Weird over heating problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

desertdogg · 08-04-2012, 07:06 PM

So I have a 1972 chevy c10 that im working on and Ive had an over heating issue so Ive flushed the radiator and currently got some prestone super clean in it to try to get all the sludge build up in it. Anyways I have noticed when my headlights are on it wont over heat I can literally run it without the head lights on and I will watch the temp gauge when it looks like the gauge is at the maximum heat range I will turn on the lights then the gauge temp goes back to normal running temp. What the hell ?...anyone have any ideas what might be going on here ?...thanks for any input

So.Cal.Super · 08-04-2012, 07:40 PM

Can you give us some more info?

Stock clutch fan, stock gauges? any recent upgrades?

I'm scratching my head.

OJ1988 · 08-04-2012, 07:42 PM

What gauge are you reading? A factory temp gauge? Have you verifired it is correct, and working?

No idea why headlights would have anything to do with it.

PanelDeland · 08-04-2012, 08:08 PM

Since the headlights seem to affect it,I would look at the wiring to the guages.Maybe a ground thru the headlights or high beam indicator causing the guage to read right either with lights or without.

bobs409 · 08-04-2012, 09:03 PM

Odd things like that usually indicate a bad ground somewhere.

Try adding a ground wire to the back of the cluster. That might fix it.

SS Tim · 08-04-2012, 09:18 PM

Verify your ground at the cluster. Might also want to check the system voltage with the headlights off and on. Is your truck actually overheating or is this based solely on the gauge indication?

desertdogg · 08-04-2012, 11:56 PM

Thanks for all the replies... It is a 350 engine with the th350 transmission Im not really sure if its overheating just going by the factory temp gauge, after reaching normal running temp the gauge goes high with accelleration pretty steadily, and when I come to a stop, it slowly comes back down to normal again I will check the ground tomorrow. when I bought this truck it had a battery drain problem 2amp leak at the regulator the fix was to remove the chassis ground from the regulator could this be the problem ?

SS Tim · 08-05-2012, 12:19 AM

Quote:

Originally Posted by desertdogg

...when I bought this truck it had a battery drain problem 2amp leak at the regulator the fix was to remove the chassis ground from the regulator could this be the problem ?

Really, A 2 amp drain! Disconnecting the factory ground to the regulator is a work around not a fix. At this point I'd worry about diagnosing and fixing the charging system problem first. Are you still running an externally regulated alternator?

cdowns · 08-05-2012, 07:23 AM

yes what he said

disconnecting that reg ground will just lead u to more problems down the road

desertdogg · 08-05-2012, 01:57 PM

Sorry ! it was 2 milliamps, and yes I know its a work around not a fix but for the moment I can wake up and not have a dead battery...Im eventually going to convert it to a alternator with the built in regulator so at the time I wasnt too concerned...Im going to reconnect that ground and see if my temp gauge problem goes away then down the road change out my alternator.....Everyone, thanks so much for your help I appreciate it !

SS Tim · 08-05-2012, 02:51 PM

2 Miliamps is a lot better! A 24 watt problem is a fire waiting to happen. Anyway good luck on that one, it should work out. Now here is a schematic, generic but probably very close for this purpose. The thing that concerns me is the regulator, alternator and the left headlamp share a body ground. Depending on where you opened the circut point A or B might be the root of the gauge problem. Also you might want to pick up one of those roll on roll off battery connectors for the negative battery terminal. Most boat places have them and it allows minor wiring issues to be lived with short term and makes it nice to do a electrical work without playing with the battery cables constantly.

desertdogg · 08-05-2012, 03:59 PM

Tim thanks for that schematic...Point B is where I disconnected that ground to sheet metal...I had a two milliamp draw at that ground drove me nuts trying to find it. Could this be a bad regulator ? the PO said it was replaced along with the alternator..im Kinda confused why that regulator is grounded due to having rubber feet to prevent it from grounding.

cdowns · 08-05-2012, 04:36 PM

rubber mounts r for vibration

desertdogg · 08-05-2012, 11:53 PM

Vibration ? haha ok that makes sense now...anyways I reconnected that ground and drove it around and now its working good but I probably will have a dead battery in the morning...Im just going to have to get that built in regulator alternator..oh welll...thanks everyone for your help

08-04-2012, 07:06 PM	#1
desertdogg Registered User Join Date: Jan 2012 Location: San Diego, Ca Posts: 249	Weird over heating problem So I have a 1972 chevy c10 that im working on and Ive had an over heating issue so Ive flushed the radiator and currently got some prestone super clean in it to try to get all the sludge build up in it. Anyways I have noticed when my headlights are on it wont over heat I can literally run it without the head lights on and I will watch the temp gauge when it looks like the gauge is at the maximum heat range I will turn on the lights then the gauge temp goes back to normal running temp. What the hell ?...anyone have any ideas what might be going on here ?...thanks for any input

