Dripping coolant when hot, hot exhaust, anything to worry about?
 

My car has been sitting in the garage since May this spring, while i did some work on it, mostly maintenance and small upgrades (HKS downpipe, fuel filter, air filter, new vacuum hoses, belts, efini Y-pipe, complete 99-spec front). The engine is stock, it has a catback exhaust from Remus. I still have the large middle cat and airpump and stock ECU.

Dripping Coolant:
So the first time i started her up last week i noticed a small drip of coolant from under the car after a while, its only there when the car is hot and the system is under pressure. It comes from somewhere on the engine assembly, and drips down on to the Turbo Control Actuator. It may or may not have been like this for a long time since i dont park it where i can notice things like this often. Anyone got some pointers to what it can be and if it is a problem or not? As of now my plan is to just keep the overflow tank filled up and keep an eye on it.

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Hot exhaust:
Secondly, i am worried about exhaust temps. How much heat should i expect from the rear mufflers? After a quick drive yesterday i parked the car and the rear muffler tips was very hot (i would burn my hands if i touched it, and the bumper was also hot) Also given that i have never really checked the temps on it before i dont have a benchmark. My first thought is that the HKS downpipe with exhaust bandage will move some heat that used to be trapped in the engine bay, back towards the muffler.But i also know that hot exhaust means its running lean, but i also know that rotary exhaust is supposed to be hot. So i dont really know, but my fear is that i may have bungled up the vacuum somehow, and its running lean because of that. Is there ny way to check if its running lean except getting a wideband? Also, i am worried that my rear bumper is gonna start melting.

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Thanks for any help :) #rotaryparanoia

I have had a similar coolant drip on my FC that caught fire.

What happens is the coolant evaporates/cooks off the hot exhaust parts and leaves a powdery white substance. This is powder can be ignited and burn from the hot exhaust.

When new FDs burned to the ground taking out peoples garages so Mazda did some recall work to the cooling system.

Just letting you know worst case scenario...

A dripping coolant line is always a thing you should worry about.

Your coolant system looses coolant which is especially in case of the rotary engine a big problem. The coolant system should be a closed circle though :nod:.

Got the coolant system on my to-do list next year. Hopefully it will last until then :) Not driving more than a couple thousand KM each year anyway.

You might have bumped one of the turbo coolant feed/return lines when installing the y-pipe.

^Agreed. Look at the turbo coolant lines. If you "bumped" a healthy line they wouldn't leak. But they tend to swell with age and heat. They're a little bit of a pain to change but not expensive.
The only other thing I can think of that might leak in that area is the small section of coolant line on the rear of the water pump housing that going to the throttle-body.

I would NOT let it go too long. Fire hazard aside, it's only leaking now, but it may fail.

It's summer, your exhaust temperatures sound normal to me.

And here i was hoping to drive the car at all this summer :D Better get to ordering those hoses :)

That looks like it's coming from a heater hose that connects the pipe on the passenger side frame to the water fill neck. That should be easy to replace with the intake removed. If all the hoses are original, they should all be replaced. There are three other heater hoses, two small hoses at the firewall on the passenger side that connect to the heater core and one on the driver side that runs from a quick disconnect to a pipe on the firewall. Those can be a pain to get to, but are doable. If you are really worried about the hoses breaking before you can get to them, you can bypass the heater core by running a hose from the driver side quick connect to the water fill neck. However, that won't help the other coolant hoses, the worst being the AWS hose that runs from the rear iron to the TB. The other AWS is from the TB to a tube right under the TB.

The FSM and parts fiche should detail all the hoses.

Don't drive the car with a coolant leak, period ;)

This probably is a good time for a Koyo N-flo i guess? :)
No point in doing half the cooling system :P

Look at the coolant hoses connected to the turbos, the top one fails at a high rate. It can have foam around it hiding a major failure waiting to happen.


https://cimg0.ibsrv.net/gimg/www.rx7...b953cec839.jpg

I will order a full set of hoses and do all of them while at it :) thanks for the image! Its super helpful to identify where stuff is while the engine is in the car.

Are the ones i marked in red the turbo hoses? Do you have more images of this engine from other sides so i can see where the rear iron hose is connected?

https://cimg7.ibsrv.net/gimg/www.rx7...a64a8382f9.png

Yes, those are the turbo coolant hoses. There are thousands of pictures of engines we have built in our customer gallery

Banzai Racing Customer Gallery

Forgot about those suckers. Post #2 from the below thread has a good colored FSM diagram that shows the hoses (except the heater hoses)

https://www.rx7club.com/3rd-generati...thread-571088/

Thanks! Both of you:D

FWIW...the nipple visible here on the rear iron is for the throttlebody coolant hose. And I wouldn't use traditional rubber coolant line if replacing. Jegs and others sell reinforced silicone in 3/8" (10 mm) that will stand up to the high heat much better IMO.
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http://www.jegs.com/i/Vibrant+Perfor...FQYIaQodm_kOOg