ran it 6 miles w/o fan belt...whatdyathink?

[teamgomez]

OK OK- I know the damned thing is air cooled...but...after all the fuss getting the car back together after dropping the engine/tranny and reliving the exhiliration of getting the track queen back out on the open road, the alternator STB yesterday while at work (16 miles of freeway from home).

Decided to buster home (max forward velocity)- alternator light on prior to Coronado bridge (bad place to decide to die...unless you have jumping off in mind). Alternator making a good "bearing's about to die" noise...

8 miles from home the alternator seizes and god-awful noise coming out of engine (5 years on the track; no DNF's- 1 freakin' highway trip and I'm lookin' for a wrecker...). Decide to pop fan belt off and press home.

2.5 miles from home- temp still 180 (thankful for awesome front oil cooler)...but pocketbook fears and consult w/ favorite mech pulls me over (.5 miles from freeway exit). Speeds thus far about 80 in fair traffic, no stopping. Decide to try to put belt back on a press home....

.5 miles later alternator seizes again and belt starts smoking...RATS! A phone call to 2 bit tow later and I'm back in the garage, taking out my freshly powdercoated fan housing and buying a new alternator.

2 Que-
1. Do you think the head temp rose significantly enuf on the 6 mile/6 minute beltless trip to cause heat damage that will rear its ugly head in the future if not already? How much does the temp rise in there (beneath cowling) sans 11 blade assistance?

2. Do any of you converters out there (exterior to interior volt reg alternator) go to the trouble of putting the resistor on the batt lite so the charging system won't dump if the bulb burns out?

Thanks- all words of wisdom entered in future drawing for new tool I plan on designing that will dislodge any alternator from any fan housing- no matter how much powdercoat has the damned thing stuck in there..............

[Evans, Marv]

I'd say you are probably OK, although I don't think I'd chance it beyond that much time. I had a 912 I drove about 5 miles from 805 out Telegraph Cyn. once & it was OK.

[Tim Walsh]

I hate to say it but 6 miles is a long time without a fan.. that fan moves LOTS of air. I broke my fanbelt about 8 months ago and my oil temps never went over 200.. 5K later I'm nearly back on the road. I have a Mg cased motor though so you might fare better than I.

[HarryD]

I would expect some damage as the fan not only cools the oil but puts lots of air over the cylinders as well. The oil may be ok but the cylinder wall temperatures went high.

[BURN-BROS]

There are two that come to mind if excessive temps are reached.
1. piston/cylinder scouring.
2. valve seat dropping

I do not know at what temp these things start to happen, so maybe someone can chime in.

[teamgomez]

Oh well....should any damage rear its ugly head, will just have to sneak in some 98mm P&C's during the rebuild to assuage my ill feelings of despair and helplessness...964 cams for the feelings of inadequacy...and a repaint to get over the amount of money I just spent on the engine. Isn't that how it's done?

[geof33]

Originally posted by teamgomez
Oh well....should any damage rear its ugly head, will just have to sneak in some 98mm P&C's during the rebuild to assuage my ill feelings of despair and helplessness...964 cams for the feelings of inadequacy...and a repaint to get over the amount of money I just spent on the engine. Isn't that how it's done?

I was just going to say... sounds like a good reason to rebuild (go big) that engine... or, didn't you say you needed a 3.6??

[Grady Clay]

Well, I won’t comment on your decision. With a cell and a flatbed tow, you can get home from anywhere.

First I would do a cylinder leak test and a cranking compression test.
Baring any excess, change the oil and check the sump screen (an ’80 has a sump screen?) Only then carefully drive it around the neighborhood.

If you have an immediate problem from this it will most likely be a broken ring or damaged P&C. These will show up with leak test. Certainly there is some long-term damage. It may show up in 1000 miles or 50,000.

He!!, just go make the engine how you want it, no problem.

It’s too bad Porsche didn’t make that red light brighter.


Sorry,
Grady

[RAM]

The same thing happened to me and I had your same question. I replaced the alt., changed the oil/filter and haven't had a problem. Granted, I don't race the Queen but she is driven!