08-04-2012, 07:40 PM	#2
So.Cal.Super It'll Buff Out! Join Date: Apr 2007 Location: San Diego Posts: 603	Re: Weird over heating problem Can you give us some more info? Stock clutch fan, stock gauges? any recent upgrades? I'm scratching my head. __________________ "Instructions are just another mans opinion" Become a Supporting Member http://67-72chevytrucks.com/vboard/payments.php Man Card Rules http://67-72chevytrucks.com/vboard/s...d.php?t=634550 72 Chevy Cheyenne Super 400 LWB

08-04-2012, 07:42 PM	#3
OJ1988 Just a car guy Join Date: Feb 2006 Location: New Washington, IN Posts: 991	Re: Weird over heating problem What gauge are you reading? A factory temp gauge? Have you verifired it is correct, and working? No idea why headlights would have anything to do with it. __________________ 1955 belair Blown Pro Street cruiser 1971 Camaro Pro Touring 1973 Vega Drag Car 1970 C20 tow rig

08-04-2012, 08:08 PM	#4
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Weird over heating problem Since the headlights seem to affect it,I would look at the wiring to the guages.Maybe a ground thru the headlights or high beam indicator causing the guage to read right either with lights or without. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

08-04-2012, 09:03 PM	#5
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Re: Weird over heating problem Odd things like that usually indicate a bad ground somewhere. Try adding a ground wire to the back of the cluster. That might fix it. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

08-04-2012, 09:18 PM	#6
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,507	Re: Weird over heating problem Verify your ground at the cluster. Might also want to check the system voltage with the headlights off and on. Is your truck actually overheating or is this based solely on the gauge indication? Attached Images __________________ Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID Blazer SPID Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders Do you have a 1972 Plaid Pickup? Plaid Blazer ** Plaid Suburban

08-04-2012, 11:56 PM	#7
desertdogg Registered User Join Date: Jan 2012 Location: San Diego, Ca Posts: 249	Re: Weird over heating problem Thanks for all the replies... It is a 350 engine with the th350 transmission Im not really sure if its overheating just going by the factory temp gauge, after reaching normal running temp the gauge goes high with accelleration pretty steadily, and when I come to a stop, it slowly comes back down to normal again I will check the ground tomorrow. when I bought this truck it had a battery drain problem 2amp leak at the regulator the fix was to remove the chassis ground from the regulator could this be the problem ?

08-05-2012, 07:23 AM	#9
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Weird over heating problem yes what he said disconnecting that reg ground will just lead u to more problems down the road __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-05-2012, 01:57 PM	#10
desertdogg Registered User Join Date: Jan 2012 Location: San Diego, Ca Posts: 249	Re: Weird over heating problem Sorry ! it was 2 milliamps, and yes I know its a work around not a fix but for the moment I can wake up and not have a dead battery...Im eventually going to convert it to a alternator with the built in regulator so at the time I wasnt too concerned...Im going to reconnect that ground and see if my temp gauge problem goes away then down the road change out my alternator.....Everyone, thanks so much for your help I appreciate it !

08-05-2012, 02:51 PM	#11
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,507	Re: Weird over heating problem 2 Miliamps is a lot better! A 24 watt problem is a fire waiting to happen. Anyway good luck on that one, it should work out. Now here is a schematic, generic but probably very close for this purpose. The thing that concerns me is the regulator, alternator and the left headlamp share a body ground. Depending on where you opened the circut point A or B might be the root of the gauge problem. Also you might want to pick up one of those roll on roll off battery connectors for the negative battery terminal. Most boat places have them and it allows minor wiring issues to be lived with short term and makes it nice to do a electrical work without playing with the battery cables constantly. Attached Images __________________ Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID Blazer SPID Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders Do you have a 1972 Plaid Pickup? Plaid Blazer ** Plaid Suburban

08-05-2012, 03:59 PM	#12
desertdogg Registered User Join Date: Jan 2012 Location: San Diego, Ca Posts: 249	Re: Weird over heating problem Tim thanks for that schematic...Point B is where I disconnected that ground to sheet metal...I had a two milliamp draw at that ground drove me nuts trying to find it. Could this be a bad regulator ? the PO said it was replaced along with the alternator..im Kinda confused why that regulator is grounded due to having rubber feet to prevent it from grounding.

08-05-2012, 04:36 PM	#13
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Weird over heating problem rubber mounts r for vibration __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-05-2012, 11:53 PM	#14
desertdogg Registered User Join Date: Jan 2012 Location: San Diego, Ca Posts: 249	Re: Weird over heating problem Vibration ? haha ok that makes sense now...anyways I reconnected that ground and drove it around and now its working good but I probably will have a dead battery in the morning...Im just going to have to get that built in regulator alternator..oh welll...thanks everyone for your help



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