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1997 E 420, 155K Miles, Stock
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I purchased a 1997 E420 a couple of months ago with a 150K miles. I've done some of the common repairs and thought I was out of the woods for while. I was driving along fine and then the check engine light came on with check engine electronics message. I took it to autozone and had the codes read and found a P0301 - which means Cylinder #1 misfire. I changed the plugs, cleaned all the electrical connectors that I could find and then also found the breather tube to be totally destroyed. I have one on order so don't know if this will take care of the problems. Any advise?

BTW - This forum is great. I've used the posts to repair: Spring perches, lower control arms, cabin and charcoal filters, blower regulator and ac condensor!
 

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1990 Mercedes-Benz 420 SEL(RIP),1997 Mercedes-Benz E420
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1,936 Posts
I purchased a 1997 E420 a couple of months ago with a 150K miles. I've done some of the common repairs and thought I was out of the woods for while. I was driving along fine and then the check engine light came on with check engine electronics message. I took it to autozone and had the codes read and found a P0301 - which means Cylinder #1 misfire. I changed the plugs, cleaned all the electrical connectors that I could find and then also found the breather tube to be totally destroyed. I have one on order so don't know if this will take care of the problems. Any advise?

BTW - This forum is great. I've used the posts to repair: Spring perches, lower control arms, cabin and charcoal filters, blower regulator and ac condensor!
You and I have the same year and model car. I was working on my car a couple of days ago to fix a tranny leak and encountered my breather hose to be MUSH almost like play dough. I could literally just pull the thing apart like cheese. I read up on it and it could effect engine performance. I noticed while driving it with the new breather hose today it was smoother and much quicker in acceleration in high gears. I'm not too sure on the misfire mishap but either way the hose should be replaced. Attached is a picture of my breather hose going from the air mass sensor to the valve cover.
 

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2001 E320
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151 Posts
while waiting, why not check out all of your other vacuum hoses - they may 'look' good, but you have to touch and feel, you'll be surprised! a properly functioning vacuum system is essential to the engine as it uses it to burn off/reuse gases and compensate for fuel/air ratio adjustments.
 

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1997 E 420, 155K Miles, Stock
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Discussion Starter #4
You and I have the same year and model car. I was working on my car a couple of days ago to fix a tranny leak and encountered my breather hose to be MUSH almost like play dough. I could literally just pull the thing apart like cheese. I read up on it and it could effect engine performance. I noticed while driving it with the new breather hose today it was smoother and much quicker in acceleration in high gears. I'm not too sure on the misfire mishap but either way the hose should be replaced. Attached is a picture of my breather hose going from the air mass sensor to the valve cover.
My breather was in the exact same condition! I'm changeing it today. Thanks for the feedback!
Steve
 

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1997 E 420, 155K Miles, Stock
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17 Posts
Discussion Starter #5
while waiting, why not check out all of your other vacuum hoses - they may 'look' good, but you have to touch and feel, you'll be surprised! a properly functioning vacuum system is essential to the engine as it uses it to burn off/reuse gases and compensate for fuel/air ratio adjustments.
Yes - thanks for the heads up! I will touch and feel each of them today! Thank you for the feedback. Steve
 

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1997 E420
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347 Posts
I know that some of my lines like this also disintegrated after a misfire. The shop I took it to got the engine running and changed some coils but they didn't replace the vacuum lines! Now my problem is that I'm not sure exactly what parts I need and how the lines are routed. I can see that there is a connection missing a hose at the far backside corner of the engine block towards the passenger seat. Does anyone have a good diagram or photos showing how this line is routed?

I suspect the attached graphic from the EPC shows some of the parts, but the problem is it doesn't show very clearly how they are connected and to what! I can't even really tell which side is the front and which is the back of the engine.

Also, do you have to buy all the individual bits to assemble your own line? Looks like Mercedes just sells tons of small parts to do so.
 

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97 E-420 (180K miles), 97 SL500, (93K miles) 2015 GMC Sierra Denali 2500HD CC/SB/4x4 Duramax(55K)
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I know that some of my lines like this also disintegrated after a misfire. The shop I took it to got the engine running and changed some coils but they didn't replace the vacuum lines! Now my problem is that I'm not sure exactly what parts I need and how the lines are routed. I can see that there is a connection missing a hose at the far backside corner of the engine block towards the passenger seat. Does anyone have a good diagram or photos showing how this line is routed?

I suspect the attached graphic from the EPC shows some of the parts, but the problem is it doesn't show very clearly how they are connected and to what! I can't even really tell which side is the front and which is the back of the engine.