[teamgomez]

Most of my shame is the result of the decision you decided not to comment on...this may turn out to be the most expensive powdercoated alternator fan housing to date...albeit as a result of my own boneheaded action...

[sammyg2]

Change the oil and alternator and run it with your fingers crossed. If it runs good, go buy a lottery ticket. With that kind of luck you can't lose.
I'll say a prayer for you and your engine and hope the best for you.

[CarreraS2]

Certainly takes guts (is that the right word here?) to run 6 miles without the belt.

I once wanted to confirm an alternator bearing noise, and I was nervous running the car, dead cold, for 5 seconds without the belt.

It will be interesting to see what happens with your car. From what I have heard over the years, it seems impossible to run a 911 without the belt for that many miles without damage. But who knows? Maybe your a lucky one, or maybe the engine can stand more time without the fan than most people seem to think.

[HarryD]

Originally posted by SoCal911SC
Certainly takes guts (is that the right word here?) to run 6 miles without the belt.

I once wanted to confirm an alternator bearing noise, and I was nervous running the car, dead cold, for 5 seconds without the belt.

It will be interesting to see what happens with your car. From what I have heard over the years, it seems impossible to run a 911 without the belt for that many miles without damage. But who knows? Maybe your a lucky one, or maybe the engine can stand more time without the fan than most people seem to think.

Sometimes things seem to work out.

See this thread.

A few years ago, we made a "real" 2.8 for PCA racing using an SC bottom end, custom cylinders with steel sleeves and 91.5mm JE pistons.

It had modified 935 heads (early stud spacing) with twin-ignition, 50mm PMO's, and a custom cam. Lots of internal mods, too....

This made 325+ HP at 8000 RPM and was VERY durable. In fact, this engine ran a 1 hour race in August at PIR with no cooling fan when the driver missed a shift on the opening lap and spit the fan belt off. It ran the whole race at 310+ F oil temps and upon teardown, only the lower side of some pistons were a tad scuffed. Mobil 1 15w-50, BTW.
Its still running just great.


__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
http://www.rennsportsystems.com

[teamgomez]

Man, this feels worse than running over my dog...gonna drop the screen tonight and do a leakdown test if I can steal my buddies test set this afternoon....details to follow tomorrow......

[Jamie79SC]

Och laddy y'er fooked fer certain.

[vash]

teamgomez, good luck buddy. if you get outta this, you owe your car something nice. bigtime! i dont mean i nice carwash and wax. i mean like a new momo wheel. something like that. keep us posted. your motor is tough.

[BURN-BROS]

935 heads have a lot more material there for temp control. Low oil temp may have saved you. Hope everything works out for you!

[Rondinone]

I just converted from the original Marchal to a new Valeo. I didn't bother with the resistor, and so far it hasn't mattered.

[addictionMS]

man oh man an bunch of pesimists, I say drive the thing, if it still runs, and has good power, and is not making noise, your good.

We broke a fan belt on our RX7 and that killed the water pump, and we finished a 3 hour night enduro, ended up boiling the car dry, but today that motor is as strong as ever, and running solid.

Never assume the worst, just go with what is there, test it, if it is ok, drive it.

Don't go looking for problems.

jim

[teamgomez]

Dropped the sump screen and all looks ok- didn't find any ring pieces or the like. Put the new alternator in (Porsche Tech bulletin shows the internal volt reg at the 6 o'clock position...won't work that way in the car...needed to put it at 12 o'clock to get rear shroud cover on...that would make it about the 5th time I've done alternator removal in the last 3 weeks..) and other than a new rub noise from the powdercoating on the interior of the fan housing rubbing on the side of the new alternator, the motor ran as tough as ever.

Didn't go with a leakdown tonite- got too late but there didn't seem to be any blow-by coming from the sump tank. We'll see how the oil consumption is after a few tanks of petrol. Who knows- I may have ditched the devil on this one. She's been a tough cookie for the past 10 years, hopefully I didn't rider her too hard this time!

Thanks all-

Gomez out.