1968 GTO Intermittant No Start: Advice?

Hey guys,

Just looking for some of your opinions, to confirm what I'm thinking before I start buying parts.

Here's the story: My '68 GTO w/ correct Pontiac 400-4V has been starting and running great, no symptoms. Hopped in for a little trip two nights ago, drove about 45 miles, swung in to a gas station for a bottle of pop. Came out to hit the road, turned the key, absolutely no sound or movement under the hood. Had good juice: horn, lights, radio, idiot lights all functioning, just no response from turning the key (except the idiot lights dimmed).

Came back home on a flatbed, fortunately owned by a fellow member of this board out of Princeton, MN, who did an outstanding job ("L88Corvette"; Thanks again, Wayne!). Let it sit since then, didn't do anything with it.

Tried the car again this afternoon. Fired up stongly on the first turn of the key. Drove it around a little, everything worked perfectly. Turned on and off a few times, absolutely perfect.

It's obviously not a charging problem. Also, I replaced the ignition switch and dash wiring harness about 12k ago, never any symptoms like this.

I'm thinking solenoid/starter. Opinions? Should I start with one, or the other, or both? Or think of something else? And what brand starter would you go with? OEM? One of those high-torque, "mini-starters"?

Thanks in advance, guys!
Steve

 

Before throwing money and parts at the problem you should pull the starter and check and maybe replace the brushes. While you have the starter off, sandpaper or file the starter cable clean where it attaches to the solenoid. Those are the two most common starter problems. I'll bet that ends your problem.

 

I,m with John on this one.

 

What shape is your battery or more important what shape are your battery cable terminals? Do they need to be cleaned or replaced? Maybe they are starting to get coroded and this is an early sign? Also, Like stated the other end of the wires to the starter. Are they clean?

When buying a starter you want to get a longer warranty for the starter. When you get the better starters they will last longer most of the time. I have never used a mini starter so I can not help you with that.
Good Luck,
Bob

 

Yep,, sounds like you are getting heat soak on your starter. My old '68 GS did that after replaced the starter. I was afraid to turn it off unless I knew I had 2 hours for it to cool off.. ou: I never did fix the problem because I sold the car before I had a chance to (yes I told the new owner about the problem :bglasses: ) Really I did.....

:beer

 

For anyone that has heat soak symptoms, pour a bottle of BLASTER TVF in your oil. It isn't snake oil, it is a very high detergent additive that will eat the carbon and varnish from behind your rings that force the rings tighter against the cylinder walls when hot. That is 90% of the cause of heat soak symptoms. The Blaster takes a couple of weeks to eat the carbon, but after you have changed batterys, cables and starters a couple of times, you will want to sell the car. Trust me on this one. I worked at a garage that had more than its share of little old lady carboned up mid 60's Oldsmobiles. We got tired of replacing starters every two week in the summer time. At first the cure for constant hot start problems (after a new battery, cables and starter) was pull the pistons, clean the grooves, put a new set of rings, reassemble. When we started putting Blaster in those problem child cars it stopped the hot crank problem without having to do the ring job.

 

My father in law would roll over in his grave on this. He replaced no fewer than 9 startes in his 1972 98 and 66 Cutlass Supreme. Used to carry one in the trunk.

 

I had that problem on my 68 with headers. I switched to Tilton super starter with the indexable solenoid. No problems. I think the GM mini starter would be a good choice too.

Keith

 

you also might want to check your wiring at the firewall forward,look for bends where over time a couple wires might have dry rotted apart,when these bad wires get hot,they can short out

 

68 Start Problems

Steve, there were a lot of ignition switch problems in the 68 model year for Pontiac, AL.

 

Great Input.

Thanks guys, I knew there'd be a wealth of expertise brought to bear here.

The car hasn't previously had any episode like this. I've driven it for extended periods, hundreds of miles a day, in the hottest weather, and the heat hasn't previously soaked the starter. It does seem to run hot, although not enough to trip the hot light.

Question: if one has cleaned the cable/terminals, and a wiring short cannot be identified, and the car is not malfunctioning.......how does one make the diagnosis? Heat soak vs. a flat spot in the starter/solenoid vs. a bad ignition switch: is there a way to sleuth it out?

Thanks again in advance,
Steve.

 

I found this one out at the Pure Stocks last year, but check your wiring at the Horn Relay! I was ready to do a dive for the starter, when I fired up at night and saw a dim 'Gen' light glowing. I started to move the wires around with my lights and underhood light on. When I moved the wires on the relay, the light underhood got real bright and the alt. started humming like a buzz saw. Amazing how much just a little bit of corrosion will stop juice flowing.

 

This is a typical hot start problem with Pontiacs. :rant: If starter is not in good shape then it will drag or not start when hot. :af: Let it set for about an hour or so it will start. :af: Starter is very close to exhaust manifold/header. Need high torque starter, good rebuild and sometimes good insulation from heat. If you go to http://www.forums/performanceyears.com you can search and find out much more. Not unusual for Pontiacs. They require a good (make that very good) starter. :Smarty:

 

I think its your battery cables. I had a similar problem last year with my 68 Dodge Coronet. I gave it a full tuneup and still had problems starting up. Then one day it just stopped(thankfully after I got home) and it was those battery cables they were over 30yrs old. Once I got them changed, the car always started up

 

I agree - my high school car was a '68 Firebird 400. The starter WOULD NOT turn the car over hot. I seem to remember that replacing it with a new GM unit solved the problem.

 

Olds had the same problems. Changed many a starter on them. But just heard that a lot of it was really due to carbon buildup behind the rings that would increase ring tension when hot to the point that it was difficult to turn them over with the stock starter. GM hi torque rebuild usually overcame this.

Guy that posted that about the rings said he used some additive in the oil that somehow cleaned out that carbon and fixed may customers cars that went through starter after starter.

Other potential issues are, lifter pump up (pushed out three rocker studs on my 63 421HO Catalina when we had to push it to jump start it). Also putting a toggle switch in-line with the hot lead to the coil will keep it from firing early if you're running a lot of advance. Hide it away and it's also a good antitheft deterrent.