lovemyseven

If my thermostat is not opening, will the coolant boil in the Air Separation Tank and in the Coolant Resevoir? Trying to figure out why my coolant is boiling. This seems to be the only reason I haven't checked out yet. Any ideas are appreciated.

wickedrx7

my thermostat went bad and I lost almost all of my coolant within five minutes. The minute I pulled in my driveway it started to spew coolant out of the overflow tank. you can test your thermotat by puting it in boiling water. It should start opening at 180.

lovemyseven

Thanks for the info. I am breaking my engine in after a rebuild, so I haven't been driving it hard, so the coolant has just been
bubbling a lot and steaming out of the overflow tank, but it seems like the thermostat must be bad.

RonKMiller

Three things you must do when installing a new engine:

1) new thermostat and new pressure cap(s)
2) pressure check the radiator and have it cored (cleaned) or better yet install a new radiator (and ALL new hoses while you're at it, use only OEM clamps)
3) ditch the plastic AST and get a metal one.
4) (optional but highly recommended) new water pump guts, they're not that expensive and if I remember correctly you need to pull it anyway to change the thermostat. There is a rebuild kit available which will save you some money vs. a new one.

New engines are way too expensive to skimp on other parts.
You are going to have to basically rebuild the cooling system as well! Flush it at least a couple of times with distilled water after you have installed the new parts to make sure you have a completely clean system - it's easy and cheap to do. You must pull the 14 mm bolt at the bottom of the engine to drain it completely. This might be considered overkill by some, but for
$10 worth of distilled water and a couple of hours of time I think it's well worth it.

After you've done this then you can start troubleshooting your boiling problem. Odds are it will have gone away.

hawaii rx-7

hey what happens when you restart the car after pulling the bolt to drain the engine block? With no coolant inside the engine, won't it heat up and dammage the engine? do you have to put water back in and prime the system or something? i'm not really sure how you are supposed to flush the cooling system. The last time i did it, i used a good 5 gallons of distilled water, and it was still coming out green. It was a little clear, but still noticable green. When it turns clear, is it supposed to be clear clear or just clear enough?

Oh yeah, if anyone knows where to get or what the part number for 180° thermostats are please post. I still havn't been able to find any info on lower temp thermostats.

lovemyseven

I don't know what would happen if I drained the engine of coolant and then cranked it. It would probably heat up very quickly. I tested my thermostat today and it is fine. It looks like my engine needs to come out again and be inspected for cracks.
Flushing could take awhile, I haven't tried it, but the car holds quite a bit of coolant.
Take it easy.

RonKMiller

You should never run the engine without coolant in it. Where did you get the idea you should? (must be smoking too much Maui
wowie......):p

RonKMiller

DO NOT run the engine without coolant - where the hell did THIS idea come from - the idiot in Hawaii?

I think you are jumping to conclusions. You don't need to pull the engine again to check for leaks. Rent a radiator pressure tester and test the system. Cracks? Highly unlikely. If you hear hoofbeats, don't go looking for Zebras. Replace the themostat anyway with a new OEM - it's nickels and dimes to compared to the money you just spent on the rebuild. You still need to have your radiator tested and cored or replaced. You do not want to introduce any old crap that might be in there into a clean water jacket, it will just accelerate any future corrosion and may lodge in your water pump impeller and or coolant passages - there are some that are really tiny.

Silver7

I went to Advanced Auto Parts for my thermostat. They had two listed in the computer. The stock replacement and the 180 degree. This was the first place I checked and they got it in one day so I didn't bother looking anywhere else.