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Discussion Starter #1
Hi,

I've been lurking for a while already getting great tips here, but time has come to ask for some help...

The 1Z in my 96 Passat has been loosing coolant very slowly - but lately it's gotten worse. Droplets to puddle-size worse. After popping the car up and taking off the bellypan, the G12 has left the tell-tale marks to show the leak on the back of the engine block. See attached photo shot from below lookin up at rear of block - red arrow shows leak on back of block. (Sorry for the bad phone-photo. Let me know if you need a better one to help out)

Good news first - I know where it leaks. WP++ shows no indication of a leak. Neither does condenser nor any hoses. No codes.

But...

1) What is my leaking part?
It looks like a tall metal bottle-cap with two 90-deg pipes sticking out of it. Looks to me like a broke O-ring / seal where the "cap" seats in the block. I don't see this part in any (alledged) 1Z cooling diagrams online, nor does it seem to be mentioned in my Haynes manual. Uneducated guess is it could be a coolant preheater?

2) Is it self-serviceable?
If so, is coolant draining/flush needed? How-tos available? VW part#?

T
 

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Hi bud, can you see where the pipes go? I cant really make it out in the pic. I was just wondering if the coolant is coming from higher up and landing there.:)
 

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Discussion Starter #4
Thanks for pitching in guys - greatly appreciated!

Attached is a vastly better, and annotated, pic of the part in question taken from the same location - from the bottom looking up the back of the engine block. Blurry part in lower edge of photo is the aft edge of the oilpan.

Both tubes seemingly run to the rad or condenser (hard to see exactly) in a single corrugated plastic sleeve. The leak does start at this part, as there's no indication of G12 above it. Looking at the picture it seems to leak both at the base *and* at the nut on the threaded bolt.

Will lookup the EGR cooler...

T
 

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Discussion Starter #5
thomanie said:
Will lookup the EGR cooler...
Doesn't seem to be connected to the EGR at all as far as my uneducated mind can see.

So we have two coolant hoses entering the block, that is not included in any official diagrams and/or repair manuals.

Could it be a engine block heater circuit, with the pipes being feed and return coolant hoses?
There *is* a DEFA plug buried in the grille somewhere, but I've never used it...

T
 

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thomanie said:
Could it be a engine block heater circuit, with the pipes being feed and return coolant hoses?
There *is* a DEFA plug buried in the grille somewhere, but I've never used it...
Looking at
http://www.defa.com/doc/koblingsskjemagb.pdf

The part named "Engine heater" looks very much like the part on my photo, doesn't it ?!?
Looks like it's in what they call the "frostplug hole".

T
 

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If you're sure that's where the leak is I think I would whip the thing out and either replace the o ring if needed or use some gasket sealer or clear silicone sealant and fit it back in.:)
 

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Discussion Starter #9
Could it be some sort of engine block heater?
Yep - it must be a Defa #411393 as seen in attached photo, and yes - the O-ring seal must be the culprit.

Probes for replacement O-ring has been fired. Worst case it's ~100USD for a new complete heater with seal. So, locating a G12 and heat capable 3rd party O-ring might be worth it too. I fear the really cheap black ones just won't stand the heat in the long run.

Thanks again for pitching in guys - ATM it looks like this problem is solved!

T
 

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Discussion Starter #10
In case anyone is still following, DEFA offers "repair kits" for all their block heaters for about 1/4th the price of a complete new element.
The repair kit for the #411393 in my 1Z contains inner and outer O-rings, nut, and bolt with T-shaped hold.

According to the helpful gentleman at the auto parts store, you're supposed to substitute the 3rd digit (normally '1') with a '9' to find your DEFA heater repair kit. The repair kit for my #411393, would then become #419393.

T
 
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