'85 4RNR heater core interchangable ?

[xcuzzi]

I have an '85 4Runner SR5 w/ AC and I have done away with the heater in the center console and installed a Tuffy Security Console. I know from the parts guy that there are two heater cores available. There is the one I have already, AND there is the one for the 4Runner that only has the front heater. The single heater model is a bit bigger (WARMER ?). Since I have done away with the rear heater I would like to replace the front heater core with the larger one . . .

Are they interchangable ??? If not, what modifications can I make to be able to install the larger (WARMER!) one ?

Appreciate any help I can get on this, Thanks !

 

[85straight]

I have a front heater only and it works almost too well, especially around here. Changing out the front core is a serious PITA. Id avoid it at all cost

 

[xcuzzi]

Yeah, I know . . . I have dug into the dash already but not that far.
I am gonna try and hook up a hose and blow out the heater core as best I can first. I was just thinking if I am gonna replace the core I would go for the best one possible. I would still like to know if the bigger heater core would fit.
Thanks!

 

[85straight]

Oh i misread your post. If your going to replace it anyway i don't blame you for wanting to put an upgraded unit if possible. I do not know if the larger would fit but if you can't find a definite answer don't do it and hope for the best.GL

 

[xcuzzi]

This car is my DD (although I do have a motorcycle). If I tear the dash apart, I want to have the part on hand so I can minimize downtime. The small one is only $35 and the larger one is special order/$140/none returnable. I am gonna try and blow this one out this weekend and see what difference it makes. Thanks for the input !

 

[BigBluePile]

That job is a pain in the butt.

IIRC, the bigger core is LONGER not wider. When I did mine (rear heater option) I think there was a foam block in the bottom of the box to support the core. I would check the specs (RockAuto Parts Catalog) and see what the difference is. I spent $80-90 at Napa on my core and rockauto had the same core for $35...

 

[nevada]

That job is a pain in the butt.

IIRC, the bigger core is LONGER not wider. When I did mine (rear heater option) I think there was a foam block in the bottom of the box to support the core. I would check the specs (RockAuto Parts Catalog) and see what the difference is. I spent $80-90 at Napa on my core and rockauto had the same core for $35...

w/ Rear Heater; 7 7/8" Tall x 5 1/4" Wide
w/o Rear Heater; 8 1/2" Tall x 6 1/2" Wide


as to whether it will fit, I cant say. the last time I swapped, I changed the entire heater box, with one I already had. honestly, until this thread, I have no idea they were different sizes.

as said above, its a big job. I think I had about 6 hours into it when I did mine.

 

[BigBluePile]

I wish I had pics of mine when I changed it out. I do remember having tons of room and I used closed cell foam tape around the core so it would sit securely in the box.

Google images came up with a ton of info

 

[xcuzzi]

Thanks for the replys guys . . .
I took the input hoses off this weekend and blew out the heater core with my water hose from both directions. During the ride to work this morning in 50 degree temp the cab was mildly . . . faintly. . . warm . . .
Not the result I'm looking for. I think the core is partially blocked so I guess the only option I have left is to remove the core and replace it.
Still trying to figure if I can use the bigger core. Since I have the dimensions, I may be able to tell when I get the dash torn apart if there is room.
We're headed to Anza Borrego and the Granite Staircase Saturday so I will not get to it for a couple weeke

 

[nevada]

Thanks for the replys guys . . .
I took the input hoses off this weekend and blew out the heater core with my water hose from both directions. During the ride to work this morning in 50 degree temp the cab was mildly . . . faintly. . . warm . . .
Not the result I'm looking for. I think the core is partially blocked so I guess the only option I have left is to remove the core and replace it.
Still trying to figure if I can use the bigger core. Since I have the dimensions, I may be able to tell when I get the dash torn apart if there is room.
We're headed to Anza Borrego and the Granite Staircase Saturday so I will not get to it for a couple weeke

you could try a chemical cooling system flush first. it may break the crud loose, and get some more coolant flowing through the core.

in fact, me personally, before changing the core, I would flush it several times.

 

[xcuzzi]

Okay, I will give the chemicals a try . . .
any flavor or technique in particular ???
just a general cooling system flush ?

 

[nevada]

Okay, I will give the chemicals a try . . .
any flavor or technique in particular ???
just a general cooling system flush ?

we usually use the prestone stuff.

just follow the directions on the bottle. I suggest doing it 2x in a row.
meaning 2 complete flushes based on the directions.

it will take several hours, but most of that time is waiting for it to cool down, and for it to drain.