No Oil Pressure After Turbo Change

[Mark & Cath]

About a month ago our turbo blew, it is a 2001 with engine code AUY. I was only 500 yards from home so I coasted it home with very low revs, it sounded fine and started first turn of the key the next morning. Further examination revealed a faulty turbo so I changed it.

 

After rebuilding it I checked the oil and it was down about 1/2 a litre. This made sense as I had changed it 4 days before the turbo went and there was next to no oil in the intercooler or the pipes, anyway I topped it up to max to be sure. Because the car hadn't run for a few weeks and it had a new turbo I decided I wanted to pump the oil around before actually starting the engine so I took the glow plugs out and cranked her over.

 

Now she sounds fine but after 5 seconds I get a low oil pressure warning on the dash and I obviously stop. I have tried it 3 or 4 times with the same result. Clearly I don't want to start the engine with low oil pressure but I am at a loss as to know why it has low oil pressure when it was idling perfectly even with the blown turbo.

 

I have swapped the oil and filter even though they were new but that has made no difference.

 

Any ideas ...

 

Thanks in advance.

[chrispb123456]

After your recent problem with your old turbo I would be inclined to check the actual engine oil pressure with a gauge, you may have oil pump/relief valve problems or partially blocked sump strainer

[Mark & Cath]

Unfortunately I haven't got a gauge but I will check the others tomorrow. Strainer is easy but where is the relief valve?

 

Thanks for responding.

[chrispb123456]

There is a relief in the oil pump and another in the oil filter housing which is usually a bypass for a blocked filter.

This could be nothing more than a faulty oil pressure switch but as you already had a problem with the turbo I would definately check pressure first, you could by a gauge and adaptor from Halfords probably cheaper than risk driving to a garage for them to check it.

[Mark & Cath]

OK then, the sump is coming off on Saturday morning to check the state of play.

 

I know the strainer is simple to remove (2 bolts) but where on the pump is the relief valve, any pictures/diagrams? I am guessing it is just a cap with a spring pushing a ball bearing into a seat in the pump housing, excess pressure will lift the ball bearing and allow oil back to the sump.

 

Finally the 2 tricky bolts that you access though the gearbox housing, are they torx or allen heads and what size? I ask because I am going to buy a long reach tool rather that struggle with extension bars etc.

 

Thanks All ...

[Mark & Cath]

I took the sump off the morning, the strainer was almost perfectly clean and the sump had no gunk in the bottom. I did find a few tiny bits of metal in the sump but they were nothing that was concerning.

 

Now I cleaned out the oil filter housing with a syringe and wiped out the sump so there was nothing left. When I topped her up with 4 litres of oil it went to Max. 15 seconds of cranking later I got the low oil pressure warning again but the oil is now down the Min, clearly there is some circulation of the oil to the top end. I topped her up again and tried a few more times with no success.

 

Normally I would just replace the glow plugs, start the car, see how she sounds at idle and see if the oil pressure is OK with her running. However I am worried about the new Turbo being dry so I am not happy doing this. If I loosen the turbo oil return pipe and I get oil then I know I have at least got some oil going through it, will this mean it is safe to try and idle the engine or do you need full pressure to protect the turbo?

 

Cheers for reading ...

[chrispb123456]

Are you actually starting the engine or is this low pressure warning just when cranking over??

 

Low oil pressure at tick over is not so drastic, it's at higher revs I would be concerned. You have eliminated the restricted flow element but I would have checked pressure first before removing sump.

On your oil filter housing do you have one or two oil pressure switches?

 

Worst case you may have to remove sump again to replace pump.

[Mark & Cath]

Thanks for the reply.

 

I am just cranking it without the glow plugs in. I did it originally to prime the new turbo with oil before I started it, that is when I got the low oil pressure light and obviously I don't want to fit the glow plugs and start an engine with an oil pressure problem.

 

I have one pressure switch on the filter housing.

Edited November 12, 2011 by Mark & Cath

[chrispb123456]

Im not 100% on this but if your doing all this cranking with the glow plugs disconnected it may be throwing a fault code similar to to glow plug light flashing when you have a faulty brake light switch.

 

Appreciate you have suffered turbo failure before but just start the engine normally and let it idle for a few moments then report back.