high engine oil temps

[masterchief]

I have a 3.1 with cast iron heads. The engine was blue-printed by Mike Myers Racing Engines of Gretna, LA. Installed was the Crane Compu 2030 cam with the associated valve train. Heads ported, polished, and ground out to gasket size. A Blue-Printed high volumn oil pump and the relief spring change to the 80 pound one. Stock compression. An oversized TB and Crane Gold series roller-rockers. Headers. Water temp runs around 190 degrees.
Problem: At 70 mph (3200rpm) my oil temp climbs to 240 degrees and will go higher if I don't slow down and this happens at any outdoor temp over 32 degrees. I use Mobil One 15-50. This engine is in a Pontiac Fiero GT. Before any mods, the oil temps were between 190 to 220. I've tried both mech. and electric oil temp gages and all read the same. Any ideas what is wrong. An oil cooler mounted in the space infront of the right rear tire made a difference before mods and after mods, it doesn't. Help!

[Superdave]

where is your oil temp sensor mounted?

[masterchief]

It is mounted about 1" from the bottom of the pan and about 2" towards the rear of the engine from the oil filter. A cradle member is between it and the exhaust pipe. There is probably 4" from the sensor to the exhaust pipe. I had an oil temp gauge on my older stock engine in the same place with normal readings. I've only had these high readings after modification (they're pretty mild mods).

[Superdave]

Might be a dead spot for flow or something...

[geoffinbc]

Well your pump is flowing too much volume for a stock motor and also the relief spring only needs to be 60 PSI. Why you got a pump like that or why you were recommended a pump like that is beyond reason. Your oil is also too thick. Why the HELL are you running 50weight oil? Run 30 weight like you should be and that should drop your temp right there.

Sorry if I sound harsh but the combo you got for the lubrication system is off.

[Joseph Upson]

The Fiero 2.8 oil pressure is ~80 psi and on a fresh engine you'll see every bit of it so that's not a problem, the high volume pump is out of place though. It creates more drag along with the heavy weight oil. I ran my oil temp gauge sender in the same line as the oil pressure sending unit because I was running a turbo so there was oil flowing past it and I did see oil temps as high as 240 but have no recollection of what my temps were on the hwy. I just finished debating the oil cooler issue with my swap stating I wanted my engine to run on the low side of normal with someone arguing for manufacturer specs. Heat breaks things quicker than prolonged cool conditions in my experience. You may want to try and locate your cooler in an air stream or get a larger one.

[masterchief]

The stock oil pressure relief spring is 70 lbs; part number 10044435, which is the same spring part number in GM's performance cataglog and that is the one I'm using. I was thinking about another car's engine that was 80 lbs.

Chevrolet Power, How to prepare Chevrolet Engines (6/90 degree engines) and Smokey Yunick's Power Secrets (60 degree engines) both recommend using a blue printed high volumn oil pump and I felt they know what they are talking about. Enough said.

I've tried going back to 10-30 Mobil One and all I see is a lowering of oil pressure, no temp change. My oil pressure on a cold engine is 70 lbs (you can see the relief spring working for I have both a mech. & electric oil pressure gauges). When the engine is at normal temp, the oil pressure is 45 lbs with 15-50 Mobil One and 40 lbs with 10-30. At idle, the oil pressure is 15 lbs (15-50) 12 lbs (10-30) respectfully.

I have used a high volumn oil pump on a stock 2.8 V-6 for 128K miles with no heating or oil pressure problems. Only since I put in this modified engine has the temp problems existed. 3,200 rpm at 70 mph in Louisiana is part of the problem. If no one feels there is a mech. problem, then I'm either running oil cooler lines to the front of the car (long haul for the Fiero is a mid-engine car) or putting a themp controled fan on the oil cooler.

[geoffinbc]

Well if you used the P/N listed in the Chevy Power manual then you are just using a stock pump. They refer to the all cast iron pumps as the High Volume pump where the Aluminum pump only found on early motors is considered a standard pump. The Aluminum pump is junk and is never used by any builder. The pressure spring you chose is fine.

You should be running 30 weight in the engine and not 50 weight. Your oil pressure with the 30 weight is fine and there is no need to run a heavy oil. All you need is at least 50 PSI at 6000 RPM. People will tell you 60 PSI which is usually what you get anyway. If you are getting 12LBS at idle your doing great I wouldn't worry unless it was lower than 5 on a hot day.

But still if a lower weight oil does not solve your problem then you need to figure something out. There is no way your engine should run with oil that hot unless you really driving hard, especially with synthetic. I am interested to know where your cooler is in relation to any exhaust tubing. What kind of filter are you running? Is it remote mounted or not?

[masterchief]

The oil pump is cast iron. I've tried just using a stock filter on the block and still have the problem. I've use a remote filter with braded lines going to a PF-35 filter and a 6 x 8 x 1 inch cooler and still have the same problem. The oil lines going to the remote filter are probably 6 inches away from the exhaust pipe. It's the same set-up I had before the engine was modified and there were no problems then. The weight of the oil is not the problem. With all the plumbing, etc., the engine now holds 6 quarts of oil.