pugtech

This is my first summer with my new 1980 US. Over the past week, I started to notice my oil pressure (gauge and light) drop to near zero when I approach a stop light and release the accelerator. When I rev the engine (1000-1500), the pressure increases and the lights go out.

Today it progressed to the point where the lights were solid unless I maintained a constant rpm of 1500 or so.

I run Valvoline 20W-50. This only occurs when the engine is hot (centered between the two white lines). When I start it cold, the gauge immediately jumps to 5 and works it's way down after warming up. The oil level was between the min and max. When I topped it off, it seemed to help a little.

Having read many previous posts on the similar issues, it sounds like I should replace oil/filter along with the oil regulator above the sender. I doubt it's the sender since the light and gauge agree.

Does anyone have any more tips or items to add to my to-do list?

Thanks Much...Scott

cfc928gt

Yeah, try the oil thermostat above the sending unit. Not expensive but it can cause your symptoms.

Mike Frye

Scott,

How long since your last oil change?

Can't oil 'break down' and lose it's viscosity (especially dino oil) over time/mileage?

You said when it's cold you get the full 5 bar. When it's warmed up and you're up over 4k rpms do you get a full 5 bar again?

You're probably right that it's mechanical if it's shown up over a short period of time like a week, I'm just throwing these out there as questions rather than a fix.

pugtech

It's been about 2000 miles. Once the engine has warmed up, 4000rpm may only get me to 4 on the oil pressure gauge. The oil pressure gauge seems to follow the tach, almost as fast. I figured the recent hot days, my love for AC and the long line at the drive thru must have pushed the oil over the edge. My mechanic wants to replace the sender but that's not my first guess since the gauge and light agree.

RngTrtl

Yeah, oil pressure is way low. If the oil thermastat is opening too much is could cause what you are describing.

Jim bailey - 928 International

The USA 1980-1984 has no oil thermostat because it has no oil cooler....no engine oil hoses at all !

pugtech

I was referring to 928.107.172.02 Regulator Insert (104#57 PET 25.08.2006). I was hoping my car had one since it's an easy fix to an otherwise scary problem. Can anyone help clarify?

Thanks!

Jim bailey - 928 International

Nope none in there since there is no reason to divert the oil to a none existant oil cooler...

classic_cars

My 84' has similar symptoms. When hot it takes about 1,000 rpm to keep the light off. As a side note- if I turn on the headlights- the oil pressure drops a bit. (probably need to check the grounds)

I'm doing an oil pan gasket soon- is it worthwhile to check/ replace the rod bearings? Will this improve the oil pressure?

Thanks!

Mrmerlin

oil pressure may increase if the rod bearings are worn, but not much, changing the oil may help also