...350 Chev in my old truck, just put new dist cap, rotor and ignition control module in it, (the old ign. module went dead) started rite up, ran great;..took off the other nite and drove about 8 miles and the engine just quit like it was shut off, pulled over, let it sit about 3-4 minutes, started rite up, ran great rest of the trip. any ideas what may have happened?...I put the heat-transfer grease on bottom of the module as directed, but didn't seem like they supplied very much,...could it be the module got heated to where it shut down,...then cooled off and started? ...I do have an Accel super coil , but usually once a coil quits, it's done for...any ideas?
When my first (ordinal GM) module died it would still run for a bit when cool. Replaced it with a cheap Ebay module. That one died dead, hot or cold, withing 50 miles. Replaced that with the second I had in the glovebox (I had bought two they were so cheap) and got me home. Bought a GM module but I have yet to put it in, car is getting painted. I also have an Accel super coil but I don't think that's an issue, the first module last 30 years with it.
A hot coil will cause trouble then once cooled down work again until hot so it if repeats itself it may be your problem.Its been awhile since I worked on that system,but as I recall heat build up can burn/melt areas.Check the underside of the coil,and make sure everything looks ok.Theres a stamped metal connection piece that all the wiring clips to.Check it,and make sure its fine.I have seen them burn off.
thanks so far,...the Accel coil is an older unit, so thot it may be that, got my new parts at NAPA and are NAPA brand , usually have good luck with their parts, but I know how new parts can perform now days.....mite try putting a bit more heat transfer grease under the module, can't hurt I guess. ...the truck starts much better with the new parts, runs nice except for this one glich.
The problem might not be your module. Below the rotor is the pickup coil. It's a bunch of wire wound on a plastic bobbin, the two connecting wires are pinched by the bobbin where they exit the windings. These wires often break at the pinch point, the copper breaks inside the insulation. It's caused by working back and forth every time the advance mechanism moves. This was a common problem with GM HEI's.
One of mine would shut down between 25/40 miles. Out of desperation, I wrapped ice out of my cooler in a rag and taped it on top of the coil. Made it about 50 miles to the next town. Replaced the coil and it has never quit since.
Just a silly simple question, did you clean the distributor plate where the old module was and install new heat transfer grease ? Seen people forget to do this a couple times....
Double check the wires Halfdozen mentioned above, should be a yellow and green wire, they break easy now that they are 40 years old!
When I worked a Chevy we always replace the coil and module in pairs. Heat will cause this. Pull on the wires from the pick coil (some call it pole) the insulation will brake if the wires are bad. Common as stated above. If you are on the road when this happens, disconnect the vacuum advance, to keep it from flexing
...if this were the problem , why would it start back up and run as it should for another 6 miles and then restart and drive back home for another 15 miles without a hitch? ...if those wires were broken would they continue to work? ...I did clean the dist. plate under the module and applied the heat transfer grease . Thanks for the help so far,...
the wire breaks but the insulation does not. When the vacuum advance pulls in it stretches the wire and it breaks contact when the advance returns the copper wire inside can make contact. The insulation stretches
Oh the irony! Yrsterday, not two hours aftet posting on this thread, my daily quit, 10 miles from home with my wife, dog and big load of bricks in the bed. Hot day, had just climbed a hill. Determined it was no spark, had power to the hei. Called a buddy, had him pick up the new module I had sitting at home (see post 2) and bring it out. Meanwhile I pulled the module, very hot, cooled it off and put back. Still nothing. He arrived, popped in the new module, fired up instantly. I was a little surprised to find that the bad module was a Napa part. Was in the truck when I bought it five years ago. Also the 'Nos made in USA' unit I bought on ebay had a Delco looking box minus the Delco but with'made in USA' written on it. Nothing on the module itself at all.
From experience if you are loosing modules something else is causing the problem with the modules. Had a bad coil on my Dad's Olds cause that. Had to drive 120 miles to fix it for him on that one. Years ago Napa Echlin put out a great flyer on trouble shooting HEI. I scanned and saved the pages a few years ago and have them on my Photobucket for people to find and use. https://s173.photobucket.com/user/mr48chev/library/Napa HEI service info bulletin?page=1 I've had those since the early 80's When the Napa Echlin put on a workshop for my auto mechanics students and left us several copies. The procedures are simple and work. There are 7 pages and I'd suggest saving them to your computer and printing them out if you have a printer. Agreed on the pickup coil wires. I had that proven to me and had to eat a bit of crow on it.
^Good stuff Mr48chev, thanks for posting. My computer must hate photobucket, had problems down loading but I got them all.
I made copies for a fellow teacher when I first got those and he took them in his motorhome on a road trip to BC. MH crapped out about 4 miles out of town up there, he remembers that he has the pages and starts troubleshooting, figures out he problem , unloads his bike and rides to town and a parts house, gets the part and pedals back, puts it on and completes the trip.
Did you move the ground strap from the old cap to the new one? If it is missing, you will have weird problems like this.
In my case, the 3 modules that died recently were, the one when I converted my Vette over 25 years ago, and it was used then, the $10 ebay I replaced it with and the one in my truck yesterday that was in it when I bought it 5 years ago, and it could well be decades old. I was a bit surprisef how worn my cap and rotor looked, with not having points to monitor it's easy to forget. I do need to have a better look at both vehicles. And buy another spare module or two.
Some have a wire like the above picture Others have a ground strap, like the picture below Here's a photo of the ground strap by itself
It's not just dielectric grease that goes on the bottom of the HEI modules. It's a specific thermal grease or heat transfer paste like what's used between the processor and the heat sink in your desktop computer. If nothing else it should be readily available at a major electronics store or neighborhood computer shop. Dielectric grease is great for insulating and sealing electrical connectors but it doesn't do much to transfer heat.
...I just checked, I did not re-install the ground strap from my old cap, put it in the new one , haven't driven it yet but started rite up, ran good,..thanks to all for your input, hope this also mite help some others.
It's the little things that make this hobby so interesting. You can go from zero to hero with a 10 cent part!
I just had to replace the coil/cap/ICM on mine and used the clear gel that the shop gave me with it. It wasnt specified on the little packet, but I assume it was just dielectric grease. I see Arctic Silver being recommended a lot for thermal grease. Anyone have an opinion on this product? http://www.arcticsilver.com/tc.htm
The stuff that comes with the ignition module is to dissipate heat. Dielectric grease is not formulated for this application. The dealership, or very best mechanic in town would use the little packet that comes with the module to do the install. Nothing else is needed. Phil
It didn't exactly come w/ it. It was laying around and I was given it. The ICM didnt have any included in the box. More interested in everyones thoughts on Arctic Silver (or a thermal grease alternative) as not all modules will come w/ new grease. Even if doing a little preventative maintenance and wiping off old grease and reapplying some new stuff during a tune up, this info will be useful.
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