Quote:
Originally Posted by BenzMacX
So I have a 1980 300GD with a European OM617 naturally aspirated engine.
Living in Colorado, this truck has to pass emissions every year, just a simple opacity test at a couple load points. The first few years I had it, it passed without issue, something like 13% opacity max with 45% being the max allowed.
Then all of the sudden it was very hard to pass, jumped up to over 50% opacity!
So I did the usual, adjusted the valves, replaced the injectors, new air filter... Nothing helped.
I then took it to a shop figuring it would need the fuel injection pump timed. However, the shop I took it to used a pizo sensor on the #1 cyl fuel to measuring the timing. He said it was basically dead on, no issues.
So I am currently trying to use the drip test to verify his results (I am a little skeptical of the pizo results). After hooking everything up and rolling it over a few times I notice some odd behavior. Basically, it appears to drip (flow actually) multiple times per revolution of the engine. There appears to be the expected flow, from ~65 degrees BTDC to 24DBTC. However, it quickly begins flowing again after it stops.
Below is a link to a video where I am rolling the engine over by hand and the video is looking at the drip pipe. I start at 24 degrees before TDC on a compression stroke of the #1 cyl. I rotate it over and you can see it start flowing again, a bit later I say I am about 180 degrees (crank degrees) away from where I started at 24 degrees.
My issue is that I would not expect fuel to start flowing again here. I would expect it to flow once for every 2 revolutions of the crank (~65 to 24 degrees during compression), then be off the reset of the time.
So, is my injection pump trashed? I also noticed the other valves in the IP for the other cylinders slightly leak fuel while I am rolling the engine over, which I would not expect...
https://www.youtube.com/watch?v=IqRXjEZm66M
Thanks for any help,
Jim |
Bio Diesel does not smoke as much as Diesel Fuel does but it will clean out your tank of crude. So you would need to drive off several tank fulls before going to the emissions test. Also drive the car as fequently as you can at high speeds (witn in the law) before the test.
Check your valve timing. It is sort of less accruate test to see if your timing gears are worn and Timing Chain stretched.
As far as what you did some details are lacking. The Throttle Lever is supposed to be in the full fuel position. I get some wire to wire it in that position and then put note on the Steering Wheel to remind me that the Throttle lever is wired at full fuel.
Your the fuel coming out of the fuel injection pump seems weird because you expectation of what you think is supposed to happen.
And If I had an element in front of you it would take only 1/2 a minute for you to understand but wit mere words it is difficult to explain.
When you use the drip methodl you remove the central valve from the Delivery Valve Assembly and the spring and put the Delivery Valve holder back on.
On eaceh of you elements inside of the Fuel Injection Pump there is one or more fuel feed holes. As long as those holes are uncovered and the Delivery Valve and Spring are gone fuel is going to come out of the top of the Fuel Injection Pump.
So we are going to say the Element Plunger is at the bottom. As it goss up fuel is going to be coming out the top. As it continues up the Plunger starts to close off the fuel feed hole and you the fuel coming out decreases till if you are turning the engine slowly you get those x amount of drips per second. Immedieatly after that as the plunger move up is the begin of Injection and the plunger is going to push fuel out of that drip tube.
As the plunger moves up the plunger still covers the fuel feed hole and is fuel will still come out. However, as the plunger rises it reaches the shutoff section (a special cut in the plunger) uncovering the fuel feed hole and fuel is going to start flowing out.
As the plunger comes back down there is also a short blip where no fuel will come as the fuel feed hole is again covered. As the top of the plunger goes down pas the fuel feed hole it is again openend and fuel flows again.
So there is only 2 tiny blips where no fuel is going to come out and if you are rotating the Engine or the Fuel Injection Pump to fast you go right past it. And as you have noticed there is a lot of time where the fuel feed hole is open.
When you re-install the fuel Injection Hard Lines you are going to need to bleed the air out of them up to the Injectors. Tighten the Fuel Injection Hard Line Nuts at the Fuel Injection Pump and just put the on loose on the Injector end of the hard lines and crank the Engine till fuel is coming out of them and then tighten them and see if you can start.