The past few months I have been having an on going issue with the oil pressure indicator. While the engine is cold the oil pressure needle will settle at around 4 and 5 bar and function normally. When the engine has been running for sometime and I restart, the LCD panel will give out a warning about low oil pressure and the oil pressure needle drops to one bar. While driving the pressure will creep up to 4-5 bar again. What is the reason for this.

 

I'm guessing you're getting low oil pressure - the question is why?

What oil are you running and what's the weight of the oil. When was the last time it was changed? Does it do this in the morning when teh engine is cold, or only on hot starts?

I'm not sure but maybe the check valves are sticking, or perhaps something to do with the oil filter bypass (I know that was deleted in '91, but maybe also for 89?)

 

This is the classic symptom of your oil thermostat failing. It sits right above your oil pressure sending unit and it's very inexpensive. I found my GT ran cooler after replacing it as well - I assume because the failed unit probably wasn't letting oil circulate to the oil cooler. Pretty frightening to see '0' oil pressure on start-up isn't it.

 

Mobile 1 10w-50 is what I use and it's replaced every 3000 miles. It only does it when the engine is hot and it does not happen every time.

 

Which part are you talking about? Are you talking about one of those springs? Which one?

Dan
'91 928GT S/C

 

Dan, I only replaced #43, which is the thermostat and comes in two pieces. If I were to do it again I'd replace the upper and lower springs as well, #42 and #44 although it's working fine with the old springs.