Hello there!
I am the proud new owner of a 1988 RX-7, and I love it. I am however a classical pianist, and not a mechanic so I need some help!
The thermostat on my dashboard tends to move from around 25% cold on the highway, up to 65% when in traffic. Regular city driving usually stays between 30% and 40%, and I am basically wondering if this a rotary thing, or do I have a problem with something. Also, When I use the air conditioner without much movement, the car heats up even faster, but on the highway, stays very cool even with the air con.
Does anybody have advice for me?
Thanks so much!
-Tom.

 

check your reservoir first, but when was the last time you flushed your system?

a few years back, when i was driving with bad water seals (and losing coolant) my car would do the same thing when the level had depleted enough to keep the reservoir low.

 

What kind of fan is on the car?

If it is the stock clutch fan (big white fan attached to motor) and shroud, then make sure that the fan spins. It should essentially freewheel when cold and progressively lock up as it warms up. If this is not the case, then you can probably find a new clutch fan in a junkyard.

If it is an electric fan, it is an aftermarket addon. It is very hard to determine how it is set up, but easy to tell if it comes on.

Try to shut off your car above half the temperature gauge. You have a Series 4 car, so the gauge is at least better than the S5's. It SHOULD read 2/5 gauge warmed up and maybe a little higher in traffic or if you're wompin on it. It shouldn't go above half though, and definitely not above 2/3.

Post up what kind of fan and any questions you have on the above procedures.

 

If he had shot coolant seals one of the very first indicators is that low coolant buzzer. Sure that buzzer can indicate lots of stuff, but if his seals were on their way out he'd hear it.

Also to the OP... When your A/C comes on, there is sometimes (I don't think all A/C equipped cars had this, but most... something like that) a separate, additional fan that comes on (in front of the rad I think... mine doesn't have AC). If this is not coming on it will not keep the A/C from making the car hotter.

You seem to ONLY have a problem at lower speeds and or stopped. This is EXACTLY when and why you need a fan on your radiator. This is why I believe you have a problem with your fan. If it was your water pump it would likely not get down to 1/4 gauge ever.

 

Check your thermostat to begin with.

Then do the basic maintenance if this car is new to you, plugs, wires, fuel filter (very mportant) and air cleaner.

Then flush your radiator and change out your thermostat with a Mazda one.

this was all preventative maint. and necessary to keep the car happy.


Now, my temp fluctuates on my FC depending on driving parameters and its not unusual for them to do this, around town sitting still in traffic in hopt weather it will climb, once moving, it drops back down, if under load (hard acceleration) it will climb.

Its not unusual for these cars to fluctuate in temp, you might not have a thermostat, therefore you might have your bypass blocked off and then you do not want to put in a thermostat.

I do not have a thermostat anymore and my temps range from 160 - 210 depending on the driving style and conditions.

 

well, you're probably right, but first the buzzer must prove to be functional. i drove around for 3 years with compromised seals - having to replenish the reservoir every 2 to 3 weeks - and my buzzer never once sounded. so, i'll assume mine was busted.

 

Thanks guys for all of your replies.
*Diabolical1: My resevoire is full, but I have not flushed my system.
*Kontakt: I do have a big white fan, and it seems to work, although, could it be that it is not turning fast enough? (I have an automatic by the way, does it still have a clutch? shows you how much I know!) I have reached temperatures up to 3/4 to hot when just in bad traffic (45 minutes of very slow motion), and with the air con, same thing but much faster. I obviously got scared and turned it off, and never let it get more hot than that.
*Jims: Good to know that the temperature does fluctuate in these cars, but I still think that there is a problem, since the car does heat overall, and it seems to be really comfortable when relatively cold on the highways...

 

I coulda sworn I responded to this.

Yes, it could be spinning too slow. You don't have a "clutch" but your fan does. The fan is operated by a thermoclutch that locks up when it gets hot, and freewheels when it gets cold. If your car is hot, and you rev your engine to 2000-2500 that thing should be moving an amazing amout of air.

Will it get hot if you have the heater on full blast, or more importantly will it cool down?

Maybe your radiator is dirty, as others said flush the system. It's pretty cheap to have a shop flush out your system, especially compared to a rebuild cost.

 

I have recently noticed that my temperature will not pass about 3/4 to the hot. The other day, I was in traffic and it stayed there for about 20 minutes, and did not heat up anymore. Good? bad? When I turn the heater on full blast, it seems to cool the engine a bit. Could it be that there is a problem with my thermometer? Recalling that on the highway, it reads radically cold (1/4 or even slightly below, almost touching the cold line) even after an hour driving, with no performance problems...

 

Well, according to my amazing mechanic, it was the clutch of the fan causing all this fuss. Thanks all for your help!