I am starting to work again on my 73 Spider. I got it running for about 1 hour. The fan didn't come on and the car overheated. I have many electrical problems. Steam was coming from the engine and the coolant flooded out onto the ground. This happened when I put it into storage. I now have it home and want to get it running again.

I am looking for advice on where to start. I hope it is as simple as a loose rad hose. Should I refill the car with coolant and see were it leaks from? Could it be from the water pump? Could it be a seal/gasket?

I have a local guy who changed the timing belt on my friends Spider coming to change mine. I plan to pull the rad to get at the timing belt.Thanks in advance for any advice

Since the fan didn't come on, it would overheat if the fan switching wiring is not working. i.e. The car SHOULD overheat if left idling for a long period of time with no fan available. Did the dash temp gauge give any warning? There are two sensors on the top of the block that provide signal. One (s/b front) gives temp reading (swings the needle), the second (s/b rear) pegs the gauge if the head overheats. The fan switch wiring itself is very easy to check, just jumper the power to ground, bypassing the fan thermo switch at the bottom of the radiator. Jumper across the C4 connector to force voltage through the fan and see if it spins. And check the ground connection at C1 and all the other connections indicated. At C5 the light blue supply wire is ALWAYS hot, even with the ignition turned off (battery connected). Sounds like first thing is to get the fan to turn on and off properly.

The two sensors on top of the head are inline with and in between the spark plugs, they should each have a single wire going to them with a Fast-On type connector.

Air in your cooling system can keep the fan from coming on as well.

Confirm that your fan works and consider installing a "T" in one of the heater core hoses before filling the system again.

The T makes checking, filling and burping the system very easy to do.

Coolant leaves a little crust behind when it dries so you might be able to snoop around and find a leak point, if you had a leak while it was in storage. Since the car recently spewed coolant any evidence of a leak may already be gone.

Now would also be a great time to flush your system using a flush kit from your local auto store.

Since "you're in there" consider replacing the radiator cap too. I hear they go bad over time.

Sometimes the cooling system will expel coolant when it's too full. I'm doubtful that being too full caused your problem, but be aware of it.

Good advice about possible air in the system and flushing the entire system as well as installing the T to make fill a much easier process. How long was the car in storage? The system "may" only be leaking while under pressure. Air in system, older hoses, crystallization of coolant, frozen water pump, electrical issues, gasket leaks can all play a role individually or in combination with these cars. May be a good thing to check items off one at a time. Good luck, hopefully it is a quick fix.

+1 on both of the previous postings! The cooling system is very good on these quirky little cars ONCE it is properly sorted.

Thanks for the suggestions. I had my plastic overflow bottle patched by a guy that does plastic welding. Once the pressure built up the plastic weld let go. I have been looking for a replacement with no luck.

I changed the timing belt yesterday. I removed the hood after marking the hinges and although I got the hood back on it is not perfect so I will fiddle with that today. When I had the rad out I loosened the radiator fan thermal switch. I don't think it works as the fan was wired direct so that it came on with the ignition. I really don't think I can fill the coolant system until I replace the fan switch or is it possible to change the switch without draining the whole system?

I changed the tension pulley as well and glad I did as it came apart when I pulled it off.

Now back to my electrical woes.

Posting a few pictures of the overflow bottle and timing belt change in previous post.

[imghttp://i939.photobucket.com/albums/ad233/glentsch1/fd963a67-e7da-4a70-ab4d-4329c47ce8d9_zpso47idqbx.jpg][/img]

I do not think you could change the fan switch with coolant in the radiator.

you can pick up an aluminum overflow from a variety of sources.

The coolant bottle cap is not tightly sealed and as such the coolant bottle is not pressurized (just atmospheric). There should be a central tube coming in from the bottom, connected to the radiator cap overflow line, that goes about halfway up inside and is roughly centered. As long as that is covered with coolant (coolant is deep enough) the expanding/contracting coolant will flow in and out of the bottle by siphon and pressure changes inside the coolant system in the engine.

Radiator has to drained to change the fan switch at the bottom, unless you are really fast at plugging it when it is removed, but this is highly unlikely and will make quite a mess!

I don't know about your particular year, but I think this schematic is accurate for the cooling system sensor, fan, etc.:

Funcar wrote:Thanks for the suggestions. I had my plastic overflow bottle patched by a guy that does plastic welding. Once the pressure built up the plastic weld let go. I have been looking for a replacement with no luck.

I changed the timing belt yesterday. I removed the hood after marking the hinges and although I got the hood back on it is not perfect so I will fiddle with that today. When I had the rad out I loosened the radiator fan thermal switch. I don't think it works as the fan was wired direct so that it came on with the ignition. I really don't think I can fill the coolant system until I replace the fan switch or is it possible to change the switch without draining the whole system?

I changed the tension pulley as well and glad I did as it came apart when I pulled it off.

Now back to my electrical woes.

Its not a pressure reservoir so most likely an incorrect plastic welding rod was used or the tank was not clean properly before the welding was done.

You need to have plastic 100% clean before it can be welded for use in a critical application.

I installed an old dishwasher in my garage for cleaning plastic, stainless and aluminum items after scraping them down and doing an initial wash down with Dawn or Purple Cleaner followed by a thorough rinse to get the soap off.

Final part of the cleaning will be with a 100% pure alcohol film remover.