Mercedes SLK World banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
Status
Not open for further replies.
1 - 20 of 25 Posts

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #1 · (Edited)
The forum wisdom (thanks!) told me I probably have a leaking injector in my SLK200. I have to buy 4 new/refurbished injectors or play the testing game to find the leaking one. I did some forum search and looks like replacing all injectors is not recommended, so I'm down to the testing game. Any tips how to do it (*) or just normal replace injector, test, repeat until problem solved?

(*) spark plug visual check after very short run? Remove rail, fix injectors in place, pressurize the rail (risky...) and watch for a leak?

P.S. What's the thread size on the fuel rail connection? I might make a normal pressure check first, but I need to buy a gauge with proper connection.
P.S.S Is the Schrader valve a possible pressure test point or better to do it on the feed line? That tester should cover all connections: Petrol and diesel fuel pump pressure tester / meter 0 - 145 PSI AT241 | eBay
 

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #3 ·
The plan how to find which and how many injectors are leaking:
1. Go for a ride with top down >:D
2. Park the car and leave for a few hours to completely cool down
3. Remove fuel rail & injectors
4. Leaking injectors should be, yes, wet or at least should have a different look of the spray surface.

Any opinions?
 

·
*Premium Member
2005 SLK55 AMG /2005 SLK350
Joined
·
6,162 Posts
There are businesses that can clean and test them for you, and rebuild them if needed. I've sent injectors off for my other cars before. Much less expensive than replacing if you can wait a week. Thorough testing requires actual combustion testing which is, uh, dangerous.

A couple bottles of injector cleaner added to your fuel tank over time might help - did you try that?
 

·
*Premium Member
2005 SLK350
Joined
·
2,562 Posts
With the kilometers (miles) that are on the engine, if you are going to go to the effort of pulling the injectors out, then it would be worth the additional effort to follow efair's suggestion to have them tested and balanced. The job will include balancing the overall volume of fuel delivered, make sure of an appropriate spray pattern, and confirm the proper shut off so no leaking. They should be returned to you with new O rings also. This will improve the overall engine performance from how smooth it idles, to fuel consumption, to power output.
 

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #6 ·
Thanks for the advice! I didn't try the cleaners - might be worth a shot. The engine has 160kkm (100k miles). Are you sure that this type of injector can be regulated/rebuild? I'll need A2710780549 or A2710780023 - I don't know yet what's in the car. The injectors are relatively cheap - 80 euro for a new piece or 70-150 for the whole rail + 4 injectors (used). I'm trying to find a garage with proper equipment to bench test the whole set, but no luck so far.

P.S. After watching some yt videos I'm seriously considering home bench testing. The leak test should be simple if I could pressurize the fuel rail (5 bar?) using bicycle track pump (easily goes over 10 bar)
 

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #7 · (Edited)
Replace injectors individually or in set?

I just checked and my M271in SLK200 is fitted with the older type green injectors (at least on the 4th cylinder), so it's part number A2710780549. Should I consider changing them all to the newer brown type or it makes no sense? EPC transladed with google from Russian says
"REPLACE ONLY COMPLETE
A 271 078 00 23 is already installed, the replacement of individual",
so it's hard to guess what that means. My own rusty Russian translation would be
"Replace only sets.
A 271 078 00 23 is already installed, replace individually"
COMPLETE with o-rings or complete set of injectors? That "replace individually" for the new type suggests that I should buy 4 injectors. Car VIN is WDB1714422F010384. Any advice will be really appreciated!

Edit: the original text:
ЗАМЕНЯТЬ ТОЛЬКО В КОМПЛЕКТЕ
A 271 078 00 23 УЖЕ УСТАНОВЛЕН, ЗАМЕНИТЬ ОТДЕЛЬНО
 

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #11 ·

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #12 ·
Fuel rail and injectors arrived >:D
They seem to be in very good shape and came with 1 year/25kkm warranty
Part numbers: 4 x A27110780023 (injectors) + A2710703598 (rail)
Price: 95 euro + shipping

Measured resistance: 11.7 to 11.8 ohm on each injector
 

Attachments

·
*Registered
2006 SLK200
Joined
·
633 Posts
Fuel rail and injectors arrived >:D
They seem to be in very good shape and came with 1 year/25kkm warranty
Part numbers: 4 x A27110780023 (injectors) + A2710703598 (rail)
Price: 95 euro + shipping

Measured resistance: 11.7 to 11.8 ohm on each injector
Racing green, what are the important and safe procedures in removing the injector assembly. Like how do you depressurize the fuel before disconnection. I notice that the cap to the fuel tank always releases pressure when opened, is that enough to depressurize the fuel at the injectors. What else to remove the Injectors and what must one do to reassemble, any important steps one must do? Just in case I need to replace or repair mine. Thanks
 

·
*Registered
2004 SLK200
Joined
·
807 Posts
Discussion Starter · #14 ·
There is probably a service procedure, but i couldn't get my hands on it.
I'll do it this way:
- safety glasses on, all the time unless you have a pair of spare eyes
- no metal on your hands/neck (wedding ring, bracelots)
- disconnect battery (minus first! or a nasty, nasty shortcut is very likely if the wrench touches car body)
- open fuel tank
- get to the rail (yt has some videos, search for "M271 maf sensor")
- release the pressure using valve on the rail
- replace the rail

I'll be making tutorial when the weather here gets better.
 

·
*Premium Member
2005 SLK55 AMG /2005 SLK350
Joined
·
6,162 Posts
Looking forward to your tutorial since I've never done it on the SLK. Did you do anything to minimize or eliminate fuel spillage? That's the part that always worries me....
 

·
**Premium Member 2004 SLK350
Joined
·
5,653 Posts
Looking forward to your tutorial since I've never done it on the SLK. Did you do anything to minimize or eliminate fuel spillage? That's the part that always worries me....
I did a manifold flap and i had to remove the injector rail. You release the pressure from the rail ( it has a special port and with a screw drive you pres the small tip ), then with a cloth you wipe the petrol, no fuel spillage.
The only think is not to work with a hot engine or while you smoke >:D
 

·
*Registered
2006 SLK200
Joined
·
633 Posts
There is probably a service procedure, but i couldn't get my hands on it.
I'll do it this way:
- safety glasses on, all the time unless you have a pair of spare eyes
- no metal on your hands/neck (wedding ring, bracelots)
- disconnect battery (minus first! or a nasty, nasty shortcut is very likely if the wrench touches car body)
- open fuel tank
- get to the rail (yt has some videos, search for "M271 maf sensor")
- release the pressure using valve on the rail
- replace the rail

I'll be making tutorial when the weather here gets better.
RG, when you say open fuel tank you mean take the cap out?
Have you a link to the videos tried search for M271 maf sensor but no luck.
When replacing the rail do you have to bleed the fuel before start.
 
1 - 20 of 25 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Status
Not open for further replies.
Top