Will starter relay solve "hot no-start" issue?

[75Carrera]

My 3.2 is about ready to go back into my '75. I kept the original 915 tranny and "original 31 year old" starter. When we had the 3.2 in and running (the first time) it wouldn't start when the motor was hot.
We cleaned all the connections and had my stock starter rebuilt but I'm still a little worried about the possibility of it having starting issues (I'm in Arizona). A 1.5 HP HD starter is at least another $300. Will the starter relay Pelican sells actually resolve the possibility of a no start? Relay is about $20...

[wholberg]

the short answer is yes. You can also fix it yourself less expensively by running a 10 gauge wire from the battery directly to the + terminal on the solenoid, so that when the circuit is closed to activate the solenoid, it gets full battery voltage. This approach requires a fusable link mounted somewhere near the battery in case of a short, and running a wire the length of the car. That being said, $20 from Pelican is more than worth it in time savings alone.

[75Carrera]

Thanks Mr. Wholberg,
It does appear to be an easy fix. Another question is the difference between the Pelican part and the starter relay Preformance offers on page 49 of their new catalog. I don't care about the slight price difference but am concerned why the two units so different? Has anyone actually installed either of these?

[wholberg]

I have not looked at the one in the performance catalog, but a relay is a relay. Most likely, they are simply relays from different manufacturers.

[75Carrera]

Okay, I think you're right. I'll talk to my wrech about rather he prefers one type over the other before making the choice.
As long as it works! Thanks for taking the time to respond.

[wholberg]

I just realized that you are from Prescott. I grew up in AZ and haven't been to Prescott since the mid 80's. Back then, my first wife's relatives owned Marler(?) Furniture. Back then it was a nice little mountain town, I'm sure that has changed though.

Good luck with the hot start issue.

[75Carrera]

Prescott is a wonderful place. I've been here for twenty years. I owned the Prescott Mining Company restaurant until 1992 when I retired to paint and play with my cars...
I'll bet you miss the all the great twisties we have going in virtually all directions and the great climate at 5000+ ft.
Thanks again and all the best.

[75Carrera]

If you grew up in AZ... I'm a Carl Hayden High, ASU guy. My family ran the Pinnacle Peak and El Corral restaurants in Tucson and Calif. I was the VP of Operations there for many years. (small world eh?)

[Early_S_Man]

I will have to strongly disagree ... the issue is not electrical in nature most similar cases -- it is friction caused by corrosion and particulate contamination [and lack of adequate lubricant] of the bendix, linkage, and solenoid plunger! The relays are band-aids, not a solution, and may give a bit of extra pull-in power to the solenoid, but that isn't what is causing the problem in the first place!

Cleaning the ground and battery cables, and signal lead connections[such as the terminal #50 lead in the 14-pin connector] is always a good idea as preventive maintenance, but so is disassembly, cleaning, and lubrication of the starter internal mechanical parts!

[75Carrera]

Thanks Warren,

I did have the starter completely rebuilt. (It was pretty caked up) All the leads and conections are clean now as well (now). I was looking for some extra insurance since heat does pop up out here in AZ from time to time. The starter did fail to start it before when it got hot but it hadn't been serviced or cleaned in it's short 31 year life! I'll pay close attention to your other suggestions as it goes back together this time for sure.

[911pcars]

I documented the installation of a remote starter relay on my early 911 (http://members.rennlist.org/911pcars). However, my goal in this project was to save the NLA ignition switch (the "start" or "crank" position is the first to expire) rather than to provide another 12 volt supply path to the solenoid.

As to whether another 12 volt source provides more current to the starter, that all depends. The ignition switch merely sends voltage to energize the starter solenoid which is itself a combination HD relay as well as solenoid. If there is excessive voltage drop in the circuit to the solenoid control terminal (yellow), there may be insufficient signal to energize it, or if the solenoid itself is borderline (weak pull-in coil, dirty high current contacts or other mechanical hangups), then an additional relay may or may not get the starter over the hump.

Before installing any relay kit, I'd check the available voltage at these points:
a. Voltage at the battery: Should be around 12.7+ or so.
b. Available voltage at the ignition switch: Should be the same as above.
c. Available voltage at the 50 terminal on the ignition switch (yellow wire)
d. Available voltage at the same yellow wire at the solenoid: Should be the same as b and c.

If the voltage at b is <.2 volts than at a, there's excessive resistance between the battery and the switch (I'm being generous, it should be <.1 volt)

Voltage at c should be the same as b, and d should be almost the same. If d is less than c by more than .2V (again, generous), there's excessive resistance between c and d.

Installing another relay to bypass the weak circuit is one way to solve the issue. However, repairing the weak circuit is preferable.

Hope this isn't too confusing,
Sherwood

[75Carrera]

Outstanding Sherwood! Thank you, thank you. This should be about all I need to assure I reach a healthy start. This is great.

I'm certainly happy to hear from another creative Pelican...

[RoninLB]

I could use a new wire from the ign sw direct to the starter..

btw.. Bosch sells a nice 75amp relay.

[ianc]

Warren (and Sherwood) are right on,

The difficulty is not usually voltage drop so much as it is heavy mechanical resistance in a gummed-up starter and\or solenoid. Most lkely the latter. This would be the usual case of course, except that youve had your starter rebuilt some time ago. Do you trust your rebuild shop?

Only way to tell is check to see if you're getting voltage at the solenoid when hot and in the no-start condition. If yes, then check\clean solenoid. If no, then check ignition switch. And on...

ianc

[wholberg]

Originally posted by ianc
Warren (and Sherwood) are right on,


ianc

I agree. I have fixed a hot start issue on three "vintage" 70's vehicles, two non-porsches and one a 911SC. In all cases, I first inspected and cleaned all electrical connections, then later replaced the starter and solenoid when the problem persisted, and finally ran the extra wire/fusable link after measuring < 12 V at the solenoid with a hot engine. All three "issues" occurred when I lived in AZ; I have not had a similar issue living in the eastern US, presumably due to the much cooler temperatures? I made the assumption, perhaps incorrectly, that Donny would have taken the above steps before diagnosing a hot start issue.