1976 suburban K20 manual, no crank

[DEK5]

Recent new member on the boards with a question about my 76 k20 burb with a manual transmission. Truck is just a hunting rig that a friend & I use around his farm, bought it about 4 yrs ago and we've been fortunate that's it's not needed any TLC other than new shocks and a window crank. This year we thought it worthwhile for a quick tune-up since nothing's been touched in years. New plugs, wires, battery, oil change, clean air filter and a bath to get rid of a couple 100 lbs of unneeded mud and junk.

Immediately following all that the burb ran great, started with no issues and no hesitation, smoked a little but no worse than it did before so all is good. Fast forward 2 weeks and now it won't start. Power to the lights, wipers, rear window, etc.. but not action on the starter. If you depress the clutch you hear what I'm guessing is the safety switch engage but that is it. I've checked all the connections and everything appears tight, I cleaned that connections I could get to without major dissassembly but perhaps I need to clean/check again. Just trying to see what the basic first steps are to trouble shoot or if anyone has had a similar condition. If you get the truck rolling and pop the clutch for a compression start it fires and runs as good as it did beforehand but once it's shut off your stuck again with no crank.

Any input is appreciated and welcome, I like to tinker and can normally figure things out but I am by no means a mechanic so even if it sounds like a newbie suggestion feel free to throw it out there. Short of pulling starter to have it and the selonoid tested I will probably try to jump the starter tonight to see if it spins. Thanks in advance for the help and I look forward to being on boards more, looks like a great Fourm with a lot of information to learn from.

[Eyegore]

I would check your stater. I'm not awate of any clutch safety switch for this year that would cause the problem, but if your able to push start then I would check the starter.
Put the truck in neutral, put on the parking brake!!!!(MAKE SURE THE PARKING BRAKE IS ON) and then have someone in the truck turn the key to starting position while you get under truck and gently smack the starter with a hammer, if it engages then your starter needs replaced.

[Zane M]

Originally Posted by Eyegore

I would check your stater. I'm not awate of any clutch safety switch for this year that would cause the problem, but if your able to push start then I would check the starter.
Put the truck in neutral, put on the parking brake!!!!(MAKE SURE THE PARKING BRAKE IS ON) and then have someone in the truck turn the key to starting position while you get under truck and gently smack the starter with a hammer, if it engages then your starter needs replaced.

I second this.
I had a buddy who couldn't get his 'burb started and was just throwing parts at the thing, like the ignition switch, etc.
I crawled under it with a hammer, told him to go to the start position and started hitting the starter with a hammer. The starter made some weak grinding sounds and the culprit was found.

[bilfman]

As stated earlier, neutral and ebrake on of course. To eliminate the electrical end just take a piece of wire directly from the + post of the battery and touch it to the little post on the starter solenoid. Most starters only use one of the 2 small posts, so touch it to the one with a wire on it. If the starter turns, you have isolated it to a break somwhere in the ignition circuit, ie column, clutch safety switch etc.

If it doesnt turn the starter then starter or solenoid is pooched.

Also while you are down there check the the large lead has a constant 12v+. Another thing to check is make sure the block is grounded, maybe with all the work the ground wire was bumped/broke.

[motornut]

check for rust on the shaft the gear comes out on...
seen thin rust stop the forward motion

[DEK5]

Thank you for the replies!!

Tonight I finally got time to fool with this again. I went with the idea of testing the starter using a wire off the + terminal to the small post. You hear a very aggressive click but the starter gear does not turn. I'm assuming that probably means the solenoid is good but the starter itself is toast??

I've checked fuses & connections & all seem good so I'm still guessing starter but want to run it by the experts first. Now that I've been underneath to hear it I can tell the click is the same sound I heard from the inside when turning the key & pushing in the clutch, just quite a bit louder when you are laying next to it.

Thanks again for the help!
Posted via Mobile Device

[hatzie]

Originally Posted by DEK5

Thank you for the replies!!

Tonight I finally got time to fool with this again. I went with the idea of testing the starter using a wire off the + terminal to the small post. You hear a very aggressive click but the starter gear does not turn. I'm assuming that probably means the solenoid is good but the starter itself is toast??

I've checked fuses & connections & all seem good so I'm still guessing starter but want to run it by the experts first. Now that I've been underneath to hear it I can tell the click is the same sound I heard from the inside when turning the key & pushing in the clutch, just quite a bit louder when you are laying next to it.

Thanks again for the help!
Posted via Mobile Device

That'd be my diagnosis. The starter is toast. Fairly cheap and easy to fix.

[bilfman]

Yup starter sounds pooched, be sure to check block ground first though, there is a slim possibility of a bad engine ground. If the ground is good, I am pretty sure it is the starter itself.

[DEK5]

We've got a winner!! swapped the starter with a new one from Advance and she fired right up even better then before.

Thanks for the replies and I'll be back for the next issue I'm sure....starting a complete tear down and resto mod of a 1957 GMC pick-up for my Dad along with the help of a few friends. If I remember to take pictures I'll do thread as we go along.