Hello everyone I've got a heater core question, my 1994 v6 4x4 is blowing steam out of the defoster and I'm getting a lot of fog on my window but it doesn't smell like anything but I am in fact going through coolant quite fast. I am not seeing any leakage on the passenger side floor and I do have heat. I know replacing the heater core is a big job so before buying parts I just want to verify it's not a smaller part of the heating system? Truck has no a/c One thing had changed ive been pulling a snowmobile trailer and it seems to pump out the stream when under heavy load like in the beginning of the tow or backing up.
thanks in advanceAdam

 

Have you checked your hoses and connections?

 

Do you mean under the hood? No I have not, I thought it would be under the dash if anything was wrong? I don't understand how the antifreeze is being turned to stream without a leak. One thing had changed ive been pulling a snowmobile trailer and it seems to pump out the stream when under heavy load like in the beginning of the tow or backing up.

 

The heater core pipes connect to the heater hoses under the hood at the firewall. I have seen the hoses leak at this point and the coolant ran along the pipes into the heater core compartment behind the dash. This didn't cause much steam, just foggy windows and a slight coolant odor.

When the actual heater core develops a leak (inside the dash), this can produced a lot of steam from the vents on a cold morning. My money would be on a failed heater core if you're getting visible steam from the vents. Feel the carpet around the transmission hump area under the dash. You'll have to put your hand pretty far back in there.

 

Thanks, are there any videos on here on how to change it? I can't seem to find much on youtube

 

I haven't seen any videos either. The entire dash comes off, steering column disconnected from the main dash support, HVAC controls and radio support/brackets removed, dash support removed. That exposes the heater and AC evaporator case, they are connected and it can be a tight squeeze to allow the heater case to lean back away from the firewall enough to remove the heater core. There used to be some posts on here with more step by step photos, but photobucket seems to have removed most of them.

I have done this twice on my 95, unfortunately. I got a brass/copper Spectra 94791 unit the first time and it started leaking after several years . At some point Spectra started making the 94791 out of aluminum, I bought that one around 2017 and so far so good...

I never documented the entire teardown and install, but here a few pics I saved from the first time to give an idea... https://www.yotatech.com/g/album/20936509

Edit: It is a bit of a process, so I'd definitely make sure you need to do it. Did you find any moisture under the center dash area/transmission hump? I had a hard time detecting it at first, if I recall correctly, what finally did it for me was lifting up the edge of the carpet and the foam mat underneath was damp.

 

Mine did the same thing. All it takes is just a tiny hole in the core to let a little steam fog the windows.

I just gave up and had the shop do mine. It took a skilled tech a whole day to get it done properly. The whole dash has to come out and the steering wheel has to be dropped. I know there is a way to maybe to it without dropping the steering wheel, but you have to know the puzzle pieces perfectly to make that happen. I think even once the dash is out, the heater core is still a royal PITA to remove and clean up all the coolant.

The shop I had do it wanted to do some tests to verify that it was coming from the heater core, but I told them to just replace the core with no testing. I didn't have anything leaking onto the floor, but once the tech got into the dash, he spotted the damp areas where it was leaking.

 

It is a job I never want to do again so I made sure to buy another OEM one:

 

 

Yep, that looks very familiar.

I don't think so. The dash support has to go. It blocks everything, and steering column is bolted to it.

 

Another key factor to be aware of is fitment, especially the pipes through the fire wall. Many of the replacements don’t fit correctly. I had a terrible time with both my 86 4Runner and 95 pickup finding cores with the correct pipe bends. Also, make sure the little o ring where the pipes meet is replaced and the tiny brass clamp is good. With my 95, fitment was such an issue that I wasn’t comfortable with the angles and the o ring connection. So, I cut the pipes and fit a coolant hose with clamps in there to be sure it wouldn’t leak. I suspect I’ll be doing it again at some point and try to have a solution that is fail proof. If you can find oem or have it cleaned and repaired, I’d do it.

 

Any progress?

 

Where did you find the OEM one? Mine just started steaming through the vents and I think its a heater core. Cant find OEM ones just the cheap $60 OE ones