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Dreaded drip on the gas pedal foot...

Started by daantjie, 09 October 2023, 12:00 PM

daantjie

Hi guys

Well, it won't be the start of colder weather (at least here in the Lower Mainland of BC:)) if we do not have a AC/Heater related gripe ;D

Took the ol' girl out for the last run of the year yesterday, and got a nice rush of ice cold water on my flip - flopped - foot...I have read some posts of other members and unfortunately this seems fairly common.

I have new tar/cork tape on the expansion valve so I doubt this is the source.  It happened when I turned right so maybe this was accumulated moisture in the heater box?  Hmmm...so I snaked the 2x "fish mouth" rubber drains, they were clear no issues.  So...I am fearing heater core issues, ugh.  But my thinking is why was the water ice cold?  I was running the heater and AC alternating to work the ACC (Chrysler crap) system and all worked great.  Full hot and full cold no problem.

I see some posts that note that on later models, 2x additional drains were added for the heater box section.  But my thinking is that all condensation should make its way fairly well to the 2x main drains already in place on earlier cars?

I guess the best way would be to remove the driver's footwell panels and go for another drive and see if I can replicate the situation to see exactly where the water is coming from.  But that would have to wait until Spring ;D

Any others with input?

Cheers



Daniel
1977 450 SEL 6.9 - Astralsilber

daantjie

Maybe to add some colour, below pic taken from an online listing shows the AC drains (yellow) and the heater box drains (red, but with no hoses attached):
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

Check drain hoses on side of tunnel near gas pedal. Unfortuately you need to remove center console to get to.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

daantjie

Quote from: rumb on 09 October 2023, 05:46 PMCheck drain hoses on side of tunnel near gas pedal. Unfortuately you need to remove center console to get to.

Yup already checked those "fish mouth" ones all clear.
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

I thought the fish mouth ones were on the firewall behind the engine. Im showing fhe verticle one you can see right of gas pedal. Goes into trans tunnel. If the hose is cracked it will leak on your foot.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

daantjie

I guess both the cowl drains and AC drains could be considered "fish mouth" as they are both closed off at the end. 
But the ones I cleared out were the 2x ones you can see on either side of the transmission tunnel so for sure they are the AC drains.
I also read that a leak in the cowl section can make its way into the blower and from there into the heater box.
Methinks this can quickly lead to a big can of worms...
Daniel
1977 450 SEL 6.9 - Astralsilber

daantjie

Not to belabour this topic too much but...I'm looking at these "secondary" drain tubes which appear to have been added to later models.   
To my eye the heater core actually sits closest to the driver and thus it appears that the "primary" drain tube is actually for the heater core?
Thus, with the heater box in situ the drains closest to the driver is for the heater core in case of leaks, and the drains closest to the firewall (added perhaps due to complaints from humid climates) is for condensation from the evaporator?  Does this make sense :( 
Daniel
1977 450 SEL 6.9 - Astralsilber

daantjie

#7
Alrighty gents (and ladies, and others ;D ) you are in for a treat today!  As usual my curiosity got the better of me and I went a fiddling with this problem...Decided to remove both driver and pax side knee rolls and plastic ducting to see what I could see.  Ran the engine and AC/Heat as well to build up condensation.

Very interesting that you can see into the heater box through main leg flap section, so if you run BI LEVEL for example, the flap on each side opens up and you can see into the belly of the thing.  I immediately saw a large puddle of water here, and also some interesting finds, more on this later...

So I removed my "treasures" I saw in there, and snaked the driver side again and she ran clear!  Hmmm, why could I not snake the thing before..?  Answer!  The drain tube (single set) you see below the car on either side of the transmission tunnel actually connects to the nipple in the case, BUT, this nipple actually splits in 2 inside the case, so in effect it drains 2x sections on the case.  So I can only summize that the front section drains a possible heater core leak, and the rear section drains the condensation from the evaporator.  But still this is 1x drain hose, for sure overtasked if there is any kind of blockage, and seeing as this hole is split in 2 in the case, the chances of a blockage is big.  So in effect when I was snaking from below, I was hitting the front section, thus there was nothing to drain, but the back section was a nice little swimming pool!  Of course it's very hard to try and hit either back and/or front when you are snaking from below (minds out of the gutter, now:)), so really you must either remove the center consol, or remove all carpeting and gently bend back the carpet.  It can be done, a bit tricky on the driver side due to gas pedal but still doable.  OK now for show and tell!

Daniel
1977 450 SEL 6.9 - Astralsilber

daantjie

Daniel
1977 450 SEL 6.9 - Astralsilber