OM603 Idles, But Won't Pick Up Speed - Page 4 - PeachParts Mercedes-Benz Forum

skelleybenzes · #46 06-01-2010, 09:38 AM

Quote:

Originally Posted by biopete

Thanks for info.

What do you mean "spotless injector"? You didn't pop test them? I've never seen a spotless injector at the needle that has run in a car. Even after 5 minutes on diesel on a brand new nozzle i pulled the injector and there was black carbon on the tip already.

To test the glow plugs, when you pull all injectors to test them just turn key and look down in injectors holes and watch how they glow. You can try it with new ones to see what good glowing is -- should get red hot in a second or two. You can spot the weak ones easy.

Sorry--should have been more clear. The injector tips did have carbon, but were not coked up. Took injectors apart and saw no undue deposits. Pop tested all, and all were in spec.

I just replaced the glow plugs when the car had some hard starts--figured I'd replace all of them at once. Now that I have the injectors out, I'll take a look at 'em. I do have a frame of reference as to checking them, since I made sure they were working properly after doing the Elsbett install.

skelleybenzes · #47 06-01-2010, 12:56 PM

Well, for my Memorial Day festivities, I ran compression and leak-down tests on the motor. Forgot my written notes, but here goes from memory:

Cylinder 1: 305 psi No significant leakage
Cylinder 2: 75 psi

Leakage!!!
Cylinder 3: 395 psi No significant leakage
Cylinder 4: 400 psi No significant leakage
Cylinder 5: 375 psi No significant leakage
Cylinder 6: 415 psi No significant leakage

So, cylinder #2 is obviously ailing. The compression started low, then built up over successive cranks. With a little 30-weight oil in the cylinder, compression bumped up to 125. From what I gather, as I suspected, all signs point to some sticky (and I hope not broken) rings.

My plan of attack is to soak the cylinder with Marvel Mystery Oil while awaiting the arrival of a water/methanol injection kit, likely from Snow Performance (I have that setup on my 2000 Ford Excursion 7.3 PSD, and have been pleased with it). From my research, others have successfully used the water/meth setup to address sticky rings resulting from WVO use. In essence this will be a more controlled, and safer, version of the "water-mist method" that Vstech mentioned earlier in this thread, and will probably act as a preventative measure as well.

ah-kay · #48 06-01-2010, 01:25 PM

I am not a heavy duty mechanic on engine internals but 1 cyl with low compression wouldn't cause the car not to pick up speed, would it? I hope you are on the right track but I am not sure. I have loosen 1 injector nut on the hard line before and car still runs with reasonable speed.

skelleybenzes · #49 06-01-2010, 02:48 PM

Quote:

Originally Posted by ah-kay

I am not a heavy duty mechanic on engine internals but 1 cyl with low compression wouldn't cause the car not to pick up speed, would it? I hope you are on the right track but I am not sure. I have loosen 1 injector nut on the hard line before and car still runs with reasonable speed.

Very true, the lack of compression itself is not technically the issue--the blow-by caused by the leaky rings is creating pressure on the injector pump shut-off mechanism, and essentially preventing the engine from developing power. With the oil cap removed, and the pressure reduced, I can get the motor to accelerate.

skelleybenzes · #50 07-13-2010, 09:51 AM

Hey all, I've been soaking rings in MMO for several weeks now--compression has come up quite a bit in my #2 cylinder, still lower than spec, but at least it's better. While waiting for the soak, I installed a Snow Performance water/methanol kit, pop-tested the injectors and adjusted the opening pressures (they all were on the low side) and got everything buttoned up last night.

Engine started right up, much smoother than before, and now able to rev the engine!. Once I got it up to temperature, I flipped the switch for the H20/Meth, and revved the engine repeatedly to build boost and trigger the H20/meth injection.

With the amount of smoke I emitted, the entire neighborhood was blanketed in greyish white smog (sorry neighbors) while the engine started to clean itself up. The smoke tapered off after a while, and I went to drive around the adjoining parking lots like a mad man (lots were empty, by the way). I'm still having low RPM power issues after the car runs for a while. Couldn't even make it up the driveway without taking a running start (probably lingering blow-by problems shutting the IP down), but at least I'm making progress. I think, and hope, that if I can get it out on the road, the H20/meth can continue cleaning out the crud, and I can be back to where I started.

As luck would have it, the fan clutch, which had been on a downhill slide for a while, gave up completely last night, so I had to shut down (was starting to run hot). Luckily I have a spare, but now have to get around to doing that.

Thanks again for everyone's input--I'll post back as things develop.

skelleybenzes · #51 07-14-2010, 10:47 AM

OK, this thread is taking yet another turn. I've got the engine running well enough, and if I can get the car moving (starting even slightly downhill), and build up RPM's, it goes like heck, shifting through gears just fine. But on a slight incline, the damn thing just will not move--RPM's will pick up slightly, but just no power. I'm starting to think that this is no longer an engine issue, but a tranny problem.

Now, this thing has always been a slug when starting off from a stop, or starting on an incline, but now it simply feels like it's trying to start off in 2d gear. Yes, I have read the posts about 1st gear/2d gear starts, and understand that this vehicle SHOULD start in 1st. My (first) question is, can a poorly adjusted Bowden cable cause this? And if I tighten it, thus raising the RPM's at which the tranny shifts, should that help? Help?

