Robert the Swordsman

Hello.

I've read through the rules and the FAQs and couldn't find an answer, so I hope I'm doing the right thing by posting here.

I have a 1984 Mazda RX-7 GSL, and in traffic, it overheats savagely. Usually I get to my destination before the temperature gauge gets all the way up to "H", but even so, I'm relatively sure that this is not typical.

If I'm on the highway and going 60+ MPH, there is no temperature problem; the needle points straight down, even further back than the little 2/3rds mark on the gauge.

I assume that the car is NOT supposed to overheat like that in traffic, though. Literally after about five minutes of slow driving, it will be past the 2/3rds mark and halfway to the "H". Has anyone had a similar problem?

Thank you very much.

Dan_s_young

iTrader: (1)

well just to let you know I would fix this before I drove the car again, I lost my last engine to overheating...

Anyways have you tried replacing the thermostat? What kind of condition is your radiator in? Have you checked you coolant/h20 concentration? My guess is you just need to replace the thermostat, but like I said don't wait till its too late...

Below is a good point as well, but if the problem is your fan clutch convert to a electric fan, the fan clutches are $$$

Rogue_Wulff

Check the fan clutch. This is a very common cause of low speed heating problems. If the fan spins freely with the engine shut off, the clutch is likely worn out.
If it heats up in traffic, but cools back down once you get on the highway, this is usually the problem.

Robert the Swordsman

Thank you very much.

I'll go check the fan as soon as I get the chance.

Kentetsu

Please!!!! Do not drive your car again until this is resolved. Overheating is the leading cause for rotary death. I can hear your car screaming from here!

Welcome to the forum...

rxtasy3

iTrader: (2)

runs cool while moving=air moving thru rad.
runs hot sitting still=no air moving thru rad.
sounds like the problem is obvious.

cdrad51

yup, fan clutch is my bet. When warmed up, if you can stop the fan with the end of a rag, your clutch is fucked.

Rotor13B

You might want to check the radiator cap also. Cheapest fix i ever did.

7aull

iTrader: (2)

Yank the rad and take it to a good rad shop and get it dunked and cleaned!!! brainless to remove. Great time to replace the hoses too!!
Stu Aull
80GS
Alaska

Robert the Swordsman

In response to a few of you:

While the car is off, I can move the fan freely. Well, it gives a bit of resistance; if I spin it, it won't just keep spinning, but I can move it without any difficulty. I haven't tried touching it with the car on.

Is the fan clutch something I can fix on my own? I'm not really too good with cars, actually, and I'm particularly unfamiliar with rotary engines.

How would I know if the radiator cap needs replacing? Would it be obvious?

I wish I knew what the Hell I was doing so I'd know what exactly needed to be done.

Kentetsu

The fan clutch is the aluminum ribbed device that the plastic fan bolts onto. Ten minutes and you should have it off. Its designed to lock up when the engine is hot, forcing the fan to turn. I would not suspect the radiator cap unless you are losing fluid into the resevior. A Haynes or Chilton's manual will be a big help to you down the road.

LongDuck

These guys have already pointed out what the likely cause is; fan clutch not working.

You had asked about how to remove/replace this part, so I thought I'd add some detail along that direction. The Fan Clutch is the metal apparatus that the white plastic fan blade assembly is mounted to, and it is a thermal 'switch' to allow the fan to freewheel when the engine is cold (to help it warm up), and to lock it to turn at Water Pump speeds when the engine is hot (to cool off the coolant in the radiator). The purpose behind the fan and clutch is to normalize the temperature of the engine, since rapid changes in engine temperature can cause all kinds of problems from thermal expansion and cooling of the internal engine parts. If it ran at the same temp all the time, it would be more reliable, which is why the fan clutch is there in the first place.

The fan clutch uses a bi-metal strip on the front of the clutch assembly that looks like a shiny metal band. This strip flexes when hot air from the radiator hits it (whether sitting still or moving). As it flexes, it pulls a clutch toward a plate on the inside of the Fan Clutch, causing the fan to grab and spin at the engine speed.

As stated, at idle, the fan clutch should be pretty tight to turning by hand when the engine has been hot. If stone cold, it will spin freely - this is normal.

As you drive on the freeway, air is forced into the front of the radiator, making operation of the fan clutch less important. Remove it using the 4x10mm bolts through the base of the fan clutch and into the water pump pulley. HTH,

glewsRx

iTrader: (1)

longduck, don't you get tired of being everybody's overheating fixer? Replace the whole setup. Thats what I did and now it doesn't overheat at all. Of course, I bashed the dizzy fixin stuff so now it doesn't even get started. Can't wait....

LongDuck

Well, he asked for information about replacing just this part, so I figured I'd help him save some cash over just replacing all the necessary parts.

What's up with your dizzy?

Robert the Swordsman

Thank you very much, seriously.

I'll see what I can do.

Robert the Swordsman

I just tested it out; I'm not sure if it's the fan clutch now, because I can't stop the fan with the end of a rag when the car is warmed up. It runs pretty hard.

Maybe I just need to flush the radiator.

Is there any other way to be sure?

glewsRx

iTrader: (1)

you could buy a used one and put it on and if that doesn't fix it you know it ain't that. Then you could sell said fan clutch to another person who has a overheating problem... and the life cycle continues.

cdrad51

Where are you located? maybe you can bring it over and I can take a look at it.