Ok, this all started after i had my leaky heater core replaced. I picked up the car and heat was a blasting out. A week or 2 later as it got colder no heat. I replaced my thermostat and not much of a difference very little to no heat.

I then flushed my heater core since the bottom heater core hose wasn't getting as hot as the top. That made little difference but not much.

My radiator took a dump so i replaced that and still just warm air. I raised the car to get out the air bubbles since i had a water rushing noise in the dash under strong acceleration. This as well did little.

Now when it is warmer out i get lots of heat , the colder it gets the less and less heat i get.

I just went out and was checking the cable that opens the valve on the firewall where the heater hoses run to the heater core. If i turn the auto climate all the way down to 65 or all the way up to 85 that cable and valve doesnt move [strange] I dissconneted the cable and open and closed the valve by hand and still no difference.

Both upper and lower radiator hoses are hot, both upper and lower heater core hoses are hot, the bottom takes a bit longer to get hot then the top. Strange thing is i can't open my radiator cap [even when the engine is still warming up] because the fluint starts shooting out, is that normal? Shouldn't i be able to open up the radiator cap while the engine isn't fully warmed?

I only get warm air if i have the heater on "head/upper body" if i put it on feet or "uuperbody/feet" i get nothing but cool air. anything but "upperbody" gives me cool air. I also noticed no difference in the temp of the air coming out if it is set to 65 or 85.

I know its a long post but for the past 3 winters it has been the same thing and i am growing tired of it and help would be greatly appreciated.

 

If air is out of system you should not have problem with opening radiator. That just doesn't sound right. Start cold with cap off and warm it all the way up. refill as needed. Make sure you are environmenatly friendly.

On the heating issue, sounds like something is restricting flow somewhere. Maybe a rag left in the system and it is caught somewhere.

Take the heater valve out and replace with a short hose. See if that works anything.

This will be messy, can you pull hoses off one at a time and check flow out of and into the heater core?

Good luck and keep posting your findings.

 

Yea I thought this was strange as well, even when it was just warming up there was too much pressure to take the cap off, as the radiator got hotter, the pressure just grew.

I doubt this since i have had almost evrything apart in the past 3 years trying to figure this out and would have seen that.

This shouldn't make a difference since i dissconnected the cable and open and closed this valve manually and it made no difference.

I have done this when i flushed the heater core , i have flow into and out of the heater core.

Keep posting any suggestions guys , this is driving me out of my mind.

 

hmm i was going to say thermostat but you said youve already repaced it...although its new are you sure its not faulty? and check for pinched hoses that could restrict flow. also, a dumb little reminder that got me once, try the "recirculate" button so it recirculates the air in your car instead of trying to heat ourside air coming in.

 

Well if nothing else comes out of this i will replace the thermostat again to see if it is faulty. The hoses are not clogged or pinched and yes i do use the recirculate button...thanx.

 

I was going to leave a new thread complaining about slow warm up but this one is so close . . . however the owner has done a lot more than I.

How long should it take a Gen 4 to reach operating temp?
When it is, say, 16C outside my Gen 4 gets to temp reasonably quickly.
However, these days when it is 6C outside, it is taking 25 minutes driving at an average of 50 mph before the gauge approaches the normal operating temp, and about the same amount of time before it really starts blowing warm air. Is that normal?
Like the previous owner I have checked the stat and the fan controls and everything seems normal. . .

 

I still suspect either air in the system which is preventing the coolant from flowing properly or a bad thermostat. One way to check is to drain the fluid in to a bucket and measure how much you have, taking into consideration that some will still be left in the heater core. Then flip your switches to high heat/wide open and refill, hopefully this will remove the air.

 

1 thing i did notice today was that when i replaced the radiator 2-3 months ago i topped off the antifreeze and filled the overflow to the "max" line, today when i checked it was empty. I refilled it and will check again tommorrow. What I am hoping is that you are right and there was/is a air pocket and thats where the antifreeze went.

 

Still nothing, it's like 19 here today and still nothing but luke warm air, even when engine is fully warmed up. Help!!!!!!!!!!!!!!!

 

Sounds like air. Take the rad cap off and start the car up and let it run till warm. Turn the heat on and fan on full. Then rev and hold the engine up to about 2000 or 2500rpms and watch the coolant in the rad. Will probably start bubbling like crazy. Would indicate air. You'll have to keep topping off the rad until you get no air bubbles and the level doesn't go down. By the end, you should have more heat than you need...

