I'm trying to track down a coolant leak on my '93 FD. I have coolant (anti-freeze) collecting and dripping from under the car at the front of the right side frame rail, under the passenger footwell. I can follow the heater hose lines from the engine to where they go through the firewall, they are clean and dry, and so is the engine bay side of the firewall below where the lines pass through. I'm thinking this is leaking behind the dash at the heater core, but when I look under the dash the trans tunnel and all carpeting, floor mats, etc are dry. I've pulled up the carpet in the passenger footwell and the upper surface of the floorpan is dry. I'm not smelling antifreeze in the car when I drive, but there is always a puddle under the car when I go to drive it.

I don't want to go through pulling the entire dash to check the heater core if that's not the most likely place to find the leak. Where could this thing be leaking that allows the interior to stay dry? Do the hard lines of the heater core stick through the firewall or are there hoses/connections between the core and the firewall? Is pulling the dash my only/best option?

The car has not overheated, I've been topping off the system religiously since I noticed the leak.

(yes I searched the site archives...)

TIA,

 

Is it a lot of fluid? If your having to fill the car back up thats not good. Have done any recent work on the car?

Do you still have the under tray thing on the car? Its possible fluid is dripping on it and then running backwards making it appear the leak is farther back than it really is.

 

There are a couple of heater hoses but they are on the driver side . FSM page E-2 will show you location. Check the water hoses on the engine and the radiator hoses - example on page c-85. There are a couple of connections on the pass side - kind of a rats nest. E2 will show you routing. Pull the undertray and get a good location - cardboard or newspaper under the car. +1 on run down the tray.

 

The most likely are the turbo coolant hoses, but the throttle body hose going to the rear iron is back in that area. If you don't know how old the coolant lines are it's time to replace them. Cheap insuance in my opinion.

Paul

 

I've had several leaks over the last year from different hoses. The best way to find the leak is to get the system pressure tested. My most recent leak came from the plastic disconnect on the drivers side under the oil pressure sending unit.

 

My guess is the hose right behind the UIM. Often when they leak they will spray water at the top of the transmission tunnel. It will run down and look like it is dripping from where you see it.

It runs from the right side of the rear iron to the TB right behind the UIM.

Dan

 

i had coolant leaking to a similar location. i checked all the hoses in the area of the turbos and UIM etc. bone dry. turned out to be a small leak from the water pump housing. you may want to check there if you don't find anything at the other locations.

in your case though i would imagine its one of the ones near the rear of the motor

 

Update - I initially only pulled up the carpet at the front of the footwell by the tunnel and at the side by the door sills. This morning I removed the passenger seat and lifted the carpet, and found coolant on the floorpan. The foam pad under the carpet has soaked up some of it, I guess that's why I didn't see it at first. Still surprised I couldn't smell it. So it looks like the leak is inside the car, behind the dash. I don't have an undertray (was not installed when I got the car) and all hoses/connections under the hood are dry and clean.

I've found FAQs for removing the instrument pod, are there similar writeups for what needs to come out to access the heater core?

 

See if this thread helps:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/leak-not-water-under-passenger-seat-519034/

 

Thanks for the link. My problem is definitely not the AC drain (since AC doesn't work) nor rain getting past weatherstripping, the leak is a nice antifreeze neon green. That link did lead me to this thread https://www.rx7club.com/2nd-generation-specific-1986-1992-17/new-heater-core-126038/ so that should help.