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 > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 04-20-2019, 10:20 AM
Registered User
 
Join Date: Nov 2012
Location: Temecula CA
Posts: 48
Broken water pump banjo bolt

What are my options to fix a broken banjo bolt that connects the block to the water pump through the U shaped steel line. The banjo bolt on the block side was welded. On 1/2 turn with little resistance and it sheered off. I ended up drilling it out in hopes of getting back to the threads but that thing was welded through and through. Now I have a bigger hole and a specialty bolt that has to be there, or does it? Can I plug it? Can I tap it with a bigger diameter thread and drill my own specialty banjo bolt? What can I do? Thanks
__________________
1980 240d auto
1977 240D manual 300 Turbo swap
Reply With Quote
  #2  
Old 04-20-2019, 10:28 AM
Dubyagee's Avatar
All fields are required
 
Join Date: Jul 2006
Location: SE
Posts: 4,666
Im not sure of the area you’re typing about but I would tap it for pipe thread and install a hose nipple. Finish by running a hose to the pipe.
Reply With Quote
  #3  
Old 04-20-2019, 10:35 AM
Registered User
 
Join Date: Nov 2012
Location: Temecula CA
Posts: 48
Quote:
Originally Posted by Dubyagee View Post
Im not sure of the area you’re typing about but I would tap it for pipe thread and install a hose nipple. Finish by running a hose to the pipe.
There is a “U” shaped 1/4” steel line as you look at the block from the front near where the head meets the block. It is attached by banjo bolts to the water pump. The line is a coolant line. Idk if it is a bypass line or if it is designed to cool the bearing of the water pump.
__________________
1980 240d auto
1977 240D manual 300 Turbo swap
Reply With Quote
  #4  
Old 04-20-2019, 01:04 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,653
Quote:
Originally Posted by stephenc1984 View Post
What are my options to fix a broken banjo bolt that connects the block to the water pump through the U shaped steel line.
More correctly, the line connects the head to the water pump housing.
__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
Reply With Quote
  #5  
Old 04-20-2019, 03:41 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
I wouldn't plug it since that coolant flow must be needed. It is a small tube so maybe it is just to help sweep out trapped air. You would expect some get clogged by rust, so perhaps wouldn't be fatal, but google it before doing that.

It sounds like you buggered up the hole in the head. Unlikely the bolt was welded to the head, rather it probably corroded in the hole. If you can't get the M-B banjo bolt, similar ones are used on some brake calipers. There are also banjo fittings on your M-B fuel supply to the IP. To fix a buggered hole, look at heli-coil. A bit pricey and I have only used for SAE bolts, but should be metric ones today. I think there are 3 different pitches for metric bolts (coarse, fine, extra-fine), so measure carefully.
__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
Reply With Quote
  #6  
Old 04-20-2019, 06:01 PM
Registered User
 
Join Date: Aug 2013
Posts: 18
It sounds like stephenc1984 is talking about the water pump purge line. It allows the pump to purge air out of the head and a small amount of water to circulate when the thermostat is closed. I would turn up a new banjo bolt on the lathe (may have issues making the hole large thru the banjo to fit the larger bolt), or install a metric Helicoil.

Reply With Quote
  #7  
Old 04-20-2019, 06:13 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,653
Quote:
Originally Posted by choprboy View Post
It allows the pump to purge air out of the head and a small amount of water to circulate when the thermostat is closed.
A bypass thermostat is never "closed." Coolant circulates any time the water pump operates.
__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
Reply With Quote
  #8  
Old 04-20-2019, 07:04 PM
Registered User
 
Join Date: Dec 2006
Posts: 3,440
Aside from the dealer, banjo bolts should be available from industrial shops.
Reply With Quote
  #9  
Old 04-20-2019, 07:53 PM
Registered User
 
Join Date: Nov 2012
Location: Temecula CA
Posts: 48
Quote:
Originally Posted by Mxfrank View Post
Aside from the dealer, banjo bolts should be available from industrial shops.
I was thinking I could just take a standard bolt. Drill out a portion of the bolt and tap the hole on the motor to the size of the bolt and call it good.
__________________
1980 240d auto
1977 240D manual 300 Turbo swap
Reply With Quote
  #10  
Old 04-20-2019, 07:59 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 27,373
I believe this might be too complicated if you are not used to drilling and tapping stuff.

The one advantage you have is that the threads hole dose not have to take any load. It just has to hold the Tube on.

If the hole is drilled out larger now you could rethread the hole for a larger bolt. Preferably brass or Aluminum (yep a local industrial supply has some aluminum bolts). Although it could be done with steel you want a bolt that is easy to cut and file down.

Screw in the new Bolt with slow curing JB Weld Epoxy. Let that cure and cut it of and file it flush with the with the cylinder head. After which you would drill a hole in the metal and tap and thread it for the new Banjo Bolt (likely metric).

The new tapped hole in the head would have to be large enough so that the bolt your going to cut off leaves enough metal that it can be drilled and tapped for the new banjo bolt.

Another problem is that the banjo bolt hole has to be drilled fairly straight in or the copper crush washers are not going to seal it.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #11  
Old 04-20-2019, 08:03 PM
Registered User
 
Join Date: Nov 2012
Location: Temecula CA
Posts: 48
Quote:
Originally Posted by choprboy View Post
It sounds like stephenc1984 is talking about the water pump purge line. It allows the pump to purge air out of the head and a small amount of water to circulate when the thermostat is closed. I would turn up a new banjo bolt on the lathe (may have issues making the hole large thru the banjo to fit the larger bolt), or install a metric Helicoil.

This is what I am referring to. Thank you.
__________________
1980 240d auto
1977 240D manual 300 Turbo swap
Reply With Quote
  #12  
Old 04-21-2019, 12:23 AM
Registered User
 
Join Date: Dec 2006
Posts: 3,440
It's not just drilling a hole. The bolt has to be turned to allow a flow path around the ID of the fitting. $5 at industrial supply, no tears.
Attached Thumbnails
Broken water pump banjo bolt-banjo.jpg  
Reply With Quote
  #13  
Old 04-21-2019, 12:28 AM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 27,373
E in the coolant diagram is listed as a vent line.

Unfortunately I know of no one that has written about your specific problem.

However, I am going to stick my neck out and speculate that it does not seem to do much as far as cooling goes. If you otherwise got the air out of the system one would think the cooling system would function OK without it.

But, if you plugged both holes off you are clearly experimenting.
Attached Thumbnails
Broken water pump banjo bolt-coolant-schamatic-vent-line.jpg  
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #14  
Old 04-21-2019, 01:53 PM
Shadetree
 
Join Date: Jan 2010
Location: Back in SC upstate
Posts: 1,422
I couldn't conclude that the passage created by that bolt and line are not needed. Back in the 1960 and earlier, thermostats would prevent all water flow until the engine was warmed enough to open them. Many cast iron heads cracked from cold water being dumped on thin, hot cast iron.

It seems MB engineers may have included at least two outlets to let small amounts of water circulate when the engine is running whether or not the thermostat is open. An engine might last a bit longer before a head cracks from heat if the thermostat freezes closed.
__________________
84 300SD
85 380SE
83 528e
95 318ic
Reply With Quote
  #15  
Old 04-21-2019, 03:36 PM
t walgamuth's Avatar
dieselarchitect
 
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 34,131
I found a place which referred to it as a bleed hole to evacuate air from the water pump. I might have the words wrong but I am pretty sure I would not try to eliminate it. I'd put it back stock.
__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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 06:55 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page