Delivery Valve Seal - Page 2 - PeachParts Mercedes-Benz Forum

bhanson · #16 12-17-2007, 09:35 AM

Hijack alert!
I have had increasingly difficult starts, especially with a hot engine, and decreased fuel economy. I've replaced all the glow plugs, checked everything else for leaks, replaced the primer pump, and am thinking at this point it is the delivery valve seals, especially since I've been running a lot of biodiesel over the last year. Do these symptoms seem to all of you to confirm my guess? The top of the IP looks dirty, oily, but I wouldn't say it looks like it's just 'wet'.

tobybul · #17 12-17-2007, 10:23 AM

Quote:

Originally Posted by bhanson

Hijack alert!
I have had increasingly difficult starts, especially with a hot engine, and decreased fuel economy. I've replaced all the glow plugs, checked everything else for leaks, replaced the primer pump, and am thinking at this point it is the delivery valve seals, especially since I've been running a lot of biodiesel over the last year. Do these symptoms seem to all of you to confirm my guess? The top of the IP looks dirty, oily, but I wouldn't say it looks like it's just 'wet'.

If you have a leak on the delivery valve, you will know it as it will show fuel coming out of the leaking valve!! But you have to observe it when the engine is running. If its off, there is no leak.

However, fuel leak in the delivery valve would not normally cause hard starting. In my case (and I would say in most cases), air inside the IP and the lines will cause hard starting. Air in the lines purges when the engine starts but air in the IP will perpetuate the problem. The only way to remove air in the IP is to pump the primer pump untill you hear it make a buzzing sound. That means, you have vented the IP.

IMHO, its always good to start with the simple stuff first.

Hope this helps.

bhanson · #18 12-17-2007, 10:30 AM

Quote:

IMHO, its always good to start with the simple stuff first.

Absolutely agree, but it feels like I've done most of the 'simple stuff'. Also I'm reading your post, and it seems like you are saying that there could be air in the IP even after running the engine? Not sure that makes sense to me. Can you clarify?

Ben

tobybul · #19 12-17-2007, 11:23 AM

Quote:

Originally Posted by bhanson

Absolutely agree, but it feels like I've done most of the 'simple stuff'. Also I'm reading your post, and it seems like you are saying that there could be air in the IP even after running the engine? Not sure that makes sense to me. Can you clarify?

Ben

Take it from me, the IP can start with air in it but only after xxx number of cranks - and then again it may not start. I did not know about air in the IP until I read the FSM. I was sort of pumping the primer just for the heck of it as I did not know what else to do. This is probably what made it start - I came close to venting it but not totally. Finally, I read the FSM and lo and behold, it says the IP has to be vented by the above procedure I explained. As soon as I did this, it started at first crank. If you have not tried it yet, what have you got to lose. Make sure you hear the buzzing (or squeaking) sound.

Diesel911 · #20 12-17-2007, 11:57 AM

There is a tool rental program going on click on that thread I believe that 2 parsons were renting their socket.
The socket sells on Ebay for around $40 and you also have to pay shipping. 2 Ebay sellers Zdmak and El Paso tools. I also comes up for sale by private owners on Ebay.
The companies who support this site most likely also sell it also and might make a special effort to get it to you faster.

bhanson · #21 12-20-2007, 09:11 AM

Pumped the *(&#@ out of the primer pump last night when it wouldn't start hot. No change. It really does act like it's not getting fuel. A spritz of WD40 in the intake and it starts right up - immediately. I'm still thinking somehow it's losing prime....fast and it's more prone to doing so the IP is heated up for sure. There's no air coming in from the incoming fuel side; I have a sight glass inline right before the injector pump. The delivery valve seals have been reported in other threads to cause this phenomenon, even without any major leakage. Where else could I be losing pressure or sucking air?

lrg · #22 03-02-2008, 09:08 PM

I just ordered the crush washers and o-rings to do this job. I have some leaking and a slight miss at idle that I hope to fix on my OM 603.

Any advice from those who have done this before? Also I want to confirm that the torque spec is 35NM.

Thanks.

wrench56 · #23 03-02-2008, 10:30 PM

Jim@fryerpower.com has vition delivery valve o-rings for replacements. They work well if you use biodiesel or veg oil. The copper washers only available from the dealer as far as I know. It's also a good time to replace your injector return lines, viton line is also available at fryerpower. Replacement is real straight forward, just keep everythiing real clean. I have the 30 point socket available also.

Wayne

lrg · #24 03-03-2008, 01:58 PM

Thanks Wayne. I ordered the socket too, cheap considering the savings vs. having someone else do it. I replaced the fuel return lines already. The IP is starting to really leak, probably due to age and the use in Cal of ULSD. I'm overdue for the project anyway.

tobybul · #25 03-07-2008, 12:53 PM

Quote:

Originally Posted by lrg

I just ordered the crush washers and o-rings to do this job. I have some leaking and a slight miss at idle that I hope to fix on my OM 603.

Any advice from those who have done this before? Also I want to confirm that the torque spec is 35NM.

Thanks.

Per the FSM, the tightening is 2-steps. Tighten to 30 and then to 35. As I discussed above, I did this on my 617 IP. Does not leak anymore. I believe it was the rubber washers that were bad but I replaced both.