 

Well I can't even open the radiator cap when the engine is running and the engine is still cold. Antifreeze just keeps pouring out the more gas i apply the fluid just keeps coming up and up and out of the radiator, what the hell is going on?

 

sounds like a restriction. start the ar with the cap off and see if you at least see a directional flow. I personally would run it without the thermostat to eliminate that as a possible source. You didnt comment on whether the resevoir was full or not after putting more in it. have a funky idle when the car is hot? new rad? used rad?

 

Because there is AIR in the system. You have to keep doing it. Remember the water pump? That's pushing coolant too. Keep the cap off-run the engine with the HEAT on. You have to keep doing it until the flow subsides.

 

I second the AIR theory. you almost certainly still have pockets of air - 3 clues 1) you heard gurgling, 2) you have no/weak heat and 3) you sucked the overflow dry.

purging the system of air is VERY important when you do ANY cooling system work, and you have done quite a bit. and purging the AIR is not easy, and can take a long time.

I'll add to the previous commentary by saying this:
1) with cold engine, fill overflow tank to MIN
2) take cap off before you start
3) slowly top off radiator, if needed.
4) with heat on high/full blast, start car. keep radiator full (above core openings) to prevent air getting sucked in.
5) allow engine to warm up. Revv it to 2k a couple times. Keep cap off. keep eye on temp gauge.
6) when engine get hot, thermostat will open spewing hot coolant into radiator and overflowing through the rad cap -- put rad cap on NOW.
7) thermocycle at least 2 times (2 fan cycles).
8) drive car. check heat output. listen for gurgling in heater core. watch temp gauge. temp gauge should go no higher than 1/2 way.
9) let car cool. top off overflow as needed.
10) repeat as needed (you may have to do this a couple times to get all air out).

 

i am gonna have to go with the air theory...classic symptoms of air in the system...but i am surprised u havent had any overheating issuses...unless i missed that part

 

I will do what most of you are recommending tonight when i get home tonight. I just checked the radiator is up to the top and the overflow is up to the max line.

 

one more thing - excess air in the system will over time cause corrosion and may cause the coolant to gel, plugging things up. so some of your symptoms may be due to crud build up in the system (curious, is that why you replaced the radiator? I've never heard of a 4th gen radiator rotting out). you may be wise to do a full flush with flushing chemicals if you have any question as to coolant gelling or internal corrosion etc.

 

so air causes coolant to gel huh?

 

it can, yes. some coolants are more susceptible than others. the original dexcool supplied by texaco was notorious for it - and faulty GM rad caps exposed the problem in many GM vehicles that were less than 3 years old. traditional silicated green is prone to gelling anyway, but air makes it worse. Japanese coolants are a bit more stable, but air in the system for a long time attacks both the system (causing corrosion) and the coolant.

depending on what type of coolant dallas had in his max for the past 3 years, corrosion/gelling could be an issue. he should still start by purging the air, though, and go from there.

there was another guy with a 5th gen who had a plugged up radiator from using prestone green and not properly purging air from the system.

 

Ok so yesterday before i left work I went out to purge the air out of my system [if that was the problem] 1st thing I noticed that as soon as i started the car the radiator started to overflow. I checked the overflow hose that goes to the overflow container and sure as shiat it was clogged, hence the reason for the radiator always overflowing with the cap off.

After clearing the hose, not sure what it was but it started draing correctly into the overflow container. I started revving the engine after it was fully warmed and sure as hell all these air bubbles start working there way up to the radiator neck. I poured roughly 25 ounces of water into it. It kept bubbling for about 15 minutes and everytime the fans would go on the level would drop quite a bit and thats when i put most of the water in. On the drive home the heat was really warm almost hot. It would gradually decrease when i came to a stop but that was the hottest it has ever been, it was also very warm yesterday when i drove home to begin with.

This morning after warming the car the heat was "ok" not luke warm like it has been but not as hot as yesterday either. I am assuming there is more air in there and will do what i did yesterday again. I think there is more air in there.

I will keep everyone updated, thatnx for all the input.

P.S I did notice that after about 20 minutes of purging the air out, eventually the radiator started to overflow and I put the rad cap back on, is this normal?

 

do a prestone flush. and i hope you didnt use only water. if you have buildup there you prob have it elsewhere too.

