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 ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-03-2001, 12:42 AM
67-250SL
Guest
 
Posts: n/a
I've got a 67 250SL with the mechanical fuel injector pump; I'm having ongoing difficulty once it warms up. Still runs, but seems to be choking on too much air. My mechanic says that I need a new "cold start speed valve", but cannot seem to locate a new or used part that will suffice. He indicates that the next option is the very expensive (yet once-in-a-lifetime) injector pump rebuild. Does anyone know how to find one of these valves? I had a look in my "Star Quality" parts catalog, but the cold start valve they show is nowhere near the injector pump.

Any comments or ideas?

Richard
Reply With Quote
  #2  
Old 01-03-2001, 09:39 AM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,777
The cold start valve he is referring to is not on the pump. It is on the intake ram.
They leak by when not energized and cause a rich condition.
Some just need cleaning. Some can be re-stoned to seal,
or just replaced.
There are other cold start devices on the pump, but I would check the valve first.
Also, the pumps on the 250-113's hava there own oil res.
and dip stick. [ way down the back, "T" handle]
Be sure there is oil in the pump. Very few know about this as the later FI pumps were lubricated from the engine crankcase and therefore did not have to be serviced.

Let me know how you make out and we can go from there.
Reply With Quote
  #3  
Old 01-03-2001, 10:16 AM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
I suspect that the device they are talking about is the cold enrichment thermostat. If it's lost its ompf it will definitely cause problems. The device is under the verticle tower at the back of the pump. It has two water hoses going to it. The thermostat is under the cover. If this is the device it is easy to test.

There is a airfilter at its base that filters the additional air that is also allowed under the cold conditions. Both activities are directly related to the length of the t/stat which of course changes with temperature. Remove the air filter and place your thump over the opening. At idle cold the act should stall the motor or severely reduce the speed. When fully warm the act should not drop the engine spedd even though a suction can still be felt. This range is critical and if full can be adjusted for final set-up, but a bad t/stat will be the same wam and cold. The piston in the housing right below the t/stat also freezes due to coolant leakage from above. The piston can be unfrozen and cleaned with emory paper.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #4  
Old 01-03-2001, 02:12 PM
67-250SL
Guest
 
Posts: n/a
Hi Steve - thanks for your reply; I met with my mechanic this morning to make sure I had a clear understanding of the problem. He says I have a new cold enrichment thermostat, and that the problem is that I need a new housing for it. That is the piece that accepts the connections to the hoses an filter. This is the piece he says that Bosch doesn't sell separately, and therefore I need a pump rebuild.

I will try your test tonight when I get home, and let you know. In the meantime, do you know how/where I can get just the housing for the thermostat?

Richard
Reply With Quote
  #5  
Old 01-03-2001, 03:22 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
I can probably help you with the housing. I would need to know which one it is. Does it have the dipstick as mentioned above? Does the thermostat have plastic around the central plunger?

The only problem this housing can cause is leaks. Before I would throw away a pump I would build a housing in stainless from the remains of the heavy bottom.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #6  
Old 01-03-2001, 03:33 PM
Jim Villers's Avatar
Registered User
 
Join Date: Jan 2000
Location: Virginia Beach, VA
Posts: 490
Richard ... The parts that you are discussing are expensive. Be sure that you or your mechanic knows a lot about these units or has spent the time with the manual fully understand the function of each component. First be absolutely sure that the linkages are adjusted correctly at idle. Then try the tests described above. Since you believe that the engine is lean when warm, if the cold start valve is not leaking, the thermostat is working (test in hot water on the stove) and is the correct thermostat for this pump (fits with the correct seal and clearance), try making the fuel mixture a little richer by lengthen the pump control rod by a twist or two for testing. If this corrects the problem, there is an adjustment in the pump to increase the fuel flow. The linkages should be reset according to the manual. This internal pump adjustment is not "normal" and should be your last resort if everything else checks out.

