so what did i break now? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ocbaud · 10-22-2006, 02:09 AM

got the temp gauge to start staying a lot steadier and not pegging out when it really wasnt 260+ degrees. i had some air in the system, and now that i got it out, the upper hose stays VERY pressurized while hot.

much better than before.

but,

every now and then i will hear this hissing type sound coming from where the heater core is located.

my floorboard isnt wet and i cant find a leak anywhere around there, but i'm sure it has something to do with the heater core.

79BIG10 · 10-22-2006, 11:43 PM

You might have a vacuum leak there Eric. The hose comes into there to pull the door open and shut when you are sliding the temp selector.

Hoods69BadBowTie · 10-23-2006, 12:58 AM

Yeah, I was going to suggest a possible vaccum leak also.
-Lates

ocbaud · 10-23-2006, 11:29 AM

i'll look under there.

it could be it, but it doesnt sound like a vacuum leak.

lurch115 · 10-23-2006, 08:03 PM

i had a truck do that too....turned out to be that the heater core was plugging up and the hissing that you hear is the antifreeze being forced through where it is plugged

79BIG10 · 10-24-2006, 01:26 AM

Eric get a vacuum tester from Harbor Frieght for like $10 and check the vacuum at a constant source. This will tell you alot about your engine's running and diagnose if it does or doesn't have a leak.

ocbaud · 10-24-2006, 09:13 AM

Quote:

Originally Posted by lurch115

i had a truck do that too....turned out to be that the heater core was plugging up and the hissing that you hear is the antifreeze being forced through where it is plugged

to me, thats what i first thought, and what it sounds like. i should add that it first did it after taking it up to around 5900rpm's one night last week. after i shifted i heard a noise and then the hissing sound was there. next few times i drove it, the sound was gone, and then last time i drove it, after driving for about 10 minutes, the hissing came back.

i checked that vacuum line behind the dash, and its all nice and tight, no leaks at all.

and i had a vacuum gauge before i moved, but now i dont know where its at

so, i planned on replacing the radiator anyways, might as well replace the heater core too....

at least my cooling system will be all brand new

10-22-2006, 02:09 AM	#1
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	so what did i break now? got the temp gauge to start staying a lot steadier and not pegging out when it really wasnt 260+ degrees. i had some air in the system, and now that i got it out, the upper hose stays VERY pressurized while hot. much better than before. but, every now and then i will hear this hissing type sound coming from where the heater core is located. my floorboard isnt wet and i cant find a leak anywhere around there, but i'm sure it has something to do with the heater core.

10-22-2006, 11:43 PM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Re: so what did i break now? You might have a vacuum leak there Eric. The hose comes into there to pull the door open and shut when you are sliding the temp selector. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

10-23-2006, 12:58 AM	#3
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	Re: so what did i break now? Yeah, I was going to suggest a possible vaccum leak also. -Lates __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

10-23-2006, 11:29 AM	#4
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	Re: so what did i break now? i'll look under there. it could be it, but it doesnt sound like a vacuum leak.

10-23-2006, 08:03 PM	#5
lurch115 Registered User Join Date: Oct 2006 Location: iowa Posts: 722	Re: so what did i break now? i had a truck do that too....turned out to be that the heater core was plugging up and the hissing that you hear is the antifreeze being forced through where it is plugged __________________ "Horsepower is how fast you hit the wall, torque is how far you carry the wall with you." '84 chevy half ton short box 2wd, 67,000 actual miles '03 chevy 1500 HD crew cab 4x4 standard box, 6.0L

10-24-2006, 01:26 AM	#6
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Re: so what did i break now? Eric get a vacuum tester from Harbor Frieght for like $10 and check the vacuum at a constant source. This will tell you alot about your engine's running and diagnose if it does or doesn't have a leak. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson



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