Anybody Else Get Short Lives on Starter Motor Relays?

[Henrius]

If there is one thing that breaks down on a regular basis on my 1972 Chrysler Newport, it is the starter motor relay.

The most I get out of them is two years. I have to keep a screwdriver in the car for emergencies, to short the power leads together. Each new relay works for a while. After awhile, out of the blue, the relay will not close, and I have to short the leads to start the car. Then it won't malfunction for a few starts. Then it starts malfunctioning more and more frequently until I replace it.

No matter if I got the part from Chrysler or NAPA, I always have the same problem. The relay in my 1965 Fury never malfunctions like this. Don't think I have ever replaced it! I am thinking about using a different relay from a different model year on my 1972.

Has anyone else had this problem? Is there something different with the 1972 400 cube engine that causes starter motor relays to fail prematurely? The starters seem to last a good long time. I have only replaced my starter once in the life of the car!

 

[Davea Lux]

The Standard Motor Products relays are prone to the type of failure you mentioned, of course they are made in in China now. Also check the two terminal plugs that activate the relay, they are prone to get loose from heating and cooling over time to where they no longer make a good contact on the relay spades.

Dave

 

[cbarge]

Make sure the connection of the relay are tight.
Do an amperage resistance test on the starter.
If it is high yet still starts the car the relay will eventually fail.
Another symptom I experienced is moisture getting into the relay.
Some cars have the relay mounted on the firewall and water can run down into its area shorting it out.
On my 87 Diplomat I put a rubber flap over it to divert the rain and snow
Hope this helps

 

[halifaxhops]

Load test the starter.

 

[Zymurgy]

Someone here can correct me if I am wrong, but I kept going through voltage regulators, mounted to the firewall, on my 66 300. I kept trying different ones.

Someone here mentioned an improperly ground VR will kill it. It and it doesn't have a separate ground lead, it is where it is bolted to the car. I had resprayed my engine bay and never scraped off any of the new paint.

I don't know if your regulator is mounted on the firewall or grounded similarly, but worth checking out, if it is. The person who mentioned this also said it wouldn't be a bad idea to actually mount a wired ground to the VR.

I was barely getting a year out of a VR, now 2 years with no issues, but I still have a new VR in the trunk.

 

[Henrius]

Make sure the connection of the relay are tight.
Do an amperage resistance test on the starter.
If it is high yet still starts the car the relay will eventually fail.
Another symptom I experienced is moisture getting into the relay.
Some cars have the relay mounted on the firewall and water can run down into its area shorting it out.
On my 87 Diplomat I put a rubber flap over it to divert the rain and snow
Hope this helps

Thanks. The connections are always tight. Through its long life, the car has been garaged periods and ungaraged periods. They always seem to fail. Mine is mounted on the firewall, but it has a deflecting flange to protect against water. I will do an amperage draw test on the motor like you say. Thanks!

 

[Big_John]

There's a couple misconceptions about how relay makes the starter work.

The relay passes current to the starter that activates the magnetic coil in the solenoid. It pulls the rod in the solenoid that is attached to the drive gear and makes the connection internally to make the starter turn over.

If the starter is drawing too much current while turning over, the relay isn't affected. If it draws too much current at the solenoid, then yes, that does run through the relay, but generally speaking, the starter is giving you problems at this point.

So... While it's not a bad idea to check the starter, that isn't the source of the issue.

I'm going to say it's more likely the new relays are just crap, but I would check all connections etc.

 

[Big_John]

The current to turn the starter runs through the circled plunger and into the stud on the back of the insulator.

Insulator

Stud

Plunger.

 

[CBODY67]

There's a couple misconceptions about how relay makes the starter work.

but I would check all connections etc.

You might check the available voltage at EACH side of the main power lead to the relay, plus the related resistance between those two electrical points. Although it could well be what the factory put there, unmolested all of these years, it's still an "open crimp" terminal. Which could allow a bit of corrosion/degrading to enter inside of it. The ultimate repair, IF one is needed at this location, would be a similar open crimp connector, but one also filled with (dribbled-in) non-acid electrical solder to fill in the air spaces between the wire strands and the connector.

Just some thoughts,
CBODY67

 

[C Body Bob]

Yes I’m having this issue with the D440 truck. The relay is fairly new.

 

[Joseph James]

How does it fail? Does it still "click"? If yes, then contacts are frying. Check connections on the starter. You also might check for corrosion, which a cleaner like Deoxit might help. I have had this problem with a lot of small standby generators.

If no "click" then the coil failed. With the China nature of manufacture, this isn't surprising. Coils can fail from a voltage spike when powered off. It's the nature of an inductor. In industrial settings, I have installed either a diode or a premade coil-capacitor combination across the coil terminals. Quench-Arc is a well known brand of these. Most industrial equipment has these installed at time of manufacture.

I also think suggestions like making sure water isn't getting on it are good ideas.