603 Shakes at HOT idle-Could it be out of balance injectors? - Page 2 - PeachParts Mercedes-Benz Forum

777funk · #16 06-18-2008, 09:59 PM

Quote:

Originally Posted by dieseldiehard

yes, 603 mounts are not long lived things! they are more like gel filled donuts than the solid rubber mounts used in the 123.
If you shake the engine you can judge whether the mounts are getting weak, on the 603 the fan can hit the shroud when the mouonts go out. Ask greasybenz.

However, even a weak mount will not result in an engine loping side to side unless there is a basic underlying reason for it to run ragged at idle.
The best plan would be to check the injectors first (thats easy), a compression test at the same time the injectors out, then take it from there.
+ replace the heat shileds under the injectors when you replace them.
Like I said the 6 cyls just normally idle so smoothly they're amazing.

I'm having the Injectors pop tested next Tuesday. It's a good 45 minute drive to have that done but I'm curious. Need to have it done.

As far as mounts etc. I am not counting on them to be the problem because as you had said, there's something not right for the engine to shake. And when it's cold there's not a shake. If it were infact mounts, I suspect that it'd shake regardless.

Hopefully I'll get it narrowed down a step at a time.

I still really wonder if it's timing. The car runs smooth on heated WVO or Engine Oil. I'd guess it's got a different burn rate than Diesel.

Hatterasguy · #17 06-18-2008, 11:39 PM

My mounts, shocks and shock mounts have all been replaced. Actualy I have another new set of engine mounts as spares.

603 mounts in the W126 are a joke, they don't seem to last that long.

The mounts are not causing this.

redassag00 · #18 06-19-2008, 12:18 AM

W126 Mounts for the 617 and 603 (and several other Gasser W126 mounts) are similar for the OM617 in the W123 cars.

The W124 with OM603 has these round UFO looking affairs that are filled with liquid. I had a 300D W124 for a while and it seemed to 'run rough'.

I changed the mounts and it was smoother than my W126. Couldn't even feel the engine when cranking after I replaced them!

Note how the right one had a ripped boot, all the liquid had drained.

Height Difference between the New and old.

I got to the passenger side one. This was my culprit.

Look how bad it was!

777funk · #19 06-25-2008, 07:52 AM

Well it's Wednesday. I had the injectors (new about 5k ago with Bosio nozzles) pop tested yesterday. The Diesel injection shop said they are popping around 100-200psi lower than spec which is 135bar or 1950 approx psi.

He also said that he wouldn't mess with it if it were his car. He said they can only get within 100psi one injector to the next and that that should be good enough. I'm not sure if this is good info or not. I think I read that a 5 bar or 72psi difference is what MB calls for. But he insisted that a 100 PSI difference between injectors would make NO noticeable difference. He also said my pattern was a little wide on a few injectors. But he didn't think it was a problem or that it'd cause the shake at hot idle.

I'm still baffled by the 'shakes ONLY when hot' thing. Next I'm trying the following:

Mark the position of the IP and rotate it a small amount to retard it. The MB dealer advanced it 3 degrees (to get it set to factory spec) about a year ago and I think it's running too advanced. It takes a few cranks for it to fire even warmed up. It seems like timing has an effect on how easy a diesel 'catches' when cranked. The MPG is only 27 and this is a 124 body. Also the exhaust doesn't smell right. I've noticed timing has an effect on the color and smell of the exhaust on a diesel. Retarded is gray/white smoke. Right on is very little smoke. And I've read too far advanced makes an engine hard to start. Of course same is true for retarded.

I noticed when I timed the pump (by smoke and ease of start) on my IDI 7.3 Ford a while back, the smell was different based on the pump timing as well.

I don't think the dealer got my timing right (I called and asked how sure he is that it's right and he said he used the A-B light method). I also mentioned that the needle on the harmonic balancer is adjustable by a few degrees. He didn't know this. But it is, it's got an allen screw that loosens and it'll slide left and right a few degrees. So it's possible that the very thing we use as a bearing could be off as well. I wonder if anyone has messed with mine.

Anyways, I'm going to mark my IP's position and experiment a little. The last thing that makes me think timing is that when I run a thicker fuel (any type of oil---heated of course) that it smooths out. Seems like a more viscous fluid would pop slightly later retarding the timing a bit. Maybe? Anyone have insight on this?

On a side note, I did a compression test while I had the injectors out and measured around 430-440psi on all cylinders! That was encouraging.

Dionysius · #20 06-25-2008, 08:16 AM

Quote:

Originally Posted by 777funk

On a side note, I did a compression test while I had the injectors out and measured around 430-440psi on all cylinders! That was encouraging.

Was the engine hot and in the faulted state when you did this test?? Since your problem is heat specific it could, emphasise could, be possible that the numbers are different when engine is up to temp.

