Cooling and oil pressure??

[LennysEleven]

Took a good drive on the Eway today and when I got of and the car got down to idle about 1000rpms, the oil pressure light comes on very dimly, and goes out when revved up. Problem is I just replaced the oil pressure sending unit and it fixd the problem, about 500 miles ago, do I just need another oil pressure s.u. or possibly a new pump?

Also, changed fan clutch and installed undertray(never had one) and my car stays about 1/4 on the expressway but after that when sitting it will keep going past halfway.(Temp didnt get over 70 today) So where do I go from here.
Heres a stupid question, in the Haynes it says to check the drivebelt tension if you are running hot, would this be affecting the water pump?

thanks
Nick

[nando]

it would probably help to know what motor you have. ;)

[LennysEleven]

Sorry 90 325i

[nando]

if your car is stuck at 1/4 while driving, and getting hot when sitting, your thermostat is probably stuck open. might be time to replace it.

also, why does your M20 idle at 1,000rpm?

[LennysEleven]

I was also wondering this, what is the normal idle?

[nando]

~650rpm.. 1000rpm is way high. might be time to clean out your ICV and check for vacuum leaks!

[LennysEleven]

So if the t-stat is stuck open and I replaced it would that cause it to just heat up quicker? Or would it help with overheating?

[nando]

it would warm up faster, yes. it should run just under the 1/2 mark.

[LennysEleven]

So if the thermostat is stuck open, replacing it wont help it from overheating right?
Also, does cleaning the ICV< involve just spray electronics cleaner into the terminals?

thanks again
Nick

[nando]

replacing the tstat can help with overheating if it's stuck open. the problem is the coolant is always circulating even when the engine is cold, so it heats up and never gets a chance to sit in the radiator to cool down.

you actually spray inside the valve of the ICV.. I used carb cleaner on mine, some people say it can damage it but mine was fine.

[LennysEleven]

Does the ICV have an arrow pointing towards the intake manifold? The Haynes doesnt show any pics for my car.