Jetlag

Hey Guys,

I need some expert advice regarding my cooling system issues. My FD currently sporting all the bolt on mods. My cooling system consist of a Koyo radiator, AST is gone, fan mod, 70/30 coolent mix,and a 2 row Greedy fmic.

My cooling issue started last week on my way home from work. The temp was around 75, and my coolent light/buzzer came on. My temp needle quickly went up to the red and I shut down the car and coast to the shoulder.

After waiting for about an hour, I added more distill water to the filler. Must have added about 1/4 a gallon. Got on the freeway and drove for another 50 miles before the light /buzzer came on again. This time I called AAA and had it flatbed to my house.

A couple of days later, I went down to the friendly AutoZone and rented their cooling presure test tool. Well, the good news are no visable leak, and presure is holding 18psi. The cap test out okey as well.

After that, I cleaned out my coolent res-tank and measure in the right amount of water/coolent. Went for a 20 minute test drive, and the same problem pops up again?

I've read about the o-ring failure, but there are not signs of water vapor/smoke or coolent smell? The system is holding presure too?

Please give me some advice.

Thanks so much, Jay

7racer

How did you test your cap? How much psi is it?

Jetlag

The cooling system check at 18psi, and the cap at 15psi.

scotty305

iTrader: (2)

Replace the thermostat with an OEM Mazda thermostat, if you haven't done so recently.


Also, check this thread out:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

-s-

Jetlag

I was thinking about the t-stat, but how can I be losing coolent because of the t-stat? The water pump seems to be working as it should, ,not leaks or drips. By the way, I've never had any cooling issues with my fmic.

pomanferrari

iTrader: (1)

Say good bye to your engine. It doesn't leak when you pressure tested cold but as the engine warms up to operating temp, combustion gases go into your system or it get sucked into your combustion chamber. I had the exact symptoms on two engines. Original motor went at 45k; reman at 47K on the same issues. It will get worse and worse until you can't drive any more.

I'm running Evans NPG with a reman now for the last 10K with no issue.

Jetlag

Man, I hope you wrong about this.. If the coolent is being sucked in while the motor is hot, wouldn't I see steam or smell something? I had my wife followed me in her Speed6 and she said no smoke or steam.
I ran the car today at 14psi and I pulled so hard in every gear. I felt really great to go through the gears until I heard the ******* buzzer/light combo. This motor has never overheated or pinged before.

car hugger

iTrader: (1)

I've had several coolant issues all of them hoses. I ordered the hose kit from Ray at Malloy Mazda and it was one of the best things I did. I couldn't replace them all at once but I always had them when I needed them.

My last leak was actually the plastic "quick-release" adapter for the heater core return located under the oil pressure sending unit. There's nothing quick about it, you actually have to break off the old one and either install a new one or clamp the hell out of the hose.

I was having to fill my coolant every couple of days. The light never went on while I was driving, only after the car cooled and I went to start it up.

Pomanferrari could be right about the motor. Get the coolant pressure tester and put it on the car overnight. See if the pressure drops, if it does it could be the coolant seals on the motor. Also check the hoses while they're still warm, some of my leaks would not show if the system was completely cold.

Lastly, check under the oil cap and see if there is excessive white goo. Also get a hydrocarbon test done on the coolant. I can only wish you the best of luck.

gracer7-rx7

iTrader: (16)

search for champagne test also

Jetlag

What champagne test? Someone throwing me a surprize party???? If this is the one you perform after removing the radi cap (engine warm)and let the car idle? Well, my coolent was overflowing out pretty good.

DaveW

The o-ring seals can hold in one direction, and not in the other. So you may not lose coolant, and the pressure test could be OK, but the higher-pressure combustion gasses could force coolant out of the system. Have your cooling system checked for the presence of combustion gasses while it's running.

