crazy'boutOlds

I haven't had heat in my 80 Cutlass cruiser all winter.
I got home one evening, pulled the radiator cap off.
There was no pressure. The radiator was full. And it looked as though there was no circulation.
Is it
1) Radiator cap
2) thermostat
3) water pump
I'm guessing water pump, but it doesn't over heat? I'm kinda stumped here.
Ant help would be greatly appreciated.
The engine is a 455 w/o air.
If this is in the wrong area, could it please be moved? Thanks.

oldcutlass

I'm going to pu my money on the thermostat failing in the open position not alowing the engine to warm up.

crazy'boutOlds

That's what I was thinking as well. Is there a trick to not breaking the bolts off in the manifold while removing the thermostat housing?

oldcutlass

Just be carefull.

jaunty75

My comments:

1. First of all, we're assuming you took the radiator cap off after the engine had cooled off. Otherwise, hot coolant would have likely sprayed all over, and you would have gotten burned. If the engine was cold when you removed the radiator cap, there wouldn't BE any pressure, so the lack of pressure doesn't tell you anything. The system is only under pressure when it starts warming up.

2. It's not likely the water pump as, if the water pump had failed, your car would likely have overheated, and you would have had all sorts of other indications of a problem besides not getting any heat.

3. Yes, it could be a thermostat stuck open. But this raises another question. You say you "haven't had heat" all winter. Does this mean absolutely no heat at all, or does the incoming air get at least a little warm but not as warm as it should be? If it warms up at all, then it IS probably a stuck-open thermostat as that would cause the engine to reach operating temperature much more slowly, and if your typical drive is only a few miles, it might never reach operating temperature before you reach your destination. Thus you'd have some heat, but it would never get very hot.

4. If you do have no heat at all, then I would suspect none of the three possibilities you mention above but something else entirely, and that's a clogged heater core. With no radiator fluid circulating through the core, you would have zero heat, but there be no other obvious symptom as the coolant would still continue to circulate properly through the rest of the system.

I would actually suspect #4 because your car is otherwise apparently operating normally as you've been driving it all winter.

crazy'boutOlds

Just drove it over 30 miles. Attempted to remove the cap and there was pressure. Both top and bottom rad. hoses were warm and both heater hoses as well.

jaunty75

Good. There should be pressure when the system is warm.

All the hoses being warm suggests there is flow through the core. Now I would suspect a problem with the ducting, vent doors, or vent door controls under the dash. Your fan may be blowing air into the passenger compartment, but if it's not being directed through the core along the way, it won't get warm.

In short, I don't think your problem is under the hood. I think it's under the dash.

pogo69

This would be my first guess also....you should also feel the hoses going to and from the heater core...I had a hose on my yukon completely blocked with sludge... no heat

jaunty75

Have you guys been paying attention? He already said that the hoses to and from the heater core are warm after a 30-mile drive. Thus, the problem is not the thermostat.

Rickman48

Having worked on the same problem with a few 'G' bodies, I'd say the core is partially blocked - if you can 'flush' it, you might be O.K.
But, also look for the door not opening, as mentioned above.

Lady72nRob71

How warm is warm? Can you describe it in more detail? Thermostat could be stuck open if it is luke-warm...
Also could you reduce your sig picture to at least half the current size please? It is a way-cool shot but it messes up the page layout for other viewers using a smaller screen or window. Thanks!

crazy'boutOlds

I'm going to say luke warm? I went ahead and delete my sig pic. Sorry about that.

Lady72nRob71

I will say stuck thermostat. Get a 180* one and replace.

No prob at all - they just need to be about half that size. As nice as it was, you should put it back, just smaller...

pogo69

Jeez...it wasnt a matter of not paying attention, if you look at the time the comments were posted two comments were posted as i was typing mine...i will try to think and type faster next time

MDchanic

SO —

How warm is the engine getting? Engine temperature gauge? Infrared Thermometer?

Is there or is there not flow through the heater core?

Is there some other flow obstruction of which we are unaware, such as a vacuum-operated heater valve stuck closed?

- Eric

crazy'boutOlds

There is no heater valve. There's just a nipple on the intake. The car is an original non air car.
I'm do some further research at work tomorrow. I can pull it in out of the cold there.

oldcutlass

Can you hook up a temp gauge and tell us what your operating temp is?

jaunty75

Yes, in thinking about this, you have to be more specific than simply saying the radiator and heater hoses were "warm" after a 30 mile drive. They should be more than warm. They should be too hot to touch. If they're not, if you can actually grab onto them and hold on without feeling like you're going to get burned, then I go back and agree with those who say you may have a stuck-open thermostat.

