89' 944 Turbo. Low oil pressure.

[944Volks]

Got a high mileage 1989. 944 Turbo.
Done over 230k miles.
Newish turbo.
Gets up and goes above 3000rpm
But doesn't feel like 250bhp anymore. Lol.

It is running 20/50 oil.
Cold starts at 4bar.
Runs at 3bar when warm above 2500rpm.
But when hot, sat in traffic, on tick-over, it drops down to 1bar.

So, what do you experts think.
Is there a possible easy solution? (Weak pressure by-pass valve?) Or engine rebuild before more serious damage?

Thanks in advance.

 

[bmnelsc]

Given the mileage you quoted I think a pressure relief valve or similar MIGHT give you some relief (sorry - couldn't resist) but I would guess its more likely bearing wear - rods and mains most likely...not sure how big an influence cam bearing are. It might be worth inspecting/changing the oil pump first just to see what difference that makes. Unrelated but I have had water pumps wear out to the point of overheating with never a drip or a noise so its conceivable an oil pump could do the same. Cheaper and easier than committing to an engine rebuild and if you do need to go ahead with an overhaul you already have one part dealt with.

 

[Waylander]

just a question
what are you using for reference re the readings, if it’s just the dash gauge, I would suggest fitting a real oil pressure gauge, to give a decent reading,

the oil, temp, fuel, and battery on the standard dash after 30 years can be very suspect in accuracy, especially if the connections have not been cleaned.

if you then discover it’s very low still, changing the oil pump is a huge job, the sump has to come off to do this, at which point you might as well remove a rod cap and a big end cap and take a look at the bearings, and replace if needed,
if they are completely stuffed and the crank needs grinding and all the rest of the engine rebuilt, prepare for a big bill, 4-6k

 

[PSH]

My first port of call would be to check the pump although these things are bullet proof and rarely fail, if ever? Check that the crank bolt is fully tightened first as this is critical to the pump working properly. If it is at full torque (IIRC this is around 155lb but do check the spec) then perhaps try replacing the geared sleeve and the silicone ring which actually drives the pump. Worn bearings would give similar symptoms but 230k is not high unless the car hasn't had the required oil changes. Porsche did their own endurance tests and after 250k measured everything finding zero wear on bearings, in fact the engine components where still good engough to paas for a new engine on the assembly line.

Pete

 

[944Volks]

Hi. Thanks for replies.
My limited knowledge is that even a oil pump change is a very involved job.... True?

Yes just off dash gauge. Spend more time looking at that than the road! Lol.

Easy to clean connections? Need to fix Speedo and digital clock anyway sometime.

 

[944Turbo]

What brand of 20/50 oil? Mineral or synthetic? not all oils are equal... a good synthetic will hold its viscosity and therefore the pressure better. Checking for boost / vacuum leaks is a good way to start with adding the horses back, that and wastegate work if it is running the standard item.
Best regards,
Tony

 

[Waylander]

Hi you don’t mention where you are roughly in your profile

the oil pump is a huge job, the front cross member needs to come part way off to get the sump off, the sump gasket is £80 so you don’t want to do it twice, most would replace the engine mounts at this point, another £600,

cleaning the connections is a fairly easy task
have to remove the cluster and then clean the rugby ball connectors, it can be done without steering wheel removal but it does make it a lot easier with it off,
if you do remove the wheel undo the nut but leave it half way down the threads, I have seen folks break noses and teeth when the wheel comes flying off

 

[Waylander]

I noticed you say oldest profession in your profile, i hope it’s not what I’m thinking of

 

[PSH]

Oil pump 'per se' is a big job, replacing just the geared sleeve and 0 ring is much simpler and quicker, and to be honest, if you suspect the pump then it's these parts that are most likely to be the problem. The pump internals as stated earlier are built to last. The workshop manual and Clark's garage aren't that good at describing the function of these parts and why the torque figure is so high. The geared sleeve has no inner spline, only the outer which engages with the pump gear. It slides onto the crankshaft and is locked in place by the O ring which is squeezed into the sleeve chamfered outer end via the high torque which forces the O ring into the chamfer taking its shape and thus locks the sleeve up against the stop on the crank, a bit like a morse taper on a lathe/mill. Over the years I have read horror stories of people trying to remove the sleeve without removing the 0 ring first and using all sorts of heavy-handed methods to remove a part that basically just slides on. Always replace the 'O' ring, it will basically come off looking a wedged shape whereas the new one will be a round section. The reason that oil pressure is lost when the crank bolt comes loose is that this breaks the bond and there is now nothing to drive the geared sleeve. it's been a long time since I worked on mine but think I have this correct even if my head is a little fuzzy these days..

Pete

 

[944Volks]

Thanks for replies chaps.
Not ignoring, trying to find time to sit down and look through the service history.

Following from other rebuild post, I am not aware of any oil usage or JB smokescreens! ??

 

[944Volks]

Sorry for delay.
I have looked through what service history I've got. It looks like previous owners have looked after/cared for the car.
Last oil change used Valvoline VR1 Racing 20W50.
Direct oil pressure readings sounds a good idea. Where would you make the connection? Is there a easy access point?

My Speedo and mileage odometer don't work, as both, could this be a sender issue?
How do I check where the fault is?

Thanks for the oil pump suggestions, I really need to get some clear images of the area, and try to understand what you are suggesting. Thanks for taking the time to reply.

 

[Waylander]

The speedo not working could just be a connection to the sender on the gearbox, they go green and crusty

the take off for a oil pressure would be a T connection where the current sender is, below and behind the oil filter