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Leak in engine coolant line that heats windshield washer reservoir
Looks like I have a slow drip in the coolant line that goes to the windshield washer bottle. It's pretty ridiculous that these two systems were commingled like this, but here we are...
I can't find any posts or videos about this line anywhere, so it must not be a common issue. Yet, I need to replace mine and it seems to be quite buried (it apparently runs from a fitting on the firewall to the washer fluid reservoir under the engine...
Has anyone done this before or has seen this system up close and can provide some guidance for replacing this?
My washer bottle itself also leaks so that'll get done too.
I believe the hose in question is #7 in this diagram:
I bought this line and have it in hand so I'm able to see what it looks like in person. It has rubber ends which get hose clamped and metal sections periodically in the middle. The front is pretty accessible down near the washer fluid reservoir, but the back of it is connected near the firewall between the heat shield and the firewall. I think the whole tray at the bottom of the windshield may need to come off to get to this, or the heat shield needs to be pulled away, but there is so much stuff routed through it that this seems almost impossible without draining and disconnecting a bunch of stuff. The dealer quoted me $1700 to replace that and the coolant breather line which is a $50 part and took me 5 minutes to swap out, so they probably consider this a several hour job on their end? The same dealer quoted me $665 for replacing both of the front sway bar links which are $60 each. This job takes probably 30 minutes, which means they're charging about $1100/hr, lol. That would mean they consider the heater line swap to take about 1.5 hours, which may imply that the tray at the bottom of the windshield does need to come off...
But again, I haven't seen any instructions on how to do this and my copy of the WIS is in the mail...
Here are some pics of my leaky line in my car (in order from washer reservoir to firewall). The line goes in and out of view as it goes under a heat shield and through some holes in the various compartments:
:
Already bought the hose I need, and the broken part that prompted the video. Tomorrow I'm going to buy a few other parts that I should do WIIT, because I don't want to do this again for another 10 years. Really not looking forward to it.
I now have a copy of the WIS and EPC and started digging around to find the instructions for replacing the cracked part in the video. I can't find that part of the engine cooling system, hvac system, and/or heated windshield wiper system mentioned anywhere in the WIS. I did find the sheets S-Prihadi pulled up in the EPC. You would think the EPC would reference a document number for replacement, but nope?
Is it just not in there?
Does anyone have any advice for finding a particular set of instructions in this software?
I wasn't familiar before, but I just looked up that part number and it is indeed a coolant line... If you have the system pressure tested, it's easier to identify where the liquid is spraying out of...
I now have a copy of the WIS and EPC and started digging around to find the instructions for replacing the cracked part in the video. I can't find that part of the engine cooling system, hvac system, and/or heated windshield wiper system mentioned anywhere in the WIS. I did find the sheets S-Prihadi pulled up in the EPC. You would think the EPC would reference a document number for replacement, but nope?
Is it just not in there?
Does anyone have any advice for finding a particular set of instructions in this software?
Mercedes WIS is a nightmare to use. Even me after 4 years, take me hours to simply find the correct document.
Give me your VIN, I will see what I can do
I noticed a leak coming off this hose but no idea if its this hose assembly or something else.. anyone familiar
M157 your engine is correct ?
It has weakness just like M278 ( I am sure 90% ) as these two engines share many similar components.
M278 has the coolant for turbocharger weakness. Plastic mix with aluminum. The plastic kapoot first.
Search the forum for M278 turbo coolant leak.
You will cry when you read the attached doc
They show ENGINE-LESS engine bay
One need to be Plastic Man to be able to actually undo those bolts/screws.
I looked at this doc because at one time I also wanted to know how remove the heat-shield / false firewall
Go to WIS and type in the same document number, leave last 2 digits, use * (wild key instead). There u see 3 similar docs, on 3 different car type.
You can type at WIS above the long list, for BULKHEAD and nothing will come out.
That is how dumb MB WIS is.
I always get a little bit of confidence in the research phase. Then when I start ripping my car apart I find, half way through, that my car differs just enough to throw a wrench in things. (As opposed to carefully applying wrenches at things...) Always good to have a spare assembled vehicle to get one to to look for tools to repurpose.
We'll see how it goes, hopefully this weekend. Until then, I'm using about a gallon of coolant a month, so it's not a dire situation as long as that holds.
If only that HVAC heater hose it is not too bad to replace, no need fake firewall to be removed.
Only wiper plastic cowling and whatever on M278 Bank 2 rear azz which block your hands
I'm on the fence about whether I want to "nudge" the fake firewall out of the way to get to that hose on the back of the block since I'll be half way in there anyway. I have a new one in hand and that might be better than having to do the whole thing again in 6 months or a year when it breaks... But I'll probably leave it for now!
Also, the design of the broken part in the video is bad. I intend to reinforce the stress riser where the crack occurred before I install the part so that it won't happen again in my lifetime. I'll explain this later when I figure out what I'm doing.
