William Buckley

1966 Coupe, 327/300, auto trans, power brakes/steering, AC, with new DeWitt's radiator, new water pump, thermostat, new starter and solonoid. Hidden grinch that is driving my mechanic and myself crazy. New 800 CCA battery that turns the stater over and starts when cold, butt when at normal operating temperature, it will not turn over and start. This car has already eaten up Santa's spending money, so I could use some advice on what is causing my problem. The two of us are at a dead end, and can use any advice.

67:72

One of the things that can affect a starter (actually anything flowing current) is increased resistance when it gets hot - and Corvette starters are right next to the exhaust pipe. Big blocks had a sheet metal heat shield to help this situation, I don't know about small blocks. Out of curiosity, can you measure the voltage on the start wires when cold vs. hot to see if it's something upstream from the starter?

R66

What is your static timing set at? Roll it back to 6 or 8 degrees BTDC and try it when it is at NOT. If you have a 66 distributor, you already have 30 degrees mechanical advance in the weights, so you don't need but 6 or 8 degrees more to get to a good total mechanical advance. Also, check the mechanical advance weights to assure they are not sticking. Don't forget to check to see if the vacuum advance is not sticking also, although not likely.
If it is not timing related, it could be a bad coil in the starter drawing excessive current.

William Buckley

Timing is not an issue because I have solid state ignition, and my temp gauge (checked with temp gun) never goes above 180 degrees with that DeWitt's radiator.
Ther starter/solenoid is brand new. My mechanic and I just keep running out of ideas for this problem. Would apprecoate any more ideas.

leif.anderson93

The solid state ignition only affects the dwelll...you don't need to set it. Timing is still part of the equation with solid state ignition.

Pop Chevy

And just because it's a new starter doesn't mean it's a good one. You could also have a bad connection at the starter.

road pilot

Heat shield on good starter motor. How much experience does your mehanic have? This should not be
a big problem for a experienced mechanic.

GordonR

First test when an issue like this happens is to disable spark and crank again (Quickly eliminates any timing issues). If the first test doesn't bear any fruit than grab a voltmeter and an amp clamp. Read across the battery terminals while cranking. Should not drop below 10 volts loaded on a good system. Also with an amp clamp attached (spark disabled) the current should not exceed 1 amp per cubic inch. These tests as well as many more should performed while the problem exists to get to the bottom of it quickly. Im not one to guess or recommend parts as it can be a waste of time/money and testing can only take minutes to figure out. Finding an Auto Electric shop in your town could be another option?

vjjack04

I think GordonR is on to something. I'd look for a problem in the ignition associated wiring. Is the harness original?

dcamick

If all else fails:

https://www.koolmat.com/contact/

Talk to Patty Hill, Tell her I sent you.......she would get a kick out of it!

Good luck!

Purple92

I'll agree with GordonR as well, you need to actually do some diagnostics.

I'd start by pulling the coil wire, and measuring voltage (at the starter) and current flow when cranking cold, then reconnect the coil, start the car - go for a nice drive, and then repeat the process with things fully warmed up.

My bet is that the starter is getting heat soaked - and that is the core of the problem. I'm assuming that you can hear the solenoid getting "pulled in" when trying to start hot (there have always been issues with GM starter solenoids and heat). I don't know how you feel about "originality" - but some aftermarket starters are somewhat smaller - and are less likely to heat soak, You may also want to consider wiring in an external solenoid, which will take on the responsibility of handling the high current feed to the starter motor.

William Buckley

The reason that the starter/solenoid (combo build) is new, is that the failute to turn over when the motor is hot was happening with the old starter/solenoid. Old starter was replaced because the thought was that this was the cause of the problem. New starter/sollenoid and new 800 CCA battery did not take care of this starting problem. We are back to square one, after money was spent on the new replacement parts. Temperature of the engine NEVER goes over 180 degrees, so overheating is not the cause of the problem.

dcamick

180 degrees operating temps have very little to do with exhaust manifold/pipe temps down at your starter.....If you have not tried to shield your starter/solenoid, you should! What do you have to loose? If you have tried shielding, Sorry!

Added thought: Check your Grounds also!

kts1962

Just to be sure I understand what is happening, Can you clarify the issue as #1 or 2 below:
1) It won't Crank When Hot (After running for a while and Coolant temp at aprox 180*) (Elec. Power, Ground, Starter, Solenoid Issue)
2) It will Crank (Turnover) but Won't Fire and run (Ignition, Timing, Coil etc issue)
Thx in advance for additional information

R66

Also is the speed the starter turns the motor nearly the same when hot or cold - or - does the starter turn the engine very slowly, like a bad battery, when hot?

Purple92

I completely agree - engine overheating is not in any way related to the problem that you are experiencing. However - Your stater may be getting to well over 200F with the exhaust pipe running so close to it.

See what kind of voltage you are seeing at the starter and current draw you are experiencing both hot and cold...

acroy

Does it turn over at all when hot?

R66

What was the last thing done to the engine before this problem started? You and your mechanic may want to work backwards. I would guess 90% of the time the problem is related to a change made to the engine.

FormerBiker

We had a 77 Chevy 4x4 that had the same problem. Our solution was to buy a ford remote seloniod and mount it on the inner fender away from the exhaust heat. Never had the starting problem again.

dplotkin

Everyone wants to help. That's what we love about this forum.
However a machine gun blast of possibilities can overwhelm and distract from the simple and obvious.

I'm going with simple and obvious because some of what the OP says makes an obvious point. This is not an insult but a valid point. That you believed a solid state ignition means timing is no longer a consideration tells us that the two of you may not be practiced in the area of mid-century car engines. The symptom and circumstances you describe point to an engine fighting against improperly set timing. Several posts above point that out. One of them, disabling ignition, will prove or disprove this instantly and should be the first thing you do next.

You have already found that firing the parts cannon has been helpful to only the auto parts store. If the engine starts fine every time cold or cool than its heat soak related. If it labors to start any time its likely timing. If your mechanic is not versed in the use of a timing light locate someone who is.

Dan