Can Heat Affect a Coil? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68 Suburban · 05-07-2004, 03:39 PM

Has anyone ever had a problem with a coil cut out when it gets hot and then works again when it is cool? Thanks

boraxman · 05-07-2004, 03:45 PM

I doubt it. Coils are hard to kill. Speaking to a mechanic of 40 years he told me he has only seen 2 bad coils. I would also think when a electrical part goes its gone.

crustysarge · 05-07-2004, 04:08 PM

Well, I once had a FIAT 131 that left me and my Italian girlfriend (now my wife) on the side of the road more than once. There was this one time outside of Munich Germany when we were on out way to Hahn Air Base and...well another time.

It was the coil and it was intermittent. Coils can and do go bad and heat is the big killer. That is why oil was/is used to cool them. They can cause all kinds of elusive electrical problems, i.e. you think it is everything else.

Sweet72 · 05-07-2004, 04:11 PM

The answer to your question is yes...
Transformers can and will break down under high temps (your ignition coil is a step-up transformer). I have experienced this with a few coils. Although I have not had one of the original oil filled coils as installed on our trucks go bad, I believe it's possible.

boraxman · 05-07-2004, 04:19 PM

Learn something new everyday

Bowtie67 · 05-07-2004, 04:44 PM

If you are running the stock coil it is possible, if you have an HEI the usual cuprit is in the module or pickup.

73stepside · 05-07-2004, 06:02 PM

the 73 i had would stumble and stall when cold and when hot would work right. changed the coil and problem went away.

FRENCHBLUE72 · 05-07-2004, 08:11 PM

I just went through the same problem on my yota it would work fine till the motor got warm and then it would kill the truck... Let it cool down and it would start agian...

Gordo · 05-07-2004, 08:58 PM

Had very few coils go bad in my years, one in particular had a small hole chaffed in the base of it and the cooling oil inside drained out without noticing, causing it to heat up and quit, then worked again after it cooled. That was on a 1970ish Dodge van with the infamous slant six.

sneakysnake · 05-07-2004, 09:50 PM

Had a coil pack go bad on a 88'grand am

Longhorn Man · 05-07-2004, 10:54 PM

I've only been driving 15 years, and I've had about 4 or 5 coils go bad. Most all my cars have been old jalopies too...100,000 miles is when they become affordable. (my first car with less than 100 K on the clock was a parts car)

Chris, if you are running an HEI and having problems like you describe, you probably have a problem with the ignition module.
Funny thing with this is, everyone complains about the modules going bad, and some even carry a spare in the glove box, I've only had one go bad so far.
Only buy GM modules, the parts store over seas ones are not worth the box they are shipped in.

RON WOODGEARD · 05-08-2004, 02:28 AM

From another backyard mechanic of 35 years,,,, Absolutely YES... When we had inferior coils in the 60's. ( technology hadn't caught up in that dept. yet) We used to mount our coils in the passenger compartment. They even sold a KIT to run it through the firewall. and the big old Accel, Supercoils had heat dissipating Ridges in them, because of the overheating possibility..

05-07-2004, 03:39 PM	#1
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	Can Heat Affect a Coil? Has anyone ever had a problem with a coil cut out when it gets hot and then works again when it is cool? Thanks __________________ Just sitting here contemplating contemplation.

05-07-2004, 03:45 PM	#2
boraxman Keepin an eye out Join Date: Feb 2003 Location: So.Cal Posts: 3,921	I doubt it. Coils are hard to kill. Speaking to a mechanic of 40 years he told me he has only seen 2 bad coils. I would also think when a electrical part goes its gone. __________________ 1970 Chevy C10 SWB 5.3 1996 Toyota Tacoma SR5 4x4 2007 Vespa GTS 250 Scooter ZIP 91351

05-07-2004, 04:11 PM	#4
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	The answer to your question is yes... Transformers can and will break down under high temps (your ignition coil is a step-up transformer). I have experienced this with a few coils. Although I have not had one of the original oil filled coils as installed on our trucks go bad, I believe it's possible. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

05-07-2004, 04:19 PM	#5
boraxman Keepin an eye out Join Date: Feb 2003 Location: So.Cal Posts: 3,921	Learn something new everyday __________________ 1970 Chevy C10 SWB 5.3 1996 Toyota Tacoma SR5 4x4 2007 Vespa GTS 250 Scooter ZIP 91351

05-07-2004, 04:44 PM	#6
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	If you are running the stock coil it is possible, if you have an HEI the usual cuprit is in the module or pickup. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

05-07-2004, 04:08 PM	#3
crustysarge Registered User Join Date: Mar 2004 Location: Aviano, Italy Posts: 221	Well, I once had a FIAT 131 that left me and my Italian girlfriend (now my wife) on the side of the road more than once. There was this one time outside of Munich Germany when we were on out way to Hahn Air Base and...well another time. It was the coil and it was intermittent. Coils can and do go bad and heat is the big killer. That is why oil was/is used to cool them. They can cause all kinds of elusive electrical problems, i.e. you think it is everything else.

05-07-2004, 06:02 PM	#7
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	the 73 i had would stumble and stall when cold and when hot would work right. changed the coil and problem went away. __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom

05-07-2004, 08:11 PM	#8
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,608	I just went through the same problem on my yota it would work fine till the motor got warm and then it would kill the truck... Let it cool down and it would start agian... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

05-07-2004, 08:58 PM	#9
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Had very few coils go bad in my years, one in particular had a small hole chaffed in the base of it and the cooling oil inside drained out without noticing, causing it to heat up and quit, then worked again after it cooled. That was on a 1970ish Dodge van with the infamous slant six. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

05-07-2004, 09:50 PM	#10
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	Had a coil pack go bad on a 88'grand am

05-07-2004, 10:54 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I've only been driving 15 years, and I've had about 4 or 5 coils go bad. Most all my cars have been old jalopies too...100,000 miles is when they become affordable. (my first car with less than 100 K on the clock was a parts car) Chris, if you are running an HEI and having problems like you describe, you probably have a problem with the ignition module. Funny thing with this is, everyone complains about the modules going bad, and some even carry a spare in the glove box, I've only had one go bad so far. Only buy GM modules, the parts store over seas ones are not worth the box they are shipped in.

05-08-2004, 02:28 AM	#12
RON WOODGEARD Resident Young Old Dude ! Join Date: Jul 2001 Location: Nevada Posts: 1,948	From another backyard mechanic of 35 years,,,, Absolutely YES... When we had inferior coils in the 60's. ( technology hadn't caught up in that dept. yet) We used to mount our coils in the passenger compartment. They even sold a KIT to run it through the firewall. and the big old Accel, Supercoils had heat dissipating Ridges in them, because of the overheating possibility..



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