Patrick Skelley
Bedford, Virginia
1970 Unimog 406
1972 350SL 4.5
1972 300SEL 6.3
1978 240GD
1979 300GD
1987 300TD

BoiseBenz · #52 07-14-2010, 11:13 AM

Now your symptoms--turbo car that goes at speed but is weak down low--point to an ALDA problem. I think the easiest way to "test" it is to (temporarily!) remove it.

Leave the transmission alone, for now. One can o'worms at a time, young Skywalker.

skelleybenzes · #53 07-14-2010, 11:27 AM

Quote:

Originally Posted by BoiseBenz

Now your symptoms--turbo car that goes at speed but is weak down low--point to an ALDA problem. I think the easiest way to "test" it is to (temporarily!) remove it.

Leave the transmission alone, for now. One can o'worms at a time, young Skywalker.

Ah, and we have come full circle Obi Wan, as we started this thread with an ALDA discussion. Points well taken, I'll leave the tranny be, and I'll yank the ALDA (again) and report back.

ROLLGUY · #54 07-14-2010, 02:52 PM

Quote:

Originally Posted by skelleybenzes

From my research, others have successfully used the water/meth setup to address sticky rings resulting from WVO use. In essence this will be a more controlled, and safer, version of the "water-mist method" that Vstech mentioned earlier in this thread, and will probably act as a preventative measure as well.

I have been using W I in my 190D for years. I am amazed at how it cleans the combustion chambers! I had to change the head gasket last year, and the chambers and piston heads were VERY clean. The cyl that was leaking was only slightly cleaner, and all 4 were just wiped with a rag to clean off the remaining carbon. I have seen more carbon on GAS engines that I have torn down. Also GP replacement has been no problem. I have had to replace them more often because of VO use, but they look almost like new when pulled to replace them. There has not been any carbon to ream!
I think water injection is a must for all Diesel engines, regardless of fuel used.

barry123400 · #55 07-14-2010, 05:05 PM

If the alda removal does not clear the issues a lot of thought should probably be applied before moving forward.

I personally would like to see a description of the present blowby remaining. The best is with using the oil cap as a descriptive refferance. Does it stay still at idle? Dance around and how much dancing or does it blow off the opening.

Yes the engine will accelerate normally in the driveway with no load.What concerns me is blowby under road load may still be heavier than at idle or otherwise with no load. Again perhaps partially trying to shut down the engine somewhat still.

The car started with one issue primarily. It has to be still considered as perhaps partially responsable until proven otherwise. I might have to consider what I just typed out overnight and add any refinements to my thinking if they occur tomorrow.

Also be meticulous with the alda check. You had it off before and something may have messed up with the reinstallation. You now know it was good at least until the removal the first time.

Not trying to be the devils advocate here either. This one may prove interesting if it is not the alda.

BoiseBenz · #56 07-14-2010, 06:22 PM

Quote:

Originally Posted by barry123400

I personally would like to see a description of the present blowby remaining. The best is with using the oil cap as a descriptive refferance. Does it stay still at idle? Dance around and how much dancing or does it blow off the opening.

Also please note the material of the cap; the metal ones are much heavier and less "dancy." Is your fuel cap still metal? They interchange.

skelleybenzes · #57 07-15-2010, 10:03 AM

Yessss .. . . . .YESSSSSS!!!!!

Took two minutes to loosen the ALDA enough to disable it. Let the car warm up for a few minutes, put the pedal down and slung gravel while rocketing UP the driveway. Drove around the block and then took it on a 50 mile round trip up and down the foothills of the Blue Ridge here with NO issues!!!!! Like a totally different vehicle.

Blowby is almost gone (plastic oil filler cap has stopped dancing), and noticed immediately that the transmission is now shifting silky smooth (it would bang into 4th before).

So I had two problems going at once--the ALDA was intermittently (and frequently) shutting down the pump at low RPM's, and the blowby was shutting down the pump at high RPM's, which is why removing the ALDA before didn't seem to help that much. Now, the question is (and I know it's been asked repeatedly before), do I ditch the ALDA (my gut feeing is "yes"), or do I try to adjust or replace it?

babymog · #58 07-15-2010, 10:39 AM

That's an opinion thing, I adjust mine so that I still have overboost-protection and altitude compensation.

winmutt · #59 07-15-2010, 11:19 AM

Quote:

Originally Posted by skelleybenzes

Blue Ridge

What is your location?

ROLLGUY · #60 07-15-2010, 12:01 PM

Quote:

Originally Posted by skelleybenzes

Now, the question is (and I know it's been asked repeatedly before), do I ditch the ALDA (my gut feeing is "yes"), or do I try to adjust or replace it?

After reading this entire thread (took about 3 hours), I removed the ALDA from my (former) 83 300D (I know it's not a 603) and I had the same reaction as most: INCREDIBLE!
This car was a total DOG off the line. Before, it did not have enough power to get out of it's own way! I sold it to a friend of mine and he was complaining about the lack of power until the turbo spools up. I drove it after the five minute repair, and it is not the same car. When I first bought this car, it did not even have enough power to drive it up on the trailer!

As far as your ALDA, my vote would be to gut it and put it back on. I am not sure if adjusting it all the way out would achieve the same results, as it still may limit the travel of the rod inside. Someone else here may have experience that we can draw from.