No heat in my 87 suburban

[Thegomezclan]

I have a 87 4x4 suburban and the heat is not working. Here is what I've done so far, checked to see if all the controls work and the do. disconnected the heater core hoses from the water pump and the radiator and flushed water through and it is not clogged. Changed the thermostat and didn't help' still blows out cold. what am i missing? Any help will be very helpful.



Thanks, Dave

 

[LJH]

Is the motor up to temp? Just asking.

 

[Thegomezclan]

LJH, yup took it for a 20min or so drive and the temp gauge showed it to be at about 195deg.

 

[TexasRedneck]

Sounds like the valve has failed - look for a valve in the water line under the hood - two of 'em goin' to the heater core. One will have a pnuematic or manual valve running to it. If pnuematic, it'll be vacuum operated. The hose might have fallen off, or it is stuck. Sometimes you can work 'em manually to loosen 'em up an' they'll work again - probably hasn't been moved since last winter.

 

[winchster]

Sounds like the valve has failed - look for a valve in the water line under the hood - two of 'em goin' to the heater core. One will have a pnuematic or manual valve running to it. If pnuematic, it'll be vacuum operated. The hose might have fallen off, or it is stuck. Sometimes you can work 'em manually to loosen 'em up an' they'll work again - probably hasn't been moved since last winter.

+1

 

[Thegomezclan]

Thanks guys, there is no valve in the hoses. There are only two hoses that go to the heater core, one from the water pump and one from the radiator. there is a hoses that comes from the back of the intake manifold that is capped off. forgot to say that this suburban is new to me.

 

[TexasRedneck]

Well then...you need to find the valve. There's a valve to turn the water flow on/off to the heater core. It's sounding like someone's done some oil-field engineerin' on it....google the heater plumbing online for your year model and see where the valve is.

 

[Thegomezclan]

Thanks, i will give that a try

 

[winchster]

Ok, so if the hoses don't have any type of valve in them try plan b. Make sure that the water flow is making it into the heater core. If the heater core is getting hot, but no heat is being produced, the problem is in the flapper in the airbox under the dash.

 

[TexasRedneck]

Are you SURE there's not a valve in the heater line??? Everything I see says that there should be one. With the engine warmed up, are both hoses going to the heater core hot?

 

[Thegomezclan]

I think I found the problem, my neighbor has the same year truck as my suburban and he let me look under the hood and the hose that was capped from the back of the intake manifold is the one that should go to the heater core. My thinking is that the hose blew by the heater core and instead of fixing it they capped it and buy passed it. It looks like it is a bear to change it because of the distributor is in the way and a few vacuum hoses also.

 

[TexasRedneck]

You sure it (the missing one) isn't the one that goes to the rear heater core? The one I had ('84), the front went to the front core, the rear (on rear of engine) went to the rear core.....IIRC

 

[Texan2]

I have an 88 4x4 3/4 ton Suburban.....im paying attention

 

[Thegomezclan]

Almost sure, my sub doesn't have rear heat. I wish it did, thank you guys for the hast response. You people on TGT are awsome.

 

[Thegomezclan]

Texan2, when are you going to come up to lubbock and paint my sub. I cant pay you but I can feed you.

 

[TexasRedneck]

That's the thing....the hoses you see goin' from the pump to the firewall, an' firewall to the radiator SHOULD be the front heater water supply. Where do the hoses go inside? Do those hoses get hot?

 

[Thegomezclan]

The hoses dont get hot, the hose that comes from the back of the intake manifold looks like it goes to the heater core. Thats the way it is routed on my neighbors truck.

 

[TexasRedneck]

Just PM'd you my number - holler....

 

[Thegomezclan]

Ok thanks TXRedneck

 

[winchster]

If the heater hoses aren't getting hot, there isn't any water flowing through them. It doesn't matter where the water comes from so long as it's in the flow loop.