Full disclosure, this car sat for awhile before I purchased it. It came with old gas,no air filter, no battery, half the electrics aren't working. I've added sea foam to the throttle body and gas tank. Filled the gas tank up, put in a new battery and K&N air filter. Last night was the longest I've been able to run it, and that's right after I added the gasoline to the tank. The car ran for about 30 minutes before the coolant began to boil. I don't think the fan was on,that's one of those electrical items that's not working. Would that do it? Or would be thermostat be to blame?
Both -- you should make sure the thermostat is not stuck closed preventing coolant flow from the radiator to the engine. If it is stuck closed, you could pull it out and run the car temporarily without it just to ensure the coolant system is up to snuff -- this will keep the car too cold while driving but should have no effect at idle. In the meantime, order a Stant Superstat.
Once that is done, you should make sure the fan is kicking on about approximately 235 degrees. If the coolant gauge is not working (or you think it extremely inaccurate), and you want to make sure the car is operationally sound before addressing the gauge, get a cheap laser thermostat gun from Lowes. Point it at the thermostat housing on top the engine. When it reads about 235 (depending on the accuracy of the laser and exactly where you point it), the fan should kick on, then cut out when the temp gets down to about 225.
If the fan ain't working, then the real diagnosis begins . . . .
So I got a little time to check out the Indy tonight. The thermostat removal trick, had already been done on the iron duke and there is not one in place, so I'll have to get a superstat regardless. The temperature gauge on the dash does indeed appear to work and be fairly accurate, as the car did indeed get to temp, no fan kicked in and she slowly began to boil and I shut her off. So I'll flush the system, for good measure, change the thermostat and track down the source of my non engaging radiator fan. Thanks again fellas, I'll keep you posted.
A common reason the fan doesn't come on is a bad fan switch. At least I had that issue on all three of my Fieros. That would be the first thing I check if my fan doesn't come on. Also, I would recommend switching to a low temp fan switch and thermostat, especially if you need a new thermostat and possibly new fan switch anyway. I have never even thought about my cars overheating since I did so. If the fan switch is working, the radiator fan relay also goes bad after much sitting. So check that too. And while you are working on the cooling system I would highly recommend replacing both the radiator cap and the thermostat housing cap. After sitting the rubber seals tend to go bad, even if they look ok. Good luck I hope you can get that Indy back on the road soon!
The thermostat removal trick, had already been done on the iron duke and there is not one in place...
Yeah, removing the thermostat is often what someone who knows nothing about cooling systems does when their car starts to overheat. Make sure the coolant reservoir by the rad is connected, doesn't leak, and is filled to the proper level... and check that the stainless steel coolant tubes that run along the underside of the rockers on both sides of the car haven't been dented in by misplaced jacks.
[This message has been edited by Patrick (edited 03-09-2017).]
got a chance to work on the Indy this weekend and it is no longer overheating. That's not to say I've completely resolved the issue but, I've narrowed it down substantially. I ran a wire from the positive post on the battery to the radiator fan, connected it once she neared 220, she cooled down and I repeated the process over and over. It's a two speed fan, I didn't know that until I got into it. I'll replace the fan relay and switch, as well as the thermostat and the gaskets and lids y'all mentioned. Also, noticed the cap on the fill tank is cracked so I'll change that too.
Looking over the car, the electrical is in a sorry state. Lots of cut wires, taped off, unplugged connectors, lights and gauges that don't work.....I've got a lot of work ahead of me with this one.