chiefttp

A few months ago I asked for help concerning a starting issue on my 1981 Vette. To start I have a new battery. Initially if the cars been sitting in the garage, it starts easily, but after I drive it for any amount of time, when I go to restart it, it is very slow to turn over, almost like a chugging. In the past if I let it sit longer it started. My last thread concerning this problem, members recommended I check the cables leading to the starter, replace the starter or the starter solenoid.
Today I purchased a new starter/solenoid, installed it, and the car started fine, I let it warm up for 15 min, shut it off, then immediately started it with no issues!, thought I fixed the problem. So I drove it about 2 miles, parked it at a friend's house, hung out for 45 minutes, then when I started the car it did the same slow turn over, chug, then caught and started.
My Question is what do you think is causing this, and could it be some kind of hot starting carb issue? I am at a loss. Any suggestions?
Thanks in advance.

bj1k

Sounds like the starter and solenoid are getting too hot and you need a starter insulator and shield to keep the heat off of them . If you are running headers it usually is a problem . It could also be vapor lock with the fuel system if the heat is getting to the fuel lines , but my money is on the starter needing protected.

chiefttp

Bj1k,
Thanks for the reply, the car is bone stock, no headers. A lot of folks mentioned the heat shield in the other thread, but more people discounted this theory as they explained the starter/solenoid is designed to handle the heat, plus the shield is in place and as I said it's a stock engine. I'm really curious about heat getting to the fuel lines. Any ideas where to look for this heated fuel line issue, common locations etc?

TimAT

Slow cranking is not a fuel issue. Have you replaced any of the battery cables? At the least, you need to check the resistance of them end to end. If I recall, GM used aluminum cables and they can and will corrode internally. That drives the resistance up and slows cranking speed since the starter can't get the required amperage.
The ground cable off the battery runs to the frame near the battery box. Easily overlooked, but it needs a good star washer between the cable and frame. Same for the short ground cable that goes to the block.

bj1k

The fuel lines also run on the same side and can get too hot but as I said I'm betting that too much heat is getting to your starter . That is a common chevy problem. What kind of a shield do you have ? Does it completely cover the outer part of the starter and solenoid ? I would buy the best shield and insulator that you can find . Have you noticed the reading on your temperature gauge ? What is it showing ? If the new starter and solenoid is doing the same thing then it is obvious and should be taken care of before you damage the new parts.

bj1k

The stock cables on our cars were copper but they can still corrode but that is something that should always be checked when replacing a starter or any other electrical part . I assume that the op would have done that . Maybe not ? ?

doorgunner

Rookie here: I had the same problem with my 1968 project car........started fine until the engine reached operating temperature.........then the starter crank slowly until the engine started. If I waited 15 minutes after turning the engine off the starter would crank normally and the engine would start.
The negative cable was original........the previous owner replace the positive cable. So I replaced the negative cable and sanded the area where the ground cable bolted to the frame.

The starter cranked better, but when the engine was at operating temp the starter still cranked slower than it should.......I bought a quality insulating blanket that wrapped around the entire starter.

Now the car starts fine whether cold or at operating temperature.

FYI.......make ONLY ONE change/repair at a time so you can determine what cause the problem to lessen/go away........(sometimes slow cranking can be a difficult problem to solve)

chiefttp

I'll confess that the car has only 32,000 original miles and the cables looked fine, though I realize they are 35 years old. Where does the ground cable bolt to the frame? I'll clean that area, and I'll look into a starter insulating blanket.

speedreed8

have you checked the initial timing setting.

maxmachz

Ditto on the timing.

I have an 81 and played with the timing, and when cold would fire right up....and hot would do exactly as you say. Remember if you adjust the initial timing, the 4 prong plug on the dist must be unplugged if you are still running the CCC and E4ME carburetor.

Metalhead140

Yep, too far advanced on the timing will cause slow cranking when hot.

chiefttp

Maxmachz,
That's a big help! I will adjust the timing and thanks for the heads up concerning the CCC Carb. It is the original setup and tips from all you guys make this a great resource for Vette owners. Thanks again, I'll let you know how it goes.

chiefttp

Update,
Advanced the timing, and it still didn't seem to help the warm starting issue. So I jump started the car after it wouldn't start/turned over really slow, and it started up pretty normally, so Tomorrow I'm going to return my "Lifetime" battery and see if the battery has been the culprit. My question is, if the battery is faulty, why does it start fine when it's been sitting overnight?

doorgunner

Rookie guess: It only takes one bad cell in the battery to fail because of engine bay heat.......then the battery seems to "drain" rapidly. Also......as the other members said---incorrect timing-----too much/not enough in a hot engine......will make it seem as though the battery is at fault.

chiefttp

Door gunner,
If the timing was off, why does it turn over fine (after it's been running at temp/warmed up) when I jump started it? Even with a good jumpstart, Wouldn't it still be slow to crank if the timing was the culprit? That's what's leading me to believe it may be the battery after all

joewill

someone 'splain to me how timing is different when hot vs cold?.. if timing is too advanced then you should have the same problem hot or cold?

to the OP: your problem is a weak battery.. no matter if it is still strong, or almost new.
when an engine gets hot, the clearances tighten up and it is harder to crank your engine. the result is that it will take more amps to crank the engine and your battery can't supply the amps.. you may have a lifetime battery but it is probably a 400 amp lifetime battery...

get you a 1000 amp battery and your troubles will be over...
I have had the same problem several times.. as your battery ages, it will deteriorate 10% or more a year and not be able to output at its rated amps even after a couple of years.

after about every 4 years, my car starts cranking slow when hot.. a new 1000 amp battery always solves the problem.

per your statement, jumping the car will get it started.. which means your solenoid and battery cables and starter connections are fine.. jumper cables add amps to the existing system.. which is exactly what you need to do by buying the biggest and baddest battery you can find..

Metalhead140

It does make a difference. Not sure on why exactly, but if you've ever dialled in rough timing without a light, you will have experienced it. Timing can be a bit too far advanced and it will start happily cold but really struggle to turn over when hot. Retard the timing a little and it will turn right over and fire up.

gungatim

because a hot engine fires easier & burns faster,as it is leaner with choke open and only a small amount of fuel is present at idle which burns faster. That is why when it is hard to start when hot, if you floor it wide open, it usually starts easier....too far advanced for easy starting cold gets compounded when warm.

that doesn't mean that you don't have other issues with grounds, cables and battery. I won't get on my heat soak soapbox, but that is the not the first thing to jump to.

chiefttp

Update,
I bought a new battery, and the car starts fine, cold or warmed up. The old battery was tested and it failed!! Thanks to everyone for your help and suggestions. I plan on getting the timing set anyway, it couldn't hurt. What a great resource this website is!

7T1vette

Just a 'heads up'....

You can't tell if battery cables are good...or bad...by looking!

Cable damage is usually at the ends, but may well be inside the insulation. If air can get to the cable strands, both copper and aluminum cable will go bad with time. With heating, cable resistance goes up; if wire is deteriorating, the resistance goes WAY up. Cut back insulation a bit, wiggle wire to see if it is solid and not corroded. Also remove connections and clean them well.

Lastly, your symptoms are 'classic' for not having a right-side 2 awg ground cable from frame to right motor mount....or having one that is in bad condition. Do yourself a favor and check that out too. A new battery can mask some remaining 'sins'.