My 65 Porsche 356C Cab is intermittently starting

[William Vumback]

I have read all of the posts but I am hoping someone can help me get to the source of the problem quickly (wishful thinking). I purchased my Porsche in April 2017 and I am having a blast with it. I am learning a lot working on the car and I am having much fun in the process. My problem is intermittent...when I turn the ignition key the red light comes on and it sometimes does absolutely nothing. I try again by turning the key completely off and then back on and sometimes it turns over and starts. I recently found that one of the battery terminal wire connections was loose so I cut it down to fresh wire and re-connected it and that seemed to work for a couple of weeks but last weekend it did it again. I hooked up the trickle charger and it displayed that the battery was fully charged so I tried to start it again and then it turned over and away I went. I see that the solenoid looks newer. I have a 6-volt system. When I was purchasing the car, it reacted this very same way. I assumed it was a simple connection/electrical problem and it still may be. I am trying to avoid getting stranded with the car when going to a show or to dinner with my wife. I am hoping that someone has had a similar experience and can help to guide me through the troubleshooting process. Thank you in advance.

Bill V

[M Penta]

Hi Bill,

If all connections are good, especially grounds and ground strap from trans to body you may have a tired ignition switch. The solenoid can be "relayed" to dramatically reduce current going through the switch. Some do this with similar symptoms to yours as a "bandaid" (not necessarily a bad thing), and some do it simply as a precaution to protect the 50 yr old switch before it has a problem.

viewtopic.php?f=4&t=40763

Mark

[David Jones]

First question Bill is where are you. There may well be someone close by who can help. Second question is if you have a wiring diagram. If not go here...
http://www.enginesinback.com/uploads/2/ ... ermark.pdf
Note that the positive from the battery for instrumentation goes first to the fuse block and without being fused goes to the light switch thence to the ignition switch. All these connections should be checked for integrity. There is another issue with old 356's especially if you have the original ignition switch and no switch saver relay, in that the contacts that make the electrical path to the solenoid can get worn and pitted over time and no longer pass sufficient current to operate the solenoid. If your solenoid looks new then it may be the case that someone did the wrong fix and it is time either for a relay or a new/rebuilt ignition switch and/or both.

[Brad Ripley]

Replace the ignition switch with a new or rebuilt one.

[Doug McDonnell]

Page three of this link shows visually what happens to the ignition switch: viewtopic.php?f=4&t=41099&start=15 I believe that Larry Markham rebuilds them if that is your problem

[Doug McDonnell]

And in this link David tells you how to determine if the switch is the problem: viewtopic.php?f=1&t=43940&hilit=ignitio ... ir&start=0 So make yourself a jumper cable and determine if it is the switch.

[Tom Coughlin]

My '65 C Cab., also 6 volt, does not have that problem but it did for a long while. The problem was always dirty battery connections. Cleaning them got the car running but the real fix was going to a closed cell battery which appears to not give off fumes that cause the problem. If your issue is not caused by the ignition switch, look for dirty battery connections. Tom

[Dick Weiss]

William,

During your intermmitant starting attempts, turning the key to the start position, do you sometimes hear the solenoid clicking, but not engaging the pinion to the F/wheel?
If so, just turn the key to the start position, but just back it up just a little to prevent the internal cancell mechanism to keep you from a full turn to start; I call this "tickling the coil" to engage fully by turning the key to the starting position again--you may have to do this more than once till the starter works. This indicates that the ignition switch needs work--I've rebuilt @ least 1/2 dozen
so the same key works in the door locks; If the same key doesn't match, someone changed the switch. I also have blank Porsche keys and stamp the code # which is scribed on the casting.

