V8QinNJ

I just bought a '90 V8Q from Craigslist in Boston and drove it to Trenton, NJ (about 6 hours) No major problems, the was was getting hot, or what was hot to me (100 Deg C) I noticed the AC fan was not kicking on, a jumper fixed that. but that's not all...

The cars starts and runs fine, the oil pressure gauge when cold and first starts reads 5bar, then when the car warms up, drops down to 2 and then to just off 0, but the car continues to run fine, (I've been driving it for a week, 50 miles a day)... any ideas on the cause? bad Sending unit? Bad IC contacts? ..bad oil pump (yikes), the TB was replaced 5000 miles ago according to the last owner (also the Oil Temp Gauge never reads more than 60 Deg C)

open to suggestions...

audi-bahston

Was this the Champange V8 in Chelmsford?

Kneale Brownson

It's not uncommon for the oil pressure gauge to read high when cold and low when warmed, but the idling pressure with a fully warmed engine shouldn't be below around 2. Do you know what sort of oil is in the sump, what kind of filter is in place?

What does it mean you "jumpered" the fan? Did you check the condition of the fusible link for the fan in the little black box mounted next to the hydraulic oil reservoir? That's an 80-amp fuse that can fail and still look intact. You need to loosen one of the screws holding it in place to be certain it's solid.

V8QinNJ

Yes, it is the fusable link, it was cracked in half for oxidation, i'm using very small gauge alligator clips to "replace" the link until I can track down a new one.

As far as the oil and filter, I have no idea, other than "it's full". Its on my list of stuff to do though.

I agree with that being around 2, that's why I think it me a instrument problem, like the sending unit or cluster.

V8QinNJ

<center><img src="http://www.scottnheather.com/images/audiv8pass.jpg"></center><p>Yes it was that car. It had been on CR for over a month.

audi-bahston

lot longer than that if it is the same car I'm thinking of. seems like a cool car.

Suffolk

Kinda sounds normal.

100 C is somewhere in the middle of the range of the gauge. With the fan kicking in compare where on the gauge it is now vs before.........

Now the Oil pressure in Bar...

Prefectly normal for 5 bar at start up (cold) and with thicker 20/50W Oils......

Now warming up, the oil thins to its lower viscosity number (20) and the pressure drops down to 1 - 2 bar, which is 14 psi to 28 psi.

PErfectly fine around idle.

It should go past 3 bar when warm on the freeway under "load"........

While its NOT a rule of thumb with Audis; to give you an idea, Porsche looks for 1 bar per 1,000 RPM, so you'd get 4 bar pressure at 4,000 RPM on their 6 cyl boxsters.......


Spin the motr faster, build up pressure; oil pump turns faster.......

HTH - Scott by BOSTON
quattro123.com

Suffolk

Re; oil temp.

Ask Carter, he had a V-8. Ask him what his oil temps were. I suspect there is a lot of oil in there, so it runs cooler.

-Scott by BOSTON

itsav8

This is how it's supposed to be.

To check the fan works turn the AC on..the fan should start to spin. All so the fusable link is on the side of PS res on driver side. Are both coolant hoses hot?? If not you may need a thermostat. Or the rad temp switch may be bad..bottom p-side of rad..is that were you used the jumper wire? If so than the switch is fine. Theres all so a fan resistor on the d-side lower front section of the motor with 3 wires going to it. It's near the "bomb"

Cold startup- 5Bar..Period...
Warm- 1.5/2Bar at idle..Period...
While driving the HW 65...100 ;&gt;..5Bar..Period...
Anything under that while cruising..you need oil..Period...

Oil temp should be at or a tad above the 1st hash..ummm hash..;P

As I said before check the IC but barring that you may have some flakey wires at the senders..pass side front of motor.