 

No i didn't just use water. I already had a 50/50 mix just added water for the amount it was low.

I just went outside and did the same thing and added another 10-12 ounces but the heat is still just luke warm, I am going out to jack it up and try again.
I notice everytime the fans come on the level really drops and that is when i add the most to it, the overflow is alittle above the max line, is that ok?

 

overflow level doesnt matter. you prob still have a restriction. especially if you say the return line was blocked.

 

Ok now get this, I notice that the top hose that goes to the heater core is hot, very hot yet the bottom hose coming from the heater core is cold, I take off the bootom hose, as the car is running and heat on full blast and I get very lttle antifreeze coming out of the heater core then it stops dribbling alltogether and get this the antifreeze is actually cold that is dribbling out. Sooooo i am assuming my heater core is clogged, either at the top where the hot antifreeze is going in or somewhere in the heater core cause nothing is coming out. I will flush the heater core when i get home and see if i can get some flow through there.

Is there any kind of valve or something at the heater core that opens or closes to allow the antifreeze to flow through the heater core?

Another question is what is the valve where the upper heater core hose runs at the firewall, there is a cable there that runs through the fireall also, is this connected to my Auto climate control? The cable doesnt seem to do anything when i turn the temp or or down, shouldn't it open and close that valve?

 

ok you're doing some good detective work.

about the valve -- this is the same valve you opened by hand in your 1st post, right? so if you open it by hand now no fluid comes out the heater core?

if so, your heater core is plugged up. you could trying flushing it with chemicals or compressed air, but likely you will have to replace it again.

and if your heater core is plugged, the rest of your system is too, and a *****-out chemical flush is in order. lets hope you can save your radiator.

just curious, how does the coolant look? if you have bad gelling/corrosion you should be able to see some solids floating in it.

before you go ahead with the chemical flushes, do figure out that valve issue, and confirm that its not just sticking closed at the wrong times. sorry I can't help you with that.

also -- after all is said and done, be absolutely sure to completely flush the system with distilled water (do NOT use tap water) and fill the radiator with full strength OAT coolant to get the 50/50 mix. One of the Japanese coolants would be best (toyota, honda, nissan), but if you insist on going cheap just make sure you don't use the "regular green" silicated stuff. and of course, purge air properly.

to answer your other question - yes it is normal for coolant to eventually spew out the radiator when you are purging air. this should happen when the thermostat opens, which will take a good 15 minutes or so when starting from cold and no driving.

 

nice going dallas....good luck

 

Yes, this is the same valve, It doesn't seem to do anything when i change the temp setting on my climate control, nor does it seem to do anything when i open and close it manually. This is the valve at the firewall where the upper heater hose runs into the heater core, yet that hose is always hot.

I won't have that done again $700+ the last time, I will keep dealing with luke warm air before i spend that kind of money again on this car.



I don't belive this to be true. I can see a very good flow of coolant withing the radiator and I have no problems at all of the temp gauge ever going up past normal. If I did have such blockage all over i believe i would have over heating issues.



No , no solids or gelling odf any kind floating around in system

As I stated above I am not sure what the actual purpose of this valve is, I am assuming it lets more hot antifreeze into the heatercore when opened fully and less when not as much heat is called for and for whatever reason it doesn't seem to be doing anything but letting hot coolant into the heater core since the hoses are hot after this valve and the hose going into the heater core is very hot.

I am sure it is a clogged or air trapped heater core, thus the reason why the hose going into the heater core is very hot and the hose coming out of the heater core is cold. Either there is a clog at the "outlet" of the heater core, which i don't believe to be true because that would mean the heater core is actually full of hot antifreeze and i should get heat, or more probably it is clogged at the "inlet" odf the heater core and that is why I have hot antifreeze in the hose yet that fluid is not getting in the heater core or very little is and that is why i am getting no heat.

Now the thing that is driving me out of my mind and the question keeps coming to my head is why do i get heat when it is warmer outside. What difference will the outside temp make as to getting or not getting heat. I realize the colder it is the longer it will take to get heat but it shouldn't make a difference on the amount of heat i get. When it is warm out I get very,very hot air out of the heating system, if my heatr core was clogged , wouldn't it be clogged always?

