300 Turbo, still rough idle - PeachParts Mercedes-Benz Forum

stcbenz83 · #1 11-29-2006, 01:26 AM

So i have made some time and done alot to the 300, well mostly did what the other owner possibly never did. the car idled rough and was not much faster than my 240d stick (if i really floored the 240) AFter changing both fuel filter, cleaning out the banjo bolt which was so full of crap there was not even a whole in the bolt.(fyi, still cant find the banjo on my euro 240

) and did a valve adjustment. Now the thing takes off and i can actully hear the turbo. Idleing is much better but...................

so hears the thing. when the car is at idle, the passanger side raddles like a friegh train. when i put it in reverse the rattle/ banging gets softer. Then when i put it in drive, OHHH JEZZ, i have to zoom off fast or my head will explod from the noise. Once it gets to about 900 rpm, it goes away, and the engine is as quite as can be, but when i stop the noise it there. The noise sounds like when u have the sunroof open and the back window open at the same time. or maybe just the back window, you know the sounds of the wind, not the regular sounds, bet the deffening sound that u have to scream over.
s

so i was wondering if anyone had any idea what that noise could be. its in the passanger side. it almost sounds like somthing is banging into the firewall, but the noise dosnt sound tinny or mettaly (sp i know)

any thoughts????

fyi this is from my 84 300 Turbo

stcbenz83 · #2 11-29-2006, 01:40 AM

is there a way to up the idle speed? it idles at about 600 rpm or so, a little over 500

bgkast · #3 11-29-2006, 01:54 AM

You can up the idle speed by loosening the lock nut on the idle adjustment screw (14 mm I think) then turning the screw clockwise. The screw is between the IP and the block and is nearly vertical. Also take a look at the rack damper bolt at the rear of the IP. If it is silver you may want to consider replacing it with a updated gold model.

PS. Your 240D does not have a banjo bolt. No turbo->no ALDA -> no banjo bolt.

stcbenz83 · #4 11-29-2006, 02:12 AM

thats what i figured about the 240, but everyone was saying it dose have a banjo bold heh

also, what can i do with the rack damper bolt? can i adjust that? or is it stationary? basically what dose that do. and is like 600 rpm normal for a turbo to idle at? sould it idle a little higher? or lower? if i replace it, were do i get the gold one? not sure if its silver yet, ill take a look tomorrow.

Ara T. · #5 11-29-2006, 02:22 AM

I think the spec is 650RPM.

stcbenz83 · #6 11-29-2006, 02:27 AM

than i must know what that wierd "jet" noise is. its driving me crazy

Shorebilly · #7 11-29-2006, 07:26 AM

Quote:

Originally Posted by stcbenz83

when the car is at idle, the passanger side raddles like a friegh train. when i put it in reverse the rattle/ banging gets softer. Then when i put it in drive, OHHH JEZZ, i have to zoom off fast or my head will explod from the noise. Once it gets to about 900 rpm, it goes away, and the engine is as quite as can be,

any thoughts????

fyi this is from my 84 300 Turbo

Air cleaner mounting bolts......the ones with the rubber inserts....

SB

airbus · #8 11-29-2006, 08:00 AM

Check transmission-to-engine bolts for tightness. Tightening them fixed my problems at 1600rpm.

rrgrassi · #9 11-29-2006, 10:35 AM

What kind of shape are the engine and tranny mounts in? When was the last time engine shocks were replaced?

When does the "jet" sound become noticeable? It could just be your turbo spooling up.

Johnhef · #10 11-29-2006, 10:40 AM

Just a guess here but make sure your exhaust is not hitting the firewall or floor area, I've seen that before as well.

Biodiesel300TD · #11 11-29-2006, 10:42 AM

I would check your motor mounts and shocks.

stcbenz83 · #12 11-29-2006, 10:47 AM

i changed the air cleaner mounts, that was actully a big part of the problem

. the sound start at start up and at idle speed, when i start to hit the gas, it goes away and it very quite. when i come to a stop its super loud, then the sounds back off just a smig when im complelety stoped, untill i go agian.

i will check the exaust. were is the engine shock on these things? that was actully my first guess on this thing

rrgrassi · #13 11-29-2006, 11:07 AM

They are near the engine mounts.

Biodiesel300TD · #14 11-29-2006, 11:25 AM

the engine shocks are mounted in a round thing close to the engine mounts. You could have a bad mount or a bad shock. I had a bad engine shock mount and I didn't notice any difference after I replaced them.

I was told the engine shocks help dampen the shuttering when you shut the car down, more than then dampen shaking while the engine is running. So I would lean more towards your engine mounts. You may have a combination too.

stcbenz83 · #15 11-29-2006, 11:45 AM

hm il check it out. I think johnhef said to check the exaust and make sure its not hitting. This seems the most logical for some reason, i dont know why. afteri ran it for a while after the valve adjustment yesterday and cleaning the banjo bolt the car idles like a dream. its just that noise like somthing is hitting the firwall now. i know at idle when i lift the hood up, the air cleaner vibrates like no other, i originally thought that it was hitting the firewall or the battery agians the firewall, but im beginging to rule that out. its raining here today but it looks like its tapering off, so maybe ill check it out. Fyi the exaust looks alot bigger than the one on my 240. Like the muffler at the end is double the size. ANd the one on my 240 was just replaced, and it looks the same as the original. But the 300 turbo, the exaust, well at least the muffler looks to be double the size of my 240's. and the guy said he had it replaced not to long ago.

also, the mounts feel fine from what i can tell, but then agian i could be wrong.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode