Please help me! Not much heat in car...and it's getting cold out!

I have a '94 chevy caprice that keeps me away from the '72 GS 'cuz I can't get the heat to work properly. It's getting colder in Chicago as well.

I have been racking my brains out, as well as the ones of my friends.....
I have flushed the system.....every component of it. Flushed the heater core, block, radiator, etc. I have replaced the heat control valve, fairly new waterpump, heater core less than 2 years old.....and it's driving me nuts.

I have spent two days.....and cannot solve the problem.

This scenario has happened three times: After flushing the system and refilling, I had blazing hot heat for about 25 minutes or so......and now it's getting cooler. Now it's luke warm, even with the climate control turned all the way to red. Same thing happened last time when I changed out a bad water pump. Both radiator hoses get super hot......of course one is hotter longer.....but when the thermo (new) opens....they get hot again.

Heater hose going to firewall is very hot.......coming from.....somewhat hot, but you can keep your hand on it. I have tough hands from wrenchin', but I can hold my hand on the heater outlet house until the car climbs to over halfway point on temp guage. Going to firewall.....you gotta pull your hand off after about 2 seconds, regardless of temp gauge reading, once it goes past the 1/5 mark. Granted this is at idle.....on a fully warmed engine.

When I flushed the core......nothing crazy came out. Some grime....perhaps rust bits from the block.......but water was flowing out in no time. Went both ways multiple times on it to make sure.

I can only think of one thing now that I haven't done different.......and that is why I come here to you guys, being hot rodders, modifiers, figure-outers, etc. Less than 2 years ago.....when I changed out the leaking radiator for a used one......I could only afford a caprice radiator from a 5.7L 350. Dunno if it was an LT1 or not....but it was a 350, and a thicker radiator. One more core I believe. I have a 4.3L in the car....or say a 283.

The question: Is it possible that after getting scorching heat for 25 minutes and then pathetic heat........could my radiator require a higher grade thermostat? Right now it's a 180, cuz that was stock thermostat rating, and according to every single auto store clerk's computer. I finally found a place (auto zone) that gave me an option......180 or 195.

Maybe I had heat initially until thermostat opened? Then once open, it cools off too quick? My temp needle never gets above 1/3 the way. If it climbs to say 5/8 (sorry, no temp numbers on gauge)at standing idle and the vent heat gets better, as soon as I drive, or even turn on the heat full blast, it falls to 1/3 again in no time......say about 1/2- mile driving at 40 mph. It was about 35 degrees out today.

Sorry to ramble.....just wanted to prevent people from asking me the basic stuff like "do you have enough coolant?" or "is the thermostat working?"
All that stuff is fine.

Every store clerk I've talked to says the thermostat won't make a difference.

What you folks think?

So I figure it's three things possible:
1. the thermostat rating being too low for the bigger radiator?
2. Maybe trapped air?
3. Heater Core clogged again?! Hope not, but anythings possible I guess.

So.....anybody have a similar situation happen to them with a radiator swap?

 

one more thing....

after doing a little web surfing...I have one more fact to spit out:

My caprice uses the reverse-pop style thermostat. It has that large thin disk that's supposed to close off a coolant route as it opens the other one, when the thermostat opens.

Does this kind of cooling system get affected even more by a bigger radiator, in terms of inside heat from the vents?

 

It sounds like you know what you're doing, so you probably ran the car for a while with the radiator cap off after filling the radiator - so I'd think that might rule out air bubbles.
I doubt the thermostat rating would be involved.
My first guess would be a clogged heater core.

I really don't know much about the radiator size issue. However, do you get heat each time you start cold (and idle it a while), only to have it cool as you drive? Or is it only hot after the flush, and never again?

If it is the former, perhaps the cooling system is working too well. I've seen some cars with cardboard partially over the radiators in the winter (like the buses and trucks do). I have no idea how to figure out how much to block it, though.

The more I reread your post, the more I'm leaning toward the cooling system working too well. Get a few opinions before taking any action, though.

 

Skybird and Truzi.....

Thanks for the time and feedback.

