Runaway Heat Issue…Off to the Shop

[Akira28]

Of all the projects I’ve worked on so far I’ve not had one kick my butt until now.

Now that the summer temperatures have gotten in the 90’s regularly and my commune has increased, the temperature of my little obsession has made it impossible to drive without panic setting in (reaching 250) slowly. During a 30 mile thirty minute drive i minimal traffic to work yesterday (90 degrees ambient) the temperature hit 270 for the first time. I got it back to the house hit the loop cooler and sump plate with the garden hose let it cool a bit then parked it.

I have done the following projects in an attempt to cool the car down by the following methods but none have worked fully.

WUR Replacement – reduced temperature by 20 degrees for 15 minutes
Oxygen Sensor - reduced temperature by 5-10 degrees for 5 minutes
Replaced Oil- reduced temperature by 5-10 degrees for 5 minutes
Tune Up – No Effect
K&N Highflow oil filter – no effect

Loop Cooler is functioning properly and opens at 220..
Temperature gauge is subjective but accurate..
Different Fuel Types and octane have no effect.
Leak Down Test shows no problems.
Hair is till in place but growing thin..
Pocket book is looking even thinner..

So I towed it to the shop (Motor Sports International in Beaverton, OR)

So far, the shop mech has indicated that he thinks the internal thermostat maybe the problem and that there looks like an old mouse nest on top of the engine. The engine needs to be dropped and will solve both problems at the same time.

So I will post up the damage and any pictures of the carnage as I go.. I figure if I have to pay the bill we all might as well all benefit from the process.. LOL

**
1983 911SC 3.0
1984 911 NA

[GH85Carrera]

That mouse nest can be a major cause of no air flowing on the cooling vent. I have seen old VWs that were packed soild with nest material.

[Akira28]

I can relate...
I've found a few hundred listings for people who have has Mouse problems causing overheating so far. It's just hard to imagine when your a first time 911 and wannabe DIYer That your heat issues could actually be something nonmechanical and random like that. When It's done I'm tempted to go to Disneyland and punt Mickey in the wooblies.. LOL

**
1983 911SC 3.0
1984 944-NA

[GH85Carrera]

The way to prevent a mouse nest is drive you Porsche every day!

[SCWDP911]

Originally Posted by Akira28

Now that the summer temperatures have gotten in the 90’s regularly and my commune has increased

Do you really think more hippies is a contributing factor to the problem? Unless that is you think the hippies built the mouse nest. They may have been trying to save the planet by getting one more petro loving car of the streets!

(sorry - had to)

[Superman]

Originally Posted by v8_ranch

Do you really think more hippies is a contributing factor to the problem? Unless that is you think the hippies built the mouse nest. They may have been trying to save the planet by getting one more petro loving car of the streets!

(sorry - had to)

I think you misinterpreted. He says his commune is increasing. Getting bigger. He's probably just a very marketing-savvy hippie. Perhaps his ads have mentioned the orgies.

As far as the overheating thing goes, your mechanic probably found the problem. Those cylinder fins must remain unobstructed. Also, the engine oil cooler (your primary defense against overheating) is under the shroud as well. It must have good air flow.

Good luck with your commune.

[Akira28]

LOL.. Sorry about that, I'm at work and typing far to fast with the autocorrect on. Don't need the boss catching me in a Porsche news group. Quite funny considering half the folks in the building are probably surfing for Porn.. :-)

Lots of Hippies in Oregon, most of whom drive Smoke spewing VW vans, and are more likely to smoke the nest then build one.

My SC is my Daily driver that I picked up 11 months ago.. and It's parked in a garage at night. Nest is probably from the PO who worked for the forest service and sold it because he was getting a divorce and was going to loose it to the old lady if not.

Thanks for the comments.. back to work and the Distinct lack of Orgies...A

[john walker's workshop]

a carrera radiator style cooler and fan is the fix as long as the engine cooler isn't blocked by a collection of dirt or dog food, and the engine t/stat actually works. most of them do. you can wire the fan to a switch or use the stock wire loom, temp sensor and relay and let it come on when the sensor closes. there is a BMW sensor that closes at around 200F. 270 is real unusual, so look for the simple thing first. pull off the fan housing/alternator unit to see if the cooler top is clean. use a infared temp sensor to read temps at the engine cooler and along the oil lines. drop a candy thermometer on a wire into the oil tank. maybe the gauge reads wrong due to a faulty sender.

[Akira28]

Thanks Mr. Workshop.. Great advice..

I shot the sump Plate with a laser thermometer and replaced the sending unit with the same indicated temperature in all three instances. The main engine itself really got hot (270) . The loop cooler is opening properly but didn't dissipate the heat 100% and only slowed the runaway process. This was made apparent as at 220 the heat stopped rising for 3 minutes and then continued slowly continued upwards. The oil reservoir was at 240, lines at 220. Also running a cold garden hose on the loop cooler dropped the temperature by 5-10 degrees, but spraying the sump plate dropped it by at least 20 within a few minutes.

While that doesn't tell us much, I'm thinking the internal thermostat is probably on the fritz, blasting water in the oil cooler and the loop cooler did very little. The Engine is being pulled as we speak (write) so we should have a final result on the process by Monday.

**
1983 911SC 3.0 - Mouse Hotel
1984 944 NA

[CliffBrown]

A lot of us have had the same problem.

If your willing to remove the alternator and fan assembly you can access the top of the motor (especially the top of the oil cooler) to clean out any old debris and avoid the expense of a motor drop at the shop.

Clean out all visible debris then use a water hose with a nozzle to blast the cylinders fins and oil cooler from the top and bottom of the motor. Clean out any debris again and repeat.

Another area we forget is the exterior of the oil tank. Over the years the rear tire throws dirt up on the oil tank and tends to insulate the tank. The tank exterior surface will help shed some heat from the oil if kept clean.

Make sure the oil is at the full level.

Check the ignition timing of the motor.

[Superman]

I wouldn't pull the motor just yet. I would remove the right side triangular cover plate at the rear edge of the shroud. With that off, you would be able to see the tops of those cylinders and the oil cooler. A shop vac might clear the debris.

[911pcars]

I'll pile on with Mr. Walker's sentiments.

After you confirm all debris and dead rodents are removed from the air cooling path, I'd deep-six the trombone "cooler" and replace it with a real cooler, the type with fins and effective heat transfer. A fan will then be necessary to create heretofore non-existent air flow over the heat transfer surfaces. Only then will you be able to maintain decent oil temperatures during the summer months.

Sherwood