Smoking oil due to broken fan belt! Help!

[rs6er]

Yesterday I drove my car about 75 miles. It ran fine.
Today I ran a few errands and I noticed my oil temperature had jumped to about 300 degrees just before I got home. The light on the oil temp gauge was on, as was the alternator light in the middle of the gauge. I opened the oil cap, and the oil was smoking. When it was cool, I started the engine briefly and checked the oil. It was at the correct level and looked clean (Mobil 1 20-50). It was then that I noticed that the fan belt had jumped the pulleys and immediately shut it off.

What should I do? I've only driven the car a few thousand miles since a total rebuild in February 2007.

John Naitove

[86 911 Targa]

Originally Posted by rs6er

Yesterday I drove my car about 75 miles. It ran fine.
Today I ran a few errands and I noticed my oil temperature had jumped to about 300 degrees just before I got home. The light on the oil temp gauge was on, as was the alternator light in the middle of the gauge. I opened the oil cap, and the oil was smoking. When it was cool, I started the engine briefly and checked the oil. It was at the correct level and looked clean (Mobil 1 20-50). It was then that I noticed that the fan belt had jumped the pulleys and immediately shut it off.

What should I do? I've only driven the car a few thousand miles since a total rebuild.

John Naitove

Replace the fan belt correctly, and let's see if all is back to normal.

[Josh D]

I would also add to change the oil. You've cooked the oil if it was actually smoking.

[rs6er]

I called my mechanic, who was out. His scheduling person said that I shouldn't drive the car at all and should flatbed it to the shop (60 miles away,) so that I don't do anymore damage. Is that really necessary?

I agree with the above two messages. Should I also have the oil analyzed?

Finally, the belt is a Contitech 10x710 (I removed my A/C.) Pelican says the belt should be 9.5x710. Is that a big deal?

[AVDCAV]

Who put the belt on ? Does the re build
Have a warranty that this issue could affect,

I would have told the shop " so when should I expect
Your flatbed to come and get it. It's probably fine
Just a silly thing that happened. But if you just
Dumped a bunch of cash in that motor. Why take the risk
Especially if you did not Install that belt.

[rs6er]

The mechanic did the rebuild, but he did it 4 1/2 years ago. I guess I don't drive the car much. I don't think it's a warranty issue, but according to our host, the Contitech belts are "service free."

[Tippy]

How long was it at 300?

Your alternator may have locked up pitching the belt.

[lindy 911]

I've seen M-1 at 400+ degrees with no issues. Put the belt on, make sure it tightens properly, start the motor and check the oil pressure. Take a good listen to the motor with the engine lid up. This is going to be a little touchy because you will think you here all kinds of noise now that your confidence level with the engine is down.

If it doesn't sound like someone dumped a bag full of bolts into the crank case, rev it a few times and let it idle until the oil temp comes up. If it acts OK try and drive it checking for any loss a power compared to your last drive. If it doesn't want to run it's hurt. Watch the oil pressure closely and keep your fingers crossed.

[crustychief]

Originally Posted by 86 911 Targa

Replace the fan belt, and see if all is back to normal.

And pay attention to the alternator light! If it is on you are probably not cooling your engine!

[rs6er]

Tippy- Not sure how long it was there. I was recalibrating the speedo after the odo gear replacement with a GPS attached to the windshield directly above the gauge pod. Sunroof was open and I wasn't really looking at the oil temp gauge. I guess I did notice it though about 5 minutes before I got home. At one point I noticed the engine was idling a bit high (around 1000) and heard a slight whine.

llindy 911- Recently my WUR has been needing adjustment, and the car has been pretty undriveable until I let it idle for 4-5 minutes. So it already sounds funky at startup.

crustychief- The alternator light was on when it was hot. When I restarted it when it was cool (before noticing that the belt was off) the light was off. Does this mean it wasn't fried?

[McLovin]

Originally Posted by lindy 911

I've seen M-1 at 400+ degrees with no issues.

Having a synthetic in an overheat situation helps, for sure.

But, in a normal car, you can have high oil temps, but the liquid coolant still keeps the heads/cylinders somewhat cool.

With a 911, that fan is doing quite a bit to keep the cylinders cool, there is no water to help with cooling. With basically no airflow over the cooling fins on the engine, by the time the oil gets to 300+, the cylinders, etc. are going to be very, very hot.

Anyways, I think all you can really do is get the fan belt back on, do an oil change and see how it runs.

[Tippy]

1st thing is determine why the belt pitched off.

[rs6er]

Just received an email back from my mechanic. Nice to know he agrees with most of you.

" I think you should change the oil, replace the belt, cross your fingers and run it.
You have a decent chance of it being ok. If it isn't you can deal with it then
I think you've got a chance"

That's what I'll do tomorrow.

Tippy. I remember showing someone my engine recently who told me the belt was a little loose. It slipped my mind however, because I drive it so infrequently. I do wonder why the belt would loosen though, since the Contitech is not supposed to stretch.

[Tippy]

My belt runs a little loose and with the turbo, goes from about 4000 to 6000+ RPM really quick without tossing.

Just wondering what would make it toss during a normal drive.

GL!

[86 911 Targa]

Originally Posted by Tippy

My belt runs a little loose and with the turbo, goes from about 4000 to 6000+ RPM really quick without tossing.

Just wondering what would make it toss during a normal drive.

GL!

FYI:

The correct P/N for our '86 is P/N 999 192 176 50 9.5mm X 710 mm

With 3 shims between the pulley halves, and 3 inside the cup.

Also check the alignment of the pulley halves.

Good luck,

Gerry

[rs6er]

Thanks Gerry.

RE: oil change. Should I change it once withy cheap oil and then again with Mobil 1 to get the burnt oil out of the lines and cooler?

[rs6er]

Originally Posted by 86 911 Targa

FYI:

The correct P/N for our '86 is P/N 999 192 176 50 9.5mm X 710 mm

With 3 shims between the pulley halves, and 3 inside the cup.

Also check the alignment of the pulley halves.

Good luck,

Gerry

Mine is an '81. Are 10x sometimes used instead of 9.5x?

[bullethole]

as for why it jumped.. check the nose bearing on the alternator. I had just a slight amount of wobble in it, and that was enough to grenade my serpentine belt.. Went through 5 belts before figuring this out. I put a new alternator in (>$300) and then took the old to a shop and they rebuilt it for $35 (cost me more in gas to get it to them and pick it up).. so now I have a really nice spare

[GaryR]

Originally Posted by rs6er

Thanks Gerry.

RE: oil change. Should I change it once withy cheap oil and then again with Mobil 1 to get the burnt oil out of the lines and cooler?

IMO No, put the same oil back in and run it.

[86 911 Targa]

Originally Posted by rs6er

Mine is an '81. Are 10x sometimes used instead of 9.5x?

Not sure about the 10 X belt size. Maybe someone else will chime in.

As for the oil, synthetics, especially Mobil 1, are very resilient to high temps.

I would suggest that you run it with the existing oil, and check for oil leaks.

Good luck,

Gerry