My 85 Z28 w/ 305 TPI has only one vacuum line coming out of the firewall. I did a search and most of you all say there should be two lines, one to the intake and one to the Heater Coolant diverter (HCD).

The car did not have an HCD when I got it nor any water lines to the core, but the lone vacuum line looks like it would reach if there was one.

Questions:
1. Does the 85 305 TPI have an HCD or only a single line that goes to the intake?

2. If only only one line, then how is coolant diverted in the 1985's?


thanks,

Art

 

Not all cars had a heater diverter valve I don't think.

 

Anybody, Please.....

 

Cars without a diverter valve didn't divert the coolant - it just ran through the heater core - all that ever did was maybe raise the cabin temps a degree or two. The diverter only served to divert coolant away from the heater core (and thus the inside of the car) so that the A/C could work more efficiently.

 

So the '85 was apparently one of those cars? Hell, even my '70 Monte had a diverter

 

I think you might've answered your own questions, Art. Regardless of whether or not there was originally a diverter valve, the car still would've had hoses going to-and-from the heater core. So if there were no heater hoses when you got the car, then they had to have been removed by a previous owner, and with them, the diverter valve would've been removed too. Also, you said there's a vacuum line that reaches the area where the diverter valve should be, which would also suggest that the valve was originally there.

I haven't noticed the set-up of a factory non-A/C TPI car, but I suppose it's possible they might've come without a diverter valve. But if your car came equipped with factory A/C, then I'd be of the belief that it also originally came with a diverter valve.

My guess is the heater core leaks, and rather than replace it, a previous owner simply removed its associated plumbing.

 

OP is there a problem your looking to diagnose?

 

And if there's no coolant lines to the heater core, that means you need a new heater core! Most folks get a leaky one, and are too lazy to change it out, so they just reroute the hoses to avoid the heater core. I'd replace it before I connected hoses to it, or else you might end up with a pass side floorboard full of antifreeze.

 

The car does have A/C. Like I said the existing vacuum line looks like it would reach an HCD if one existed. Maybe the other vacuum line is broken off inside the car....ARGHH Will have to tear apart the dash again to investigate

Just wish I could get a concrete yes or no, did the '85 with TPI and A/C have two vacuum lines coming out of firewall?

 

Sorry for replying so late and bringing back an old thread back to life. Your 1985 Camaro does not have a heater diverter valve at all, and neither did any other engine code from 1982-1986. GM revised the cooling system in 1987 and incorporated heater diverter valves on all engine codes on both Camaro and Firebird in 1987 and stayed like that until 1992. Your car, like mine, should have one vacuum hardline coming out of the firewall and running along the harness loom up (over the engine) to the vacuum tank on the left hand corner (looking out of the car) underneath the canister purge tank. Make sure the rubber 5/16 or 7/32 vacuum line is not cracked or damaged from the tank to the back of the intake plenum. Also take note that these cars had no three-way vacuum check valve at this connection. Also, make sure to check to see if your vacuum hardline is not broken from heat fatigue. By the way don't get confused with the washer fluid line coming out of the cowl going towards the washer pump on the older cowl mounted washer nozzle cars. Hope this can help you.