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-   -   Got an 83 300SD, what's the normal idle RPM? (http://www.peachparts.com/shopforum/diesel-discussion/64802-got-83-300sd-whats-normal-idle-rpm.html)

gawlbpd 05-13-2003 05:37 PM

Got an 83 300SD, what's the normal idle RPM?
 
I've posted this before, but got no responses.

I'm idling at about 750 RPM's. I've got bad compression on two cylinders, so it rocks more than a bit. If I bump and hold the pedal, getting me up to about 850-900 RPM's, it smoothes out considerably.

Question is, can I bump up the idle and not run into other problems? Secondly, where is the darn idle adjustment screw?

83 300 SD 172K "Goldie" Abused before I got her, but now being loved.

Zoonhollis 05-13-2003 05:42 PM

It might be more useful to adjust the rack mount screw on the injection pump...provided you can access it and there are any threads left. It's near the oil filter housing.

rickg 05-13-2003 05:42 PM

I don't think it should do any harm. Will just keep more pressure on the trannie when you're at a stop light, which may make the trannie run a little hotter in a lot of stop and go traffic. May make it act kinda wierd as to going back to 1st gear too. Other then that, try it and see.

gawlbpd 05-13-2003 05:56 PM

Rickg/Zoonhollis,

I already adjusted the rack adjustment screw. I might need to go to a new spring on it according to my expert. Where's the idle adjustment screw?

sixto 05-13-2003 06:10 PM

Quote:

Originally posted by gawlbpd
Where's the idle adjustment screw?
Would you believe there isn't one?

Sixto
91 300SE
87 300SDL
83 300SD ... any takers at $1100?

gawlbpd 05-13-2003 06:24 PM

Then I have to adjust the idle via the Rack Adjustment Screw?

speedy300Dturbo 05-13-2003 06:39 PM

1 Attachment(s)
On the inboard side of the injection pump there is an adjustment screw (#4) with a slotted head. Use a deep socket to release the locknut (#3) at the bottom.

GR_Lou 05-13-2003 08:26 PM

Mine idles about 900, just under the 1K rpm.

I'd go out and check, but it's up on jacks in the garage 'cuz I can't get the rotor off the hub. I'm sending them both to the shop with the wife's minivan and let them have a go.

What kind of SD do you get for $1100? DON"T tell me. I'm waiting on a 300E 4matic sedan from a couple at church. Only has 244,000 on it.

Good luck!

84300DT 05-13-2003 09:02 PM

maybe you could try a different fuel supplier and run some power service additive through/change fuel filters and then see if the idle smooths out before trying to increase the rpm's. 172 k does not sound like a lot of miles at all on the engine. also what is your approximate location? as in what is the ambient temperature where the car is.

sixto 05-14-2003 12:15 AM

So there is an idle adjustment screw? I thought only the non-turbo 617s had an idle adjustment screw.

Sixto
91 300SE
87 300SDL
83 300SD ... any takers at $1100?

gawlbpd 05-14-2003 10:12 AM

Thanks speedy300Dturbo for the photo, it really helps. I'll keep you guys posted to see if it works for me.

speedy300Dturbo 05-14-2003 06:26 PM

Yup, if your rack damper pin is silver, it's the old one. The new one is somewhat brass / gold looking.

Wes Bender 05-14-2003 06:36 PM

If my memory serves correctly (and it doesn't always....) the correct idle for most of our diesels is the lowest rpm that still gives a smooth idle. 700 to 800 seems to be the norm. Of course, the assumption is that everything is in proper running order. With a couple flat cylinders, you might not get a smooth idle until you really speed things up and I don't think your tranny (not to mention the rest of the drive train) will like it.

Wes

gawlbpd 05-14-2003 06:45 PM

Is the rack adjustment screw the same thing as the governor idle adjustment pin?

Holson Adi 05-14-2003 07:36 PM

Be careful when you try to loosen the lock nut for the idle screw. I really suggest soaking the lock nut + idle bolt assembly with WD-40 or something similar before attempting to loosen it if it hasn't been touched for a while.

DO NOT !!! Overtighten the locknut... I learnt the hard way...
You don't need to tighten it that much.


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