Heat, oil pressure, oil tipe, and everything in between...

ezl · ezl's Garage

Hi guys

It has been a month with my new 1977 911 in Israel and the questions are piling up...

The car has no heat exchangors, has front oil cooler with fan. temp is 200-210 at 70 mph, which may not be that much in Israeli hot days, but still a bit high. if i increase speed, temp will rise.

Engine has 89000 Arizona miles. sounds good, preforms good, doesnt smoke at all, doesnt leek (!) all is good on that department...

Oil preasure is between 0 - 2 bar at 2500rpm. that doesnt look too good..worse, when you press it it will not build up more preasure than that. i cant make much sence of this considering the overall condition of the engine.

I tried changing the oil to 20-50 Castroll, and put a BG aditive. i put just one to see what will happen though BG prupose 1 every gallon or so. preasure went up a bit, but now it is dropping back.

The only thing i can figure out is that oil pump is weak for some reason. is it worth changin/ruibilding? are there any upgrades to the pump? the connection between the preasure and the temp sims obvious, so somehow, i have to rise the preasure. as it doesnt smoke, it must be the pump. or so i think...

About the oil, i am confused...i dont know what is the original recomendation, and i cant find it anywere! the 20-50 sims like a good solution but a mecanic told me it will fill the engine with "mud" which sims logical. the best solution seems to be Diesel and Turbo engine oil, but they are all, for some reason, 10-40. couldnt find thicker Diesel oil than that. I am trying to get hold of an oil engineer, but until then...

Can you guys make sanse of all this?...

Thanks
Eitan

Mo_Gearhead · 06:53 AM

Eitan,
If the car spent its life in Arizona (heat) and seems to be running well (good power, NO oil leaks!) I think you may be worrying for no cause. 200-210 is borderline, but not all that warm.

Oil debates are all over the board, most suggest 20w-50 in hot climates and MOST do not advocate additives. As for a mechanic telling me 20w-50 is like filling a car with "mud" ??? I would change mechanics.

Others may chime in on checking oil thermostat operation, etc.

Changing the oil pump is a case splitting / major operation. If the engine has not had the cam pressure fitting upgrade, I would do that (an easy fix).

911s55 · 06-24-2007, 07:22 AM

Eitan; Check to see if your pressure gauge, sending unit, and pump are working, many threads about this, just type in topic in search feature, also 20/50 oil is what you want to use in your climate, new mechanic recommended, check out this site and find an approporiate oil available in your location, Motul maybe?
http://www.lnengineering.com/oil.html
David

Jim Sims · 06-24-2007, 07:54 AM

911 oil pump wear typically is not a problem (they tend to last "forever" as they run in oil) ; what pressure do you see when the engine is cold? If that pressure isn't above 2.5 bar when the engine is cold then the oil pressure sender may be defective or there could be an oil pressure relief valve piston or spring problem. Both of these issues are relatively easy to address (engine can remain in the car.) One warning: the oil pressure sender mounting block should be removed from the passenger side cam tower oil line and taken to a work bench vise for removal of the oil pressure sender from the mounting block. Do not attempt to remove the sender from the block with the block mounted to the engine - irrepairable damage to the engine case can result from the high torque required to remove and reinstall the oil pressure senders. My 1976 911S (basically identical to your car) has been run for 20 years with 20W50 oil (Castrol GTX 20W50 or equivalent) without any sign of sludging ("mud"). It is important to change the oil and filter every three moneths or 3000 miles. Perhaps your mechanic is not familar with air cooled engines and is basing his comments on his experience with water cooled engines some of which "sludge" badly due to poor designs and excessive oil change interval recommendatioins.

Cheers, Jim Sims

randywebb · 06-24-2007, 11:51 AM

I would use Mobil One or another synthetic. They are superior esp. at high temps.

The oil pump is about the last thing I'd worry about. 210 oF is fine.

"no heat exchangers," ?? does it have headers? or what?

Avoid running flat out thru the Negev on super hot days...