Timing adjustment methods - Page 3 - PeachParts Mercedes-Benz Forum

fdanielson · #31 01-05-2011, 02:19 PM

At the risk of throwing more fuel on the fire here I'm going to try and point out that there are two timing methods that use the word 'Bubble' in the name and this leads to some confusion. First is the "Bubble Up" method that involves no drip or injector tube and has the person looking for fuel to bubble up from the port on the injection pump. Second is the bubble method described in previous posts in this thread that, if you read it carefully, is the same as the drip method except that that you are dripping air instead of fuel.

Personally I don't have much confidence in the Bubble Up method but have never tested it. The bubble method that uses compressed air instead of fuel pressure to find start of delivery seems to add some convenience if you don't have enough hands to pump the primer and fiddle with the pump and/or motor position while watching a drip tube. There is probably a good argument to be made for the difference between the injection pump moving air instead of fuel but I would be willing to guess that it is not a large difference which leads to the previously stated opinion that the method is accurate enough.

funola · #32 01-05-2011, 02:27 PM

I find the FSM IP timing instructions very confusing. It gives no explnations of why and what's happening for each step. And why are there so many methods given?

Here's a list of the different methods I found in an online FSM

07_1-108 Checking injection timing (begin of delivery) with digital tester (RIV method)

07_1-110 Checking injection timing (begin of delivery) (flow pressure method)

07_1-111 Checking injection timing (begin of delivery) (position indicator RIV method)

07_1-114 Checking injection timing (begin of delivery) with digital tester (RIV method) - following checkup

07_1-115 Checking injection timing (begin of delivery) (high pressure method) - following checkup

07_1-116 Checking injection timing (begin of delivery) (position indicator RIV method) - following checkup

Stevo · #33 01-05-2011, 03:33 PM

Quote:

Originally Posted by fdanielson

At the risk of throwing more fuel on the fire here I'm going to try and point out that there are two timing methods that use the word 'Bubble' in the name and this leads to some confusion. First is the "Bubble Up" method that involves no drip or injector tube and has the person looking for fuel to bubble up from the port on the injection pump. Second is the bubble method described in previous posts in this thread that, if you read it carefully, is the same as the drip method except that that you are dripping air instead of fuel.

Personally I don't have much confidence in the Bubble Up method but have never tested it. The bubble method that uses compressed air instead of fuel pressure to find start of delivery seems to add some convenience if you don't have enough hands to pump the primer and fiddle with the pump and/or motor position while watching a drip tube. There is probably a good argument to be made for the difference between the injection pump moving air instead of fuel but I would be willing to guess that it is not a large difference which leads to the previously stated opinion that the method is accurate enough.

Oh Yes, the bubble "UP" method, I'm not trying to peddle that

The bubble method is nice because your not dealing with fuel to spill or pumps to pump and if you gently blow through the upper hose (remembering not to inhale

) you wont taste any diesel, while you slowly turn the engine(by hand) till the bubbles stop coming from the hose in the container of water.

4thesporty · #34 01-05-2011, 03:44 PM

Aren't one of these bubble tests also called the "well up method"?

Stevo · #35 01-05-2011, 07:07 PM

I edited my post above, the hose in the jar, not "welling up" of fuel. hope that helps to clarify things.

ForcedInduction · #36 01-05-2011, 07:10 PM

Quote:

Originally Posted by Stevo

if you gently blow through the upper hose

What CFM and pressure is the standard for "gently blow"?

Stevo · #37 01-06-2011, 11:10 AM

Quote:

Originally Posted by ForcedInduction

What CFM and pressure is the standard for "gently blow"?

It should be found in the FSM in the chapter right after installing an intercooler, oh wait ....

Diesel911 · #38 01-15-2011, 02:15 AM

In this thread there there is a pic of an IP with a Drip Tube on it and it has the fuel supplied to it by a Gravity Feed set up.

http://www.benzworld.org/forums/vintage-mercedes-benz/1494188-75-240d-injection-pump-oil-consumption.html

Rooster300SD · #39 01-15-2011, 02:32 AM

Where is the port for the A-B timing device located on the IP?

Thanks,
Jeff

leathermang · #40 01-15-2011, 02:35 AM

Quote:

Originally Posted by fdanielson

Second is the bubble method described in previous posts in this thread that, if you read it carefully, is the same as the drip method except that that you are dripping air instead of fuel.

