really high oil pressure

[GTTURBO1988]

hi guys

I'm hoping someone can help me out. I have a 1988 Renault 5 gt turbo and it is running really high oil pressure. when I start the car up the oil pressure gauge rises really fast. I have been told that the original qauge on the car are a load of s..t. When I drive the it all seems to drive ok and I don't feel any loss of power. As soon as the car goes on boost I get a load of black smoke coming out of the exhaust. I originally thought that the turbo seals had gone so I took it out and seen that there was some oil inside the turbo on the fan blades so i sent it off to be refurbished. I have done this process 3 times and I am still having the same problem. I have checked all the breather hoses and there is no blockage in any of them. I sent the car of to a very reparable tuning company to have a few modifications done on the car. I have been in contact with them and the say they have never seen this sort of problem on the car. I have checked numerous things on the car and have not found any problem that can cause the issue I am having. any opinions would be much appreciated.

[tubbyG]

If possible get a mechanical oil pressure gauge hooked up. Ideally fitted/T'd into the turbo oil pressure feed.
Not overly expensive to do and will give a much better indication of what's going on.
I would be pretty frustrated too after having the turbo rebuilt 3 times 😡!!
Have you done a compression test?
What grade oil?
What turbo are you using? Some units require a restrictor to be fitted to the oil inlet to reduce pressure as the bearings don't like it too high.
Pressure relief valve on the oil pump itself could be faulty/sticky.
Have you ever had the engine apart?
I can only think that if it were possibly shimmed in the past (a mod to increase oil pressure) that the shim has been dislodged or moved increasing the pressure on the relief spring.

[GTTURBO1988]

nothing is standard on the car piston,liners,cams,clutch,fuel pump the whole lot has been forged to cope with increase in power i have had the whole engine rebuilt. when I first got the car I had a problem with the carb running rich. I spent a fortune trying to get it fixed and in the end I decided to have the car changed to injection last year. 10 grand and seven months I had an injection Renault 5. The whole engine was rebuilt had new clutch water pump fuel pump and various other things added to the car. I had it back for 2 days and covered about 20 miles when this problem reared its head. I have not abused the car I drove it responsibly as I didn't want anything to go wrong. The car is running on 20-50 thickness oil and the tuning company not to change it as that is the right thickness for the car. I haven't got the car running at crazy power as I wanted to get it running. I have owned the car for 6 years and have not covered more then 300 miles in it since I owned it due to various issues with it. just don't really seem to be getting anywhere with it

[Mad_Mat]

Definitely fit a good oil pressure gauge to find out whats going on.
Black smoke coming on boost sounds more like a fuelling issue. Perhaps the fuel pressure reg has gone tits up.
But then again I am just a keyboard warrior enthusiast so wtf do I know.
why not just get whoever built it to sort it out?

[Jimmy_GTT]

Have you checked your oil return pipe from turbo to sump?
If it is blocked or just narrowed you can get turbo problems.
Your car should be a phase 2 with 22mm return it is much better than the 16mm on the phase 1 but worths checking.

[Matt Cole]

Pressure relief could be jammed in oil pump.

[Alex]

As mentioned you really need an after market oil pressure gauge plumbed in to accurately see what pressure you're getting, I'm doubtful it'll be too high though as most GTT's struggle to produce just enough to start with!

The black smoke won't be anything to do with your turbo. I'd start by having a look at the carb and what size jets are in it, the main jet in particular. Do you have an AFR gauge?

[Ian S]

Those standard gauges initially show oil level. Then oil pressure. So that seems to be behaving normally.

How high oil pressure? When cold, with the new engine and turbo, mine would show 6Bar on the standard gauge.

I would say 20 is too thick. I used 0 in mine (0W40; the 0 when cold is about as thick as the the 40 when hot.) Many people favour a 50, as in 5W50 up to 15W50.

[Trevhib]

Which tuning company did you take it to and who did the EFI, same place?