Help me....I'm cold! 94 caprice heating problem! Brrrrr!

[Musician423]

Alright....here's the problem. I live right outside Chicago, and it was 22 today, during the day in the sun. My 1994 chevy caprice has practically no heat. It's "fairly" warm outside now.....so time is running out. January and February get brutal. It's got the 4.3L v8, with bout 106k miles. Here' s the sum of it all:

1. Replaced heater core about 2 winters ago. That was a pain!
2. I put in a new thermostat and new/reman. water pump (oem went bad) at the end of september '04.
3. After battling the no heat issue since sept., I went out and bought the heater control valve for $70.00.....it's a plastic valve at the end of a house that's connected to another house with a tee spliced in the middle. One end goes into the heater core......other end to motor. A short fatter house from the tee goes into the bottom of the coolant reservoir tank. I cannot see into the radiator. The coolant tank is the only way it pours in.
4. After flushing out the heater core.......I used a garden hose at full.......going both ways through the core until clear water came out.......and refilling with fresh coolant....I still cannot get heat! It gets woosy warm in vent, heat, defrost, under acceleration......but cools off at stoplights.
5. Temp gauge seems to not climb past the halfway mark. I put in a 180 thermostat.......several stores say 180 is the only one available. I thought maybe 180 was too low of a thermostat number to use. Chicago can get cold.
6. In July '03, I replaced the leaking radiator with a used one from a '96 caprice with a 350. I have the 4.3 v8.........can a bigger radiator cause this?

I'm dumbfounded. I have pretty much replaced the whole heating system. I'm poor nowadays....so it bites to buy parts, freeze and wrench, and still have no heat.

Any ideas? Maybe this is a common thing with 4.3L caprices?

Thanks for any help!

Mark

[RageCage]

I removed the heater control valve from my 85 Caprice, since it was leaking. I put a plastic straight pipe in instead, so coolant is always flowing thoriough my htr core. The control valve is there so when the a/c is on, the valve shuts and the core does not receive hot coolant.

The valve could be not working right, and not allowing the coolant to flow through the core ?

The thermostat could be not working, i.e., stuck open ?

The big rad is working too well, keeping the car too cool ? Putting a piece of cardboard in front of part of the rad will make it run hotter (the schoolbus solution).

The heat blend door is not opening enough ?

Have you been using a "stop leak" product? They are supposed to clog heater cores sometimes.

OK, out of ideas.... Let us know what happens

[Musician423]

Thanks for the reply......


I don't believe it's the blend door, as I can hear it slap closed when I turn the temp guage on the dash, fast to full hot.

As for the valve, I didn't think it was a problem, but I put a new one in last night. I don't have a vacuum controlled valve like the type you're used to seeing. It's a flow restrictor that's inline with the hose going to firewall. The Chilton manual describes the "heater control valve" as simply the flap that directs air through either the heat core/ ac condensor in the core housing under the dash.

thermostat is lass than a year old......and both radiator hoses do get too hot to touch.

But alas......BEFORE I changed out a leaking radiator to this current 350 chevy radiator......I used Bar's Stop Leak twice.

I flushed out the heater core....but maybe as it's flushed......the next load of crap from the stop leak falls into place?

Argh......I was hoping no one would say "radiator stop leak can clog heater core".....but it may be true after all.

Back in august when I changed out the water pump (it was leaking), I ran a garden hose through both ways of the core.......nothing unusual came out....
and the water ran clear. I then had good heat for about 2 days. Then it got worse.

If it is the Bar's Stop Leak........any methods/suggestions of making sure it's all out of the system? A mechanic felt it wouldn't be The Stop Leak, 'cuz practically everything in the heating/cooling system has been changed out. But then again.....

~Mark

[TommySS]

I believe a 195 t-stat was stock.

[RageCage]

-----thermostat is lass than a year old......and both radiator hoses do get too hot to touch.

>>>> and heater hoses get hot, of course ?

-----But alas......BEFORE I changed out a leaking radiator to this current 350 chevy radiator......I used Bar's Stop Leak twice.

I flushed out the heater core....but maybe as it's flushed......the next load of crap from the stop leak falls into place?

Argh......I was hoping no one would say "radiator stop leak can clog heater core".....but it may be true after all.

