Troubleshooting cooling system

[Danno]

I'm not really overly concerned by this, but I threw my new thermostat on today and It seems to work correctly. It runs right at the high end of the 0 on 190, but no biggie. at least it's holding a temp.

Did notice that the heater isn't working. I thought I did a good job of bleeding all the air out of the system, but let's say that I didn't get it all out, could that be my problem with no heat?

[rlux4]

Yes Danno, low coolant level would be a cause of no heat from heater. Assuming your heater control valve is working, it would almost have to be the problem. By default, the water to your heater core comes from the top of the coolant loop, this way if it has a low level your engine wouldn't be robbed of whatever coolant was diverted into the heater core. At least that's my understanding, and experience.

[Danno]

Thanks. I was almost sure there must be an air bubble in there (or some other simple problem) because the heater worked on Thursday.

[mbouse]

more'n likely it is a failed heater control valve. if you had an air bubble, the engine would prolly overheat.

that is, unless you are driving in the freezing cold, in which case the heater prolly is working and you just don't know it and the engine is about to over heat, but just can't due to the extreme ambient temp.

[Danno]

I'll let you know. I pulled it up on the ramps this morning before work and burped out quite a bit of air. Then when I started heading towards work the stupid speedo isn't working again, so I turned right back around and parked it. I think the cable popped off the back, seems like it wouldn't stay put when I replaced it. I'll try some zip tie magic with it tonight.

[mdrburchette]

Dan, you did open the heater valve before you bled the system, right? Maybe that's where the extra air is coming from.
Mike, I'm lucky enough not to worry about frigid temps, but is there anyone that really couldn't feel the heat from a Fiat or at least smell their shoes melting? That is cooolllddd weather!

[racydave]

An air bubble will usually show up as no heat! As part of the events to bleed a system my last step is to go out and drive the -iss outta it to help push out the air! Fiats arent the only cars thatll do this.

[Danno]

OK, good news, bad news.
Good news first. just air, heater and cooling system are all working as they should.

Bad news. Speedo had come disconnected. I reconnected and then held it with three zip ties to the screws that hold the speedo gauge in the dash. I was very proud of this handiwork, so I then wentfor a test drive. not showing any speed.....weird. Go around the block, pull into drive, disconnect everything. The flipping end of the speedo cable twisted itself right in two. I think I had the geometry out of wack or something awry when I tightly zipped it in place. So now I have to work on getting ANOTHER cable. freaking crap. I'm drinking a big bloody mary right now. not bad in the grand scheme of things, but I don't like to drive with just my GPS for speed monitoring. justfrustrating because i got such a good deal on Jon L's LAST cable that would work for me.

[So Cal Mark]

my speedo has never worked since I've had my car. If anyone is passing me I know I'm not going fast enough

[mdrburchette]

Good grief Mark! And you work on these things for a living? What's that say about the shoe maker's kids having no shoes?

[So Cal Mark]

it just hasn't been a priority. I just look at the tach and listen to the lovely exhaust note

[manoa matt]

When I had my first spider, you would turn on the heat after the car was fully warmed up and the heat would last 10 min then blow cold air for 20 min then 10 min of hot air then repeat this cycle.

During the rebuild of my current spider I took the cowel panel off and found a heap of old leaves covering the fresh air flap.
There was also a heap of leaves covering the top surface of the heater core.

Once all the debris is removed the heater fan can actually blow air thru the heater core and up thru the vents at the dash. If there is debris on top of the heater core you will get less than optimal heat. Also make sure all the heater levers are hooked up properly and to the proper item, then adjust.

After I optimized the heater system and made sure everything was working properly, It still performed erratically. With the heater valve completly closed I would still get heat at my feet at about the 10min on 20 min off cycle. I believe this to be attributed to the thermostat opening and closing.

The last thing I wanted was hot air forced onto my feet when it never gets below 73 in Hawaii. So I removed the heater core and connected the hose from the top of the head at the rear to the heater tube that connects to the back of the water pump.

Even with no heater core inside the cabin every now and then It feels like the heat is on for a few minutes, all while the water temp stays at a constant temp.

Matt