The bubble method that uses compressed air instead of fuel pressure to find start of delivery seems to add some convenience if you don't have enough hands to pump the primer and fiddle with the pump and/or motor position while watching a drip tube. There is probably a good argument to be made for the difference between the injection pump moving air instead of fuel but I would be willing to guess that it is not a large difference which leads to the previously stated opinion that the method is accurate enough.

You have missed the most important point. That is that DRIPS are pretty much standard in size... so when they call for one drip per second... that is something one can time and adjust TO...

Please explain how AIR is DRIPPED ..... ?????

You are just making stuff up when you say there is probably a good argument because there is no easy way to standardize the amount of air coming out... as compared to the very easy standard of ' drop per second'..

You are willing to guess... that is exactly what you will be doing if you deal with air in these processes...

Tell me why so many engines with this type injection system use the drip method....and why the FSM would specify it in the Shop Manual if there were easier methods ?

paddo · #41 01-15-2011, 12:09 PM

What are the symptoms of timng being out?
My motor sometimes has a "rattling tin can" sound which I think is a timing issue in a gas engine.

Also sometimes the engine has a "thump" when it first starts, but this is intermittent so probably not related to timing.

Diesel911 · #42 01-15-2011, 12:40 PM

Quote:

Originally Posted by paddo

What are the symptoms of timng being out?
My motor sometimes has a "rattling tin can" sound which I think is a timing issue in a gas engine.

Also sometimes the engine has a "thump" when it first starts, but this is intermittent so probably not related to timing.

The thumping is most likely being caused by the Motor Mounts and Transmission mounts and maybe the Engine Shocks (if you have them).
Have someone crank your Engine and see of the thumping is caused by your Engine Block being jerked to one side.
If the thumping is coming from the Air Filter housing there is some threads on how to deal with that.

There is more than one thing that can cause the Ratteling Sound.
If it rattles after starting and the ratteling goes away after the Engine ie warmed you could have a Glow Plug Issue. Easy to check them with an Ohm Meter
Things that you can do yourself without spending much money are a Valve Adjustment and the Timing.
After that it is an Injector or Compression issue and maybe Camshaft Timing late due to Timing Chain/Gear wear.

Diesel911 · #43 01-15-2011, 01:02 PM

Quote:

Originally Posted by Rooster300SD

Where is the port for the A-B timing device located on the IP?

Thanks,
Jeff

See post number 2 in the below thread for a pic (an IP Locking Pin is show in the A-B Port):
Diesel Injection Locking Tool

scottmcphee · #44 01-15-2011, 07:25 PM

This kills me.

You guys all know that it depends on engine load as to when is the best point in time to inject. The fact that we have to set timing to "one point", because it's mechanical, and it's fixed... is a compromise. Finding "the exact point" using any method is still a compromise. Modern diesels adjust injection timing under all kinds of conditions, and even adjust how many and when to inject micro bursts during the same stroke. We're stuck with one lump of fuel going in at a given piston position, no matter what..

All manuals and methods and precision aside... find a timing point that you like. For your climate, your altitude, your style of driving, your fuel efficiency desires, your power needs, startability, the condition of your timing chain slack, quality of injectors, etc... and just drive it and enjoy it. If your conditions change, give tilt the IP a degree or two either way... did it improve? Make it worse? Test and try again.

Personally, I'm set for a preference toward mid to upper power range, when boost is 30% or more. That's where I want my injection to respond.

Diesel911 · #45 01-15-2011, 09:37 PM

Quote:

Originally Posted by scottmcphee

This kills me.

You guys all know that it depends on engine load as to when is the best point in time to inject. The fact that we have to set timing to "one point", because it's mechanical, and it's fixed... is a compromise. Finding "the exact point" using any method is still a compromise. Modern diesels adjust injection timing under all kinds of conditions, and even adjust how many and when to inject micro bursts during the same stroke. We're stuck with one lump of fuel going in at a given piston position, no matter what..

All manuals and methods and precision aside... find a timing point that you like. For your climate, your altitude, your style of driving, your fuel efficiency desires, your power needs, startability, the condition of your timing chain slack, quality of injectors, etc... and just drive it and enjoy it. If your conditions change, give tilt the IP a degree or two either way... did it improve? Make it worse? Test and try again.

Personally, I'm set for a preference toward mid to upper power range, when boost is 30% or more. That's where I want my injection to respond.

Result of me advancing the timing to 28 degrees
http://www.peachparts.com/shopforum/showthread.php?t=248979

What to set the timing to is different argument than how to set it.