Also, do you have to buy all the individual bits to assemble your own line? Looks like Mercedes just sells tons of small parts to do so.
The back side of the engine is where hose 144 is.

I ended up replacing all of my vacuum lines several years ago. virtually all of them were falling apart. Parts aren't that expensive from the dealer and several of them, including the breather tube have been upgraded and are now composed of fewer pieces and are sold as a complete replacement. for example 144 is a direct replacement for that collection of pieces starting with 155. Likewise for 126. Any leaks can give a bad case of idle shakes and trigger codes indicating a lean mixture or unable to adjust the mixture.
 

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1997 E420
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347 Posts
OK, that helps quite a bit. I'm pretty sure that I'm missing the hose starting from 155, so it looks like I'll need 144, and maybe more. Does 144 run up to 116? or past that?

I'll try to trace where that goes as it all looks like it ends up around 158, so I'll see if I can find a connection there. It looks like the hoses on the front Y shape are separate from the ones running from the back?

Guess I'll replace all of them while I'm in there. Going out to the garage now to pull off my engine cover to do some detective work.
 

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'01-E320 & 02-ST2
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It's probably useful to order them all at once from parts.com, that will be OE quality and far cheaper than your local stealer. Toss in a new set of carbon filters or something to offset the shipping. :thumbsup:

Also, if you're looking at the EPC, be sure to check the notes, it will tell you about superseded or replaced items.

Good luck.
 

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1997 E420
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347 Posts
Gah! Just got back from Mercedes of Beverly Hills -- thought that these are not that expensive so how much more could it be? The answer is more than double the price from respected online merchant (parts.com is just slightly higher, but still huge savings). The total for all the breather hoses and connectors came to about $250 with tax in beverly hills. So I decided I'd price online and also pull off my engine cover to take another look at what I'm dealing with first.

So that brings me back to the problem of not knowing where the hose gets routed to! Ugh!! Attached are some photos of the top of my engine. For the life of me, I can't see where the hose from the back is routed to. It looks like it should hook up somewhere near #158 in the EPC diagram, but I don't see anything obvious there at all.

There isn't a chance that this line just gets routed up to the top like a snorkel somehow, is there? Where there'd be no connection for the hose?

Please let me know if you can provide any guidance.
 

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1997 E420
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A few more details, but I'm still unable to figure out where the hose connects at the top of the engine. I've deduced that the connection up toward the passenger seat is to the cylinder head cover since item 155 is a loom tie between the hose and that part. But the EPC doesn't have more details about the other end of the hose. Just says "connector" for that end....

#155 "Loom Tie - Molded Hose to Cylinder Head Cover - 1179970790"
#144 "Hose - From Connector to Cylinder Head Cover - 1190901982"

And part number 1190901982 replaces EVERYTHING along the line of parts on that side except the loom tie #155.

Please let me know if you have any ideas on where the end of this hose goes! Otherwise, I'm going to stop by a wrecking yard and see if they'll let me look at an E420 engine bay.
 

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1997 E420
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347 Posts
Well, I failed at the wrecker today as the E420 they had was balanced precariously on the roof of another car (which itself was balanced precariously on upturned rims). Figured it wasn't worth the risk of life and limb to gander under the hood.

So I'm still in need of any clues as to where this line routes to... anyone have any ideas, even from memory on what I am looking for? (See photos from a couple posts back as to where I've been looking.)
 

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1997 E420
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347 Posts
Just want to update this for anyone coming across this in the future. The connection that I couldn't find was on the other side of where I was looking for it (see photos previously attached). Basically the hose attaches on the passenger side of the car near the throttle body. It is kind of a bear to get down there to connect it with fingers and pliers!

I also just replaced all the little hoses yesterday (the Y connection, etc) -- those are REALLY easy to replace but I strongly advise you to buy the nipples that connect the hoses together rather than try to reuse your existing. These hoses were hard as a rock (which surprised me as the longer cable previously discussed was soft, mushy and had disintegrated) and it was nearly impossible to get them to come off the nipples without damaging them beyond reuse. I was going to buy replacements just in case I needed them but the parts place I ordered from only had a single one in stock. I got that one and figured I'd be able to reuse some of the others. After slicing my finger pretty good with a razor trying to carve off the hardened tube I caved in and hopped in the car to the dealer to buy a couple more.

Aside from the connection of the aforementioned hose down near the throttle body, you can replace all these lines in 15 minutes if you get all the parts you need, including the nipples.
 
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