My fiance and I have an 88 GXL NA. We are fixing her up together and will hopefully get a nice race car/weekend car out of it Here's the deal:

I hear that 1/2 way on the stock temp gauge is bad/not bad. It's been about 90+ degree out here in Colorado. Anyway, the temperature gauge is running 1/2 way all the time. It never goes past that and without it being under 90 degrees (maybe I should test in the morning...) I don't know if the gauge is shot or the sensor is messed up or I have something wrong with the coolant system.

The previous owner replaced the radiator and it was sitting a while when we got it (no white smoke before we purchased it either, that was one of the first things we checked) been sitting a while but we have been driving it just fine and there isn't any white smoke after we let it sit for a few days. Nor does the temp go above 1/2 after driving it for a few hours either (mostly highway)

Coolant looks a little crappy (overflow tank is full of semi brownish coolant), I'm sure a coolant flush wouldn't hurt?

Is the sensor working right? Is the gauge working right?

 

i have a s4 turbo and mine only goes 1/2 way on really hot days when i have the a/c on.

normal temp is inbetween 1/4 and 1/2

when i first brought her back to life it was going 1/2 to 3/4 and i replaced my fan clutch and it fixed it.

you can see if it is working when the car gets warmed up you can feel a lot more airflow from the fan. make sure you have your fan shroud on and the bottom splash gard as that will cause high temps too.

i got my fan clutch from rockauto.com for cheap and it the beck-arnely one is damn near close to the mazda oem one.

 

1/2 on the gauge is around 195-200, confirmed with aftermarket gauge and my Haltech (standalone computer) sensor.

 

I'll take a look at that tomorrow. I was planning on showing my coworkers tomorrow so I'll do a bit of an inspection in the parking lot after it gets warmed up from the drive to work. Plan on doing a coolant flush tomorrow evening after work. I am pretty sure that the fan is working fine, it runs great and I can hear it spool at low speeds when revving the engine.

 

Thermostat is worth a shot too

 

Okay so I did a coolant change, and the old coolant was very nasty. I know the last owner replaced the radiator after he put the jack under it and broke it Anyway, I think the radiator fluid had some oil in it. How can I confirm that?

After I started the car up and the low coolant warning buzzer scared me half to death the car died and then my engine flooded lol, did the deflooding trick waited for half an hour then started right up. After that, I did 2 highway pulls to see if anything had changed temperature wise. Today's high was I think *maybe* 70 degrees so going 80+ mph on the road with the gauge reading 1/2 means there has to be something wrong with the coolant system.

What should I check next and how do I check it?

 

thermostat or weak fan clutch if you have no leaks. water pump too. but if it was the pump i would expect full overheating

you can check the sensor by using a infread temp gun you can pick up locally at any autozone type place and you should read 200 at 1/2 way at the lower rad hose

oil in the coolant means bad seals and a rebuild. but if the coolant is very old it could not be oil just old nasty coolant.. run the car with the radiator cap off and check for a lot of bubbles or steam. do it when the car is cold and keep it off till it is 1/2 way. if you see a lot of steam or a lot of bubbles rebuild time.


you will get a few bubbles depending on how well you blead you system

 

I'll run it tonight or if I don't get a chance tonight then tomorrow and I'll post the results to figure out what to do next

 

So bad news, just went out to try and start the car, and walked into the garage and it was HOT. It has been a little over 2 hours since I did the freeway pulls (less than 4 miles of driving) I figured the engine would be cool by now. The upper radiator hose was hot so I put a rag over the filler cap and took it off really slow. Didn't spray me Then went to try and start the car... Didn't turn over. It's now acting like it's flooded. I'll try again tomorrow. I wonder if the engine was hosed from the start and just now decided to crap out on me. The previous owner couldn't have had they old fluid in the engine longer than (at most) 5 years as that was when he got the car. And like I said he had replaced the radiator so I would think something more like 4 years since the last change. He only put 19k miles on it when he got it in the 5 years that he had it. What can I use to clean out deposits/rust/crap from the system? (After a possible rebuild)

Any way, I'll check again tomorrow morning and if there is steam then time for a rebuild or just go the turbo route

 

Mazda used 3 different temp gauge senders in the FC's. I have found that two of them put the temp gauge needle at the center at operating temp, and one is 1/4 or less at operating temp.

 

Spinning and not starting or not even spinning at all? Big difference in diagnostics.

 

Spinning and not starting. It happened earlier as well after the low cooland buzzer went off and the engine died. I did the ing fuse pull a few cranks and then let it sit for 30 minutes. Started right up

Side note. These forums are not smartphone/tablet friendly. Keyboard chugs when typing.

 

My phone pops up every time asking if I wish the use the mobile theme, which is just a .CSS designed for a narrow width screen. I have no problems with it on my Droid Charge, 1/3 of my recent posts come from it in fact.

 

On an S4 [86-88] your temp gauge [if everything is working correctly] should read ~1/4. S5 [89-92] should read exactly half.

I'd say you should try to find and borrow [or buy] an infrared thermometer to see what the *actual* temp is. But since it's not starting now.. >_> Bad sign. Does it, or has it pushed coolant out of the overflow?

You can clean out the coolant system by:
Draining it
Rinsing once with distilled water
Filling with 1gal white vinegar and then distilled water
Running it up to temp
Let it sit overnight [or a few hrs]
Drain again
Rinse again with distilled water
Fill with coolant and distilled water.

..Though, I did this and a few days later I blew out a couple coolant seal channel locations [I think the rust and crud was all that held them in] my coolant channel walls were very thin when I pulled the engine apart, so this should be fine on a motor that's not about to blow them.

 

If the old coolant was so nasty, then your best bet is to just replace everything

New water pump, new thermostat, new rad hoses, make sure the "new" rad isn't clogged.

Something obvious, but the fan shroud is in place, correct?

The FSM contains instructions for testing the clutch fan. A weak clutch would show consistently high temperatures, though it would cool down on the highway.

http://www.aaroncake.net/rx-7/cooling.htm

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: http://foxed.ca/foxed/index.php?page=rx7manual . They contain all common service information information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

 

I do have the Haynes manual, it's great!

The fan shroud is in place and the fan appeared to be working correctly. I'll read through the guide to diagnose the fan clutch. Didn't think it would be the fan since it runs to 1/2 temp at 80 mph in 70 degree weather. I'll also do the bubbles/steam test when I get a chance to get out there today. And thanks for the link for the FSM!

 

Grr curse not having an edit button!!! I just remember that yesterday there was a hose on the passenger side of the car and below it was coolant that looked like it came out of it.

 

Went out and started the car again but after a few seconds it smelled like gas so i turnd the car off worried about the PD which I was going to replace with a banjo bolt. Either way I didnt get to run it long enough to check for bubbles. Ill try again when my fiance/helper comes home