Symptoms of excessive distributor shaft end play ?

[Rod80SC]

Have been working this problem for some time now. Car starts up and runs fine until it warms up, then the tach begins to fluctuate, and it dies sometimes with a backfire. After just a couple of minutes I am able to restart but dies if I try to accellerate. I have thrown a number of parts at it. MSD 6AL and blaster coil, cap, rotor, plugs and wires.

Yesterday I noticed that the distributor shaft seems pretty sloppy and was reading through some archives here and understand that the shaft should not have any slop. I am talking probably and eighth of an inch up and down, and abou the same left and right.

Would this slop cause this only when it heats up?

Sure would appreciate a little feed back before throwing a $$$ Distributor at the problem.

Thanks

[Mysterytrain]

Rod,
I had a horrific distributor failure on my 78SC. The distributor seized and sheared off the drive gear..which then dropped down into the case and was launched via the intermediate shaft gear out the side of the case! My first warning was some slop in the shaft and the destruction of a distributor cap. The local porsche wrenches told me I most likely didn't have the cap secured properly..so a new cap and 3 miles later and the rest is 12k worth of history. The car is talking to you. In my case it looks like the lower bearing went south which allowed the upper section ( under the vacuum advance plate) to wobble enough to bind.

[Rod80SC]

Thanks Ron, I know its trying to tell me something....Sorry to hear about your worst case senario. I would sort of expect to see some result of this slop in the cap but everything looks good. Even the old cap didnt look bad.
I see you are from Monmouth, my last good road trip in the Targa was up there to the MSC training center. I stayed at the Army base there in Monmouth. It was a great trip !

[kach22i]

Dear God, it's a $900 part!

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_igniti_pg4.htm#item17

[Rod80SC]

I know I saw that last night, may have to go with the rebuild option.

[Rod80SC]

Bump for the West coast and hopefully the legendary JW...

[Mysterytrain]

$900 for you look at the 78/79 =$1500

[Determined]

I bought an 84 Carrera Engine on a 76 911 Targa frame that had a distributor gear go through the side of the case near the intermediate shaft. Of course, I did not know this at the time but I got a good deal on the whole car. I managed to repair the case and agree that the distributor gear if not addressed quickly will result in major engine failure, don't take any chances...replace if needed.

Best Regards,

Alex

[}{arlequin]

Rod, are you using points? Excessive shaft play may make the car skip and stutter as well. If it's loose enough, points may end up not opening at all too. This could also be caused by worn lobes on the shaft. I'm suffering from the same thing and I hope I don't end up w/ the "worst case" scenario like above....

I got another distributor from the classifieds for $125 shipped. I recommend you look for your model so it will have the same advance curve... this link was very useful to me for disassembly and cleaning:

http://webpages.charter.net/addictionms/

If you find a different model of distributor, but other than the part #'s it's identical, you may have to transfer the weights and springs etc. (the actual advance mechanism) from your dist. to the new one.

You can have them re-curved, but it can be avoided. It's a lot harder to get rid of the shaft play since those (brass, bronze??) items are NLA. Good luck.

[targatop]

I had a similar problem, but unknown until after one rebuild and one partial rebuild due to broken pistons. The solution came clear after breaking a rotor: in and out motion of the distr. shaft and some sideways motion. I cocluded that the internals were pushing past the allowed advance at high RPMs such as when on the track where both pistons broke. A search of the internet and local shops yielded a distributor for less than $500 (still ouch!) but no problems since with pistons after 6 years. pete

[Early_S_Man]

Rod,

The amount and type of play you describe indicates a need for replacement of both the bronze 'oilite' bushings and fiber washers and shims between the body and gear. It is not a trivial job, but doable with care and a few pics during the disassembly process. Neither Bosch nor Porsche ever sold the bushings and washers/shims needed for a complete rebuild ... but that isn't a problem, really! Local bearing supply stores can get [or may have in stock] any bushing you need, and the fiber washers and shims are available from motor/generator rebuilders ... and some large hardware stores and suppliers!

Even the magnetic pickup coil replacement part is available at low cost ... Echlin MP304 for $27.49, and Beck-Arnley BA 1800144 for $25.99 are available from NAPA stores! Bosch still sells it, too, but not readily available to the public!

Good luck!

[mb911]

Are they not suppose to have any up and down movement??? If thats the case I need to address mine as well. I have no side to side but Some up and down!!!!!!!

[Mysterytrain]

I think the excessive up/down is what blows off the distributor cap..as in my case.

[mb911]

Whats excessive in inches?? 1/8th1/16th?? or are we talking 1/4"??

[Rod80SC]

Thanks to all for the response, I am really wondering if that amount of play would cause my symptoms of stalling only after the engine warms up. I would expect some sings of damage or wear in the cap but it looks pretty good.

I am afraid that I may have just stumbled upon the distributor slop but it may not be the fix to the problem I am encountering. In a previous thread some one had very similar symptoms and fixed it with a new fuel pump. While I dont think a bad fuel pump would cuase excessive tach fluctuations I just need awarm and fuzzy before investing in the distributor.
Has any one taken advantage of the rebuild option from our host for about a quarter of the cost of new.

Thanks again for all your help

[twin plugged targa]

Rod


Check /search under my old use name '86ragtop' I spent a month or more diagnosing this same fault until I removed the dist. and posted a pic here- some one picked up on the excessive end float
This was pushing the rotor up into the cap distroying caps and rotors over a period of time.
Symptoms- fine when cold- 5 mins down the road, splutter, back fire, die!
Very very VERY annoying and perplexing!

Someone here put me onto a used suppler for distributors in NJ it think- again you may pick this up in the search in the archives- dating back to 2001-2
long time ago

This episode made me nearly give up on old porsches- it was at the end of a series of failures, fuel pump, headlight switch, alternator, etc etc all which led me stranded a long way from home!.


Would look for you but am busy at work and saw this and was compelled to help!
Let me know how it goes

Ben
AKA 86ragtop

[Superman]

Frankly, a healthy distributor has very little slop in the shaft. A few thousanths. Barely enough to feel, if at all. A little play is tolerable. 1/4" is colossal. It could be that the heat expansion of the distributor body, greater than the shaft expansion, may increase the slop when warm. So yeah, it could be the performance problem. But it seems clear to me that that is academic. It seems to me there is another, better reason to never start that engine again until a stable unit is installed. The carnage described above is painful to visualize.

I've got a failed distributor with tight bushings but a failed Hall Sender. Now Warren tells me that replacement senders are out there. Warren, the NAPA site seemed to be having some challenges yesterday, but I hope to take a look, and I wonder if the electrical connection is the same, so that my existing wiring will fit into it. I would think it would have to be the same, because there is just one hole in the case.

[Rod80SC]

You are absolutely right superman, I intend to pull that out and do the kitchen counter rebuild as Warren and Ben have done.
Thanks again and you will be hearing from me soon with pics.

[mb911]

I have not Done one yet But I think that may be happening this weekend. Its something about that hole in the case that probably won't let me sleep until I have taken care of that. Now does anybody have the specs for end play etc so we can do this properly??

[Mysterytrain]

Damaged case from a bad distributor