To start: I already had put a piece of cardboard and it is still blocking half the radiator. With that in mind.....isn't it strange that the temp gauge can still wander so much when heat fan is on full blast or under fast driving speeds? I also remember in the summer (without cardboard of course) that the temp gauge still never really went much past 1/3 unless in slow traffic or stopped idle.

I will try once more tomorrow 'fore work. I will disonnect heater core return from water pump, put it in bucket and start 'er up to see if any coolant shoots out or not.

I am hoping it isn't a clogged core.....but it may well be. I just don't know how many times I can keep flushing the core out before this weird behavior stops?! I've fully flushed it last winter, this past sept. when I changed water pump, and twice today.

I have a coolant/water/prestone power flush combo in the cooling system now. Maybe sitting in it overnight will loosen more crap up if Truzi is right.

Another thing:
Before changing out radiator to the current 350 one......I battled the leaking
factory radiator by using Bar's Stop Leak twice.

Any bad stories from using Bar's?

Skybird, the climate is controlled with a cable driven flap/door. The car is designed to have the heater core on at all times, and the flap then changes airflow through either the core or a/c condensor, or both.

Truzi, The car has no radiator cap. Just a pressure rated cap on the coolant reserve tank. I did run it w/ cap off. There is a valve on the t-stat housing. I bled that too.....but maybe I'm doing it wrong. Are you supposed to bleed the valve with the reserve tank cap on? That's how I did it.

Oh yeah, a reason for the air in system idea: My low coolant light is still on. I know it may be a faulty sensor......but it wasn't on before the flush.

Also I noticed that the thermostat I bought today doesn't have a tiny hole in the flat part (that sits in groove of housing) , while the 195 at Autozone came with a 1/16 sized hole. Maybe that's for bleeding air when t-stat is fully closed?

Argh! It's gonna be 20/3 degrees on saturday!

 

I'm not too sure about the newer cars, so I can't tell you how to bleed it. Stop leak stuff can plug all sorts of thing, though I don't know if it will clog up something as large as the tubes in the heater core.

It might not be the core, but if it is, flushing might not help if stuff is really jammed in there.

I wonder if the valve in the heater hose might be doing something strange. Is it vacuum controlled? And if so, how good is the vacuum hose? Its a wild idea, but maybe when you're driving the control valve isn't staying open. If its electronic, that could result in what Tom said.

 

Many of the symptoms you describe are typical of an air pocket trapped in the cooling system. On LT1 engines, I've found that drilling a 1/16" hole in the thermostat before installation will allow air pockets to be bled more effectively. Some of the better thermostats come with the hole pre-drilled. When bleeding the system, start the car with the pressure cap off. Place the temperature selector in the full heat position and let the car idle. It may surge and overflow before the thermostat opens, followed by a rapid drop in coolant level as the thermostat opens. Continue to top off the coolant level until the label stabilizes. It is imperative that this operation be completed with the pressure cap off. Another thought also, there could be a vacuum operated heater control valve inline with the heater core on that car. If the valve or its vacuum control has failed, it may obstruct the proper flow of coolant through the heater core. Let me know if you need any more info.

 

<img src="http://www.thirdgen.org/techbb2/attachment.php?s=&postid=2100633">

 

Are you bleeding the air using the bleeder screw next to the thermostat housing? Very important to getting air out of the system on a reverse cooled car.

Also, the low coolant sensor is in your overflow tank and are notorious for sticking after a coolant flush. Lightly rap on the side of the tank with a rubbr mallet. This has a 90% success rate in freeing up the sensor.

When you flushed the heater core, did you remove both hoses and flush it in both directions several times??? When you do this, use your hand as a coupling as the direct pressure from a hose would be too much. When the water runs free and clear, you're done.

If you're getting blazing heat for 20 minutes or whatever, it really sounds lore like the system has not been properly bled. One other note, when you bleed it, make sure you jave some shop towels to prevent dripping onto the Optispark. I've also had succes with opening the bleeder screw with the car off, taking the cap off the overflow tank and applying lunk pressure to the tank opening. Yeah, may sound odd, but it drives those bubbles out.

If this is all know and rudimentary for you, sorry to take up your time.

 

Does that system have an air door in the heater box? If so is it staying open.

The heater core may be fine, just the heater box air controls are not.

 

Go to the hardware store and get some of the clear vinyl hose for drinking water uses, the vinyl without the cord is good to about 40psi and you can put it on temporily to see whats happining. You will see air bubles in the hose just like you will see air in a a/c sight glass and you can diagnose it alot better when you can see what need fixing. You can see the coolant flowing thru it and you will know if it is restricked or not. Thanks Jim

 

My buick had that same problem. All I do is pop off the display plastic banner onthe dash and move the threaded rod. The door is control by that rod and it sits ina U shaped cup.You can pop it out and make it say open or closed manualy. I could never get it to work how it should.That darn eletric thermo stat / auto climate wheel does nothing.

That clear hose trick is a good idea, Jim

I have been told before that a pressure washer can blow out a plugged heater core. It find out if its leaking quick. Just goto the u do it car wash and use their wand and flush it out backwards. Make sure you go backwards.

 

Wow!

Thanks to everyone for the advice and info! Much appreciated. I hesitated posting this problem, 'cuz I'm sure we all want to keep this site buick related......but all of you have told me things that I believed myself, yet NO ONE would agree with me at the store, garage, etc. And no one needs to apologize for rambling, 'cuz every ramble has pieces to this puzzle. I just said the statement about "I know what I'm doing" 'cuz on other car sites....there are posts that make you say "wow.....what a dope!"

Thanks again!

-as for the heater door/flap......if I spin it quick enough to hot, I can hear the flap close. But then again, haven't looked inside to make sure it isn't slowly opening.

-I ran the hose back and forth through the heater core several times today.....and it came out clear and strong.

-Yet again, with the 25 minute sahara heat after flush and fill. It's warmer now.......I belive 'cuz I switched out the t-stat for a 195 from Autozone. And YES, this one does have a hole predrilled. Thanks for bringing that up.....cuz I noticed it at the store and said "hmmmmmm". The t-stat from yesterday, the 180, had no holes drilled whatsoever.

-Now I feel that it has to be an air pocket. Now with the hole-drilled thermostat, the bleed valve on the t-stat housing should work better. I used the bleed valve yesterday......not much luck......but then again, with a different t-stat in car at the time.

-Also, it seems like everytime I shut off the car to cool, when I come back, the heat doesn't get as strong. Maybe air pockets like to move to heater core during cooldown?

-I will try the clear hose idea! Awesome idea. Jim, can i leave it in permanently? Say like a 3" section? If it's good to 40 psi.....would it last long?

finally......what's the best method for using the bleeder valve?

~Mark

PS No valve inline of heater hose. There's a plastic restrictor? I think that's what it is......or maybe a one way spring loaded valve? But no wires or vacuum hoses are involved with the heater hoses under the hood.

PPS I think life would be easier if Chevy had just put a damn cap on the radiator in the first place. Geez....... ou:

 

I wonder if using a radiator from the reverse flow system of the LT-1 in a forward flow system of the 4.3L might be causing part of the problem? I've screwed with those LT-1 pumps & cooling systems...talk about a pain in the @ss! I'm glad they went back to the forward flow system and eliminated the whole distributor/pump fiasco for my LS-1!

 

Best way to eliminate air bubbles in a new car system is to overfill the reservoir, get the vehicle hot, then shut it off and walk away, When it cools, it will draw fluid from the reservoir back in and dissipate the air.

Loosening the radiator cap allows air back in and you'll chase your tail that way. Lots of new systems have the heater core located higher in vehicle than the radiator cap. It becomes the highest point in the system. Bernoulli reigns again.

Took me 2 years to convince the Mazda Climate Control development engineers of this as their procedure always called for loosening the radiator cap and checking for fluid level before they started a heater performance test. No matter what, they always followed procedures to the leter. Once they tried it, and their big bosses acknowledged it:

"Heilala-san, you velly important person!" :laugh: :laugh: :laugh:

 

Update

Once again, thanks to everyone's help and pointers.

Last night after starting the car, i had heat after a few minutes. Took the 25 mile trek to my girlfriend's place. By the time I was 2 miles away, the vents were cool again. WTF?! I thought to myself. Cold air?! How?!

