S-10 blazer, no heat, challenge yourself on this one!

[Theevinman]

I changed the thermostat and low and behold everything works great-hot hot heat. So that was it, but I still dont get why the truck wasn't overheating with a busted stat?

[BlazerLT]

Originally Posted by Theevinman

I changed the thermostat and low and behold everything works great-hot hot heat. So that was it, but I still dont get why the truck wasn't overheating with a busted stat?

It will overheat if it was stuck closed.

Yours was stuck open.

[JoulesWinfield]

Geeze, howd I miss this one.

Lt is right. When the T-stat is stuck open you are cooling the engine as much as your cooling system can (minus the fan, which probably never had a chance to turn on).

[IndianaAbsentee]

OK, I've sat and read this whole thread because I'm having a similar problem(muddy coolant, incosistent heat) in my '98 ZR2. I replaced my therm. a week ago(192F), ran the truck, topped off the coolant, everything was great for a week.

Today, inconsistant heat again.

I've got something different in my problem though. My truck IS overheating. . .Kinda. The temp will get up to around 230-240 for awhile, then go back down to normal for awhile, then back up for awhile, but it never really hits 250 and sets the "check gauges" light off. When it's at normal temp., I get great heat. When it's hot, I get no heat. I've turned the heat on and off and tried it both ways, temp. gauge still goes up and down constantly.

Any more suggestions?

[BlazerLT]

Originally Posted by IndianaAbsentee

OK, I've sat and read this whole thread because I'm having a similar problem(muddy coolant, incosistent heat) in my '98 ZR2. I replaced my therm. a week ago(192F), ran the truck, topped off the coolant, everything was great for a week.

Today, inconsistant heat again.

I've got something different in my problem though. My truck IS overheating. . .Kinda. The temp will get up to around 230-240 for awhile, then go back down to normal for awhile, then back up for awhile, but it never really hits 250 and sets the "check gauges" light off. When it's at normal temp., I get great heat. When it's hot, I get no heat. I've turned the heat on and off and tried it both ways, temp. gauge still goes up and down constantly.

Any more suggestions?

1.) You continue to drive it like that and the engine will be toast.
2.) Flush your cooling system including the heater core ASAP.
3.) Install a Stant rad cap.

I don't get why in gods name you have muddy coolant, yet you are not flushing the cooling system and just topping it off and driving it some more?

Comon man, common sense.

[IndianaAbsentee]

I've flushed the damn thing once already. . .I'm doing it tonight and using a chemical cleaner this time. If you'd like to offer intelligent and positive suggestions, that's great. Don't "common sense" me.

Anyway, I pulled the hoses leading to the heater core off tonight so that I could flush the whole thing out again. They were badly clogged with what appears to be crystalized radiator fluid (??) Is that even possible? I suppose it could be rust or something else, but it sure looks to be like reddish black, burnt-up radiator fluid. When I drained the radiator this time I let everything flow into a clear one-gallon container so I could look at it (last time I drained it into an oil pan). There were obivously chunks of the same solid gunk floating in the fluid.

Radiator fluid doesn't evaporate and crystalize, does it? What else could this crap floating in there be? I'm not driving it the rest of the week, so that I can screw with it this weekend.

Thanks for any mature and intelligent advice.

[BlazerLT]

Originally Posted by IndianaAbsentee

I've flushed the damn thing once already. . .I'm doing it tonight and using a chemical cleaner this time. If you'd like to offer intelligent and positive suggestions, that's great. Don't "common sense" me.

Anyway, I pulled the hoses leading to the heater core off tonight so that I could flush the whole thing out again. They were badly clogged with what appears to be crystalized radiator fluid (??) Is that even possible? I suppose it could be rust or something else, but it sure looks to be like reddish black, burnt-up radiator fluid. When I drained the radiator this time I let everything flow into a clear one-gallon container so I could look at it (last time I drained it into an oil pan). There were obivously chunks of the same solid gunk floating in the fluid.

Radiator fluid doesn't evaporate and crystalize, does it? What else could this crap floating in there be? I'm not driving it the rest of the week, so that I can screw with it this weekend.

Thanks for any mature and intelligent advice.

Flushing your cooling system is not just cleaning the rad, and piss off about the intelligent and mature advice bullshit, I was trying to help you.

You didn't flush it last time seeing if you did, you wouldn't have crud in your cooling system. You said you topped it off, if you flushed it, then SAY THAT and don't think we are all goign to read your mind.

Replace your rad cap ASAP, it is what is causing the cooling system to failure and allowing air into the cooling system.

You can do all the flushing you can, but it will return to crap all in short order with the stock AC Delco defective rad cap.

[MT-2500]

Originally Posted by IndianaAbsentee

I've flushed the damn thing once already. . .I'm doing it tonight and using a chemical cleaner this time. If you'd like to offer intelligent and positive suggestions, that's great. Don't "common sense" me.

Anyway, I pulled the hoses leading to the heater core off tonight so that I could flush the whole thing out again. They were badly clogged with what appears to be crystalized radiator fluid (??) Is that even possible? I suppose it could be rust or something else, but it sure looks to be like reddish black, burnt-up radiator fluid. When I drained the radiator this time I let everything flow into a clear one-gallon container so I could look at it (last time I drained it into an oil pan). There were obivously chunks of the same solid gunk floating in the fluid.

Radiator fluid doesn't evaporate and crystalize, does it? What else could this crap floating in there be? I'm not driving it the rest of the week, so that I can screw with it this weekend.

Thanks for any mature and intelligent advice.

As said if you done a proper flush the coolant would be clean.

Are you sure it is actually heating up or is your gauge not reading right?

If the coolant has that much crap in it has the Dex Cool been mixed with old green coolant?

You mix yellow and green and you will get brown mud.

[BlazerLT]

Originally Posted by MT-2500

As said if you done a proper flush the coolant would be clean.

Are you sure it is actually heating up or is your gauge not reading right?

If the coolant has that much crap in it has the Dex Cool been mixed with old green coolant?

You mix yellow and green and you will get brown mud.

I had the same problem occuring in my truck a year or so ago, it was the rad cap not holding pressure and allowing the coolant temperature to rise and the boiling point to drop.

[IndianaAbsentee]

OK, I took off the hoses into and out of the heater core and radiator tonight. All four hoses were lined with the same rust-colored crystalized chunks. I replaced all four with new hoses.

I used a prestone "superflush" kit to chemically flush the entire system, then I flushed with just water two more times. After that third flush I finally got clear water to run out consistently, even with the motor running and such.

You wouldn't believe the amount of that crystalized crap I had in my system. I've got a gallon jug sitting in my garage that is half full of anti-freeze, and half full of what looks like rust-colored gravel. When I drained the fluid last week, I got thick muddy fluid, but no sediment. I guess it was stuck in the system somewhere.

I need to replace the therm again (it's stuck open now) and I probably need a whole new radiator (I'm thinking the chunks are rusted pieces of my radiator's guts). But the truck isn't overheating for now. I drove it around for about a half hour tonight and it never got over 195 for a second.

I'm trying to figure out what could have caused that much heavy sediment in the cooling system. The truck only has 70,000 on it, and I've never touched the cooling system until last week. I just want a gameplan for what's getting replaced this weekend.

[MT-2500]

Quote from your upper post.
The truck only has 70,000 on it, and I've never touched the cooling system until last week.

A cooling system should be serviced every 3 years or 50K.
People that do have no trouble.

Not servicing system and bad rad caps and bad pressure systems and leaks and mixing green and Dex cools are leading causes to problems like yours.
MT

[IndianaAbsentee]

I bought the truck from a chevy dealer last year with 51K on it. I would HOPE they at least changed the fluids when they got it in. Even if not, the Owner's Manual says the Dex-Cool should last 100K with no issues.

Anyway, back to my last question. Any ideas (other than mixing the wrong coolant types, I know that didn't happen) on what would have caused rust chunks or whatever they are to be floating loose it there? I just want to know so that I can

a) decided if I'm putting on a new radiator this weekend
b) keep it from happening again

Also, if I'm radiator shopping in a junkyard, any warning signs of missuse I should be looking for before buying one?

Thanks for all the help and advice.

[MT-2500]

Originally Posted by IndianaAbsentee

I bought the truck from a chevy dealer last year with 51K on it. I would HOPE they at least changed the fluids when they got it in. Even if not, the Owner's Manual says the Dex-Cool should last 100K with no issues.

Anyway, back to my last question. Any ideas (other than mixing the wrong coolant types, I know that didn't happen) on what would have caused rust chunks or whatever they are to be floating loose it there? I just want to know so that I can

a) decided if I'm putting on a new radiator this weekend
b) keep it from happening again

Also, if I'm radiator shopping in a junkyard, any warning signs of missuse I should be looking for before buying one?

Thanks for all the help and advice.

Read pois no 26.

Gm streaches things a little on the 150K 7 year coolant.
Like Blazer LT has been trying to tell you even a bad rad cap will mess up things.

[MT-2500]

Junk yard is not a very good place to find a rad.
Parts places or 1 800 radiator has new rad's at a good price.

If the truck is a 98 and coolant has never been changed is a good reason for coolant to be bad.
Even GM best shot is 7 years on Dex Cool coolant.
Good luck MT

[someguy000001]

Originally Posted by IndianaAbsentee

Anyway, back to my last question. Any ideas (other than mixing the wrong coolant types, I know that didn't happen) on what would have caused rust chunks or whatever they are to be floating loose it there? I just want to know so that I can

a) decided if I'm putting on a new radiator this weekend
b) keep it from happening again

If you get low on dex-cool or if too much air gets in there you can get chunks. Leaking intake manifold gaskets on these model years help this along. That's why everyone is saying to replace the cap. Very important. A bad cap will allow air to suck in.
Also, if you overheat dex-cool it will clump up. Personally, I flushed the dex-cool out about 3 years ago and replaced it with the 'safe for all colors' coolant. I haven't had any problems since. My water pump died right after the flush, but that always seems to happen to me.
I wouldn't bother with a junkyard rad.