| Author |
Message |
Mark Eberhardt (Me_k)
New member
Username: Me_k
Post Number: 37
Registered: 5-2002
| | Posted on Sunday, June 09, 2002 - 9:39 am: | |
What Steve and Bruno said sounds about right. The only thing I would and is a quick oil explanation. Oil gets much thinner as it warms up, so it is perfectly normal for pressure to drop. A multi weight oil is formulated to have a more stable viscosity. 20W-50 for example, has the viscosity of a 20 weight (thin) oil when cold (w stands for winter), but when it warms up, it doesn�t get as thin as a 20 would, it only gets as tin as a 50 weight would. |
Steve (Steve)
Junior Member
Username: Steve
Post Number: 161
Registered: 2-2001
| | Posted on Sunday, June 09, 2002 - 7:35 am: | |
1st need to understand what weight oil you are using. If 20W-50 and outside temp is say 60 degrees then you start the engine and pressure will run fairly high 50-70 lbs at idle. As oil warms up it's viscosity increases to the 50W and pressure should increase at 6000rpm (70-90 psi). Also at idle it should be around 20-40psi. The pressure light usually comes on at 5psi.On my 308 at 70-80degree day with oil temp up 200deg. and running in 5th at 3500rpm I have an oil pressure of 70psi. At 6000rpm its at maybe 90psi.So the best thing to do is go to your local auto shop and get a mechanical gage and hook it up to where your oil sending unit is near the oil filter and get a reading. If its OK then most likely the oil sending unit is bad. My 2 cents here. |
bruno bandaras (Originalsinner)
New member
Username: Originalsinner
Post Number: 37
Registered: 5-2002
| | Posted on Saturday, June 08, 2002 - 9:14 pm: | |
Both my 308's did it. I changed the sending unit and got a steady reading on my 78 at speed. It still drops off at stops but not all the way to 0 like it use to. I tell everybody with car hot and running remove the oil fill cap and look in with flashlight if oil is pumping up and around parts good it is not your engine. Of course you can always put a manual gauge on it. If you were at 0 the thing would be very loud and would come apart fast.Sending units for my 78 were $45.00. A cheap invvestment. |
sfulmer (98f355gts)
New member
Username: 98f355gts
Post Number: 9
Registered: 5-2002
| | Posted on Saturday, June 08, 2002 - 12:09 am: | |
Can anyone explain how and why the oil pressure readings vary so much? When I first start the car (and it is cold) the oil pressure is high, but after the car warms up, the pressure drops dramatically. When I first got this car in February, once the car was warmed-up, the oil pressure guage was in the middle (about 70). Now, 2000 miles later and in the hot weather, the car (warmed up) has an average oil pressure of about 40. When the car idles (and hot), the pressure is just barely above 0. However, the low oil pressure light never comes on and the engines is running smoothly. According to the manual, the pressure should be between 72 and 87 at an oil temp of 212 @ 6000 RPM. I'm not sure my car is properly maintaining this pressure (the only indication is the gauge reading - car seems to run fine). Anyone have any ideas about what these readings and variations may mean? |
|