m_walker26 Reader
10/17/19 3:41 p.m.

Help!  I just installed a new radiator on my 94 Miata (that has an Acura V6 engine by Superfast Miatas) and the heater core now has a drip into the drivers side footwell.    I would like to try to cure without pulling the dash or other major surgery.    I don't remember (can't find) the Stop Leak type product there was a lot of love for in a not too long ago discussion.   I would like to try it before doing a lot of underdash surgery.   Does anybody remember the name of the product?   Do you see any problem with trying it with a brand new radiator before addressing the problem the hard (correct) way?   Thanks for the help.   Mark

93gsxturbo SuperDork
10/17/19 5:00 p.m.

Fix it right or loop the lines till you can.  Stop leak is just gonna give you more headaches down the road.

MulletTruck HalfDork
10/17/19 5:19 p.m.

Wih the amount of effort the stop leak takes and the possible headaches down the road I would say change the heater core and enjoy the comfort of defrosters and knocking the chill off since its coming up on winter.

Rodan Dork
10/17/19 5:31 p.m.
93gsxturbo said:

Fix it right or loop the lines till you can.  Stop leak is just gonna give you more headaches down the road.


Error404 Reader
10/17/19 6:13 p.m.
Rodan said:
93gsxturbo said:

Fix it right or loop the lines till you can.  Stop leak is just gonna give you more headaches down the road.


This this.

To elaborate, if you half-ass it then it will come back to bite you in yours at the least opportune time.

stuart in mn
stuart in mn MegaDork
10/17/19 6:20 p.m.

When I was young and poor I used Bar's Leaks to fix a leaky radiator.  It worked, but besides plugging leaks it can also clog the cooling system.  If this is a stopgap procedure before you put in the new radiator give it a try, but I wouldn't use it after the new radiator is installed - you don't want to gum it up.

L5wolvesf New Reader
10/17/19 7:07 p.m.

IME, those products can also stop the flow of coolant through the cooling system too.

PMRacing SuperDork
10/17/19 7:16 p.m.

It's a 3 hr job to swap heater cores taking your time. Also, check to make sure you didn't oval the pipes poking out of the firewall. If you do that it can cause leaks even if the hose clamps are tight. Use a socket on the inside to make them round again. 

_ HalfDork
10/17/19 7:50 p.m.

you can simply cut that heater pipe back some and just use some chunk of heater hose to join them back together. Makes replacement super simple. 

ShinnyGroove Reader
10/18/19 10:11 a.m.

The aluminum heater cores from the NB cars are more durable than the copper ones from the NA cars, and they drop right in.

WonkoTheSane SuperDork
10/18/19 12:15 p.m.

Yeah, check to make sure that you actually have a good fit at the heater core hose (by the exhaust manifold).

I just replaced all coolant hoses last week in my track Miata..  I used all new Mazda coolant hoses and spring clamps.  At the end of the first session this weekend, I found my passenger floorboard had a bunch of coolant in it.   Because the PO had used worm/screw clamps, the heater core tubing wasn't round enough to use spring clamps.  A quick stop at Napa by the track fixed me for $1.

m_walker26 Reader
10/18/19 2:34 p.m.

Thanks for the guidance.   I was expecting the generic "Do eet" but these comments are actually helpful.   I think I will take a week (on Hilton Head) to ponder then decide to go with 

https://richardscarblog.com/2016/06/19/heater-core-replacement-in-the-93-mazda-miata-third-and-final-part/   .   Looks to be doable with my skills.     Thanks _ .

_ HalfDork
10/18/19 2:40 p.m.

In reply to m_walker26 :

Totally. Of note, I also had a drip of hot coolant on my foot once and it was just as Wonko described. I didn't even have to remove the hose or lose any coolant. I just slid the spring clamp forward, undid a worm drive clamp, put it around the offending heater hose, and clamped it back together. Never leaked again. 

10/18/19 4:01 p.m.

Pulling the dash does kinda suck, it will kil a day for a newbie, and I will admit that it was intimidating the first time, but in reality it is well documented and not all that difficult. Easier than doing a top.

The $$ savings for doing this yourself over paying to have the core replaced would be significant.



Curtis UltimaDork
10/19/19 12:46 p.m.

Image result for nooooo gif


But seriously, that stuff is the debbil.  You'll likely just end up plugging the heater core entirely.  I'm going through that with my Mazda B4000.  I replaced the heater core, flushed the whole system multiple times, and the fresh coolant gets about 5000 miles before it's diarrhea brown again.  I got one winter before the heater core plugged up again, and upon removal it was caked with the crap.  Tried flushing it with solvent, soap, pressure washer... another new heater core.

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