eriksseven

iTrader: (6)

I've been having this problem with thermostats. They seem to work for several days, or weeks, but then one day it will stay shut and I'll come close to overheating my car... This has happened so many times that it's really getting old. I've used different brands, including two Mazda OEM thermostat's, and nothing seems to work. My last OEM thermostat worked normally for about two weeks before I had to remove it since it stopped opening. My latest Stant thermostat wouldn't open the day after I got it.

Basically my stock gauge will start rising, but my aftermarket gauge (on the OTHER side of the thermostat) will be still at 0 degrees. Oh yeah, and my heater will be blowing cold air. Several times the thermostat will magically open (very suddenly) and my aftermarket gauge will jump from 0-200 degrees instantly before settling back down to 180 after several moments--while the hot and cold coolant mix and circulate. Either way, I've gotten lucky so far and caught my engine from seriously overheating on many occasions. As soon as I pull out the thermostat, refill the coolant and drive my car--my engine is fine. It runs pretty cool (about 160 fully warmed up), the heater blows decenly hot air, and everything is basically just fine aside from the 20 minute long warm-up... I'm sick of it though!

My question is, what is wrong with my Rx7 that it can't open a thermostat? Are there air-bubbles forming underneath the thermostat and therefore it's not "reading" the coolant temp? WHAT could possibly cause this...?

And yes, my engine has been pissing and sucking coolant for a couple months now, but I'd really like to be able to drive it for several months until the next rebuild... And yes, I'd really like to be able to drive it WITH a thermostat.

Imput?

jackhild59

iTrader: (7)

Classic symptoms of air in the cooling system. It is unlikely that anyone could have that many consecutive faulty t-stats, and I know of no way an engine could cause a t-stat to fail.

If your heater is not blowing hot air, but the temp is rising on the oem guage, most likely you are air locked. You probably have lots of air in the system. Maybe you just havent gotten it completely burped, or maybe air is getting reintroduced later. This could be caused by a leak in the system that will hold pressure but won't hold vacuum.

Try taking one of your failed t-stats and putting it in a pan of water on the stove. Heat the water slowly and use a thermometer to measure the water temp. Should begin to open at 187 and fully open at 203.

If you don't have a thermometer and can't/won't get one for this test, just slowly boil the water. it should be opening well before it boils and completely open as the water starts to 'rattle and rumble' just immediately before it boils.

If the stat opens on the stove, it is opening in the car. This test will allow you to focus your attention elsewhere, rather than the t-stat, if necessary. I was having similar problems when my car was leaving coolant in the overflow tank and not pulling it back into the radiator.

SpooledupRacing

u may have a plugged heater core too... have u used any "fix a leak"stuff in the radiator?I would pull the hoses from the heater core, back flush the heater core then refill with a 60/40 mix water to coolant and burp the system real well...

if u have the car running and pull the radiator cap do u see bubbles? if so u have air in the system or a bad seal.

ericgrau

iTrader: (1)

Easy way to remove air from the coolant shown below. Basically it's a tight fitting funnel. You fill it with coolant and then turn on the engine. Bubbles go out, coolant goes in.

Lisle 22150 - Spill-free radiator funnel kit
http://www.sjdiscounttools.com/lis22150.html
Don't forget to jack up front end of car to make fill point the high point.
Works extremely well, according to users. A search through these forums will yield plenty of positive comments.

NZConvertible

The filler cap (S4) or the radiator cap (S5) is the system high point. You'll probably be okay jacking up an S5 but with an S4 this will effectively move the high point lower.

Jacking and fancy funnels are not needed anyway. I don't use either and I've never had a problem with air in the system after filling. Running the engine with the filler cap off until the engine is at operating temp and then waiting until no more bubbles are appearing is all you need to do.

eriksseven

iTrader: (6)

Thanks for the tips guys. I plan on giving my cooling system a full overhaul next weekend--so I really appreciate the help.

ericgrau

iTrader: (1)

The funnel is there to add more coolant as the bubbles go by. The jacking the car up sentance I pulled from my notes; I don't remember anything about it. I can see it being unnecessary in an s4. Anyhoo a quick search through the forums will yield more info. I just know it helped multiple people here burp their cooling systems with a heck of a lot less fuss.

jackhild59

iTrader: (7)

I can tell you that I never had any trouble burping the cooling system of any car I ever had.

That being said, the Lisle Spill-Free funnel is the handiest little gadget I have ever used. I have now used mine to 'cook' all the residual water out of my cooling system when I changed over to Evans NPG+. I have used it when replacing the Rad on my ford van and on two different toyota Celica cooling systems. It is useful for flushing and for filling, and it really is spill-free.

NZConvertible

I do that with a 50c funnel I stole from the kitchen...

You shouldn't actually need to add coolant as the bubbles come out. I add coolant until I can only just see it in the filler neck, which leaves plenty of room for the coolant to expand as it heats up without overflowing. Usually by the time the coolant has reached the top the bubbles have stopped and I stick the cap on. If there's any air left it'll be an insignificant amount that won't cause a problem and will quickly leave on it's own. When the system cools down it'll suck coolant out of the overflow reserviour, which I alway fill up to above the FULL line (because it seems silly not to). Easy and free.

Actually I think it helped them do it with a lot less thinking. People make this job sound a lot harder than it is. If extra gadgets make make that much difference to a job that should be easy, maybe you're just not doing it right...