You need to replace ALL these if you want to play safe.
01. The plastic pipe/s out of engine block towards 1st hose before fake firewall.
02. 1st hose from plastic pipe to fake firewall.
03. The 2nd hose, behind firewall to HVAC heater core - INPUT
04. The 3rd hose + alu pipe combo, heater HVAC core-OUTPUT, which is back to coolant circulation pump input Tee.
I am replacing all these equivalent hoses + pipes on my M276 3.0 TT, but item 1 is a two pipes system for my engine.
Below shows item 3 and 4, for my engine. Wiper cowling removed. Also the plastic water trap tray removed.
Item 2 hose, would be somewhere at the red arrow. So you got to remove also that water trap plastic tray, after removing wiper plastic cowling.
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That water trap plastic tray
Remember my car is RHD. So visualize opposite position of everything you see at true firewall.
It's pretty hard to correlate these things to my car based on the pics and the EPC... I might have to do this first job to fix the immediate needs and take stock of what I have once I'm in there. I can pull the part numbers off the hoses I can actually see and have a better idea what they look like. It's comical how some of the parts are represented in the EPC--if you can even find them--vs. what they look like in real life.
You need to learn my trick when trying to see actual parts shape. EPC drawing a lot of them are GENERIC and misleading.
Use Ebay and used parts store to see parts you are interested. Some of them have very good photos.
When looking at a hose assembly with more than 1 hose, becareful looking at its used parts in Ebay, as MB sometime has its own P/N for the hose, but the actual P/N is a complete assy of hose + Tee or fittings.
Teslong Boroscope is a good friend to ID true P/N of the items in your car.
I am on a RHD car and an E400, not only RHD car is a small market, E400 is not a good seller, as such EPC has lots of mistake for my coolant hoses.
Read below :
Mine being a NOT popular/common engine and chassis , EPC screw up CAN happen. My true P/N as per on my hose item 280 is not detected by EPC when I use the VIN, but will appear when I use only chassis code W212.065
I must use CLS400 to find a hose "missing" from my EPC drawing. LOL.
Use pre-owned engine photos to visualize parts install location.
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EPC has search feature, use it when you have the real P/N of your component , to see if VIN based search in EPC has a screw up.
Engine M276.860 : See item 30.
EPC vs the real parts
EPC serves so many different market regions, as such their drawing can be too simple and you can't visualize it because there could be 5 different variants of the same type of product
You need to learn my trick when trying to see actual parts shape. EPC drawing a lot of them are GENERIC and misleading.
Use Ebay and used parts store to see parts you are interested. Some of them have very good photos.
Yeah, that's a good trick. I've been doing the same using google images to look things up and cross check. Such a pain though!
Thank you! I still don't have all of the parts, so I'm putting this off until next weekend. Not longer than that though because my coolant loss is starting to increase.
Well, I did, in fact, keep putting it off longer because I just couldn't find the time to get this done. The leak rate subsided for a bit and I added fluid every so often, but last weekend the rate increased again.
I still didn't have time, so I ended up having the dealer do the job with my parts. They replaced the washer heater hose and the connector that mounts at the firewall--both were leaky according to them. The crazy thing is they didn't take off the drip shield and they booked it as a roughly 3 hour job. Let's start speculating on how this was possible...
So overall, it wasn't that expensive and I'm happy to have it done.
Good to hear.
A LHD car HVAC heater core is at the Left side of the car, so the hose behind the fake firewall is shorter run to the heater core than mine a RHD car.
They probably did not remove the wiper assy and secondary water tray like I had to, but the wiper plastic cowling/tray I am sure has to be removed.
Don't the wipers need to come off to get the cowling/tray off (the piece called the "drip tray"? They probably didn't remove this because I gave them a new one to install (which I bought from their parts counter) if they took the old one off, but they didn't install it. Also, the "drip tray" was still full of twigs and maple helicopters and I think those things would have been disturbed if they had taken it off.
I can't discount the possibility that they removed it and installed it and just put all the plant material back in there either to disguise how they did the job or just because they're boyscouts and wanted to leave things the way they found them.
This is how one access the heater hose from fake firewall to heater core
01. Remove 2 wiper arms. Only the arms for now. Below is the same chassis as ours, W212
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Remove wiper cowling, item 1, not item 2
Item 2 is what I call secondary water drip tray. Item 1 is the cowling you have brand new ? yes...
Above, the wiper motor of the wiper assy is blocking any hands going to access the heater hose, item 3 in EPC below
Now I am using W203 C Class, but it is the same. Visualize where the heater core is compared to brake booster.
How to do the heater hose to heater core without removing at least wiper cowling #1 ?
The wiper assy is not small size. The dual-thin-arms side happens to be blocking heater core area.
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I think the MB Tech is simply too lazy to transfer the 2 windshield water spray nozzles from your old cowling to new cowling or even remove the water hose.
03-25-2024, 09:40 PM
