Fiveforwardgears

this is where my gauage would sit doing 70-75 a week ago, now its getting there doing 60 or so.

Coolant is full and not going anywhere, been full and has not moved for a few weeks. My question is, do you think i just need a flush? thermostat? waterpump? i hear the fan come on at lower speeds and on start up. Ive googled thermostat location, found a few people saying its behind the waterpump, others say its on top. i cant find any how to's or pictures?

If i just need a flush, i'll go to the local shop as i have a coupon, but if im wasting my time and am just gonna have to drain the fluid again to replace something, i guess id like to know what you guys think first.

Brett

j_tso

iTrader: (2)

A flush and new thermostat would be a good place to start. Fairly easy to do yourself.

Download a service manual at foxed.ca

Fiveforwardgears

thank you for the advice. I work at 10am tomorrow, and if the concensous is that i can get away with a flush im going to have a local shop do it, they have the machine anyway. If everyone thinks i need a thermostat or waterpump im gonna just have to borrow a car and wait until tuesday when i have a day off.

I should also note that the tempature in the picture above is sustained at those speeds, it doesnt go higher, and when you slow to cruising speeds i.e. 3k or less the temp drops back down.

j9fd3s

iTrader: (3)

start with a thermostat, flush is good too.

next stop is a radiator, you used to be able to have them rodded out, but its hard to find a radiator shop, so these days its easier to replace

Fiveforwardgears

I figured as much and shops wanted 100 plus for a flush which is insane.

Does anyone know of a how to or pictures on location. Not car illiterate but new to working on a Rotary.

Fiveforwardgears

Wouldn't a faulty thermostat have different symptoms? Wouldn't It over heat completely?

j9fd3s

iTrader: (3)

no, they usually get slow before they fail completely.

Fiveforwardgears

HThat's where I'll start then. Is there any how to on this or pictures? Is it behind the water pump? Where is the water pump located? I'm visual so pics would be amazing. While searching I read there's a drain plug for coolant on the block? Where is that located? Pictures? Thanks guys!

Edit: It would be especially helpful so I could hit the required bolts with some penetrating oil tonight

KansasCityREPU

iTrader: (9)

Please download the Factory Service Manual from foxed.ca like recommenced. It has the pictures and procedures you are looking for.

http://foxed.ca/rx7manual/manuals/19...%29cooling.pdf contains what you want.

Page 3.3 shows the location of the engine drain plug.
Page 3.4 shows the location of the thermostat.

If you do a flush, make sure to turn the heat on while flushing. This will ensure the heater core gets flushed also.

Fiveforwardgears

I really do appreciate the fast response, and didn't mean to ignore his suggestions, I'm bad at reading those diagrams always have been, that's why I was hoping someone Had done a write up.

Cameron38

iTrader: (2)

Definitely think it's your thermostat not opening up all the way. When I start mine cold and jump on the freeway, I can actually see the thermostat open. The needle goes up to about middle of the dial and then suddenly drops down to about 1/3 as the thermostat opens.

t_g_farrell

iTrader: (1)

I'm leaning towards a clogged radiator. Make sure the radiator fins are cleaned up good. Sounds
like its cooling fine when the clutch fan is engaged but at highway speed the ambient air flow is
not enough to cool the radiator. Also make sure you have the bottom pan on that goes between
the bottom of the radiator and the crossmember.

Fiveforwardgears

Is that the metal pan directly under the radiator that obstructs access to the drain plug on the radiator?

I replaced the thermostat, and the radiator cap looked corroded so replaced that too. Problem still persists. Only overheats like you said freeway speeds

t_g_farrell

iTrader: (1)

Yep, that pan. It helps keep the air from running around the bottom of the radiator
and forces it to come through the radiator. Basically creates a vacuum behind the
radiator and helps with cooling efficiency. Many have found if not in place they run
hotter.

Fiveforwardgears

Said pan is still. In place. Problem still persists.

LongDuck

Have you downloaded the Factory Service Manual (FSM), yet? It has great diagrams and Mazda has done the writeup - so you know it's correct.

Several things;

1) the thermostat is located UNDER the upper radiator hose where it goes onto the engine. There are 2x12mm bolts which hold the top coolant outlet in place, remove the hose and those 2 bolts and you'll be staring directly at the thermostat, however - that's not your problem.

2) the real issue is that your radiator is crudded up internally and unable to flow enough coolant to see cool air from the front to cool it. Whenever a rotary overheats at highway speeds, it's because of poor/blocked airflow or a crudded-up radiator.

3) DON'T DRIVE THE CAR UNTIL YOU GET IT FIXED! The first picture you showed is bordering on a severe overheat condition which will toast the engine quickly. Even ONE overheat will ruin the oil control rings, water seals, and a number of other parts that are temperature sensitive - so don't do it. Driving it at the indicated temp in your first post is doing damage.

Also, there was another post on overheating less than 2 weeks ago where we covered all of this, so a search might turn that up. Welcome aboard,

Fiveforwardgears

where do I start? Normal radiator flush? to late For that?

LongDuck

Please start by not driving it - the picture you posted would be enough for me to shut the engine down and get a tow.

After that, remove the radiator and take it to a radiator shop to have it 'rodded-out'; they will unsolder the top tank and run a rod down each of the cooling passages, forcing out the calcium and crap while they run water through it - this cleans out all the passages so it will work properly again. Aside from that, a new radiator would do the trick, too.

t_g_farrell

iTrader: (1)

Or get a new radiator, the restoration of the old one may cost almost as much these days and
it may not last very long. Ask me how I know.

jim_chung

iTrader: (2)

I second the idea of getting a new rad, I replaced mine a decade ago after discovered lots of the cooling fins had just rusted off leading to overheating when stuck in standing traffic.

Carl

iTrader: (2)

RockAuto radiator is less than $150. We have been running them in our 12a race cars for years without any problems, failures or overheating. Just did 1500 miles at Texas World Speedway and temp never went over 190degF. Except when my son was inching his way through impound to get the car weighed. We don't have a cooling fan and even then it only reached 200 degF.

Carl

andernamen

iTrader: (2)

+1

demongo

iTrader: (2)

Is it a drop-in replacement? I've been considering replacing mine, but have seen too many posts about radiators that are *almost* a perfect fit--"just a little bit of fabrication required."

Carl

iTrader: (2)

Yes. They are a direct fit. I just noticed that they do not list the short radiator for the early first gen any more though. Just the long one for 12A with beehive cooler.

Carl

KansasCityREPU

iTrader: (9)

Here's what I bought. Exact fit and great price right now. Free shipping. Use code F51. Price was $116.79 after discount.

CARQUEST or ToughOne Radiator 810097: Advance Auto Parts