500 SEC M117 Injector Source

Page may contain affiliate links. Please see terms for details.

Gear1275

Member
Joined
Aug 7, 2019
Messages
36
Location
Bristol
Car
500 sec
evening gents,
I need to replace the injectors and seals on my 500 SEC and I’m seeing “genuine” injectors on eBay at £20 each but I’m sure Mercedes would want a small fortune more from experience. Has anybody gone down the eBay route before and got any experience with the cheaper ones?
Or does anybody have a “go to guy” for injectors?
I’ve done some research on cleaning the injectors with mixed results and views but I’m also open to getting them cleaned if you think it’s possible?
Again, any experience and real world experience would be well received.
James.
 
What year is your 500SEC? earlier cars used CIS and late cars use CIS-E. The injectors look the same but open at different pressures. CIS and CIS E went into a million different brand of cars during the 70's and 80's which is why fuel pumps and injectors are so cheap (928, Ford Capri 2.8i, VW GTI, Mercedes etc). That said, they're just nozzles on these cars that get gummed up from carbon build up and sitting fuel. You can usually clean them for the cost of a few cans of brake clean.
 
What year is your 500SEC? earlier cars used CIS and late cars use CIS-E. The injectors look the same but open at different pressures. CIS and CIS E went into a million different brand of cars during the 70's and 80's which is why fuel pumps and injectors are so cheap (928, Ford Capri 2.8i, VW GTI, Mercedes etc). That said, they're just nozzles on these cars that get gummed up from carbon build up and sitting fuel. You can usually clean them for the cost of a few cans of brake clean.

The car is April ‘85.
Thanks for the reply. I watch a lot of the Mercedes source videos on YouTube and he seems to really know his stuff and was struggling to clean the injectors.
How would I identify which system I had?
If I could get genuine Bosch for £20 a time then I would just replace them for that money but don’t want to put money into dodgy non genuine rubbish.
 
Kent has some very informative videos and does a great service to the MB community but over the years, I've gotten several MB running after they had seat for years (decades sometimes) using this method and the only time I thought i failed and bought a set of injectors turned out to be a poorly seated spark plug due to crossed threads. I have the factory cleaning tool but never use it because the brake clean method works well. In some cases compressed air has to be used and you might need to give the injector a knock but that's only if they're truly blocked.

If your car is running 14" wheels and ribbed cladding, it's probably the earlier car with CIS but the best way to tell is to look under the hood and see if it has a warm up regulator. If it does, then it's a CIS car. If not, then it's the later CIS-E car

The Bosch # that you want for the CIS cars is 62274 and 62231 for the CIS-E cars

Make sure you buy the boots as the old ones will be as hard as a rock and unlikely to save. This is regardless of whether you reuse your old ones or get new ones.
 
Kent has some very informative videos and does a great service to the MB community but over the years, I've gotten several MB running after they had seat for years (decades sometimes) using this method and the only time I thought i failed and bought a set of injectors turned out to be a poorly seated spark plug due to crossed threads. I have the factory cleaning tool but never use it because the brake clean method works well. In some cases compressed air has to be used and you might need to give the injector a knock but that's only if they're truly blocked.

If your car is running 14" wheels and ribbed cladding, it's probably the earlier car with CIS but the best way to tell is to look under the hood and see if it has a warm up regulator. If it does, then it's a CIS car. If not, then it's the later CIS-E car

The Bosch # that you want for the CIS cars is 62274 and 62231 for the CIS-E cars

Make sure you buy the boots as the old ones will be as hard as a rock and unlikely to save. This is regardless of whether you reuse your old ones or get new ones.

Perfect! Thanks for the in depth reply.
I will buy some seals and have a go at cleaning them...
Have you got a particular way that you go about doing them?
I’ve heard they have a screen in them that blocks up too?
I would hazard a guess at blasting the brake cleaner into the top of the injector in the direction the fuel would flow and then blow them through with compressed air after?
I’m assuming that air at 120psi wouldn’t open the injector as they open at over 200? So the air would be only to blow deposits out as opposed to actually blowing the injector open to see a spray pattern and clean the nozzle area?
 
You should be able to get the pintle open by just using a fresh can of brake clean with a straw attachment that you stick in the injector. By efficient by putting all the other injectors in a bowl and directing the injector that you're cleaning the inside off towards it so that you can use it to clean the outside of the other injectors.

Injectors that are really blocked will require compressed air and maybe a knock on wooden table to get the crud to break loose. If your car is running right now, you shouldnt need it.

I wrote a write up about a decade ago when i was working on a 450SLC. Not enough pictures but you'll get the idea.

Cleaning CIS Injectors
 
Perfect mate, many thanks.
The car runs but has a slight miss at idle but gets on and drives lovely. I have set the timing and checked mechanical advance and replaced rotor arm and dizzy cap and plugs and this is something I want to eliminate next.
Any chance you’ve got a part number for the seals or are they all the same for the sl and Sec of the era?
 

Users who are viewing this thread

Back
Top Bottom