Some problems with my 1977 s...Idle, clutch, heat

[ezl]

Hi Guys

This night i drove my 911, and the clutch pedal went to the floor.
Didnt have the chance to see if its just the cable yet, but i had a few earlier signs something was wrong. I am in Israel and i have to order the parts, so if anything alse needs attention on the way, i should do it...

The signs were: heavy cluch since i bought it.

Cluch was seperating very low (close to floor position) and has changed to about halfway.

Crunching started at 3erd gear after everything was fine.

2 days ago heavy squicking when pressing the pedal. this was after the car sat for a week. after half an hour of driving squicking stopped.

Yesterday, going into 1rst gear or reverse, sometimes will crunch like there was no cluch...this happened 2 or 3 times, rest of the time this was o.k. this was strange...

When this happened i thought the pedal wasnt going far enough so i pressed it hard against the floor, there was a cracking sound...strangly enough nothing hapened and all was o.k., until today it dropped alltogether.

Diagnosis? cable or worse? multiple problem???


Now to the idling problem.

Car starts fine, runs a little bit high which is good, and dropps to 1000 rpm wich also sounds good, allthough at that speed it is not alltogether smooth.

After 2 minutes it dropps to 500 rpm, and will barely stay running.

As heat increases it will run highyer and highyer at idle. after a good one hour drive it will idle at about 1500 and up. engaging into 1rst, releasing the clutch a bit, and puling back into nuetral, will sometimes take the revs down for about 10-20 seconds.

By the way, rubber seals for the intake are new.

This adds up to a problem with the mixture. when adjusting to a normal mixture (about 0.50- 0.80) idle is better, but the car doesnt rev as i think it should. when adjusting to a very lean mixture (about 0.20 or less) it revvs great, but idle problem gets much worse.

I'm realy clueless here...


Heating problem

My car has an aditional external oil cooler.

Car was running 180 when i bought it, gredualy went up and today its running 210.

Replaced the external oil thermostat without any change.

Hoses cooming into the thermostat housin are both warm.

The hoses going from the thermostat housing into the front cooler, one gets mildly warm, one is stone cold. cooler is cold at all times.

Does this mean a clogged oil cooler? i asked my mecanic who claimes this doesnt sound logical, though i dont know what alse to think.

On one of the connections of the lines into the cooler there is a large "lump", i.e. it is much thicker then the other connection. this connection is the one which is mildly warm. can there be any kind of valve there? can this couse the problem?

Sorry for the lenghy question but as the car is in Israel we dont have a very long Porsche tradition or knowladge here...

Will appriciate any help.

Thanks
Eitan

[Walter_Middie]

ezl,

You need to get under the car and take a look at the clutch cable. If this is broken, that's your clutch problem. If not, it could be something wrong with your pedal system, or it could be a broken clutch fork. The broken clutch fork would require the engine and trans to come out.

The idle problem sounds like a vacuum leak. Classic signs are a hunting idle. You need to do some research on the typical air leak problems.

[ezl]

Walter, thanks.

This was indeed only broken cable, big sigh of releief...

Thanks
Eitan

[ossiblue]

ezl,

Rex (Walter_Middie) has put you on the right track for your idle problem--sounds like a vacuum leak, and there are many possible areas besides the intakes though it will eliminate those. If you haven't already, use the search function to read up on vacuum leaks and the likely areas to find them and post any results of what you find when you check for leaks yourself. Adjusting the mixture screw should be the last thing done, and only after leaks have been corrected and fuel pressures set to specs. Feel free to ask any questions in your hunt for leaks. BTW, do you have a pop-off valve in the airbox? If not, you should install one asap and if you do have one, make that your first check for leaks.

As far as the heating goes, I would agree with you--there seems to be a blockage in the line into the cooler or your new thermostat is defective. From what you describe, the oil is plenty warm enough to open the thermostat and the line to the front is warm. The fact that the cooler always remains cold tells you the oil is not flowing through the cooler.

If you have an OEM thermostat, the line to the cooler is always open. When cold and the thermostat is closed, the oil flows through the thermostat, through the cooler, and through the return line where it stops because the bypass valve closes it off. Oil is circulated only through the thermostat at the bypass which is open to the tank line. As the oil heats the thermostat, the bypass begins to open at the return line from the cooler which will allow the oil to circulate through the cooler and into the tank. That is when you will notice heat on both lines and the cooler.

Either your new thermostat is also defective (a slight possibility), or there is a blockage in the line to the cooler. My first suggestion is to inspect the bulge you mentioned in the feed line to the cooler. Let us know what you find.

[Walter_Middie]

This adds up to a problem with the mixture. when adjusting to a normal mixture (about 0.50- 0.80) idle is better, but the car doesn't rev as i think it should. when adjusting to a very lean mixture (about 0.20 or less) it revvs great, but idle problem gets much worse.

I'm really clueless here...

I should have read this more closely the first time. Ossiblue is correct, the mixture should be adjusted last.

What's happening is that you have a small air leak. At idle, when the engine is intaking a small amount of air, a small air leak can add up too way too much air. Richening the mixture makes the idle good. At higher RPMs, the engine is taking in a lot of air, and a small air leak adds a relatively small and insignificant amount of air. If you have richened the mixture to make the idle good, the high RPM will now be way too rich.

As you can see, you must find and fix the air leak for your car to run well at all RPMs.

P.S. Good Job in finding the broken clutch cable. It's always nice to find it's something simple and inexpensive.