Just got back from a show at Big Bear Lake and on the way up the mountain the engine gagged and stopped. It was 104 degrees and the climb fairly steep. No A/C and no apparent boilover of the cooling system. Ford 351W w/MSD distro and an MSD coil. Question: am I crazy to believe that the coil would be causing the engine to stop under this heat? How hot should a coil be able to operate before failing? The run home today was hot too, 105 or so but no hills to climb and no further problems with the engine. Kinda stumped on this one.
Did it restart when coll? How about a fuel issue, MSD stuff shouldnt overheat, regular coils run fine at this temp. Need more info. Going uphill doesnt load the motor that hard at cruise rpm.
I don't believe that the heat CAUSED your coil problem. I do believe that the additional heat CAN cause more resistance in the coil than normal temps when it works fine. I was told that I had a vapor lock problem 45 years ago. When it wouldn't start while hot (normal operating temps) a friend put his hat over the carb and doused the coil with a CO2 fire extinguisher (same as cooling a 6 pack of beer) and the car started immediately. It was never a vapor lock problem but an older coil problem. This may or may not be your problem but it is something to investigate.
For the last few years late model performance forums have discussions of ignition issues created by MSD coils. It's seems to be connected with MSD products made in Mexico.Usually is a module failure caused by shorted windings the coil.Likely not your problem but something to keep in mind...
Thanks guys. The engine did start when it cooled off and it ran fine all weekend and on the 150 mile trip home through 100+ heat. IF the coil is causing this problem I believe that it is the heat that is causing the coil to breakdown, either because the coil is defective or because something else has happened to make it heat-sensitive. If I had thought about it at the time I would have packed some ice around the coil to see if cooling it down made a difference. I gave vapor lock some thought too...the carb seemed to have plenty of gas, almost like it was flooded. I had to manually close the choke to get it to kick over after it had cooled off for awhile. Tommy, glad to hear about your experience with the hot coil...I might have to get a can of freeze spray to keep on hand just in case this happens again. I'd swap the coil out in a heartbeat but I really would like to know that this is the part that is bad first.
I believe this behavior to be typical of a coil on its way out...temperature needed to cause trouble will keep going down. Engine starts normally, starts to miss a bit, reaches complete failure...then starts up fine after cooling down. If you trigger the hot, dead coil by hand with a grounding wire touched to ground and secondary wire held near engine it will produce a pale yellow thready looking spark rather than the fat blue one it makes when cold. If this is what you are experiencing, get a new coil before it goes any further downhill.
Hard to diagnose but we replaced quite a few coils and they always failed when they/it got hot in the 50s and 60s. When hot some will short.
Bruce this is true according to my experience but he also has a second problem, he has a control mod that can also get hot and fail. When I was still living in mexico a lot of the fellas were running those ford with the external control mod, when they would get a few miles on them they would heat up and quit working, we would wrap a wet rag around them to get home, often cooling them several times along the way. now take that and the fact that the control mod is smaller and enclosed and you have another problem to look at. While it acts like a coil on its way out it is also acting like a control mod on its way out.
When we first got my Son's rpu running a couple of years ago, we had what we thought was a vapor lock issue. It would run fine for maybe 10 miles and then it would start to miss and finally shut down altogether. We would remove the fuel lines and pull the tops off of the carbs, and it would restart and then go another few miles before it would crap out again. One day, when it happened, he put a wet rag on the coil because it felt hot and it fired right back up. Evidently, during the time we were tearing carbs apart the coil would cool down and it would start, so we were thinking we cured it via the carbs, when it was the coil the whole time. We moved the coil from the side of the block (where it had been mounted horizontally) to the front of the engine (this time we mounted it straight up and down) and the problem has never come back. The reason we mounted it straight up and down is that I read where coils can overheat if mounted horizontally, at least the oil filled ones. That might be what you have going on. Don
Don, Someone once said that 90% of all electrical problems were fule delivery problems and that 90% of all fuel delivery problems were electrical. Pretty easy to tell if the car is not getting fuel, take the carb cover off and look down the carb, now open the throttle linkeage and see if it gets a squirt of fuel. if it is not getting fuel to the carb it will not squirt.
Good point on the control mod...I am assuming that you are speaking to the module in the distibutor and not the 6AL box. On this truck the 6AL box is mounted under the dash on the inside firewall. The controller probably got as hot as the ambient air not not nearly has hot as it was under the hood. Sure wish I had a way to cool the coil and the distro seperately when the failure was ocurring. Don, the coil is mounted vertically on the front of the right head. I believe that this particular coil is not fluid filled but that is a good point to remember on the mounting.
Just cool the coil if things don't change you can rule the coil out. You can have the distributer tested but donot go to O'Reilly's or the like, things get past those cheapo tresters that they use, go to a good distributer shop.
I was up there for the show, I did see alot of cars on the way up having issues due to the heat. What a good show and some crazy weather.
Never miss the Big Bear show...a couple of our trucks took "Best F-100" and "Best Chrome". The guy who took Best of Show is a good friend from El Centro...damn nice 40 Ford PU, although not very HAMB-friendly.
On the module...there are numerous sites and I think some tech here on adapting GM HEI modules remotely to various ignitions/triggers of all makes, with substantial benefits... durable module, remote location in cool area, and a part you can replace anywhere (unlike aftermarket modules) if it ever does break. Also there's a radical new gadget out there, it replaces the module with two little pieces of metal that just move together and apart to make sparky, almost completely oblivious to heat! Cost is like $5, but it does need a few minutes of attention every 10,000 miles...
I bought a Stude Delco dist to be converted to electronic ign. I love the instant start but I realized that my old points ign starts as quickly as any electronic system that I run so I've never bought the module. I did a tuneup on it when I bought it and with my mileage it will be a while before it needs attention.
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