or connection(s) become loose?

 

[Giles_Paul]

I checked and they look ok, the tappets sound awful so I think the gauge is reading correctly.

Could it be a bad oil filter?

 

[Dan944t]

Has the sender failed or connection(s) become loose?

I also was thinking this ^^^ but then re read the post and this would only cause a wrong reading being a sensor but becuase you say it sounds load up top sounds like oil starvation.

Therefore all all I can think at the minute is :

is whats the oil level.

as has been said before check the crank bolt is tight (210nm I think but don’t quote me on that ?? )

is there any oil leaks anywhere

was the oil pump stripped and examined internally and resealed

was the drive sleeve examined for wear

was a new porsche rubber oil pump crush oring used or other?

any blue smoke out exhaust

did you put sump gasket on dry or did you use RTV or some sort of sealant? ( wondering if any excess could have blocked any oil holes or pick up?)

was pick up tube inspected ect

did you replace crank and Conrod bearings or check any tolerances ect?

I’d deffinately try a different oil filter?

What was the oil preasure reading before on cold start up and at idle after a drive?

This is what would be going through my mind and what I’d be checking.

I hope it is something as as simple as your crank bolt torque or the crush oring slipping.

I had this in in my non turbo when I was about 20 and I rebuilt the top end and bought a bottom end with all the bearings already fitted to the crank/rods ect.

it drive me nuts that my oil pressure would drop to point of stalling and I changed Opv sender, torqued crank bolt , changed and inspected oil pump, new crush oring ect ect. im now 37 and that car is still in my garage since that day and I know can put it down to 99.9% the bearing clearances must be way out as I had problems with my balance shaft bearings were way too tight so they obviously slapped it together (not saying that you did, just that it’s quite critical for good oil preasure through the crank ect) something I didn’t know allot about way back then.

ive now got a turbo that I’ve just finish a total engine build on myself and checked and measured everything and wrote a journal on the build with my measurements and photos so I can go to if needs be .

Something you could do is get ready to catch some oil , take off the oil filter and in nutral with spark plugs remooved, try and turn the crank by hand and see if the pump is making any preasure by seeing if it will spirt some oil out the oil filter housing?

let us know how you get on ????

Daniel

 

[richardjjs1]

20.00 fix to change the oil filter

Doubt it would be that be nice though manufacturer would be liable !!

I checked and they look ok, the tappets sound awful so I think the gauge is reading correctly.

Could it be a bad oil filter?

 

[PSH]

It won't be the filter, you don't get a total loss of oil pressure, it just drains back which isn't good for starts.

I know that Giles_Paul stated a 'massive rebuild' but does this include the block, it doesn't seem to suggest so in the description? You said that you had a spirited drive Wednesday and that Thursday morning when starting you had zero pressure and a noisy top end, this worries me. It takes a little time for the top end to make noise when pressure fails, not long but it's not instant, are you sure that the car was fine when switched off the night before, did you have loud music playing during your spirited drive which could have masked possible problems? Crank bolts do come loose even when untouched, any problems with the alternator or A/C compressor bearings as I think that the failure of these two due to a freak frequency resonance caused my own crank pulley bolt to come loose. Did you notice any change in pressure during your drive, I tend to drive on my gauges. I don't know which model you have, does it have power steering and if so was it working fine when you switched off Wednesday? The pickup tube is a possibility if you were throwing the car around and hit any potholes, you could try overfilling the oil and turn the car over but not let it fire up, remove the coil lead or such. If it's the tube the pressure should start to build, if it doesn't start building after a few seconds immediately switch off.
Good luck and I hope it's something simple..

Pete

 

[944Turbo]

Sorry had wrongly assumed crank pulley would have been off during the rebuild, might be more tricky to locate then assuming oil level is correct

 

[Frenchy]

You can get a genuine flywheel lock from Porsche, mine was £30 odd quid, crank pulley is 220 NM, pull the DME relay when test cranking so that the car does not fire up.

 

[edh]

The pickup tube is a possibility if you were throwing the car around and hit any potholes, you could try overfilling the oil and turn the car over but not let it fire up, remove the coil lead or such. If it's the tube the pressure should start to build, if it doesn't start building after a few seconds immediately switch off.
Good luck and I hope it's something simple..

Pete

Definitely worth checking.. I had a similar oil pressure loss at Spa a few years ago. We overfilled the sump, pressure came back & I drove it home (Not that I'd recommend this but the tappets were already knackered by the oil pressure loss @ 6k rpm, so we felt that on balance we wouldn't do much more damage on the way back, & the engine was swapped afterwards anyway - much cheaper than a rebuild)

 

[Waylander]

Lock Tool

000 721 920 60 £43.00 OPC, Inc Vat

Porsche Shop £50, Plus Vat, Plus Delivery,

 

[944Turbo]

Lock Tool

000 721 920 60 £43.00 OPC, Inc Vat

Porsche Shop £50, Plus Vat, Plus Delivery,

less 10% for being a club member at the OPC, also http://www.arnnworx.com/catalog/index.php?main_page=index&cPath=69 but no cheaper for the flywheel lock

 

[Frenchy]

That's exactly how pork chop make their money, some stuff from them has a fair old lead time, why, because they have to wait for Porsche to deliver it to them, they then mark it up and flog to the punters.

 

[GlennS]

My money is on the oil pickup tube fracturing. Mine (on the 2.7) let go on the back straight at Bedford Autodrome at @6,600 rpm. It wrecked the top end, scored the bores and did some damage to the bottom end too. I sold the shell on, but the car needed a replacement engine before it was recommissioned for road use. The pickup tube is a weak point in the 944 engine design and the reason I no longer use one on track.

Here is the offending item.

 

[GlennS]

and here is where it should have been attached to