Heater core repair. Green drips gone bad

[Big-Bird]

Like all things in life if you wait long enough they can either get better or worse. A small drop turned into a puddle on the passenger side floor mat.....then a realization that the heater core was leaking.

All I could say after the first puddle was WTF! The whole process to fix it took about 8 hours and that included a few beers and lunch.

First you have to remove most of the bits that support the dashboard. Dashboard does not get removed....it just has to lift up enought to give the heater box some room to move during extraction.


The engine bay is a player here too. The intercooler had to be pulled so I could access the heatercore's 2 hoses at the firewall.


The box is easy to pull as long as the dashboard has been freed up to lift up out of the way.


The heater box and the circle identifies the offending leak. The clamp seems to rub against the core and causes this common leak. Thankfully its easy to fix if you know what you're doing.


the fresh plumbers grade solder clearly shows the area that was repaired. I also reinforced the area so that future leaks won't appear any time soon. I think a thin layer of rubber on that clamp plate would prevent leaks all together. If you are getting new core do yourself a favor and put a thin piece of rubber on that metal plate in the photo above.

[Rattlenbang]

That's one of those kinds of jobs I loathe: endless hours for a small fix, most of the time just trying to get to the darn thing. Good on you for persevering!

[thelazygreenfox]

Hey Bigbird I pm'd you with the following question

How did separate the push pull cables from the temp/air flow controller? My dash doesn't lift up as much as in your picture, hopefully when the air flow box is removed it will.

You made it look easy but not so for me.
thanks

I got it!!!! It's so hard to see the little cable retainer clip in the back that can be pried up and off. Presto the controller box was off and in my hand.
thx
TLGF

[thelazygreenfox]

http://www.mdocuk.co.uk/forums/viewtopi ... ter+matrix

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[thelazygreenfox]

1.-If it was plugged then backflush the heater core from under the hood in case it can be fixed w/o dismantling the dash. Remove the heater hoses and backflush the core several times. Try pickling with phosphoric acid or bleach and low pressure water flow. If the backflush water cleans up reconnect the hoses, refill the coolant, bleed the air out and turn on the heat. Happy? Have a beer!

2.-If not take the battery terminals off and remove your front seats. The whole job is easier and there's room to store all the bits and pieces onboard.

3.-With a flat screwdriver pop off the back of the 3 instrument pod, this will give you access to the screws that hold the pod on as well as the ones that hold the top part of the centre console on.

4.-Pop open the drinks tray holder, either side are gold screws, take these out and the drinks tray and the centre console/clock should come out. Disconnect the wiring after removal.

5.- Remove your cd player and ash tray along with the wiring behind.

The heater control unit is HCU and the air box/ heater core is AB.

6.- Remove your glove box. This gives access to the HCU push/pull cable connectors and one of the nuts on the AB. (Undo the other 3 nuts holding the AB to the firewall after you remove the dash top side vent connectors and lift the dash for easier access.)

7.-.pop the front HCU cable out of it’s AB retainer on the AB and remove the round end from the post. The rear cable clip is held on the white AB and needs pried up and off. Lift off the rear cable connector round end (near the firewall) and remove the black HCU.

8.-Remove the front plastic dash covers as needed for access to components behind it. Pop those little vents that demist the small side windows, they do take a fair bit of force to get off, undo the screws that hold on the side vent duct and pull them out.

9.- On the dash right side side remove the black ECU screws, then the bolts that retain it to the bracket. Let it hang. Remove the white duct section on the left side of the AB. The AB will not come out without these two removed.

10.-Time to get under the hood. There’s 4 pointed bolts on the upper firewall holding the whole dash in. They may need to be removed to lift the dash up.
Lower the inlet air vent and remove intercooler parts as needed then remove the 4 nuts on the upper firewall.



11.- Your dash speakers may need to be removed.

12.-With all that done the dash should lift. Gently lift the dash and brace it as high as possible woithout breaking anything. Pull up the large wiring cable above the round metal tube section. If the dash won’t lift easily more parts may need to be removed.

13.-Remove the last 3 bolts and the AB from under the dash and undo the heater core screws on the top of the AB. Repair or replace the heater core as needed and replace everything in the reverse order.

14.-Refill the cooling system with antifreeze/water, bleed the air at the vent under the hood and test drive. Check for leaks at this point. Have a beer and pat yourself on the back.

15.- Ocassionally check for leaks as clamps tend to loosen up after the job is completed.

This is just a guideline. Your application may be different and need more parts removed to repair/replace the heater core.

[thedjjack]

WOW what a bad design!!!!

Last one I did was on my F350 in a parking lot... Four screws & 2 hose clamps and it came out through the glove box..

took 10 minutes and cost $23.00 for the brand new core....(plus taxes)

[thelazygreenfox]

DJ that doesn't compare to the number of 4 letter words I used to describe it.

[Big-Bird]

Not a fun job anyway you look at it!

The L400 manual I have describes the removal the way I did it...the dash is not removed, it was merely lifted up and propped in place. 9 hours of time for my R&R included brews, lunch, locating and soldering the small crack in the core.

I was amazed very few 4 letter words were uttered! I only got one cut from sharp metal bits.

[thelazygreenfox]

BB You're right again. Lifting the dash allows access to that upper right hand bolt, no need to remove the dash. I'll edit above, add a few pics and post as well in the L400 Dedicated Category Reference Forum.

Send me your comments on the edited version.
TLGF

[aaronk]

Well this is my current problem exactly! A little bit of green fluid dripping under dash on the passenger side and now quite a lot more :(

Thanks Big-Bird and thelazygreenfox for all the detailed instructions I'm hoping will help in my situation! Big-Bird your step by step photos no longer show.. Wondering if there would be anyway to get to look at those or if they're posted elsewhere? Now I'm a few days shipping away from any parts so I'm wondering if I should rip it apart now and see what is leaking and where or should I first order parts? I'm not terribly good with mechanics luckily have a couple friends that help.. Any more tips or information on this problem, let me know!

Cheers

[Big-Bird]

Sorry the pics are lost.....I did not keep backups as I didn't expect to need to do this again.

[Big-Bird]

Sorry the pics are lost.....I did not keep backups as I didn't expect to need to do this again.