heating issues '94 chevy

[Randy92782]

Ok so my truck has officially pissed me off to the point i'm just about to say **** it and start driving the turd again (83 GMC)

Let me just start. Ok this past summer my truck started gettin hot so i decided right then to just yank out the thermostat since i didn't need a heater in summertime anyways Went the next day and bought one so i'll have it later.

It starts gettin cold in the mornings so i decided one day to go out and put it in so i don't have to freeze on the way to work. Put it in and waited til i went to work the next day. Got about halfway there and it started gettin hot. I mean it was almost to the red so i scooted my ass back home quick fast and in a hurry. MY stepdad tells me sometimes they are just junk brand new. So i went back and got a replacement.

Seemed fine all week then that weekend it started doing it again. Jerked that one out and was pissed!! SO my stepdad tells me of a failsafe so when it stciks it'll stick open. I go for that cause i'm not about to blow a motor up for a $10 POS.

All works out fine for about 2 weeks then my truck would just not get over 100*. Just said screw it i'll just tough it out this winter on not having a heater.

Fast forward to Thursday night. I was drinkin so i asked a friend to drive my truck home. He said ok. as He's driving it starts gettin hot again I'm at a total loss. I mean the waterpump is working i think.

So what say you guys??

I have this to choose from

-Junk heatercore (isn't leaking or smelling or foggin up the window but can still be bad right??)
-Thermostat is once again a POS
-radiator needs flushed
-hoses are collapsing causing it to overheat
-maybe a new waterpump is i order??

Not really sure what else it could be I just went and bought every brand new hose possible for this thing and 2 gallons of anitfreeze. Going to go change them now and if this doesn't work i'm sure to seriously **** something up

 

[toomany]

I'd start with replacing the hoses, mainly the lower. Get one with a spring in it...keeps it from colapsing. It won't hurt to flush out the old coolant either. I think the chances of getting two bad thermostats are very small. When it gets hot do you have any heat?

 

[Randy92782]

I'd start with replacing the hoses, mainly the lower. Get one with a spring in it...keeps it from colapsing. It won't hurt to flush out the old coolant either. I think the chances of getting two bad thermostats are very small. When it gets hot do you have any heat?

nope no heat. That's what has me thinking the hoses. When the temp gauge shows around 100* the heat works fine. I usually start it up about 15 minutes before i take off in the morning. In case the heater actually wants to work. Usually don't start heating up inside until i get going down the road and even then it shows 100* when it gets around 200-210 my heater starts blowing out cold. Aggrivating (sp) as hell too cause i don't have defrost.

What sucks is if i do start driving the old truck the heater sucks in it too so i'm pretty much gonna freeze to death either way this winter if it gets cold

I may just have to go and buy me another one if i can't figure this **** out got about $4000 layin here

 

[Randy92782]

Ok update. changed everything cept the heater core and let it run for a good 15-20 minutes. Never got over 100*. Took it about 2 miles down the road and still nothing but the heater seems to be getting better

Either way i'm going to drive it into town and wash it so we''l see how THAT trip goes

If it overheats i'm going to burn it.....j/k i guess i'll move on to the heater core.

I couldn't figure out a good way to flush out the radiator so i just left the bottom hose on and shoved a beerbottle up in it. (it's out of the truck at this time) Turned on the hose and let er rip til i didn't see anything else but water come out. Now i have 10 gallons of anitfreeze/water to get rid of.

What do you guys do with the stuff??

 

[longbedder]

You can test thermostats on the stove using a pot of water and a thermometer. Just heat it up, monitor the temp, and see if it opens up at the right temperature.

Your truck should run better if you use a thermostat in the summer too. You don't want it to run too cool.

It sounds like the actuator system that controls the heat/cold mixture into the cab may not be working correctly.

 

[Randy92782]

It sounds like the actuator system that controls the heat/cold mixture into the cab may not be working correctly.

Well it really isn't the most brilliant GM design. Its one thing i could do without. W/e happened to the old cable operated ones

 

[apache]

Man,sounds frustrating. Id was gonna suggest air in the system but sounds like you`ve driven it enough to burp it out. The other thought was the thermo`s in backwards,but you sound like no rookie at wrenchin. I have actually seen a pump impeller that was 90% rusted/corroded away from a neglected system but that iffy and should give consistent overheating which you dont seem to have. Personally I can say Ive had more bad new thermos than good specially from Napa,my problem was constant cycling which annoys the hell outta me. Some of our work trucks (Fords)that did constant short trips and never warmed up fully saw thermo failures every couple months,they would stick open for whatever reason.

 

[4X4HIGH]

Ok, first off a bad heater core WILL NOT make your engine overheat (you just won't get any heat from your heater or very little). Secondly, in most cases of overheat issues it is the radiator at fault. The radiator will plug from the bottom up. The test for this is to run the engine long enough that it should be normal operating temp then use a IR heat gun and check all areas of the radiator and see if there are any cold spots (if so that area is plugged). A bad lower hose that is sucking closed could definately cause an overheat issue as well. It is rare for a water pump to cause overheating (the only way is if the impeller fell off or corroded away).

