Found another coolant leak - heater core (Page 1/4)
Cliff Pennock SEP 28, 08:08 AM
As the title says, I found another coolant leak. It's coming from under the dashboard, passenger side so it's the heater core.

My 86.5 GT V6 has no A/C, so is this the one I need?
82-T/A [At Work] SEP 28, 08:34 AM

quote
Originally posted by Cliff Pennock:

As the title says, I found another coolant leak. It's coming from under the dashboard, passenger side so it's the heater core.

My 86.5 GT V6 has no A/C, so is this the one I need?




Yes, and also Cliff... get new heater core hoses. There are two, and they're not very big... I just tried looking them up and my head hurt. But basically they're two (less than 1 foot long hoses each) that connect the heater core to the two smaller coolant pipes that run the length of the car next to the gas tank (not to be confused with the big ones that run under the sides of the car).

If you've never replaced your heater core before, then you'll likely end up destroying the hoses (or they are already destroyed) when you remove them... and you'll want to have them replaced anyway. Easiest way to get them off is to slit them down the side with a razor, and then you can just peel them off the heater core outlet/inlet.

They should be like $10 bucks each. They are specifically molded for your car, but they sell replacement hose cheap at the local auto parts stores (at least here in the US). The majority of the cars I've seen here in the US that are that old, they usually just replace them with these aftermarket "one size fits all" hoses.
RWDPLZ SEP 28, 09:20 AM
X2 on the hoses. Replacing the heater core on a non-A/C car is even easier than an A/C car:
Cliff Pennock SEP 28, 03:32 PM

quote
Originally posted by 82-T/A [At Work]:

They are specifically molded for your car, but they sell replacement hose cheap at the local auto parts stores (at least here in the US).



Are they on rockauto perhaps (since I'm going to order the heater core from them anyway)?
olejoedad SEP 28, 04:41 PM
The hoses are not held on with clamps, they are crimped on to the aluminum heater core lines.

Corrected this bit of misinformation, sorry guys!

Thanks Patrick!

[This message has been edited by olejoedad (edited 09-28-2023).]

Patrick SEP 28, 04:46 PM

I've replaced numerous heater cores on several Fieros over the years and never had to replace a hose yet. I find that the hoses have more than enough extra length to easily allow the sacrifice of a half inch (or more) during removal. I make a very short slit, stick a small pick under the rubber to get it partially loosened, and then grab hold with my hand and twist that sucker right off.
Patrick SEP 28, 05:02 PM

quote
Originally posted by olejoedad:

The hoses are not held on with clamps, they are crimped on to the aluminum heater core lines.



Joe, are you sure? Is it perhaps different for '88? As stated in my previous post, I've never replaced a heater core hose. However, earlier this year I was dealing with a slight coolant leak with my Formula. I took this photo of it, and not only are the clamps obvious, but there's even a ridge evident on the metal tubes indicating where the rubber hoses need to be pushed up to. I'll admit that I have no way of knowing this car's previous history prior to my acquisition in 2013, but judging from the rest of the car, I'd be surprised if these heater core hoses were not original.


quote
Originally posted by Patrick Here:
olejoedad SEP 28, 07:37 PM
Patrick, you are correct.
I just checked an original low mileage 88 GT that's on the rack in the shop.
It's only got 31K on the odometer and the hoses are clamped at both ends.

Thanks!
fierogt28 SEP 29, 10:33 PM
I have replaced a non -A/C heater core 3 times in my over 20 years owning Fieros. And 2 on the same car.
The issue is the heat will stick the hose to the copper core tube. Making it very difficult to remove and lots of effort and muscle to remove.
Something I just tried this year on installation of the new heater core is to apply silicone grease on assembly of the hose. This might make dis-assembly easier than a Fiero with a fail heater core with less than 10,000km.
But was replaced 13 years before.
My conclusion is I probably had old / contaminated coolant. I still believe the coolant was original coolant or from 1994 or earlier. That’s really old.
I did flush the coolant completely, and put new 50/50 Peak antifreeze. (Green)

------------------
fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

Cliff Pennock SEP 30, 07:39 PM

quote
Originally posted by Cliff Pennock:

As the title says, I found another coolant leak. It's coming from under the dashboard, passenger side so it's the heater core.



So yeah, that was the last time I drove the Fiero. There were only a few drops coming from under the passenger's side dashboard.

Today I was on my way to a birthday. First time I drove it since Thursday. After about a mile I see my temp go up like crazy, past the red. And steam was coming out of the vents. So I quickly parked the car. Looked under the car and saw it was loosing a lot of coolant. Now the thing that suprises me, is that there wasn't much coolant leaking under the dash. Everything came out from under the car. So did the heater core fail, or the hoses, or what?

I still need to get the car home so I can work on it. So what is the best way to bypass the heater core? Can I simply loosen the hoses and plug them? Or do I need to connect the hoses together?

And do I need coolant or can I just use tap water (just to get it home)?