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Engine Specific Info and Questions => IDI Engine => Topic started by: mx597turbo on January 12, 2010, 01:52:42 pm

Title: Heater Core replacement - Can I just cut the fire wall?
Post by: mx597turbo on January 12, 2010, 01:52:42 pm
The heater core went on my '91 n/a. I'm not going to tear the dash out, the car isn't worth the time. Has anyone ever just cut the firewall and changed the heater core that way? Maybe I'll be the first? I have seen this done on other cars before, but I don't know about clearance issues with the Jetta. Otherwise, I'll just bypass it.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: the caveman on January 12, 2010, 05:17:01 pm
If you don't have AC ,even if you've never done it before , it will take less than 4 hours tops. Even better if you're motor isn't turbo'd
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: the caveman on January 12, 2010, 05:17:41 pm
The dash doen't have to come out, just the center console and other center dash bits.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: jtanguay on January 12, 2010, 05:38:14 pm
caveman helped me with some good advice on how to replace mine :)

check out my thread here (http://www.vwdiesel.net/forum/index.php?topic=20448.0).

even if you have a/c, you can do it without taking the whole assembly out, but you need to be very flexible. it's hard to make out from my pics, but there are two clips holding the heater box to the a/c box in the back and a few in the front. some mechanic told me to try that route, but i did try and couldn't get it because its so cramped. so i just yanked out the whole assembly and voila! it takes a lot of man handling to wiggle that thing out so be patient and don't ram things too hard  ;D

i'm not even sure if cutting the firewall will be much help...
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: GEE-BEE on January 12, 2010, 06:09:39 pm
Replace the hoses with silicone type while your there..

GB
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: burn_your_money on January 12, 2010, 07:11:56 pm
You'll spend more time welding the hole in the firewall then you would doing it properly. And if you don't weld the hole up you'll spend more time waking up in the ditch wondering why you keep falling asleep at the wheel.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Powered by Spearco on January 12, 2010, 10:00:47 pm
Yes! Get the torch out with the "rosebud tip" on it. Some chisles and hammers and go for it  :o.
Just kidding.
Bypass the heater core, buy an pwr. inverter and plug in an AC heater from that,  ;D.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: mx597turbo on January 12, 2010, 10:04:32 pm
Quote
Bypass the heater core, buy an pwr. inverter and plug in an AC heater from that

That's exactly what I was thinking. Getting this whole setup on ebay is equal to the cost of a heater core from Autozone, but MUCH easier.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Powered by Spearco on January 12, 2010, 10:15:04 pm
Good. Get some pics of it when its all done. We'd like to see them.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Vincent Waldon on January 12, 2010, 10:20:09 pm
Just make sure you do the math before you invest:

Amps = watts / volts

If the inverter is perfectly efficient, even a wimpy 400W heater is going to draw 400/12 or 33 amps from your alternator.

Since the inverter is probably only 80% efficient at best, you're looking at 33 X 1.2 or 40 amps.

This is why you can't run block heaters off an inverter and battery... at least not for long.  ;)


FWIW: the heater core is really not that bad... a reasonable job for a Saturday with a beverage break or two. 
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Powered by Spearco on January 12, 2010, 10:23:30 pm
Then take out the passenger seat and build a fire  ;D.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Vincent Waldon on January 12, 2010, 11:13:53 pm
Getting just a tiny bit off topic, but some models of the 2010 TDIs have a 1000W 12V heater core in front of the traditional coolant core:

(http://i197.photobucket.com/albums/aa85/vwaldon/TDI_heater.jpg)

The wiring to it is as thick as your finger and it's protected by a 100A fuse. :o

Guys that have 'em report that you do get instant heat, but it's still only enough to defrost the windows and start to take the chill off... the real heat happens once the engine warms up.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: truckoSaurus08 on January 13, 2010, 04:56:01 am
taking out the dash is no big deal. Theres a lot of screws and pieces but if you can do a puzzle, then you can change a heater core. If I were to do mine again, it would probably take me 2-3 hours. 4-5 for your first time maybe.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: janb on January 14, 2010, 12:47:37 am
no need to remove dash (I've done many a2's w/o), just slide back / remove console (4 screws?)

just don't forget the 3 screws for heater box accessed from engine side of firewall. 2 about mid way op the wall and horizontal, and one lower (IIRC)

Take a good look at your 'blend door' while you have it apart, and replace the foam if it is crumbling.

Check your VIN, I don't know about '91, but I have gotten FREE heater core installs on safety recall for early A2's.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: SolarSteve on January 14, 2010, 07:43:30 pm
Just make sure you do the math before you invest:

Amps = watts / volts

If the inverter is perfectly efficient, even a wimpy 400W heater is going to draw 400/12 or 33 amps from your alternator.

Since the inverter is probably only 80% efficient at best, you're looking at 33 X 1.2 or 40 amps.

This is why you can't run block heaters off an inverter and battery... at least not for long.  ;)

I actually built a setup to do just that...  It didn't really work, but it was a neat project.
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: jtanguay on January 15, 2010, 07:06:52 am
Then take out the passenger seat and build a fire  ;D.

A wood stove would be better.

Seriously, electric heaters are a terrible way to generate heat.  You'd do better energy-wise installing an A/C compressor on the engine and placing the evaporator in front of the radiator and the condenser in the passenger compartment.  The thought of all of it is a bit silly, IMO, when the engine is dumping 1/3rd of it's BTUs as waste heat into the cooling system.

with all of the big truck EGR coolers out there on ebay, i've been contemplating putting one on my car.. it would help heat the coolant up fairly quick, but the whole setup would be quite complex. complex as in the coolant would need to be diverted when the exhaust gets too hot...

as for the 12v 1000 watt heater, that thing is garbage. 120v @ 1000 watt is wayyyy more efficient. i'm still blown away that car manufacturers are sticking with 12v DC. i thought i heard that they were going to 36vdc sometime in the future, and that is a step up, but a real baby step...

IMO, cars should have a 3 phase 1000 watt inverter for 24vdc for things like afterrun rad fan etc, and then simply use the alternator to run everything when the car is on. the efficiency of a/c power is incredible. plus the benefit i like the most, is not needing these huge wires going throughout the whole car. 3 phase motors are very efficient and last much longer and provide higher output than similarly sized DC motors.

a non electronic vw diesel would be a perfect candidate to make the swap to using AC :)

i wonder what the size of the '09 tdi's battery and alt is? probably 160 amp alt with a ginormous battery... it'll suck for whoever has to replace that down the line  :o
Title: Re: Heater Core replacement - Can I just cut the fire wall?
Post by: Laurentian on January 17, 2010, 01:28:17 pm
Looking into this for my Toy pick-up.
Nice quality !
http://www.flex-a-lite.com/auto/html/mojave-heater.html (http://www.flex-a-lite.com/auto/html/mojave-heater.html)