250° is too hot - help

[scarletbegonias]

I have a 1968 912 and the oil temperature runs about 250°. It has about 700 miles since a rebuild and the engine looks new, so I don't think it's a dirty oil cooler. I changed to 20/50 and that helped (it doesn't get up there as fast), but it still goes up around 250°.

Can anyone help with any suggestions?

Should my next step be checking the timing? Could correct timing make enough difference to get the temperature down?

Thanks

[WFBowen]

Howard:
Definitely check the maximum advance timing. You've probably done this, but double check your belt (may have loosened up if new); make sure the heater flaps at rear of motor are open. Might be a good idea to double check the valve clearances.

Does this happen under various conditions (i.e. an hour of around-town driving vs. 20 minutes at 70 mph? Are the ambient temps hot (80 deg + ?)

Are you sure you're at 250 deg? If you have a stock oil temp gauge, are you at the top 10% area? (Many US bound Porsches had non-numerical gauges, as Americans were used to 180 or so, which usually isn't the case in air-cooled motors.) Also, the motor could still be a little tight from the rebuild. If possible, try a 70 mph drive & make a note of the the temp gauge when fully heated - then try a similar night drive & see if there is a notable difference in oil temp reading.
Good luck,
Bill.

[scarletbegonias]

Bill, thanks for your input.

I did a rough check on the timing and it looks like it's about 3 at idle and 28-30 at 3000 rpm.

About the belt - when I push it in, it looks like it's the correct tightness (as shown in the owner's manual). But when I turn the engine using the generator pulley it seems loose. It doesn't turn the engine on every turn of the generator pulley, it slips sometimes. When the engine's running the belt looks like it wobbles a bit. Is the belt too loose?

Sorry about my ignorance, but how do I check if the heater flaps are open?

The problem is worse when ambient temperatures are higher (like in the 80s), but it always seems to get around that 250° range. It has a 911 oil temp/pressure gauge and I think the reading is accurate - did a quick test using available resources - a meat thermometer in the oil dipstick tube returned about the same temp as the gauge.

[Duke]

I had the same problem years ago with my 69. The oil cooler was clogged with debris. You would be surprised what winds up back there. Just a thought about the overhaul-maybe the cooler was not even touched/cleaned.

[cgarr]

A clean cooler can make a huge diff,, I think you can get to it when you take the generator/fan out, at least its eaiser than trying to pull the shroud with the engine still in.

Craig

[scarletbegonias]

I want to try other things before I check the oil cooler. I'm not comfortable pulling the engine and it will have to go to Rick for that.

I found a belt tension checking technique at the 912bbs. With the correct tension you should be able to rotate the belt about 90° mid-way between the pulleys. More is too loose, less is too tight.

I can pretty easily rotate mine 180°, so I'm thinking I'm going to struggle with the generator pulley nut (I've read some horror stories) and move 1 or 2 shims from between the pulley halves.

[tbonz]

Howard...hey It's Tim M from the SoCal 912 board...
Mr. Mike B. and I used a oil dipstick temp gauge to calibrate the numberless temp gauge that many 912 's have and in a pinch I carry a candy thermometer along in case the engine starts to read hot on the gauge. Just pull the dipstick right after shutting the engine off and give it a little time to
get a sightly hotter than running temp level (remember the engine isn't cooling when the fan isn't turning so your car actually gets hotter when you turn it off it will spike after a few minutes.)

I'd say timing too advanced and carbs too lean and you left your parking brake on or
you are dragging your feet! ...patch those floorboards Howard!

In a pinch do as Mr. Mike B. and I did bringing his '62 356a back across the Central California Valley from the Tahoe area to L.A. one sweltering summer day in August.....http://www.912bbs.org/index.php?a=thread&t=5631

[cobra-6]

No need to pull the motor to get a look at the cooler for checking condition and some cleaning. You can remove the generator/blower as a whole.
Here's a description: Generator removal

[ediamiam]

I would suspect some debris, like a paper towel left under the sheet metal, has covered your oil cooler and air isn't getting to it. Or perhaps, if the fan sounds a little loud, same type of debris is lodged back there and isn't passing air over the cooler.

[scarletbegonias]

My 912 doesn't have connector hoses to these tubes (see yellow arrows in the photo below). On other 912 engine pictures, I've seen connector hoses here. Can these help to draw hot air from the oil cooler area or were these removed to take out old smog control parts?

[cgarr]

[QUOTE]Originally posted by gratefuldead
[B]Can these help to draw hot air from the oil cooler area or were these removed to take out old smog control parts?

Thats a good point I forgot about, If your seals around the engine tin are bad you can draw up hot air from the exhaust which will really heat up everything, after running my engine both 69 912 and 86 carrera, pop the lid and feel the engine, they should be quite cool on the top, it is very necessary to have that area sealed.

Craig

[cobra-6]

I think you're pointing to the carb pre-heat openings. Follow the tube down and you'll see it goes to the flapper boxes.
I really think checking your oil cooler is the place to start...

[silver912e]

As silly as it sounds, many an engine has been cooked by mice stashing dog kibble or other food stuffs near the oil cooler or heads. If you park it in a garage that has mice, this is worth considering.