However, given that the hoses were at least warm, if the heater core is not partially or totally blocked, I find it hard to believe that you wouldn't have at least some heat. While the engine may not warm as quickly as it should, it's obviously warming up some as your feeling of the hoses indicates.

I still think the most likely problem is the heater core or the air-flow controls under the dash.

jaunty75

Sorry.

joe_padavano

Same answer I gave you in the other forum. It's either a broken heater blend door (common on these cars - remove the glove box liner and look at it) or a plugged heater core.

crazy'boutOlds

Well, brought it inside at work today. It's the blend door cable. Once it's put in the defrost position, it doesn't return to the heater position.

jaunty75

Ha ha! Your solution is obvious. Don't use the defroster!

crazy'boutOlds

If I was in your location, I don't think that would be a problem

droldsmorland

Heres probably more info than you need because I'm in a meeting right now...snore...
Do yourself a favor and flush the entire system if you haven't performed this or are unsure when it was last done. Pull the heater core lines from the intake/block side and flush separately with garden hose, both directions...careful not too much pressure just enough to blow out the mud. Same drill for the block and radiator. Then remove as much of the tap water as you can from the flush procedure. Only DI or RO H20 is good for a cooling system no tap water. Then replace coolant with 50/50 premixed, all new hoses, belts, a T-stat, fix the blend door and your off. May want a 190* or 195* Tstat? What ever the spec calls for especially in the Buckeye? FYI...Stant makes a light & HD duty stats. HDs are worth it.
With the T-stat housing bolts a little (note little) heat will do wonders as will a 24 hr Kroil or PB Blaster soak. Work them in and out slowly. If you feel them starting to gall spin them back in and cut off the heads. Pull the housing. Cut a slot in the top of the remaining studs and drive them through into the intake with a slotted screw driver. Might have to shorten them if they bottom out? Dress the cut threads so they don't strip the threads on the way in. Go get yourself the same style stainless steel fasteners & flat washers to replace the steel. Use a dab of antiseize on the new fasteners coating the entire bolt especially the tip that is exposed to the coolant. Make sure the housing isn't warped... sand on a flat surface w/200-300 wet-n-dry sand paper and WD40. I use spray adhesive on the housing side of the gasket and a very thin application of RTV on the intake side. Recheck the bolt torque after a few thermal cycles. Go a little less on the torque spec if you use the anti seize, about 10-15% less, especially into aluminum. You may want to chase the intake holes out. You have to De-rate a torque spec with anti seize if its a dry torque spec.

Redog

I would replace the t-stat. If that doesn't work, maybe the heater control valve.

My HCV was really messed up. The previous owner broke the valve (I think it was the wrong one. Never seen one like it before. It wasnt stock for my car) and then RTV'ed it back together. The RTV was sucked into the base of the valve and lucky it didn't go into the head. I broke it all the way when I removed it, had to use an impact to remove the base, which at that point, was just a nut

droldsmorland

Good point Redog forgot about the HCV, if it has a HCV??? A company called 4 Seasons is making them. I know the earlier cars (60s) you cant find them this company has them. The HCV also controls pressure so the heater core doesn't blow out from full water pump pressure. SO don't bypass it unless you install some type of restrictor on the inlet line.

CaptOharry

What is the mix of Antifreeze.Years ago my Sister had the same problem,her Boyfriend Flushed the Radiator and replaced the Antifreeze and did not dilute it,ran strait antifreeze Engine never got up to Temp.

jaunty75

It sounds like your sister's boyfriend was an idiot.

Did she dump him after that episode, or is he now your brother-in-law?

MDchanic

It sounds like that whole story is BS.

If your sister's boyfriend told it to you, he is definitely an idiot.

- Eric

joe_padavano

NO NO NO. Why does everyone focus on the heater control valve? You all need to read the Chassis Service Manual. The HCV is normally open and only closes when the A/C is on Max Cold. It is nearly impossible for it to fail closed. The most common failure is that it leaks coolant.

More to the point, the OP has already said that this is a HEATER ONLY car. There is NO heater control valve on this car. As with nearly every 1977-1990 B/C body and 1978-1988 A/G body, the problem was once again a broken blend door.