Dave

red_devil

You might just have air in your system. You said your AST tank is gone? right. If your motor was bad you'll would have a hard time strating it up.. And when it does start up you'll have alot of smoke and it would have like a sweet smell to it... About the thermostat just check the radiator if its cold or hot.. After running the car for like 10 mins if you t-stat is still good your radiator should be hot or warm. If not then you have a bad thermostat..

cesarx7

iTrader: (1)

Maybe you should try this to eliminate or verify a bad coolant seal:

http://www.rotaryresurrection.com/3r...l_failure.html

Jetlag

The t-stat is working because the top of the radiator is nice and hot when it's running longer than 10 minutes. Yeap, no smoke of any kind. The idle is stable/vacumm is good and starts at first try everytime. Although, I would like a new streetport motor, now just isn't the right time for me.

Thanks a bunch guys.

Mahjik

iTrader: (1)

A leaking o-ring doesn't always mean smoke. It is possible to have a leak that burns coolant but not enough to make noticeable smoke. The engine that was in my car when I bought it was like that. I drove it for about 7-8 months before it got bad enough that I was clearing mosquitoes in the parking in the morning.

As DaveW already mentioned, a Hydrocarbon test on the cooling system will tell you for sure if the system is compromised.

Jetlag

Hey Kyle,

Glad to hear from you..I was just doing the seach to find your rebuilt thread. I wanted to do some reseach some of the parts used and the going rated for machine shop work.

I've rebuilt two boingers before, but never a rotary. Wanted to know what can and can be reused in 13B engine, which video to get, I have the FSM. I know that this project is going to be really pricey since I have to replace my wiring harness, porting, hoses, turbos, clutch, mounts, and maybe some plates due to over heating.

As you can see, this why I'm willing to wait for a rebuilt, and start collecting parts slowly so it doen't hurt all at once.

Anyways, I guess I'll be reading up on engine rebuilt from fellow forum members. Any advice on parts used would be great. Are the teflon o-ring any good, which apex seals to go with, factory 2mm cryo or ?

Thanks, jay

Mahjik

iTrader: (1)

Hey Jay,

I wouldn't go rebuild crazy just yet. IMO, I would try to burb the system for a few days and then just monitor the coolant levels. Really as long as your temps are ok and you aren't hiding an Army platoon with a smoke screen, you are fine.

If you have some spare case, the hydrocarbon test would be a good thing to have done just for the heck of it. I can't imagine some shop charging more than $60-65 for it. Most places that do coolant flushes will have the tester.

When/if it is rebuild time, I would stay with OEM 2mm seals. The Teflon o-rings are difficult to work with. Unless you just enjoy pain, I would say with OEM coolant o-rings.

Silverstone

Good thread. Having some of the same issues. Pressure tester blew off like a missle when I had it tested at the shop. Looks like partial o-ring failure. Same as Jay, no major symptoms other than some coolant loss during last summer heat wave. Like Pomanferrari switching to Evans coolant has given my engine new life without coolant loss so if you do confirm the partial o-ring thing I would advise the Evans switch. If you don't put too many miles on your car you could make is last a few more years without the dreaded rebuild. Eventually if I keep my car, which I'm inclined to do, I will have to face the music. Just know that it is real common for the dang o-rings to fail around 50K. No one seems to know why they do this. One theory is that sitting too long dries out the seals and makes them fail early. Mine only had 42K miles on it when I bought it so I'm figuring it sat in someone's garage for a while too long. Ironic that having "low miles" is sometimes the thing that can kill them. Well that's why they say you need to have a good job to get involved with these cars. They are just so beautiful and unique they draw you in. I'm hoping to keep mine forever and see it turn into a sought after classic worth big bucks (the next shelby cobra?). Time will tell.

Jetlag

Well, I've just ordered the RA rebuilt video. I guess I'll watch the RA video 10 times before I tackle this, much like my first **** tape. If I feel cinfident, them I'll take a poke at it.

Mahjik

iTrader: (1)

If you decide to do your own rebuild, take notes when watching the video. That way if you need to refer to something while working with the engine parts, you don't have to fire the video back up and find what you are needing.

I would still suggest getting that hydrocarbon test before cracking open any motors.

Jetlag

Yeap, I'm planning on doing the Hydrocarbon test before I do anything else.