Engine likes to shut off....? - PeachParts Mercedes-Benz Forum

pawoSD · #1 10-14-2004, 06:23 PM

Earlier I posted that I thought my car had a rather low idle speed, and that I was thinking it would be the reason why it can't maintain an idle on a cold start, but the engine will also shut off when its at operating temp, today it happened twice, both just after I let off the gas and was coasting, once at about 10-15mph, and again at about 30mph, it will restart immediately however, there is no lack of power at all, it moves very strong and runs very smooth, even moreso than our '83, but it is impossible to make the '83 shut off, when cold, hot, whatever, it just keeps running when you try the same things that make mine shut off. The vacuum lines to my EGR are disconnected/missing, would this cause it? I don't think it is the fuel filter, as it has always done the shut off thing, I am going to change the screw in filter tomorrow, I replaced the pre-filter about 4 months ago....I doubt this is what is causing it. I'd really like to eliminate this problem, because its not fun having it shut off when coasting in traffic and so on, and the cold start issue is just annoying but must be related. Help?

whunter · #2 10-14-2004, 06:50 PM

What is going on when it cuts off?
Idle or drive.
Do you see bubbles in the fuel lines?
Do you see bubbles in the transparent fuel filter?
Do you hear sucking when fuel tank cap is removed?
Picture of injection pump side of engine may help.

pawoSD · #3 10-14-2004, 08:51 PM

It always happens when I let off the gas from slower driving (below 35), it also shuts off if I start it up cold and let off the gas. There is the normal small air bubble in the pre-filter, but no bubbles in the other lines, they are all fine....I filled it up today, and there was no sucking sound when I uncapped the tank, our '83 does make a sucking sound however, but it runs fine. I can also get it to shut off when its idling in park or neutral too, if I do a quick pedal romp it will rev up normally but 2 in 3 times afterwards it will lose it and turn off without ever returning to idle. The '83 is impossible to kill this way. I am going to change the screw on fuel filter tomorrow, and see if that changes anything, I will also take a picture. Otherwise, what could be causing this?

Wasuchi · #4 10-14-2004, 09:00 PM

What does it idle at?

pawoSD · #5 10-14-2004, 09:42 PM

I don't know for sure, as my tach doesn't work, despite my desperate and multiple attempts at getting it to do so. (new cluster pod AND amplifier, still no reading!!) Our '83 idles close to 900 or so, and I know mine runs slower because it just sounds slower, I am guessing probably like 650-700 tops....there is an audible difference between the two.....what is the optimum rpm? I also live in a cold climate here....(GR, Michigan) so a slightly higher idle would be a nice thing to help it along when its super cold out. I even installed a new glow plug relay and plugs about 4 months ago, one of the "extended" glow systems, it glows for like 2-3 minutes....didn't help with the cold startup however.

whunter · #6 10-14-2004, 11:49 PM

Quote:

Originally Posted by pawoSD

I also live in a cold climate here....(GR, Michigan) so a slightly higher idle would be a nice thing to help it along when its super cold out.

If you are close enough, I can offer hands on help.
There are three other members much further north, who may be able to help also.

pawoSD · #7 10-16-2004, 03:29 PM

That is very nice to know, thanks!

I changed my main fuel filter yesterday, after finally getting the bolt loose, it was on there like it was fused

, however, it didn't make a difference with performance or the cold idle problem....essentially, it just seems like the engine is not getting enough fuel at its idle setting to allow it to start up when cold, or idle cold. Also when it is colder out, for the first 10 mins of driving or so, the engine "bounces" its idle, the oil pressure gauge kindof moves up and down by about .3 bar or so, and you can hear the engine go "rev up. rev down. rev up. rev down and so on" It never causes it to shut off or anything, and it goes away after a while, but it seems odd. I can't find the right size socket for the idle adjustment.....could someone tell me the actual part from a brand or what specific size/length I'd need, I haven't been able to find a deep socket long enough...

soydrivermatt · #8 10-16-2004, 03:37 PM

That sounds just like my '83 SD was acting until I cleaned the tank strainer,had to pump the accelerator at stoplights to keep it going. There;'s a pic of it in the W.Hunter sticky about part pics.

soydrivermatt · #9 10-16-2004, 03:41 PM

O.K. guess it's not there anymore.

pawoSD · #10 10-16-2004, 03:44 PM

The strange thing is that the engine will start/idle no problem when its warmer outside or if the engine itself is warm....how does one clean the tank strainer? Is that a big project? I think I have good fuel flow, after the initial problem of cold idle it runs fine.....when I changed the fuel filter I pumped the primer with the filter off to get some fuel, and it was spraying a ton out when I pumped it....definatley more than the engine would ever need....

The pre-filter has been there for about 5 months, and its still perfectly clean too...

So what tool do I need to adjust the idle....?

psfred · #11 10-16-2004, 05:06 PM

Rack dampner pin is screwed in too far (to cure the rough idle).

I suspect you will have a choice between a shaking idle (side to side rocking) or cold start problems/cold idle problems.

re-adjust the rack pin before doing anything else.

Peter

pawoSD · #12 10-16-2004, 11:43 PM

Where can I find the rack pin....is it part of the throttle linkages? or is it on the injection pump.....? I did notice if I increase the idle a bit by hand (moving the throttle a little) I do get a shaking idle, which would be very unpleasant, as I don't want the car rocking back and forth......

So what is the location of the rack pin...?

phantoms · #13 10-17-2004, 12:15 AM

There's a good picture about halfway through the thread located at 300SD shake - idle speed?

pawoSD · #14 10-17-2004, 12:24 AM

That thread answered all my questions! thanks for the link!

whunter · #15 10-17-2004, 03:55 AM

Quote:

Originally Posted by soydrivermatt

That sounds just like my '83 SD was acting until I cleaned the tank strainer,had to pump the accelerator at stoplights to keep it going. There;'s a pic of it in the W.Hunter sticky about part pics.

Don't know why you could not find it.

Name these parts, to help new members.