Back in august when I changed out the water pump (it was leaking), I ran a garden hose through both ways of the core.......nothing unusual came out....
and the water ran clear. I then had good heat for about 2 days. Then it got worse.

>>>>>>>>>> Very interesting that the heat came back for a couple days, eh ?

I only have my BarsLeak tales to relate : I used it a couple times for a leaking intake manifold gasket on my 85. I believe it caused overheating on long trips by coating the inside of everything and reducing the heat transfer abilities of the metal. I took my rad out and down to my mechanic, who did the hose test on it. The water ran through clear and strong, and he declared the rad to be fine. I tried EVERYTHING to stop the overheating. Finally I put in a new 3-row rad and the oveheating was history. Ironically, my heater core never had a problem with the BarsLeak; I had plenty of heat, in fact I used to put the heater on full blast and roll down the windows to help cool down the engine.

I also had a nasty, persistent knock from one cylinder in first gear when the engine was hot. This knock went away, eventually, after I flushed out the BarsLeak, and ran regular a/f for about 3 years. Little blobs of whitish crap would show up in the overflow reservoir a lot, which I think was the BL slowly being eroded from the system. The whitish crap is gone now, finally. I think the BL had sealed up one of the water passages near that cylinder, creating a "hot spot", causing the knock.

The BL did its job very well. Sealed up the leak for about 2 years. Now it leaks again, but I just let it leak, and top it up every so often.



----If it is the Bar's Stop Leak........any methods/suggestions of making sure it's all out of the system? A mechanic felt it wouldn't be The Stop Leak, 'cuz practically everything in the heating/cooling system has been changed out. But then again.....


>>>>>>

Yes, a mech has told me the BL can make htr cores less effective, but it happens incrementally. Each time you coat it again with the BL, it gets worse.

Maybe there is some chemical that would clean the BarsLeak off the surfaces ??? I used a Prestone chemical flush once, but didn't notice any difference in anything afterwards.

Does the 94 have coolant drain plugs on the bottom of the sides of the block ?

All I can suggest is to flush the system again, and hope. And as a last resort, put in a new htr core.


Rage



~Mark[/quote]

[Musician423]

Thanks to eveyone for the info! It's great that there's a place on the net where gearheads hang out.

I'm going to try flushiing the system out once more tomorrow. Going to reflush the heater core....and refill the radiator.

A mechanic mentioned that on the '94 caprices....because there's no radiator cap, only a reservoir cap.......it can be tricky to get air pockets out of the cooling system. He still believes I have air trapped in there. He mentioned starting the car up with the heater core return hose in a bucket and run it for like 10 seconds or so? Anyone do this kinda thing?

Any suggestions/pointers on making sure the cooling system is air-pocket free?

Mark

[Musician423]

alright........UPDATE TIME

I flushed the whole system; radiator, heater core, engine block, etc. New thermostat as well. I flushed them all seperately to make sure nothing was missed.

I had blazing sahara hot heat for about 20 minutes. After driving around town.....the air from the vents got cooler. They're still warm, but not as hot as when I first fired 'er up.

What's that sound like? Air in the system still? There is no way in hell the heater core got plugged up that fast. When I flushed it earlier......nothing strange came out, except for tiny little blobs of Bar's Stop Leak. Nothing major though.....garden house had no probs pushing hard stream of water, when core was flushed both ways. I went inlet then outlet, then again like 5 times.......and water ran hard and clear from the heater core every time.

I'll ask again......any pointers on removing air from a '94 caprice 4.3 V8 cooling system?

Thanks in advance!

[RageCage]

Hey Musician,

Get heat yet ? Sounds very challenging.

Your mech's idea with the htr hose sounds good, for expelling air. The heater hose connections at the core tubes are the highest point in the cooling system, right ?
FWIW, what I've often heard is that air "works itself out" of the system over time.

Rage

[TommySS]

When I flushed mine, I always would fill the overflow bottle up past the "full hot" line. After driving it around for a day or so, I'd have to top it off. That's how I got rid of the air in the system.

There's no reason you shouldn't be making good heat, unless the control valve isn't working correctly.

When I used Bars Leaks, it always flushed out - looked like ramon noodles.

[BobM46128]

Did you ever get heat? I had the same trouble with my old '91. I resisted putting another heater core in until I almost froze! Finally I put in the heater core and never had to worry again. Sold the car with about 230,XXX on it! Wish I had it back!