heater going hot/cold [Archive] - GrandAmGT.com Forum

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zhd1000
01-13-2011, 09:11 AM
I drive 35 miles to work, heater warms up when I get on the road. However when I let the rpms down (either coming to a stop or even driving at 30 etc), the heater goes cold. Basically, engine working = heat, engine idling = cold, what gives?

[ChaosweaveR]
01-13-2011, 09:54 AM
The system is losing pressure somewhere, or the thermostat could be starting to go. I'd check to see if any lines are clogged by the heater core, or if the heater core itself is clogged.

When was the last time the coolant system was flushed?

2000 GT Coupe
01-13-2011, 12:24 PM
I would ask you what does the engine coolant temp say? that sounds like a thermostat problem to me but if it is you will see corresponding temp fluctuations on the gauge.

zhd1000
01-13-2011, 08:32 PM
So I watched the gauge on the way home tonight. It sat 2-2.5 clicks below 200 the whole time. This time it did cool off while still cruising at 60.

zhd1000
01-16-2011, 07:38 PM
bump

JRYAN34
01-16-2011, 08:31 PM
maybe katy perry is in there?

350rs
01-17-2011, 07:18 AM
check your coolant level and as stated check that both lines going into and from the core are hot. Check your upper and lower radiator hoses as well. Sounds like you have either got a clog or starting to run low coolant. Is your engine overheating at all at a stop light? or if sitting for awhile running?

juanvan
01-17-2011, 07:39 AM
HG - Mine did the same thing for the past yr with the temperature gauge, little over 200 cool down - wash rinse repeat driving any where - 15miles or 60miles - up down up down up down

Over the past summer I changed the thermo, Radiator, water pump - this was all in hopes the HG was not blown, but in the end that was it..

I don't turn on the heat too often, since I drive it in the summer. But a simple HG test kit from Napa I bet the color changes from Blue to yellow after a little.

Mine finally started bubbling from the pressure when I was testing. I turned on the heat and it was cold even though the temp sensor was at 200. Parked it after that. Waiting on getting new heads.

zhd1000
01-24-2011, 01:56 PM
check your coolant level and as stated check that both lines going into and from the core are hot. Check your upper and lower radiator hoses as well. Sounds like you have either got a clog or starting to run low coolant. Is your engine overheating at all at a stop light? or if sitting for awhile running?

where is the heater core and the two lines located? seems to be the easiest place to check first..

juanvan
01-24-2011, 02:07 PM
by the passenger firewall you will see the hoses running into the FW.

zhd1000
01-25-2011, 08:34 AM
thanks. so last night driving through the neighbor hood, engine overheats. gauge went all the way to the red, light came on, chimes everything.. soooo, checked coolant, pretty much gone. topped up with dexcool and heat seemed to work fine this morning. Now to figure out where the coolant is going...

juanvan
01-25-2011, 08:43 AM
Not only do you need a HG now you need to have the heads fixed too.. Stop driving the car before you blow the heck out of it. (just a dad comment)

But really your doing more harm then good driving it.

zhd1000
01-25-2011, 02:53 PM
what makes you think it is the HG? because the heat was going? isn't it typical to blame the LIM for leaking coolant? I'll see if the local Napa has one of those gasket test kits

juanvan
01-25-2011, 03:03 PM
More so that the coolant is coming out the res. Meaning there is more pressure then there should be - Your losing coolant, and its not in the oil. LIM usually go into the oil unless they are on the outside puddle areas.

Edit how far are you from indy? I Might be down there over V-day next month.

zhd1000
01-25-2011, 03:24 PM
about 5hrs or so

zhd1000
01-31-2011, 07:54 PM
does this help? changed the oil, came out as black as normally would. Not milkshaky at all..

Malaclypse
01-31-2011, 09:46 PM
Intake gaskets. I've seen coolant leaks cause this problem. The path to the heater core for the coolant is made in such a way that air pockets are able to form in the core itself.

The condensation on the oil cap is somewhat common in winter though.

Still, check the intake gaskets.

juanvan
02-01-2011, 09:09 AM
Nope my oil change was fine and my oil is still fine.

zhd1000
02-01-2011, 11:17 AM
so what's the tan crap covering the inside of the valve cover and oil cap? bad oil?

juanvan
02-01-2011, 11:19 AM
Condensation from the winter? That is milk shake

02GT_SkyHigh
02-01-2011, 11:37 AM
maybe katy perry is in there?
Hahaha! Oh my Id love to see her head get wrapped up in the belt....

Malaclypse
02-01-2011, 06:49 PM
Condensation from the winter? That is milk shake

Milkshake would be covering EVERYTHING in the head. It'd be all over the springs etc etc.

The extra condensation is likely caused by colder, damp winter weather and possibly an intake gasket leak.

OP: Please listen to me.. I've been working on these cars professionaly for 8 years. I've dealt with this complaint numerous times and it ends up being a low coolant level caused by either the intake gaskets or water pump. Those are the two most common coolant leaks from these cars.

hass
02-09-2011, 05:10 PM
if it's overheating like that, it's probably head gasket.
most likely head gasket.

Unless you were really just low on coolant...
But even being low on coolant, your car should signal low coolant well before it would get to the point of overheating from not enough coolant in the system.
if that makes any sense.

Did it overheat on it's rise to operating temp? Or did it just overheat randomly from driving?
Just because your oil is clean doesn't mean anything.
Can be leaking externally.