Can too much oil make car run hot

redstormcoach · 04-26-2009, 12:54 PM

Can too much oil make car run hot?

1978 911SC 3.0

Alan L · Alan L's Garage

No.
What do you mean by too much.
The car uses the oil for coolant. More is better than less.
Blocked cooler, stuck thermo valve, dirty engine?
Alan

Steve@Rennsport · 04-26-2009, 03:00 PM

Quote:

Originally Posted by redstormcoach

Can too much oil make car run hot?

1978 911SC 3.0

Yessir,....absolutely!

One really must maintain proper oil levels using the dipstick.

Alan L · Alan L's Garage

Ooh.
I'm wrong then.
How does too much (how much too much) make it run hot?
Alan

Steve@Rennsport · 04-26-2009, 03:13 PM

Quote:

Originally Posted by Alan L

Ooh.
I'm wrong then.
How does too much (how much too much) make it run hot?
Alan

The more you add (over the max marking on the dipstick), the hotter it will run. This is due to foaming as air/oil mixtures are not efficiently pumped nor cooled.

redstormcoach · 04-26-2009, 03:24 PM

Thanks.

I drained a little of the oil. I just had the oil changed about 900 miles ago and noticed it was very dark. It didn't smell like burnt toast or anything. Anyway, after draining it did still run a little hot. The Oil Temp needle was pointing at 9

clock which is approx 220 degrees. i will change the oil next and see what happens. I have been using 20w/50. Should I change oil weight or away from Mahle filter as part of the test?

Alan L · Alan L's Garage

Well Steve, I would defer to your experience completely.
But I do know after I rebuilt my SC engine, I inadvertently over filled it at the 2nd oil fill (ie after I ditched the run- in oil). And it remained overfull until the next oil change (18 mths and a few thousand ks). I never added any oil in between that change, and the oil gauge was still pegged at top when I drained that oil after 18 mths. And the car certainly never ran hot.
So, it would seem they maybe don't all behave like that.
What he could check is the cooler lines when it heats up - see if the valve is opening to the front cooler, and when Temp wise.
Alan

sig_a · 04-26-2009, 05:48 PM

Quote:

Originally Posted by redstormcoach

Thanks.

I drained a little of the oil. I just had the oil changed about 900 miles ago and noticed it was very dark. It didn't smell like burnt toast or anything. Anyway, after draining it did still run a little hot. The Oil Temp needle was pointing at 9

clock which is approx 220 degrees. i will change the oil next and see what happens. I have been using 20w/50. Should I change oil weight or away from Mahle filter as part of the test?

Oil temperature needle at 9 o-clock is equal to 100c. or 212f.

redstormcoach · 04-29-2009, 05:08 PM

Well, I found what was causing the high temp. When I did a static timing after I removed the distributor I didn't quite get it lined up right. (TDC and distrib pointing to the one wire) I went off the wrong notch on the crank pulley. Don't know how it even started. Anyway, read Waynes Project book, went to Sears and bought a timing light and now its all good.

Thanks.

jurhip · 04-29-2009, 06:39 PM

In a dry sump engine, you do not get typical oil foaming and as you found out it wasn't the cause of the high temps. BUT - additional oil in a 911 typically won't help cool as residual time in the oil tank will not change by much. Given the excessive capacity of the 911 oil tank, I think its safer to run slightly low than high as you do not run the risk of oil spillover. One must remember that even though oil is low on the dipstick, you probably still have 9-10 qt in the system.

In a normal wet sump engine, yes you could get high temps but the main reason is that as the oil is whipped around it foams and oil pumps cannot pump foam. So, you lose oil pressure and lubrication to critical bearings possibly resulting in damage (or at the least an oil light)

kidrock · 04-30-2009, 07:42 PM

Quote:

Originally Posted by redstormcoach

Well, I found what was causing the high temp. When I did a static timing after I removed the distributor I didn't quite get it lined up right. (TDC and distrib pointing to the one wire) I went off the wrong notch on the crank pulley. Don't know how it even started. Anyway, read Waynes Project book, went to Sears and bought a timing light and now its all good.

Thanks.

What degree did you set the timing at?

redstormcoach · 05-01-2009, 03:46 AM

5 degrees BTC at idle

DohertyCM · DohertyCM's Garage

I have to disagree here in some capacity...(sorry steve)

Having too much oil in the tank is not going to affect the foaming in the engine.

If that were the case then the oil would fill the case from the tank just sitting in the garage. Foaming is an entirely separate issue..

If you want to kill the foaming you have to attack that problem directly.
And the best way is described in waynes book, and that is replacing the oil supply nut at the cams with the 930 parts...(sorry i dont have a picture...)

I am assuming that you have the CIS system on this car, over filling the tank will cause you to backflow into the airbox...so running the system about a quart low is usually where it needs to be. Also if you are foaming that much you should see some oil leaking out of the oil breather on the top of the engine case in the back.
I believe wayne talks about this also.

I notice my oil temps drop when I reservice my engine.
If I were you I would spend about 5 bucks on the two nuts and get more oil flow through your motor which will bring your temps down as well.

Would it be practical for me to say, you might have a oil clog somewhere preventing oil flow which is causing it to go dark..and cause higher temps?
Higher temps...hmmm another easy check is to check your front cooler when you drive and see if it is hot...maybe the oil is not flowing. Alan L suggestions is what I am thinking as well.