It was freakin black. It looked more like oil then coolant. The guy that owned it before me must not have changed the coolant or something. So i filled up the radiator with water and let it drain a few times untill clear water came out. Then i filled it up with presone 55-45 mixture and water wetter. It runs a little cooler now. I think. I plan on flushing the system when i get my aluminum radiator and probally run that special stuff that starts with an N i forget what it's called, but i mean damn. Black coolant. I was like

 

I don't know much about coolant, but I know enough to know that it should not be black at all. Have you ever had the coolant light go off yet? Did you actually look at the coolant upclose and your sure it was'nt oil in the coolant? If your sure and everything is fine and she running how she's suppose too then I would'nt care if it was black, brown, blue or green as long as she's fine! J/K don't listen too me.

 

lol, yeah it wasn't oil that i know of. I just think it was burned if that is even possible. But no i haven't had any coolant lights or any temp problems. But im sure having black coolant couldn't have been a good thing.

 

well black coolant cant be good. whats it taste like. i was about to tell you to lower the water to antifreeze ratio, then i noticed you were in deleware. you should drain and flush it again because of the water wetter. this stuff has been (i havent heard of it personally, just read about it) known to eat coolant seals. a bad coolant seal in a rotary is a big no no. get rid of that stuff fast man.
kris

 

uh oh, not good. yeah ill have to do that probally this weekend. What is a good way to flush the system????? I've never done it before. I know it's easy but could someone fill me in.

 

can some on confirm this or not confirm this, because it's really bugging me now. Im at work and it's only been like 7 minutes since i read what suprfast wrote.

 

I've never heard of water wetter eating coolant seals since I've been on the forum.

Anyway, if it is oil in the coolant, the oil will not mix with the coolant; it will separate into two phases. It is also possible that the previous owner put some sort of stop leak stuff in the coolant, which is black. At least the stuff I used was black.

 

Go to http://www.rx7turboturbo.com/robrobinette/flush.htm

I use Water Wetter...never heard of eating coolant seals???

 

The stuff you are talking about is the Evans NPG+, I converted to the 7psi system and the coolant light never came on again. This stuff is suppose to last 500,000 miles.

 

how do you flush the system to get out the water? That evans stuff doesn't mix with water. I've got three gallons and am about to make the switch also.

Matt

 

It gives you detailed instructions on how to flush the system at www.pineappleracing.com

Garrett

 

You first flush out the system with water (lots of it)and let it drain (both at the rad and the engine block). Then fill the system with Sierra (propelyne glycol) coolant, run the car for a few hours (or days) with the heater on high (this flushes out the heater core). Drain again (don't flush with water this time), fill up with NPG+ and your done. (If you are totally **** about it, drain again after a couple of days, and fill with NPG+, it's just going to cost you another 70 bucks.) Have fun.

 

I've seen other people say this, and it makes absolutely no sense to me. Unless the RX7's heater system is different from other cars, coolant flows through the heater core constantly, regardless of where you have the heater temperature. Moving the heater temperature simply opens/closes a door in you ventilation system that allows air to pass through the heater core and into the cabin.

 

one other thing, how do you flush the water/coolant out of the block?? I know there is a drain plug on it i think near the spark plugs. But once you drain it out how do you fill it back up since the thermostat doesn't open up untill the car is hot and once that happens the radiator would be empty. Or im just stupid. Can someone please clarify this for me. Or does the coolant filler cap go into the block? I dunno but yeah i am gonna switch to Evans NPG+ when i purchase my fluidyne radiator.

 

Tehre is a heater control valve on the system to control the amount of coolant that goes through the core.

 

I've seen (forgive me, but I was young and didn’t know better) piston engines with hoses that were so old and rotten that they were causing the water in the cooling system to be stained black, but I don't think the water got as black as described here.

My point is that hoses can deteriate on their inside, but still look OK from the outside. Since you need to drain and flush the system again anyway, I'd sure think about replacing the all of the cooling system's hoses at the same time. And assuming stock twin turbos, don't forget the two there.

 

Take the thermostat out from the housing (filler neck) and re-attach the neck. Close the radiator drain plug now flush away. Put a new thermostat back when you re-install.

 

so do i fill it after it take the thermostat out, and then run it for like 3 minutes? Im so retarded about some things. But i definately don't wanna mess this up.

 

just had my oil changed and the guy checked my coolant and it had some light sludge. I asked if it was common and he said it was very and it is caused by the breakdown of the coolant.

FWIW.

 

yeah, slimey sludge is common in old coolant, but not black.
scrub, my opinion is that the previous owner filled the coolant with that black powder you add to seal engine block cracks, do you know the stuff?
that stuff will completly liqiufy and tint the surrounding water black after many miles.

 

It could be, but the engine is running great, i don't think that it's had problems. Hopefully at least.

 

Don't run the engine after the t-stat is out! Only flush with clean water until you see no traces of old coolant anymore, make sure to drain as much as you can. Then re-install the new t-stat and drain plugs and refill and purge the air out.

 

For this much trouble I would just take it to NuCar Mazda on R1 13 in NewCastle, DE. They can flush it for you. And they've been working on rotaries since they came out in the early 70's and have a dedicated mechanic who works on RX-7's (before someone flames me for sending them to the 'dealer'). I let NuCar do this type of maintenance for me . They should do it for around $40 with the coupon from www.nucar.com http://www.nucar.com/parts-service/s...ce%20-%20Mazda Just go to www.nucar.com and to parts and service, Mazda.

 

oh okay sounds good. Im pretty sure that i can do it myself and save some cash for other parts. But i alwasy go to nucar for all the OEM parts i need. There pretty cheap too.