M103 Cold Start Injector Sealing Problem - PeachParts Mercedes-Benz Forum

Rahulio1989300E · #1 03-30-2015, 10:26 AM

Hello,

It's been a while since I posted, but I could use some help on this one.

I recently installed a newly painted valve cover and resealed the front timing cover using the Tech Info links posted at the top of the website. Very helpful!

While I had everything apart, I decided to replace the vacuum hose between the head and idle control valve. To do this, I had to remove the cold start fuel injection valve, which needed the top metal hard line to be removed first.

Anyways, I have buttoned everything back up, I reconnected the battery and turned the ignition to position 2 just to get the fuel pumps primed and inspect for leaks before starting the car. I am getting fuel leaking out from the top of the metal hard line that connects to the top of the cold start injector. I attempted to reseal this connection by removing it, cleaning the threads, oiling the threads with a very small amount of grease and retightening the connection with my 12mm wrench while also pushing down on the metal hard line to try to get a good, tight connection between the hard line and the injector.

Are there any tips of tricks to getting this connection resealed? I fear either the injection valve mating surface or the mating surface on the metal line has some kind of bur that is preventing a good seal, but the metal line is really hard to move, and impossible to inspect without removal from the fuel distributor. Open to suggestions if anyone has run into this problem before.

Thank you

Picture:
https://drive.google.com/file/d/0B3le5-Lcwkv0S3RxZndGS2RYMkk/view?usp=sharing

lsmalley · #2 03-30-2015, 12:35 PM

Hmmmm, the only time I've encountered that problem is when I did not tighten the line enough, and I've removed that line, I fact, my entire fuel distributor, at least 30 times in the past 6 months. Undo the line and brush the csv threads with a wire brush making sure to cover the hole of the csv. And don't worry, as long as you're not bending the line at a sharp angle, you should be ok. I personally went to a junk yard for the sole purpose of testing the strength of some of the parts and let me tell you, I had to use vice grips and twist that line around 10 times and wiggle it back and forth before it broke.....and trying to cut through the "rubber" brake line with a pair of beefy titanium scissors.....forget about it, easier just to unscrew it :-) hope this helps

Rahulio1989300E · #3 03-31-2015, 10:17 AM

Thank you for the reply, I am going to give it another attempt this afternoon.

Rahulio1989300E · #4 04-04-2015, 09:05 PM

Just came back from the garage. I pulled the cold start injector out this time.

I tried tightening the hard line connecting to the top of the valve, I put quite a bit of force into it, and got the nut to rotate a bit more. I then primed the fuel pumps twice and checked for seeping fuel at the top of the cold start valve, did not see any, which was a great step in the right direction.

I went ahead and started the car, but only for about 5 seconds, as my air cleaner is off so I can see if it started to leak. Sure enough, after I switched off the engine, I checked the top of the valve and the area was soaked with fuel (top, and sides of cold start injector)

I disconnected the battery, relieved the fuel pressure in the system by loosening the gas cap, and undid the hard line again slowly and caught the excess fuel with 3 folded up paper towels. I removed the two allen bolts that hold the cold start valve into the rubber hose below, disconnected the plug after prying off the metal clip and am going to see what I can do to the conical surface to make it smoother and get a better seal.

The part number is 0 280 170 412 (Bosch part number). It does not appear in any online Google searches so far. There are a couple used ones on eBay, but does anyone know if Bosch makes a replacement part that can be used for this application? The Bosch auto parts website crashes when I input my 1989 300E's data.

Cold Start Valve Part Numbers:
Mercedes-Benz: 0000714137
Bosch: 0280170412
Standard Motor Products: CJ79
Wells: CVS66
Airtex: 6C2066

Rahulio1989300E · #5 04-13-2015, 04:06 PM

Just wanted to close up the thread with how I ended up fixing the sealing issue. I removed the cold start injector/valve completely. I then plugged the inlet hole with a piece of dried up glue from a hot glue gun. Then, I used a green brillo pad, held the conical surface against the pad and rotated the valve a few times. I cut a small square of brillo pad and rotated it against the hard line which goes into the top of the injector.

I removed the glue piece from the cold start valve and wrapped the threads in about 2 layers of tightly pulled PTFE tape. I slipped the injector back into the hole in the hose that the injector sprays into, but did not tighten the two allen screws that hold it in place. I first threaded on and tightened the hard line (12MM open end wrench) as much as I could, then used an old brake pad pin I had to align the holes for the two allen screws (5MM). Got 1 in, then the other. Tightened those and went for a final tightening of the 12MM hard line.

Primed the fuel pumps a few times, checked for leaks, then started the engine for about 10 seconds, turned off and checked for leaks again. Replaced air cleaner, started car and with a flash light, monitored the cold start injector for leaks. (You can still see it from the side, between the valve cover and the air cleaner.)

Problem solved, case closed!