I pulled up to her place, didn't shut off, went out and popped the hood. BAM! The big radiator hose coming from t-stat housing was cool. After 25 miles of expressway driving, there's no way it should be cool. It should be burning hot.

I grabbed the flat head screwdriver and with the cap still on (obviously, or I woulda had a hot fountain of scalding pain) I opened that l'il t-stat housing valve. Coolant sprayed forward in a little stream that went 6ft. out or so. After a few seconds the stream lost its distance and became a steady downward trickle. Right away the rad. hose got super hot. I closed off the valve. Voila! Hot air coming out of the vents! Woo hoo!

I'm ashamed to admit that if I had just done that method from the beginnning, I would'nt have wasted 2 days to anger, frustration, and defeat.
D'oh! ou:

Thanks again! If it wasn't for you folks, I'd still be cold.

HAPPY HOLIDAYS! May we all have heat in our cars! :beer

 

Glad you got it worked out.

 

AARRRGH!! No heat!

Ok guys.....I'm about ready to take this piece of s**t car to the mechanic and throw more of my money out the window. I guess it's the price ya pay for heat.

But before I do..............

I removed the bleeder valve from the t-stat housing and put in a Menard's bought 1/8" 90 degree valve.....typically used for drinking water systems. I hooked up a clear water tube to it, and put one end in a bucket with a li'l coolant in it. I start the car, get her warmed up, and then open up the valve. I see green coolant and lots o' air bubbles traveling along the tubing. After about 20 minutes..........the bubbles disappear, tube is solid green, the heater hose gets hot, and I get hot air blowing through the vents.

I take it out and drive it......about 10 minutes or so, the heat disappears and I get cold air blowing. I get back home, leave it running, and pop the hood. The radiator hose coming from t-stat housing....is cool. I put the tube back on the valve....open it.....more bubbles. The bubbles stop and I get heat.

and this whole thing happens over and over and over.

So I cooled 'er off......took the reservoir cap off and ran the car 'til coolant began bubbling over. Temp gauge shot up to about 3/4, and as I pour coolant in, it keeps bubbling over. After about 2 minutes, it stops bubbling over, and I ad coolant in reservoir until level stops dropping. Level is at correct tank indicator mark, and again with the valve. After the bubbles stop, the vents are pushing scorching hot air. I close the valve. Add a bit more coolant, and screw the reservoir cap back on. Halfway to work, roughly 10 minutes, no more heat. Zero. Cool air at idle. Somewhat warm under hard acceleration.

It always like this.....heat, drive, no heat, pull over, cool feeling radiator hose, bleed air outa valve, radiator hose gets hot, heat in vents, drive, no heat, etc. etc. etc.

What gives? Anybody have any idea? I'm totally outa clues. I need to know if anyone can give me some ideas, so I don't end up wasting $$$ at the mechanic, if he happens to get the same results I'm getting.

new thermostat, fairly new heater core, 2 mo. old water pump, new underhood cooling system valve, etc. Flushing system shows no problems at all. Water flows out of heater core clear with great pressure.

Please help 'fore I cry. :ball:

And once again, you've all been very helpful so far. Thanks.

 

If you're getting "air" somehow into the coolant....

I hope you don't have a blown head gasket!!!

Might be time for a pressure test on the cooling system. I certainly hope this theory is wrong.

 

Air will not get into the system once it's bled out. Leave the radiator cap loose for now, and try driving around for a few minutes. If you don't lose heat, then a head gasket problem is likely. Then it's time for a "block test" kit to be used, it involves using a special tool that you pour liquid into, you hold it on top of the orifice where the cap goes. If the liquid changes color, you have a bad head gasket.

 

Crud!

I had a bad feeling about that. My buddy's dad told me about the head gsaket, and I read it on another auto forum as well.

I am taking 'er in tomorrow to have 'er tasted for that, after I do the "loosening the cap" trick.

On the drive home today, the air did get a l'il bit warm after the car heated up, and then got cool again.

I pulled up to home, and popped the hood with car still running.
The radiator hose coming from bottom was cool and hard again. After loosening reservoir cap (loosen/tighten, watched for raising level) and taking it off, that same hose got hot again, and was "squishier". Heat got better inside as well.

Does sound like a bad gasket to me as well.

Mark

:ball: