Heater Core = Grenade!

[psu_Crash]

So I was so excited to be driving my newly MPI Starion ... and I got about 10 miles on it before the heater core came apart like a bomb! I was driving around just tuning MS not really getting on it at all and my windshield started to fog on the inside. Uh oh ... I knew what that meant but I wasn't too concerned until about a mile later when all of the sudden the Niagara Falls of coolant coolant starts to dump on my feet and spray the windshield!!! So needless to say I parked the car immediately to avoid any serious damage. It got to about 235 degrees according to MS but only for maybe a minute before I shut down so I think it should be fine.

 

I have had heater cores leak before but never like that. Upon further inspection once water stopped spraying everywhere I can see the metal nipple on my firewall is split and I am assuming it split inside too. What would cause this? I had the defrost on and the heater was working fine with car temps normal. For now I am just going to run a line and bypass the core. Looks like a real PITA to change.

[IntercooledFlatty]

...it is

[GCNTSi]

I don't think there is any other way but to remove the entire dash to replace the heater core. I'd also recommend replacing the other shorter hoses on the unit while it is out, when mine started leaking it was one of those hoses on the top that had split, and I did remove the complete dash. It's a time consuming job, but you should take your time or you will probably braeak something.

 

But you say that you can see a split in the pipe on the engine bay side? Sounds like the pipe may have been crushed and bent back, maybe more than once. This is why it is best when pulling a motor not to remove the heater hose from the firewall, or else do it very carefully, they are a tight fit and it is easily to bend the pipe up on the inside of the hose trying to pull the hose off with pliers. This is why if you must remove that hose, you should cut it off with a razor blade.

 

Here's a picture from the FSM of the bolts/screws to remove in order to pull the dash out, and I drew in some more that weren't marked.

 

 

And when you re-install the dash check to make sure the vent rods are in place before bolting it all back in place. Mine got stuck behind the dash so it's always open to outside air, by the time I realized it I wasn't going to pull the dash back out to fix it.

 

-GCNTSi.

[psu_Crash]

Thanks for the diagram! That will be GREAT!, the manual (Chilton's) isn't really clear.

I planned to pull the dash off eventually to install my set of white face gauges, and add a few things, but for now I just bypassed the core. Once snow flies she will be getting ripped apart for a paint job so that will be a good opportunity to pull the dash without a time limit.

 

I thought maybe the connection on the firewall had been bent too. Now I don't think so, I think it just split for unknown reasons, like being 22 years old. There is a small outward curve to the pipe where it burst.

[Edde]

Probably froze there. Sucks.

[TopDawg_43]

I gotta change my heater-core too. It's been by-passed for about a year now. I got a spare heater box, I'm going to change all the hoses and everything before I tear into the car. This will be a one time thing. The next time, the car will be up for sale!!!!

 

And I'm sure that diagram will REALLY help!!!!

[Indiana]

That split may have just let the coolant get past where you had the clamp and the core is fine. I'd remove the gromment from the firewall and look, you can insulate the firewall with something and as long as you feel comfortable doing it, just solder that crack back up its a copper tube and will accept that weld easily and you not have to remove the dash. Important part is to make sure you don't blow flame directly into that opening and have the car set on fire. Maybe you could push some steel wool into the crack to keep the flame from entering. Its an all day job to take that dash out and fix that

[Edde]

^^ now that's an excellent suggestion.

[psu_Crash]

I pulled the grommet off the firewall and it looks like it is just cracked about an inch from the flare. Should be able to solder that without issues. Ran a line to bypass it for now so I can get some tuning done on the new MPI setup. Sometime next week I will tear into it.

 

Thanks for the suggestion Indy!

[Shelby]

i don't have the quest manuals back on this pc yet after reformating but i seem to recall the heater core does not run all the way to the fire wall,,the out side hose pipes are part of a water valve and if mem serves me theres another rubber hose from there to the actual heater core ,not 100% positive on this it's been too long sence i was actualy looking at one

[Technology]

I would hope not, Shelby, but I have seen a heater core from a '98 expedition and there was no valve in it.

 

I think the HVAC system just opens a door or something, and there's always hot coolant running through it, but I could be wrong, I've heard of the valve before, and older VW's have a valve out in the engine bay doing the same thing you're talking about, so it's not impossible.

 

OP, post pics when you take it out.

[StarquestRescue]

88-89 shown. Earlier cars had a temp switch on the water valve pipe. Newer valve pipe can be used on older cars. That short rubber hose and valve should be checked for leaks. When i pull a dash i remove the steering wheel and the turn signal assembly and loosen the steering column bolts under the dash. Take your time it is easy to miss a fastener or wire plug some where.

 

http://i237.photobucket.com/albums/ff45/StarquestRescue/c9dcdcde.jpg

[Lusion972]

wow..that is alot of work to go through to replace it...can one run the car with out it and just bypass it completely? Will it have any harm on the car? Also, I removed the blower motor and evaporator out of the car and dont really feel like putting it back on...can I still have the coolant go through the heater core and not have leakage?

[Edde]

wow..that is alot of work to go through to replace it...can one run the car with out it and just bypass it completely? Will it have any harm on the car? Also, I removed the blower motor and evaporator out of the car and dont really feel like putting it back on...can I still have the coolant go through the heater core and not have leakage?

 

Just about every car with ac is like this. Heater core = all day job.

 

You can bypass one forever as long as you don't mind being cold or live in warm weather. Keep in mind that you can fail safety inspection without defrost, though.

[TM]

I'm in the middle of trying to replace my heater core, as I got the window fogging too. (Thankfully no granade! -Antifreeze is kind of difficult to get out of the carpet and everywhere it finds.) But I've run into another problem - or two. First of all a source of a new heater core. Mitsu disconntinued them; n/a from NAPA; Carquest oredered the last 2 in their inventory - the first was damaged and the second had problems too. -Like the pipes being smaller in diameter, making the hoses between the control valve and 1 under the hood useless. Then found the long twisted pipe which goes out wasn't soldered in place correctly. The fin density was much less dense than the OEM too. And if all that isn't enough, the OEM has a self adhesive foam seal around it, which was not included and I don't believe listed separately in the Mitsu part book. I'm told some use that camper seal foam to fashion an equivalent seal.

 

I'm told they don't rebuild heater cores anymore, or at least of this design, and with the nightmare it is to remove it, I don't want to take a chance on another hole, just due to the age and miles on it. Has anyone found a source for these? Or have any suggestions on the seal?

 

BTW, the 1989 SM is very poor on both the dash and heater removal! The diagram posted earlier on this thread is vague and flat wrong in a couple of cases. I found a SM for an earlier model which was a little better, (identified bolts from screws and speed fastener) but have no idea what the letter designations were intended to convey on this diagram. Letter designations are used for some of the components that must be removed prior to the dash, but I don't see a relationship to the ones on this drawing. I've done a lot of work on my car since buying it new, but this is the worst! One big hint for someone who has never removed their dash, is that the framework under the steering wheel and glove box are removed with the pad. You do not need to remove the phillips head screws attaching the dash pad to them, but instead remove the ones which attach the inner end of each to the center support. (a minor point that was omitted in the SM) The screws to remove from the bottom edge are those holding the ducts to the back side of the metal frames - much nearer the ends of the dash than depicted.

[StarquestRescue]

I ran into the same issues. I ended up having a radiator shop repair the new core and got the foam at the hard ware store. I trashed some of the soaked felt and replaced it with some i got from JC Whitney. I think the letters in the fsm indicate the fastener type. If you look hard enough you should be able to find some one to re core the old one. New hoses and some silicon heater hose should help with the pipe size issue. Edited September 27, 2008 by StarquestRescue

[Lusion972]

Get with Texan88 on this forum...he should have 2 or 3 heater cores coming available