1982 z28 with 350. Heater Does not get hot unless i park and wait 15 to 20 mins. Going down the hwy it blows ice cold. Red Light to red light in town its Warm but not hot. I have to sit and wait for it to get hot, then when i drive it cools down.

At first i thought it may be thermostat. I had a 185 stat in, so i changed it to a hotter stat 195. Didnt make a difference in heater.

So i assumed Heater core. I replaced it with a new one. No change.

Waterpump is already bran new. but i have not changed it to determine if its the problem.

Same with radiator. Its new, but i have not changed it either to see if it makes a difference. But i cant see both radiator and waterpump not working right if they are new. radiator is Toped off full and clean fluid. i have also flushed and flushed. Ive also tryed bleeding any air pockets. none.

Car runs and drives fine. No over heating issues or anything. Pump is flowing correct direction and all hoses are new. Heater hoses are hooked up from water pump to firewall, then out the firewall to radiator.

I have to let my car sit and idle, temp reaches 200 and then i have to rev my car to 2k rpms, as the temp goes down the heater gets really hot. and then stays hot.

Driving down the hwy, forget it. wont get hot at all. temp stays down below 180. car runs cold.

anyone have any ideas?

 

well first of all if you radiator or water pump was bad you would over heat your car. now you said u have flushed you radiator? did u flush the heater core by passenger seat where it takes the warm air from? my friend had a problem like this in his s10 pickup and all he had to do was flush of blow out the heater core infront of the passanger seat where it takes the heat from. hope this helps

 

Is there a heater control valve on the heater hoses? Maybe its closing. If it has one, try removing it, its only there to help the a/c to blow colder.

 

The heater core is new. and the car came factory with no ac. there is no heater control valve.

 

I see you have a vortec engine, do you have a external coolant bypass? Maybe try pinching it off as a test to see if the heater gets hot.

 

my car came factory without ac, and there is no ac set up on it. I do have a compressor on but its only there to run the belt system. i havent baught a adapting belt or kit yet for its place.
and there is no heater control valve in the hoses. just st8t hoses.

im not sure wat u mean by external coolant bypass. do u mean a port on the intake vs the port on the water pump? if so i do have port on my intake beside my thermostat. i have not tryed that. Should i plug off the port on my water pump and run the input heater hose to the intake?

Is it possiable:

Maybe my radiator (which is supposed to be replica of stock) is a double pass or triple pass radiator that Cools too much fluid down causing the car to run cold?


or


Maybe my water pump isnt turning fast enugh at idle? it turns fast enuff to keep engine cool at idle, but maybe not fast enuff to push water thro heater core? Because like i mentioned, if im setting at idle i must wait atleast 10 mins for the car to reach 200 degrese. but heater dont get hot unless i rev my engine up, then the temp goes down about 10 degrese and heater blows hot hot! My car does have a custome water pump pulley made to fit seperatine belt system like 1989-1995 TBI V8. But this makes no sense if im going down the hwy with rpms over 2k.


idk, im stumped. idk wat could possible be wrong. Ive had severl shops look at it and they are all stumped too. everything is new and hooked up the correct way without any valves or blockages and everything seems to flow fine. car does not over heat and runs and drives fine. maybe my engine just naturally runs cold? lol maybe my pistons are firing on ice cicles bahaha.


i do know my car is hard to start in the morings. Cold natured. I have to pump gas a few times to start. and keep trying until it finally idles low around 500 rpms and keeps trying to die. eventually after about 5 mins it warms up and idles fine around 700 rpms. and if i give it gas while its still cold it backfires thro the carb! but after it warms up i can drive it any where and dog the crap out of it burning tires with no problem. doubt that may have anything to do with my heater but who knows...

 

Take a picture of your heater hoses, I'd like to see your set up.
You can disconnect the return heater hose (the one that goes to either the rad or wp) & start the engine up briefly, coolant should pour out strongly.
When you loose heat, how hot does the hoses get? You shouldn't be able to touch them very long because they get hot.

 

Here are a few pics. i hope the links work.

http://i1248.photobucket.com/albums/...62201151_n.jpg

http://i1248.photobucket.com/albums/...45082132_n.jpg

http://i1248.photobucket.com/albums/...1/IMG_0054.jpg

http://i1248.photobucket.com/albums/...1/IMG_0053.jpg

 

Ok thats your problem, the heater hoses go to the radiator & the water pump. Those are the suckition sides. You need to put a fitting in the intake & run that to the heater core, then the other one can go to either the pump or the radiator.
Anything behind the pump is under pressure (& heated).
I'd put the fitting (the 3rd picture) where that plug is in the front of the intake.

 

im building a motor for my 92 and trying to figure out how to run my hoses. i do not have the nipple on the water pump but i do have a heater valve, any ideas?

 

A fitting on the intake feeds the heater core w/ hot coolant, the other line has to go either the water pump or the radiator tank. What kind of heater valve is it? Stock type?

 

yes its the stock one that is on the 305 now.

 

I took ur advice and re-routed my lines like u said. It works! Thank you, now i burn the hell up inside my car going down the hwy. lol turn heater all the way up and roll down the windows n t-tops off and cruise bahaha. most people lookin at me like ima retard but ohwell. im warm, they just cant see it lol.

IDK why the shop i visited couldnt have done that or if they didnt feel like messing with it, could have atleast told me that. But idk. some shop employees are just dim witted or just lazy i suppose. Thanks again.

 

Yeah, they way you had it looked really clean, nothing hanging over the valve cover, but it just won't work that way.