1994 Coolant Leak Near Firewall (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Nov 13, 2017
Threads
9
Messages
52
Location
Jacksonville, NC
This is going to be long: I’ve got a 1994 FZJ80. At the beginning of the month, I flushed the coolant, and changed most of the hoses (3 big ones, PHH, heater hoses and heater valve, and the rubber rear heater hoses in the engine bay on the passenger firewall). No issues until last night with coolant leaks.

Yesterday, I changed the valve cover gasket, plugs, wires, dizzy o ring, dizzy cap/rotor, PCV, etc.

I set off on a test drive around the block, and when I got back to the house I noticed the passenger side lower radiator hose was loose at the radiator and dripping coolant. No issue, says I, and I tightened it down. No more leak.

Today, I drove to work. No issues. Ran out to grab some lunch. Returned to work, and noticed a fairly steady dripping of coolant along the inner passenger side frame rail, right near the cats. I figure it’s my rear heater lines finally going out, so I close the heater valve all the way to keep it from dripping excessively. Top off with coolant on my drive home, and see it’s still dripping. Crawl under, and the rear heater lines are dry. I trace the leak back up to behind the small heat shield that sits on the firewall. Pull it off. Nothing super noticeable. Take a closer look, and notice the firewall insulation in the engine bay on the passenger side, is damp with coolant. I check hose connections at the coolant tee, and they’re all dry, including the rear heater hard line that runs down the firewall to the passenger side of the transmission. I also checked the passenger side carpet inside the car. It too, was dry.

Anyone experienced this before? I’m hoping it’s one of the stubby heater hoses leaking on the backside of the hardline (towards the cab), and I just can’t see it. If that’s the case, I’ll just bypass the rear heater.

No noticeable leaks from the rear heater hard lines that sit just above the cats. It hasn’t leaked a drop of coolant until last night. I’m going to go out in a bit and get under there while it’s running to see if I can spot anything.

TIA.
 
Answered my own question. Got a chance to take a look at it while running. It’s the passenger side heater hose that runs from the firewall to the coolant tee. I guess the OEM clamp was more worn out than I thought. Since I have to remove the hose and replace the clamp, I’ll likely go ahead and bypass the rear heater. I never use it anyways.
 
There are a couple of vendors on here who sell a pre-formed bypass hose. @NLXTACY (wits end) and @LandCruiserPhil. Makes the bypass job so much easier.

Oh yes I’m well aware of both of them (who isn’t lol). And now kicking myself for not just doing the easy bypass when I replaced all the hoses and had everything apart.
 
My truck has this exact same leak, coolant from the small heat shied at the passenger side firewall , just above the exhaust , and right above the frame rail. Inside passenger side floorboard is dry. It only drips when the front heater is turned ON (maybe the rear heated is also turned on too... I never messed with it)

I have never used the rear heater, in which case I guess the best option is to do the rear heater bypass ?

IMG_5804.PNG
 
1997 :

IMG_5805.PNG
 
My truck has this exact same leak, coolant from the small heat shied at the passenger side firewall , just above the exhaust , and right above the frame rail. Inside passenger side floorboard is dry. It only drips when the front heater is turned ON (maybe the rear heated is also turned on too... I never messed with it)

I have never used the rear heater, in which case I guess the best option is to do the rear heater bypass ?

View attachment 2269205

This turned out not to be a rear heater problem for me. It was leaking from the top brass connector pipe on the firewall (the one that goes from the front heater to the return coolant line on the block). It ended up having nothing to do with my rear heater, I just opted to bypass the rear heater to give myself fewer connections in the heater system.
 
This turned out not to be a rear heater problem for me. It was leaking from the top brass connector pipe on the firewall (the one that goes from the front heater to the return coolant line on the block). It ended up having nothing to do with my rear heater, I just opted to bypass the rear heater to give myself fewer connections in the heater system.
Hey. Sorry to jump in here after 2 years!
The brass pipe on the firewall, any input on how to fix the leak? So I need to remove the insulation and then I see the pipe?

Thank you!
 
Can you post up a photo of the area in question?
 
Can't really see anything from that one photo, can you post up more photos
with a couple of close-up shots, showing the leaks?
 
Can't really see anything from that one photo, can you post up more photos
with a couple of close-up shots, showing the leaks?
My problem is that I can’t see where the hole, or crack is because the only visible is the wet insulation and then dripping down by the heat shield. Looking at the photos you put up in your original post, I have the exact same leaks. It’s as if you took photos of my truck and described my leak.
It looks like it all comes from that area. I’m guessing the culprit is the hose going from the thermostat housing away towards the firewall (to the left of the heater control valve).

When you fixed your brass fitting: which fitting was that and how did you fix?

Thank you!!
 
I was not the original poster (OP) of this thread.

More photos of where the leaks are located with some better shots showing
what hoses you've already replaced would help.
 
I was not the original poster (OP) of this thread.

More photos of where the leaks are located with some better shots showing
what hoses you've already replaced would help.
Ah ok! Sorry I thought it was you!

I will take a bunch of photos tomorrow!
Thanks a million!!
 
I found the problem, the pipe leading to the heater core was not round at all and the hose couldn’t cover it properly. Also I pushed the heater hose all the way into the firewall, which meant that the fluid was pushed through the grommet into the backside of the firewall. Hence I could not see that this was where the leak came from.
With advise from legends I used a pointy round wood stick and slowly made the pipe as round as possible, and then clamped the hose more carefully. Now, not a drop leaking!

255CA8B3-5EBF-48F8-A4CC-F657B9113753.jpeg
 
Glad you got it fixed.

As those pipes are soft brass I've also learned to be very careful when removing an old hose that's become fused to the metal. A Hobby (X-Acto) type knife (looks like a surgeon's scalpel) works well to first slice the end of the old hose back lengthwise about an inch in a couple of locations.

Then using my fingers, or maybe a small pick pulling along the long axis of the hose-pipe to get the flap started then gently peel back that flap followed by peeling the rest of the hose off with my fingers. Avoid the use of pliers on those brass heater core pipes.

FWIW

There are many brands, here's one example for future reference:

 
Glad you got it fixed.

As those pipes are soft brass I've also learned to be very careful when removing an old hose that's become fused to the metal. A Hobby (X-Acto) type knife (looks like a surgeon's scalpel) works well to first slice the end of the old hose back lengthwise about an inch in a couple of locations.

Then using my fingers, or maybe a small pick pulling along the long axis of the hose-pipe to get the flap started then gently peel back that flap followed by peeling the rest of the hose off with my fingers. Avoid the use of pliers on those brass heater core pipes.

FWIW

There are many brands, here's one example for future reference:


I hate to put words in your mouth but I believe you are implying is to use the X-Acto knife to only cut through the outer layers of the hose. If you cut too deeply you can score the brass tubes which can cause leaks when the new hoses are installed.
 
Yes, of course, be careful to not cut deeply into the brass pipe. IME however I've rarely seen any significant damage from the small X-Acto type knives I've used to remvoe old hoses. I cut some, then see if I can peel the hose back, then cut some more, etc, incremental steps until I can get the hose to start peeling away.

The shape of the knife can also make a difference, I prefer the type that look like a long 90' triangle, top dull side straight, sharp edge diagonal out to the tip.

Hobby knife blade.jpg



I suppose if a gorilla pulled out a mega utility knife, or KBar, they might damage the brass pipe.
 

Users who are viewing this thread

Back
Top Bottom