777funk · #21 06-25-2008, 08:47 AM

Quote:

Originally Posted by Dionysius

Was the engine hot and in the faulted state when you did this test?? Since your problem is heat specific it could, emphasise could, be possible that the numbers are different when engine is up to temp.

I would guess it's possible but the springs in those things are pretty heavy duty. I also think MB made those to deal with heat since they're screwed into the head. I would certainly think MB used this as a consideration and most likely made them so the spring coefficient would be similar through the range of temperatures. I don't know this but I'd certainly consider it if I were designing the injection system.

But yes I actually drove the 300 to the Injection shop and pulled them in the lot. That way they would be hot when tested. They had to come out anyways so might as well had done it there I figured. Really the only way to duplicate the 'in a hot running engine condition' would be to have them popped in an ambient chamber of some type which I'm sure they didn't do.

Tymbrymi · #22 06-25-2008, 09:50 AM

Instead of getting a rebuilt IP, you could always get a used one on eBay

Bio300TDTdriver · #23 06-25-2008, 10:02 AM

For my money, I would have mine rebuilt before spending money on an unknown one on Fleabay.

777funk · #24 06-25-2008, 10:32 AM

Quote:

Originally Posted by Bio300TDTdriver

For my money, I would have mine rebuilt before spending money on an unknown one on Fleabay.

+1 for that! Yep, on an IP I think there's a good chance one on ebay would be the same old pumps and in the condition we've already got with our MBs. Really mine's not too bad. Maybe fine, I'll never know unless I keep trying to narrow it down. Unless a person had NO cash and the IP was completely shot, it's probably not a good idea to ebay one. Performance Products sells 603 rebuilt IPs for around 900. I'm not buying one until I need it though. The car still runs great, just a little shaky at idle. Not bad really (except after a really long drive-i.e. several hours).

Really I still think it may be a timing issue. When I get a minute I'm going to move the pump a small amount at a time toward retarding it and see what effect it has on this.

Tymbrymi · #25 06-25-2008, 02:28 PM

There are often rebuilt IPs for less than $200 on eBay. I'd try it at that rate.... if nothing else you could sell it to someone in the performance section for half that so they can tinker with it.

Personally, I would buy an IP from the forum sponsor (Fastlane) or Rusty at buymbparts. They're likely to be cheaper and have a more reputable rebuilder.

Hatterasguy · #26 06-25-2008, 02:33 PM

I don't see how you can "rebuild" an IP for $200. Most likely they did nothing other than polish it up and reseal any exterior leaks.

I priced out a rebuild from Phil back in January for my brokers SDL, about $1,100ish.

Tymbrymi · #27 06-25-2008, 02:37 PM

Quote:

Originally Posted by Hatterasguy

I don't see how you can "rebuild" an IP for $200. Most likely they did nothing other than polish it up and reseal any exterior leaks.

Whoops!! I misspoke... I meant to say used IP's. Basically, for $200 I'd take a gamble. That is if I was doing the work myself. If I had to pay shop labor to replace it I'd just get a rebuilt pump! Try Rusty (call him, forget his website)... he's been the cheapest I could find on 99% of the MB parts out there.

Hatterasguy · #28 06-25-2008, 05:10 PM

I'm going to pull mine and have the local Bosch shop test it before doing anything.

I'll trust their rebuild more than some unknown ordered online. Some 11 year old kid probably does them in China.

777funk · #29 06-27-2008, 09:16 PM

I just adjusted my timing a hair toward retarding it (i.e. pump's top moved toward the driver's side fender). I can't believe how EASY this IP is to adjust. The 3 - 14mm bolts by the vacuum pump loose and it'll move very easily with the small fine timing adjustment bolt (similar to the alternator fine adjuster on a W123 diesel). Screw it in (clockwise) and you retard the pump. Counterclockwise and you advance it. Easy as cake.

Anyways, the important part...
Now the exhaust smells more diesel-ish and the idle seems to be smoother. I need to make some good long drives and that'll tell whether or not this thing really made the difference or not. I still may retard it a little more since I moved it just around a 1/16" or so with reference of the pump to the engine.

I'll update this later with the HOT engine results since that's what the thread pertains to anyways.

TimFreeh · #30 06-27-2008, 09:25 PM

Quote:

Originally Posted by 777funk

I can't believe how EASY this IP is to adjust. The 3 - 14mm bolts by the vacuum pump loose and it'll move very easily with the small fine timing adjustment bolt (similar to the alternator fine adjuster on a W123 diesel). Screw it in (clockwise) and you retard the pump. Counterclockwise and you advance it. Easy as cake.

There are actually 4 bolts that must be loosened before you adjust the timing on an OM603... and after you find the 4th bolt and get it loose I'm guessing you are going to revise your "easy as cake" description of the process.

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