Dick

[Wayne Arny]

William, As another possibility, check out your solenoid. I had what seems to be a similar issue with an intermittent, but getting to mostly not working, starter. I tried everything above, including checking all the wires and even replacing the ignition switch (which needed to be done anyway, as it was an old "post and screw" aftermarket). And what made it even more frustrating is that I had had the engine out, and it worked fine on the test stand, and then worked fine when I put it back in. Then it sat for a while, and then started, and then wouldn't! I even took it to a good mechanic who checked it out as OK, after desoldering some bad wiring work I'd done, after which it ran fine... until after, fortunately, I'd driven it home. And as always, I could hear something clicking back by the engine, but no starting! I finally bit the bullet and removed the starter and checked it out by wiring it directly to the battery. Sure enough, the solenoid was intermittent. It would "click" all the time, but only every 12th time or so would the starter gear extend like it is supposed to. I replaced it with a good solenoid off of a VW starter, thanks to David Jones, and it worked fine! I reinstalled, and now I'm back in business! Good Luck! Wayne

[Brad Ripley]

William,
After all such great suggestions, let's us know what fixed your problem. Live and Learn.

[Rusty Ferrell]

going through the same issue on the 59 I recently purchased. Had a series parallel switch with two Optima batteries, but a six volt starter. I changed everything back to 6 volt starting with a new starter (Rebuilt). Still have the intermittent issue, used a remote start directly to the starter,
still have an issue. cleaned all grounds, changed the positive terminal on the battery (new 6 volt). my next move is to remove the battery and hook both leads directly to the starter. I have also replaced the starter bushing.
During this process I also purchased a high torque 12 volt starter to use with the series parallel switch. For those curious about the S-P switch, it works by hooking two 6 volts in parallel and the car only sees 6 volts until the ignition is put in start mode and then the starter and only the starter sees 12 volts as the switch goes from parallel to series.
I'll provide an update when I get the car back on the lift. My gut is telling me the issue is with too much resistance in the main battery cable.

[Doug McDonnell]

http://www.cyberwerkstatt.com/Members_O ... ooting.htm I use this for starter troubleshooting.

[William Vumback]

Everyone, thank you for all of the suggestions. I have not had the time to work on my Porsche yet. I drove it through the rest of the summer and fall every weekend. I put over 1500 miles on it. To be honest, I have been so excited with my purchase that I just wanted to drive it. I am now storing it for the winter. I have been starting it about once per week and taking it for a ride on not so freezing days in RI. Through trial and error I have found that my Porsche only starts after I put it on the trickle charger to bring the charge up from 95% to 97% plus and it starts every time. When I let the car sit and discharge back down to 95% or below (about 3-days) it fails to start again. I put it back on the trickle charger for ten minutes and it starts again. Does this new information provide any further clues? I plan to utilize your suggestions in the spring to see if I can finally resolve this issue. Thank you for the help.
As a second topic, I am looking for someone that can rebuild my engine while maintaining it originality as much as possible. I am looking for someone in the Rhode Island area. Thanks,
Bill

[Jeffrey Leeds]

THe first thing it tells us is that you should get a Battery Maintainer. Infrequent Short drives are not sufficient to keep your battery fully charged.
A Battery Charger is not a Maintainer. Several of our vendors offer chargers and maintainers. My personal choice is sold by member Ed Rutherford https://klasse356.com/catalog/showCategories.asp
How old is your 6 volt battery? You should disconnect and vigorously clean all of the electrical connections - especially the GROUNDS. This especially means the ground straps - particularly the one from the engine/transmission to your car's chassis/body underneath the car. The addition of a starter relay is very helpful.

Information about all of these suggestions can be found here under the Resources Tab at the top of the page in the 356 Archive Title.
You also live within the geography of the regional group: TYP356NE http://typ356ne.org/index.htm If you are not already a member consider joining to make contact with 356 owners/members local to you, who can assist.

Jeff

[Phil Planck]

I would take battery in for a load test. Could be time for a new battery. If the battery is ok, I would next put an ampmeter between positive battery terminal and positive cable. If no current draw I would then check the engine ground strap and all battery cable connections. If current draw, find the source. If all is well there I would remove starter and have it tested at a shop that can mount it to support the exposed shaft. Check/ replace starter bushing while starter is out.