 

This is getting stranger by the minute. I just drove home and had soo much heat I actually had to turn it off for a while!!!!!!!!!! WTF is goin on? The only thing that i can think of is maybe from taken off the lower heater core hose i released some type of vacuum effect that was going on in the heater core, almost like a giant air pocket but confined to the heater core. Before the lower heater core hose was ice cold now it is just as hot as the top. I was going to flush out the heater core now that i am home but now i am afraid to touch anything, I ACTUALLY HAVE HEAT!!!!!!!. I am going to leave it and see what happens tommorrow.

 

sweet! good work. sounds like it was a pressure thing from the trapped air that could not be purged the normal way. don't touch it.

 

Sounds good. Did you still have heat when you stopped, like maybe at a light?

 

Well heat was still very good today while driving to work, even at a stop. The only thing I can think of is what i wrote in my previous post and that was my heater core had some type of vapor lock. I had the car jacked up with ramps and I was purging the air out of the system. I noticed that the lower heater core hose was cold and the top hose was hot. I took off the bottom hose while the car was running and heat on full blast. I figured antifreeze would come pouring out since the car had been running for some 15-20 minutes. To my surprise very little came out and was just dripping out for a few seconds and the antifreeze that was coming out was cold. The top hose was very hot so i wasn't about to take that off. I had the radiator cap off at this time so i put it back on and re-attached the hose. Within a couple minutes the bottom hose that i had just taken off became very hot just like the top and heat was coming out very hot.

So it must have been like a giant air pocket in the heater core that wasn't letting antifreeze get into the heater core and when i took off the bottom hose that relieved all the pressure in the heater core that wasn't allowing the antifreeze in. This is my best guess as to what was going on. My heat has been awesome even though it hasn't been to cold around here lately, i will update again after we get a nice cold day to really test it out.

Thanx for all the input guys, much appreciated.

 

That sounds like a blown head gasket. Combustion gasses are entering your cooling system and pressurizing it. That causes lots of strange cooling/heating problems.

 

It wasn't a blown head gasket , the overflow tube was clogged.

 

Well I'm back! And more disgusted then ever. After the past week or 2 of nice weather and more heat then I could handle, today was rather cold in the morning and my car was back to the usual "luke warm " heat. This has got me thinking that the problem lies in some type of sensor. Why would i get tons of heat when it isn't really cold out but as soon as the cold air comes the heat basically dissapears? As if the engine is cooled off too much but when it is alittle warmer out the engine actually puts out too much heat.

 

flush the system. If you drove for a couple of hours and had your fans on from the first minute to the last, your coolant would not luke-warm. and, if your coolant was lukewarm, you would see it on your engine temp guage. Do you have an automatic climate control? have you checked to see if perhaps the control unit itself is bad?

 

The temp gauge always goes to the middle point after about 5 or so minutes of driving. I felt the hoses after I got to work and they were rather hot, more then enough to produce heat. Yes I have a auto-climate control and I have no idea how to check to see if it is working properly, any suggestions?

 

unfortunately, the only way i can think of checking it is to put in another one. BUT!! there is one last thing you may want to try before changing it. For the auto climate controls, there is a little vent to the side. inside of that vent is a sensor that senses the heat in the car. It often gets covered in dust and if you armourall your dash alot that could have gotten on it too. If you have some laying around i would try some electronics cleaner. MAF would prob be even better as i am sure the MAF sensor is even more sensitive. if it were my car, i would even try some rubbing alcohol but i didnt tell you to do that! try it at your own risk. that is the only sensor that may beyour problem. If that doesnt work, and you feel like coming to NYC i have an auto climate laying around here. you are welcome to come and try it out.

 

I will take a look at that vent/sensor...thanks. Thanks for the offer of switching the auto climates to see if yours works, but i will probably just buy another if nothing comes of all this trouble. Maybe even bring it to the dealer and see what they say

 

before anything, do a prestone flush. you said there was buildup even after the work you had done so it is not hard to conceive some scales coming loose and plugging up that core. either way it cant hurt.

 

Well believe it or not another thing has gone wrong. My heater core is shot, started steaming out the vents and a very tiny drip. It got me thinking that this has been my problem from day 1[ a bad heater core] So I have put aside sat and sunday for a nice job of changing the heater core . From what the radiator place said it's about 7-10 hrs worth of work because I have to take the whole dash apart. Great. Wish me luck and I plan on taking alot of pics and a step by step for any future lucky guys here that get to do this job in the future.