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Old 09-09-1999, 01:03 AM
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Join Date: Jul 1999
Posts: 239
The 81 300SD has lost the usual throttle response when starting out from standstill. I mash down on the pedal and it creeps along until the turbo kicks in at higher RPMs...This problem comes and goes. Haven't figured out a pattern yet but this symptom started yesterday. Both fuel filters were replaced maybe a month ago.
Since the problem is starting from standstill, shifting down to the lowest gear isn't helping. This isn't good when trying to dart across an intersection...Otherwise it runs fine once cruising speed is reached.
Injectors ? Fuel pump ? Please don't say it's something with the injector pump assembly...
Another hurdle to clear for the privilage of operating an MB diesel.
I need hints, suggestions, tips, or whatever.
Thanks for your help !

Old 09-09-1999, 08:19 AM
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Join Date: Aug 1999
Location: KS.
Posts: 477
Afew easy things to check.Check the air filter also.
Have some one sit in the car without the engine running and have them push the accelerater to the floor, from the engine side, make sure that it travels all the way open.
ON the back of the intake manifold there is a banjo bolt with a clear tube connected to it that goes across to the driver side of the firewall. Remove the bolt to see that it isn't plugged with soot. If it is plugged, clean with brakekleen and reinstall.

[This message has been edited by Alain V. (edited 09-09-1999).]
Old 09-09-1999, 10:52 AM
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Thanks so much, Alain -

Now is the time for me to find out what this banjo bolt is. I've seen this thing mentioned numerous times in other discussions but still have a hard time picturing what it looks like.

(The air filter is new as well, by the way.)

Take care -
Old 09-09-1999, 11:30 AM
Posts: n/a
That's the easy part (I figured it out last week myself...): a banjo fitting is a tube that ends in a colar.

Basically like a banjo if you remove the leather and make the handle hollow. The banjo fitting on the intake manifold is screwed in with a hollow bolt with hole just below the nut, which allow air to flow from the manifold through the bolt then trough the banjo fitting to tube connected to the banjo fitting.

There's a nice picture of one here:

Kinda cool, isn't it?


[This message has been edited by Webmaster (edited 09-09-1999).]
Old 09-09-1999, 11:42 AM
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Join Date: Jul 1999
Posts: 239

Thanks a lot, Nicolas !

That picture did the trick.
Looks like it was shot in a spotless engine compartment.
Kindof a stretch, but, heck, I'll go along with "banjo".
I printed it out (in color) and it's part of the stack of printouts from this newsgroup.

And thanks for the speedy reply.

Old 09-09-1999, 12:59 PM
Posts: n/a
This board is sooooo cool! I just pasted the adress of the image and it displays the image. Coolsome!

Anyway, that picture is of a *generic* banjo fitting. The one on the manifold is the same thing except that the hose is rubber and it plugs into the backward side of the manifold.

Don't know what kind of engine it's from, either... not an MB diesel, that's for sure! :^)
Old 09-09-1999, 01:50 PM
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Join Date: Jul 1999
Posts: 239

That's great !
Maybe our Webmaster started something with the image of the Topsider.

Let's hope we don't start seeing "for sale" pictures and the Webmaster limits it only for illustrations.
Old 09-09-1999, 08:40 PM
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Posts: 239
Hi, TXBill -

Thanks for the tip -
I did notice the vaccuum tube goes to a thingamajig mounted to the firewall and is connected to it by a black rubber boot of some sort which seems to be very flexible and mushy.
There also another tube connected to it the same way....
Old 09-09-1999, 09:23 PM
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Join Date: Jul 1999
Posts: 239
TXBill -

Thanks !
Does this mean the black rubber connector on the fireall end is a separate part ?
The tube plugs into it and is held in place with a clamp.

Yes, I did see the bracket that the hose is supposed to clip onto - it wasn't....
Old 09-10-1999, 11:57 AM
Posts: n/a
That thingie is the overboost protection valve. It's supposed to do something (cut the fuel supply?) if boost goes over a certain level, to prevent arm to the engine.

There is an interesting article about all this at


1982 300D -

Old 09-10-1999, 09:47 PM
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Join Date: Jul 1999
Posts: 239
TXBill, Nicolas and Alain -

Please see my new post "I can't believe this".

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