 

[Randy92782]

Ok, first off a bad heater core WILL NOT make your engine overheat (you just won't get any heat from your heater or very little). Secondly, in most cases of overheat issues it is the radiator at fault. The radiator will plug from the bottom up. The test for this is to run the engine long enough that it should be normal operating temp then use a IR heat gun and check all areas of the radiator and see if there are any cold spots (if so that area is plugged). A bad lower hose that is sucking closed could definately cause an overheat issue as well. It is rare for a water pump to cause overheating (the only way is if the impeller fell off or corroded away).

I've been drinking so bear with me. Not much on heater cores so that's always nice to know.

I did my best to flush out the radiator so i hope it's enough. Drove it all night and even sat in a parking lot for hours (long story) and it never overheated. Atleast the radiator

Wasn't sure about the hoses so i changed them all. Would'nt want to **** anything up for a $20 thermo or a $20 hose

 

[dyeager535]

Wait a minute. I thought engines overheated without thermostats? I'll leave it at this: too many variables for that to be a true or false statement all the time.

In any case, if it cools without a thermostat, then it's not your radiator.

Did you drive/idle it with a thermostat and now it sounds like it's fixed? Obviously you can't base engine temp on heater outlet temp, since they aren't necessarily tied together, IF the heater system isn't working right. Need to verify actual engine temp with your gauge, and make sure that it's right.

Radiator flushes do NOT work in bad cases. The radiator can look fine up top, but you can't see the bottom. As mentioned, IR temp gun is the only way to check it on the vehicle, and a flow test is the only way out of the vehicle.

 

[sweetk30]

and removing tstat on computer controled motors will mess up all the functions. trans looks for 140* to run diffrently. and comp looks for this temp also to switch to diffrent fuel map programs.

 

[Randy92782]

So in that case if a motor overheats in a computer controlled truck it could **** up some ****?? Mainly the computer??

this is the reason i own 3 old trucks So much less complicated.

Did you drive/idle it with a thermostat and now it sounds like it's fixed?

Yes. It seems to be alright now other than it not going over 100*.
I know i should get one of those heat things to see if the temp gauge is actually working but the heater still doens't work all that great. I mean it's good enough for now but the girls have been bitchin cause its cold in there

they should try ridin in my Blazer with no top in 30* weather

Seriosuly though i'd like to get it fixed right but will suffer the cold to not have a junk thermostat warp a head or blow my motor

 

[dyeager535]

If the engine keeps cool without a thermostat, there should be no reason JUST installing a thermostat should make it overheat. it's obvious the cooling system is adequate to keep the engine more than cool.

I'd really want to verify that your gauge sender is not acting up on you.

Any chance you've got the wrong water pump? Doesn't sound like you changed it, if you haven't since the problem occurred, I'd look at replacing it. At least pull it and inspect it. If it's the problem, you'd be able to see what's causing it. As mentioned, it may be shot and moving just enough liquid to keep it cold with absolutely no restriction, ie the thermostat.

Engine getting hot or cold will not harm the computer. It will simply not operate correctly. This is no different or more complex than a malfunctioning choke...if the ECM THINKS the engine is above or below "normal" operating temperature, it "chokes" the engine, according to the temperature it thinks the engine is at.

 

[Randy92782]

Well i just assumed (yes i know what assume means :doah) that since when it shows 100* the heater works but faintly and when it gets hot (around 22-240) it starts spittin out fluid out of places it shouldn't, that the gauge is accurate.

It may be the water pump but i'm gonna say it may be ther heater core No idea why i say this but probably that cause in my case it's usually the harder to replace of the 2

 

[dyeager535]

You can completely bypass the heater core, but again, the heater core is insignificant in regards to the overall cooling of the engine. You could certainly try it and see.

If the engine is spitting fluid, the heater should be cranking out serious BTU's if the vent system is operating right.

How about an air pocket in the block? I know on some of the later motors there was a plug that could be pulled to bleed off air back there.

 

[Randy92782]

How about an air pocket in the block? I know on some of the later motors there was a plug that could be pulled to bleed off air back there.

that's the second time i've heard about this. I mean i've changed the thermostat 3 times now so theres a good chance that could be the case but not sure about how to go about bleeding it. Guess i'll have to look

Oh and it did it again this morning on the way to work. I'm pretty sure my radiators busted now. It's got a slow leak that i never noticed before. Gonna pull it yet again or take it somewhere to have it checked. Filled it up after work and drove it home and around town for 30-45 minutes and no overheating just a slow leak when i park.

Found 2 jeeps. one for $2500 and the other for $3500. Gonna go check em out. Just gonna say i'll probaly drive one home this week

So i can fix my truck and have a second dependable rig.