Idling questions - PeachParts Mercedes-Benz Forum

JMan300sd · #1 11-04-2005, 12:49 PM

When i start my car it idles right around 600 and shakes and sputters, but as soon as I rev the engine and then let it Idle it steadies consistently at around 750. Ive seen posts about the Alda or something like that and the rack dampener...Could this be the issue behind this. Please educate me on some of these issues. Thanks guys.

samiam4 · #2 11-04-2005, 01:01 PM

It sounds to me like a cylinder isn't firing off until you rev the engine.

Check the glow plugs resistances and make sure they are all still good. Bet you have (1) bad plug.

Michael

JMan300sd · #3 11-04-2005, 01:07 PM

Actually I changed all of my glow plugs and relay last sunday...Could it be a clogged injector or something of the sort.

JMan300sd · #4 11-04-2005, 01:10 PM

I also forgot to mention there is a big air bubble in the prefilter and air squeezes out when I use the primer pump. I am changing out the primer and the two fuel filters this weekend and hopefully that will get rid of the air in the fuel line (I really hope). But would this cause the initial low idling and stumble.

boneheaddoctor · #5 11-04-2005, 01:17 PM

Quote:

Originally Posted by JMan300sd

When i start my car it idles right around 600 and shakes and sputters, but as soon as I rev the engine and then let it Idle it steadies consistently at around 7500. Ive seen posts about the Alda or something like that and the rack dampener...Could this be the issue behind this. Please educate me on some of these issues. Thanks guys.

7,500 damn mine would throw rods long before it went that fast.....

better check and edit the typo......

JMan300sd · #6 11-04-2005, 01:21 PM

Thanks...

boneheaddoctor · #7 11-04-2005, 01:37 PM

Quote:

Originally Posted by JMan300sd

Thanks...

Rack damper is what you need to adjust....

JamesDean · #8 11-04-2005, 02:13 PM

I have the same issue in my 82-300SD. My engine idle's aroung 500-550. I have adjusted the idle adjust screw. I broke it. A friend and I repaired it by fixing a L flange to the back of the full-load stop screw with the idle screw in the exact same position it was before. We couldnt adjust the screw any futher down. It sputters and shakes a lot until i hit the pedal and then it will settle down back at 500-550 and be fine.

JMan300sd · #9 11-08-2005, 10:31 PM

Alright....I changed my two fuel filters and the primer pump. I still have an air bubble in the prefilter and I still have an idling problem.

Like I said, I Idle right around 600 immediatley at start up, then If I rev at all it settles to a nice 750. Problem is after its been up on the highway and comes back to park and idle it sits at 900. WTF! Can all this be explained by the rack damper?

Also...about the air leak in my fuel line. Where else should I be looking? Somethin makes me feel like I didnt tighten that primer pump as much I need to, but its very hard to get at. I do need some better tools.

Palangi · #10 11-08-2005, 10:41 PM

A big air bubble in the prefilter is normal. Tiny bubbles are not normal.

Make sure you have lubed all of the throttle linkage ball sockets. Use ATF or something similar. Check where the linkage pivots at the rubber block on the firewall to make sure that isn't coming apart.

If the the two rubber fuel lines which attach to the metal lines from the tank have cracks in them, they are NG, need to be replaced.

You can get to the primer pump by removing the fuel hose next to it and unthreading the nipple that the hose attaches to. Then you will have room to swing a wrench in there. Also, it has been my experience that the new style primer pump does not come with a copper washer. You have to purchase that separately.

JMan300sd · #11 11-08-2005, 10:46 PM

Thankyou for noting about the washer...and yes I did make sure to install that with the primer pump.

I wish I could show you pictures of my linkage as I am very ignorant of it. But, like you said it does stick. I will lubricate it... Also what is the black rubber accordion piece that attaches to the rear of the linkage as it and the plastic componenet attached to it seem very degraded?

Palangi · #12 11-08-2005, 10:52 PM

You are probably referring to the bowden cable which goes to the transmission. (Controls the shift point).

Pete Burton · #13 11-09-2005, 08:12 AM

Quote:

Originally Posted by JMan300sd

Alright....I changed my two fuel filters and the primer pump. I still have an air bubble in the prefilter and I still have an idling problem.

Like I said, I Idle right around 600 immediatley at start up, then If I rev at all it settles to a nice 750. Problem is after its been up on the highway and comes back to park and idle it sits at 900. WTF! Can all this be explained by the rack damper?

Also...about the air leak in my fuel line. Where else should I be looking? Somethin makes me feel like I didnt tighten that primer pump as much I need to, but its very hard to get at. I do need some better tools.

Yes, this is classic symptom of worn out rack dampener. I ordered one recently from for about $37. The internal spring pressure is much more than the old one.

samiam4 · #14 11-09-2005, 10:27 AM

Air bubbles in the pre-filter are always there and not a problem.

JamesDean · #15 11-09-2005, 03:12 PM

any thoughts as to mine? I have the idle adjust screw down as far as i can get it (even before it broke i had it all the way down and it did nothing) any other ideas?

thanks

kris