Try continuing this on the "Vintage" board.
__________________
Jim Villers
190SL, 230SL 5-speed, 95 E320 Wagon, 01 E320 Wagon, MGB, Boxster 'S', 190SL "Barn Find"
Reply With Quote
  #7  
Old 01-03-2001, 10:36 PM
67-250SL
Guest
 
Posts: n/a
Hi again Steve - I have had a good look at my injector pump, and it does not have a dipstick. There is however a red plastic "Oel" fill cap beside the thermostat/air filter housing. I did check my service records, and my mechanic did install a new thermostat in October; I didn't see the one that they put in. If necessary, I could e-mail you a picture of the injection pump and the housing in question.

I think that my mechanic feels that the housing is leaking as you say. I'd like to give this a try if possible. When this was not a problem, the engine ran beautifully (~1 year); I'd prefer not to yank out the injector pump until I've exhausted all other options.
Reply With Quote
  #8  
Old 01-03-2001, 10:47 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
I understand the concern with a coolant leak, but I don't see where this has anything to do with your running problem.
If your shop doesn't want to invest the time on setting up your pump properly because they are afraid they will have to replace it for the housing leak, I would say to go for the performance fix first as I'm sure we could find a cover. I'm also sure I could fix your cover.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #9  
Old 01-03-2001, 10:56 PM
67-250SL
Guest
 
Posts: n/a
Hi Steve - maybe I didn't relay this correctly... I'm a neophyte when it comes to this stuff. I think the leak is coming from the housing beneath the thermostat cover... the one that is below where the air filter attaches. That is the component that my mechanic pointed out that he can't obtain separately. Apparently the tried to "shim it up" because they could not obtain one, but this fix only lasted for a month.

Ideas?
Reply With Quote
  #10  
Old 01-03-2001, 11:20 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Below the steel housing of the t/stat itself is the aluminum body of the airvalve (extra air for cold running). The water leaks between these two. Beneath the aluminum housing is the pump body itself and the shim adjustments for these systems relative normal governing.

The only leaking I can think is happening would be coolant and I don't see what this has to do with your running unless it contributes to the airvalve sticking in its aluminum housing.

The t/stat itself is the only part serviced separately anymore (it is inside the top housing with the hoses connected), but like I say parts should be easily available used. I just don't see the point to solving the leak unless the pump can be made to perform correctly.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #11  
Old 01-03-2001, 11:43 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,777
Richard,
I do have some part pumps here.
I suspect you have an R18 series pump.
If it has an "Oel" cap, it has a dip stick. Or it has
been lost and plugged. [Rear of the pump, T handle]
A pump # will tell. The Bosch # will be the last series of #'s. R18, R 18y, R18z , etc.
The force feed engine oil pumps without dip stick did not come out until the R 20 pump. [ 280sl]
Though this may not be your problem , I would be concerned to find out if the pump does in fact have any oil in the res.
If you find the pump #, I will check and see what I have in used parts

Arthur
.
Reply With Quote
  #12  
Old 01-04-2001, 02:45 AM
67-250SL
Guest
 
Posts: n/a
Thanks for your replies guys - based on your feedback, I am not convinced my regular mechanic is diagnosing the problem correctly, and am going to take it to my secondary shop for a second opinion. I'll post an update when that is completed. Thanks,
Reply With Quote
  #13  
Old 01-11-2001, 09:29 PM
67-250SL
Guest
 
Posts: n/a
Fixed!

Well, thanks to my local MB dealer, I'm back in business - no parts and no re-build. Turns out the same mechanics that worked on this car back in the 70s are still working there. 4 hours of fine tuning and adjustments, and it runs beautifully - cold, warm and hot. Thanks for the feedback; without it, I might have been taking out the injector pump right now.

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cost of 603 Engine Rebuild HGV Diesel Discussion 21 01-17-2006 12:56 PM
differential rebuild parts xp190 Tech Help 5 05-04-2003 01:12 PM
Suspension rebuild a review and questions dmorrison Tech Help 7 02-18-2003 12:24 AM
Who still sell ac servo rebuild kit? Lue Tech Help 3 01-10-2003 07:00 PM
Brake rebuild rebootit Diesel Discussion 5 11-29-2002 05:17 PM



All times are GMT -4. The time now is 05:39 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page