Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 04-25-2009, 06:24 PM
Registered User
 
Join Date: Jul 2007
Location: Raleigh, North Carolina USA
Posts: 61
How to replace "Bypass Hose" for 1990 300 SEL

Is this a big job?

My bypass hose has a leak. I can't just replace the hose, it looks like I have to take somethings off such as the thermostat or the water pump.

Does anyone know what I need to do?

I have no idea why Mercedes engineers made this so difficult.

Thanks,
Matt

__________________
1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)
Reply With Quote
  #2  
Old 04-25-2009, 09:01 PM
Registered User
 
Join Date: Jan 2008
Location: Melbourne Australia
Posts: 844
You need to remove the waterpump to replace this hose.

Not a simple job but is doable - it's just time consuming and you need to have all the correct tools.

There is a DIY on this in the resources section under DIY articles.
Reply With Quote
  #3  
Old 04-25-2009, 09:21 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

Been there done, that. It's not hard just time consuming. May as well replace the water pump while in there, any other hoses, new belt, and flush the system.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #4  
Old 04-25-2009, 09:30 PM
Registered User
 
Join Date: Jul 2007
Location: Raleigh, North Carolina USA
Posts: 61
thank you.

This may sounds like a dum question though, what would be the harm to taking a hacksaw and cutting a 1/2 inch off the pipe that connects to the block? This would allow me replace the hose in 2 minutes.
Is there any reason why the bypass hose has to be so short? Any reason why the thermostat is so close to that pipe? My hunch tells me that the reason why it is so close is because of the pressure from.the water pump may cause a leak if not so close.
__________________
1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)
Reply With Quote
  #5  
Old 04-25-2009, 09:37 PM
pawoSD's Avatar
Dieselsüchtiger
 
Join Date: Oct 2004
Location: Grand Rapids, MI
Posts: 15,438
I doubt it generates enough pressure to rupture a hose. Its probably designed that close because the German engineers like to have metal between connections more than rubber. I'd leave it alone and repair it correctly. Hacksaw = metal particles into cooling system, not good.
__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)
Reply With Quote
  #6  
Old 04-25-2009, 09:37 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

Quote:
Originally Posted by matchek1 View Post
thank you.

This may sounds like a dum question though, what would be the harm to taking a hacksaw and cutting a 1/2 inch off the pipe that connects to the block? This would allow me replace the hose in 2 minutes.
Is there any reason why the bypass hose has to be so short? Any reason why the thermostat is so close to that pipe? My hunch tells me that the reason why it is so close is because of the pressure from.the water pump may cause a leak if not so close.


Don't know, let us know how it turns out.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #7  
Old 04-25-2009, 09:40 PM
Registered User
 
Join Date: Jul 2007
Location: Raleigh, North Carolina USA
Posts: 61
Thanks.

My other thought that this is how mercedes gets people to go to the dealership for repair$.
__________________
1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)
Reply With Quote
  #8  
Old 04-25-2009, 09:43 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

Well, it's bound to happen sometime...

Just about everyone here isn't the first, second, or even third owner of their cars. So knowing what has been done and what hasn't is an issue.

You could be on your second one and second water pump. That's pretty good for over 300K.................
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #9  
Old 04-25-2009, 10:37 PM
Registered User
 
Join Date: Jan 2008
Location: Melbourne Australia
Posts: 844
Quote:
Originally Posted by matchek1 View Post
thank you.

Is there any reason why the bypass hose has to be so short? Any reason why the thermostat is so close to that pipe? My hunch tells me that the reason why it is so close is because of the pressure from.the water pump may cause a leak if not so close.
I would guess that MB timed it so if this hose needed replacing then so did the water pump. There is also an O ring between the water-pump and engine block that gets hard.

AS the vehicle is nearly twenty years old, you should replace water pump, thermostat, tensioner, belts and hoses. (flush radiator)
Reply With Quote
  #10  
Old 04-26-2009, 09:01 AM
J.HIDALGO's Avatar
Registered User
 
Join Date: Jul 1999
Location: Jax, FL
Posts: 1,785
I replaced it...

without removing the water pump in my 300e. Yes, I cut the hose and installed the new one through the gap. The secret is buying the hose from the dealer as it is more flexible than after market. You will need lubrication and a lot of patience but, it will get in there. Worse comes to worse, you will need to remove the water pump. By the way, if you need to cut the pipe, make sure it is on the water pump side.

Good luck!
__________________
J.H.
'86 300E

Last edited by J.HIDALGO; 04-26-2009 at 05:43 PM.
Reply With Quote
  #11  
Old 04-26-2009, 10:43 AM
Registered User
 
Join Date: Jul 2007
Location: Raleigh, North Carolina USA
Posts: 61
thanks.

by the way, why on the pump side? i was thinking of cutting the pipe on the block side. seems long enough.
__________________
1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)
Reply With Quote
  #12  
Old 04-26-2009, 12:13 PM
Registered User
 
Join Date: Oct 2004
Location: Baton Rouge La
Posts: 2,632
i second the line on replacing the water pump.....as you are replacing the hose.

i was out of town...and my wife started driving on a water pump that was weeping slightly she didn't notice..

cost me a water pump and a head gasket.... 2k. if i had been in town i could have done the water pump for 150 dollars... oh well.
__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]
Reply With Quote
  #13  
Old 04-26-2009, 05:46 PM
J.HIDALGO's Avatar
Registered User
 
Join Date: Jul 1999
Location: Jax, FL
Posts: 1,785
Pump side...

Worse comes to worse, you can replace the pump. You do not even need 1/2 inch, may be a 1/4 inch. Do a search...I am sure I posted something about it.
However, if you are keeping the car, buy a new pump.
__________________
J.H.
'86 300E
Reply With Quote
  #14  
Old 04-26-2009, 07:38 PM
86560SEL's Avatar
Registered User
 
Join Date: Jan 2003
Location: east Tennessee (southeast USA)
Posts: 3,015
Overall these are easy to work on, but some things are difficult, as with most other cars. I think they do it deliberately just to annoy people.
Reply With Quote
  #15  
Old 04-27-2009, 12:59 AM
Registered User
 
Join Date: Nov 2006
Posts: 290
Quote:
Originally Posted by J.HIDALGO View Post
without removing the water pump in my 300e. Yes, I cut the hose and installed the new one through the gap. The secret is buying the hose from the dealer as it is more flexible than after market. You will need lubrication and a lot of patience but, it will get in there. Worse comes to worse, you will need to remove the water pump. By the way, if you need to cut the pipe, make sure it is on the water pump side.

Good luck!
Seriously? You managed to slip the hose into that 1/4" gap? I thought even god can't do that. What kind of lubricant did you use (engine oil?). Can you give us some details? I think sooner or later I would have to replace that hose on my W124.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:02 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page