Hello everybody,

First off, I am new to this forum but from an inspection of the archives it seems like you guys know what you are talking about! I have searched the archives, but the suggestions did not help my problem, so I thought I would ask!

So here is my problem:

On the highway at about 50 mph the temperature will reach about 3/4, but as soon as I get into stop-and-go traffic, the temperature will go down to a more normal 1/2!

If I try to go any faster than about 50-55, the temperature will begin to slowly climb! At first I thought it was the thermostat, so just to make sure I took the thermostat out completely. That measure only had a slight effect. So then I flushed the systems completely with water and checked all my hoses. They all seemed fine as well, but the temperature still rises unacceptably.

I think the temperature sending unit and the gauge are working correctly because when the gauge says the temperature is high, the system pressure is very high (determined by squeezing the upper radiator hose) thus indicating that at least some of the water in the cooling system is trying to turn into steam.

I will be very grateful for any suggestions or comments,
Sam

 

how old is your radiator? what kind of shape does it appear to be in? its possible that enought coolant is getting through to pressurize the system, but is still clogged. Just a thought, somehting to check. oh yea, welcome to the forum

 

My car will NEVER get that hot!! Id shut it off first, lol. I dont know, maybe Im paranoid. Anyway, Im thinking water pump cavitation? Check your coolant levels.

~T.J.

 

Thanks for the quick replies! The radiator seems to be all right, although I have no way of knowing for sure.

I to had thought of water pump cavitation, because that was the only solution to fit the symptoms, but what would cause the water pump to cavitate!? I did not really think that that could really happen!

(FYI: I did replace the water pump recently for the second time, because the first replacement failed. The new pump seemed to have different vanes than the first one, but I did not give much thought at the time.)

Sam

 

Question: Did you have the problem before changing the pump? Or is it new since then? Also, have you checked that the belt's tight enough and is not slipping at higher rpms (a problem sometimes, particularly if the air pump's been removed - so I've been told)

 

I am not sure if the problems that I had before where related to the pump itself, or to the leak that the pump was!

I just went out and checked the tension on the belts to the water pump. To my immense surprise I could twist the water pump with my hand!!!! I do believe you have solved my problem!! WOW!!

I will tighten it and post the results!

Sam

 

Put it back! Running a rotary without a thermostat will cause overheating.

 

Yeah, the belts have to be run really tight after the air pump is removed. Some of those cheap Korean belts will continue to stretch their entire (short) lifetime, requiring fairly constant re-tensioning. The only belts I've found which work well are the stock Mazda belts, made by Mitsuboshi, and Gates brand belts. Neither one is particularly cheap, but they are more than worth the extra couple dollars in longevity and lack of maintenance. They stretch ever so slightly right after they are installed, but then after an initial re-tensioning, they settle in pretty well, usually requiring no further adjustment. FWIW. -WG

 

Yeah, then go here and read why. http://members.ij.net/mrmazda/cfaqtext.html#TSTAT

This site also has loads of info on RX-7s and rotary engines.

Good luck with the overheating problem

 

I had that prob, it's ur radiator, it's not flowing enough.

 

Id say the biggest part of the problem is gonna be the loose belts not turning the water pump...Like someone mentioned earlier, some of the cheaper belts will just stretch and stretch, and you ahve to constantly monitor them to make sure theyre always tight. Im running a dual belt setup on my car since I have removed my air pump. The dual belt setup is meant to help keep a better hold on that water pump pulley so this doesnt happen .

~T.J.

 

The rats nest removal tutorial tells you what belt to use to keep things tight after the airpump removal. /shameless plug

click the pic in the sig.

 

Man, I waited for like 45 minutes for that thing to load and then I got a message that said the plugin did not initialize properly.
Eventually someone will make this information more accessible, without extorting $ for a printer-friendly version.
Even porno sites'll give you a free tour. -WG

 

If you still have the problem you might check the (clutch) fan. If it (the thermo charitiristics) is engaged all the time it could account for the problem. At idle it will draw air and cool the rad.,,,,but if it engaged at highway speeds it could actually BLOCK sufficient air flow because because the motor is not is not turning it as fast as the airflow from the driving speed would. Also, the temp gauge has markings INSIDE the max. and min. marks. This is concidered the normal operating range.

 

Next time, RIGHT-CLICK the Link and select SAVE-AS.

 

Both versions are pdf, and yes, if your plug-in didn't initialize, just download it. RE:Extortion for print friendly version - time/energy/skill/abilities went into the tutorial. View it for free, waste $50 in printer ink printing the white on black version, or save $40 in printer ink by dontating a few bones in appreciation of our effort... I think we're quite reasonable. Or you can always do the tutorial without printing anything, and save the money and still profit from the knowledge given there - up to you.

Unlike **** sites, we don't keep billing your credit card, nor will we ever have to mail you anything in a plain, brown wrapper.

I hope you don't get your 7 worked on by someone who runs a **** site...

 

Sooo... you still overheatin' or what?

 

when you remove the thermostat you must plug the bypass in the water pump housing. otherwise some to all water will flow thru the bypass and not go thru the radiator. tap that bypass hole with 1/2" npt and plug it with teflon tape on the threads, or better yet loctite so it won't ever backout.

this type of mod is commonly done with racecars since it'll remove a point of failure (thermosta) and reduce restriction in the colling system (thermostat). But you do need a little restriction in the system which is why we gut out the thermostat and just leave the ring in there. overkill for street and it takes a LONG time to warm the motor up especially with the mechanical fan spinning all the time.

-bp-

 

do you still have the underbody tray under ther car? my old TII was missing it when I bought it and that did cause overheating. the air was going around the radiator, rather than through it.

 

definatly put the thermostat back in.... try to get a 160 F degree soit will run cooler.... the problem you have is 2 things.....1 if you remove the thermostat you need to plug up the hole or the coolant will keep recirculating back into the motor and overheat....2 without the thermostat, the coolant travels too fast and dosn't have time dissapate heat when it goes through the radiator...

 

Any progress???

 

mine has been doing the same thing for some time now. pulled the radiator, and it was about to fall apart (no way it could survive rotting it). so i replaced it with a three row radiator.. still overheating like mad..

(i am going to check the belt when i get home).

if the temp sender is bad (and that being the only reason that it goes up), is there any problem with running the car like that??