So....today was a colder than average day. This is my first summer with the car, (only had it for 4 months) and I went out and started it up and it revved up to 3k like normal. Usually after around 15 seconds the idle will drop down to a steady 650-850 RPMs(streetport-no emissions), and I would be on my way driving gingerly until I saw my temp gauge raise its 2mm to full temperature. Well it acted funny today. Drove fine when I had it in gear but when it was popped into neutral and sat at a light it idled around 2000 all the way to school! (20 minute drive with stop and go finished with a short highway ride.). I shut it down at one of the lights and started it up and it did its normal ruotine, and came down to 850 and then I tapped the gas and it jumped back up to 2000! So I delt with it and by the time iIgot to the last light at school after the highway ride and the temp gauge rising SLIGHTLY it was idling at around 1100-1200.

im guessing since I have an s4, it was rebuilt with an s5 shortblock causing the temp gauge to hardly rise up? or the only other thing i could think of is that i dont have a thermostat in the car and it takes forever to warm up.

also what is the deal with my temp gauge? the s4 has 3 lines on the bottom of the temp gauge, it starts out at the lowest one, and at "full temp" it sits right between the 2nd and 3rd line. it NEVER goes in the huge possible space.

whats up with this?

 

Why not install a t-stat? It's like $10 from Mazda.

 

i don't think the tstat is the problem u said u shut it down and started it back up and it did the accelerated warmup again? thats really weird i know when i get off work start my car let it finish the warmup cycle pul it around front (witch is like 10 sec never out of 1st gear) and after i clock out it has never done the warmup again even when its like 40 degrees out. im not an expert but it sounds like a bac thing

 

Do I need to empty out my coolant system to get to the thermostat? I'm not sure if I have a thermostat in there currently.

 

u don't need to empty it that thing poking up on the (if ur facing it ) left side is ur housing. 2 bolts think their like 9mm or something like that. now be weary that gasket will prolly be **** so either have 1 on hand or make one ur self out of cardboard. ive done it and it works great to be honest

 

cardboard? lmfao....no. For this it is fine to get a roll of paper gasket(make sure its the proper gasket roll) Some are made for waterpumps, and ect while other are for areas that dont have to do with coolant in the area. est $5 for a big roll! Also make sure you get a OEM t-stat!!!! Ive done this before and the gasket roll did a fine job for a long time before i sold the car off.

P.s You have to place the t-stat in a certain position. The jiggle pin has to face 3 o'clock position i belive but confirm this by searching first.

 

Follow the upper radiator hose from the rad to the engine.
The neck that the hose terminates on is the top of the thermostat housing.
Undo the two (possibly three if S5) 6mm bolts and the thermostat is right there.
You'll lose a bit of coolant (hold the now loose hose up or it'll drain also) but nothing major.

I just got a Mazda thermostat locally...it was $27.
Had the jiggle pin and a nice rubber o-ring (S5).

The S4 gauge, while reputedly more linear than the moronic S5 pretend gauge, is still an ergonomic nightmare because a: it isn't marked numerically (I alway get a kick from earnest discussions of water temps that start with "My gauge reads about 1/8 from the bottom!"
Then someone responds, "Yeah, that's normal, mine reads about 1/3", on an on. Never once a mention of what the ******* actual temp is, just these vague estimates from an unmarked dial.)

...and b: Normal operating temp is around 1/8 to 1/3 of the scale.
This is stupid because we are hardwired to expect NORMAL to be centered in the sweep, so the S4 gauge is a constant distraction.

Sack up and get a real temp gauge, especially given that you seem to be having cooling issues, now is exactly the time you need to know what's really going on.

Also, your accelerated warmup sequence is not correct.
Yes, against all common sense Mazda runs the RPM up at cold start, but when it drops after 15-17 seconds, it should drop to @1200 rpm till the water heats up...then it should idle at 750rpm.
You don't seem to be experiencing the second step.

 

good info from aaron cake himself about the cooling issues:

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

and i've seen myslef in the haynes manual this direct quote:

" DO NOT DRIVE WITH OUT THERMOSAT, THE COMPUTER WILL STAY IN OPEN LOOP AND
EMISSIONS AND FUEL ECONOMY WILL SUFFER"

and almost anyone else will tell u the engine damage will result!

i use to run my 1st fc without one not knowing the harm it could cause, and it slowly and more violently over heated more and more!!

just my personal opinion and what ive learned take it or leave it

 

Clokker, What kind of gauge would you reccomend? something I could pick up from pepboys, or something off the net that is better than others?

Also I had a lot of emissions equipment removed, which I believe is why the accelerated warm up system doesnt work all of the way. ALSO I started my car up today and it did the same thing, and I believe what the case is that it is just the tachometer is off. The RPMs sound normal but it idles at 2000. After the engine bay was warmed up it dropped back to normal (around the time i got to school.).

and R.O.D, my car is not overheating, if anything its overcooled right now...

This weekend I will see if i can pop in and look for the thermostat. The engine was rebuilt last summer, would the gasket still be reusable?

Thanks guys.

 

Everyone has their favorites, IMO the best bang per buck in gauges is VDO.
You can get a Vision series gauge with sending unit for @ $40 at egauges.com.

They ain't flashy or color coordinated with the stock cluster but durable, reasonably accurate and cheap.

 

drift now u think its "overcooled" but theres hot spots u can see on a temp gauge. also ur oil system is doing alot of the cooling. and unless u've found the perfect rpm to drive at the coolant is prolly moving to fast to absorb the heat from the engine so the temp will read fine but its actually running hot. i know cause i have no tstat in my 7 now but i don';t drive it much only very short trips.

 

If you NEED an open t-stat...get an old one and clip the return spring so it's held open. The t-stat also acts as a flow regular so the coolant has time to absorb the heat.

Your experiencing the same issue I got when I gutted my pre-cats. BUT, I also get combustion air pushed into my coolant system.

Are you getting air in your coolant?

 

i dont think i have air in my coolant...and i am a god damn retard. i have a parts car right next to my car in the driveway and when started up the temp gauge does rise to what looks to be a normal temp. i'll put that in my car and see if it makes a difference.

 

A cheap temp gauge that will work great for a n/a DD is prosport. $50 If this were to be a track car i would look into better quality gauges but prosport works just fine IMHO. Tee the temp sensor into the BAC coolant line. You can get the proper fittings at a hardware store for under $6 like i did.