No Heat in Michigan

[mike zielinski]

Michigan Winters can be very cold especially when I can't get any heat out of my '89 Veloce. The engine temperature is controled nicely at 170F. The shop manual said to back flush the heater core which I tried to do but couold get no flow. I reversed the flow and after some pressure build up some black gunk broke free and water fowed freely through the heater core in the direction that the book says it should. I thought the problem was solved but when I tried again to back flush the heater core it was like there was a check valve in the line. No flow. With the hose connected in the correct direction of flow to the heater the flow was unrestricted and the hot/cold flow valve worked perfectly. I reconnected all the hoses, refilled and bled the system, warmed up the engine and still got no heat. Any suggestions? Anybody?

[Tifosi]

If you're getting good flow through the core then:

1) bleed the system again to be sure

2) check that the flapper/directional vane thingies that change the flow from off to floor to defrost on the heaterbox proper actually move to allow warm air into the cabin (what the right slider control operates)

[mike zielinski]

I am gettring good air flow to the defrost and the floor but the air is all cold. Why would water flow in the correct direction thru the heater core but not in the reverse direction? The flow diagram does not show a check valve of any kind. The water pump must be working OK since the engine temperature is controled well. The water is just not flowing through the heater core. Water from the tap flows OK through the core and the valve will control its flow. I do not get it.

[turbolarespider]

Bear in mind that with the temps we are recently having in Michigan, 170 water temp isn't going to warm things a lot.

If you can re-circ the air inside the cabin, things would warm up better.

Eric

[he3r0]

just a shot, there is a bleed screw on intake plenum, but im sure you did bleed it with this screw as well right?

[Subtle]

Years ago, I had a Spider as a Daily Driver in Winnipeg.

Installed an additional heater forward on the tranny tunnel--lot's of heat--even at 35 below.

[Erik]

My 1970 Spider have a water valve controlled by the temp lever. These valve will by time get stuck either open or closed. Have you checked that yours opens?
Erik

[mike zielinski]

The water valve works fine. It will close off the flow completely when the tap water is connected and open completely to allow full flow through the heater core when the tap water is connected. There is simply no flow when the engine is warmed up and the water pump should be supplying the water. I think that I have to dig into the thermostat housing to find the problem.

[Joe Papa Sr]

Quote:

Originally Posted by turbolarespider Bear in mind that with the temps we are recently having in Michigan, 170 water temp isn't going to warm things a lot. Eric

[Joe Papa Sr]

Quote:

Originally Posted by mike zielinski The water valve works fine. It will close off the flow completely when the tap water is connected and open completely to allow full flow through the heater core when the tap water is connected. There is simply no flow when the engine is warmed up and the water pump should be supplying the water. I think that I have to dig into the thermostat housing to find the problem.

[peglegtom]

I would check/replace the hoses between the engine and heater core. One may be plugged, or the inner lining may have collaped, creating a restriction.

Of course, this does not explain why the water will flow one way through the core and not the other way. Are you only checking the flow through the core, or are other components also in the test path?

[J.PETER]

First of all - I think that water should flow in both directions thru your system. Find that problem and fix it first.
I have a 67 Duetto and I rebuilt the whole heater core box assembly including the flow control valve.
I had to vent the cooling system utilizing the vent screw on the intake manifold.
My engine ran at the correct temperature however I still could not get heat - The same problem that you have.
I live in Wisconsin - so I liked a bit of heat most of the time.
I just drove the car for a few weeks and eventually the water started to flow correctly and the heater works fine - just as it did on my workbench as tested.
I believe that the water pressure differential which causes the water to flow through the heater is very subtle on these cars and even a slight bit of airlock will cause it to not flow.
The other thing to sort out is to look at what type of radiator bypass system you have. Maybe the sizing and plumbing is allowing no water flow through the heater core.
So my suggestion would be to replace all the hoses with new hoses and assemble it and drive it a few weeks to get all the bubbles moving around.

[Erik]

Mike, are you sure that the hoses connect the right way. A PO can have changed the hoses at a time and got it wrong assempling.
I would still check that the valve really works and let water thru when i the open possision, it might be clocked. The radiator unit inside the plastic box should be checked visiably.
Good luck, a Spider heater can really make lovely warm air.
Erik

[mike zielinski]

Thank you to all for the help. It was 3F this morning. I will let you know what I find.

[mike zielinski]

It is a MIRACLE! Yesterday morning it was 37°F in Michigan with Frost. I had to take the Alfa to work and just for the heck of it I tried the heater. There was more hot air than I could handle. I had pretty much given up on finding the problem and was ready to take it to a specialist at the end of the season. I certainly would have put a few more miles on it if it wasn't for those cold mornings with no heater.

Now I'm wondering how many miles I have to drive it before the odometer starts working!