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  #1  
Old 03-07-2013, 05:43 PM
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1982 300cdt won't idle cold

..have to give it throttle cold and keep my foot in it for 15 minutes. Runs great at speed. Idles when hot.

this is what I've done to troubleshoot:
Adjust valves
replaced glow plugs
cleaned , checked injectors for proper spray and pressure with injector tester.
adjust timing (injector pump)

For another issue but thought i would say:
rebuilt vacum pump

Have regularly changed fuel filters

Don't know what else to check?

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  #2  
Old 03-07-2013, 06:55 PM
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Call me

Friday to discuss the issue.

I may need to listen to it start - run..

.
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  #3  
Old 03-07-2013, 09:59 PM
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Milage on the Engine?

Does it start easily and when it starts is ther any Smoke and the Color?

What is the Idle Speed after it runs OK and the Engine is Hot?

If it is cold where You are are you useing a Winter Grade Oil.

Ckeck the Camshaft Timing by lining up the mark behind Camshaft Drive Gear with the Mark on the Front Camshaft Bearing tower; do that as exacely as possible. Take a look at what degrees the Pointer Points to on the Cranshaft Damper.

Compression Check.
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  #4  
Old 03-08-2013, 01:23 AM
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Diesel911:

300k miles.

Starts easily. No smoke

Idle speed sounds and feels great to me when hot. Don't know rpms however. Tach hasn't moved in a while (broke).

No winter grade oil. Use Delo 400 15-40. Rarely gets below 32. Oregon
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  #5  
Old 03-08-2013, 04:36 AM
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idle

.

sounds like you are in low idle rpm's ie. bellow 600...
you can do easy experiment
cold engine - turn idle screw 2-3 full times CW.
start the car
if idles fine... problem solved and you can order cheap IR (10$ hobby king) for
occasional and precise idle rpm adjustments.

for the precise adjusment - engine warm - 700-800 ...


cheers


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  #6  
Old 03-08-2013, 01:14 PM
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Verify what the idle rpms are hot. A rpm device may be around ten dollars by now from China. If it is still doing the same and the idle rpms are right a cold compression check may be a good ideal.

You might also catch a cylinder not on line when engine is cold by simply hooking up a meter set to milli volts and checking all the glow plugs voltages with the glow plug harness unpluggged at the relay box. You check the glow plugs voltages at that plug. The glow plug not generating any voltage from the cylinder not firing will be obvious if there.

Ground for the meter must be the engine block. Personally I like this way because it leaves some questions out of the equation. Things like if or if not will that cylinder be offline if the cold compression is a given number. It is also a lot quicker than having to pull the injectors or glow plugs and do a compresion check initially. Also you may not own a compression gauge or rpm reader(tachometer). Thats not to say you may not yet need one.

There is a better chance you might own a cheap digital volmeter in my opinion. If not they are availble very reasonably. Really an item any individual should own anyways. They can save you a fortune over time running down many things. At 300k if the engine is original and allowing for the odometer always not showing an accurate picture. Tends to create a slight bias or more suspicion it just might be a cylinder issue.

First though you have to see and find out if a cylinder is staying off line until the engine is getting up into operational temperatures. Since it appears to take about fifteen minutes until it will self idle there is time for testing using the milli volts test. Incidentally a thermal reader or spot reading thermometer if you wish may be an alternative. This is after the engine has been runing for perhaps a couple of minutes might pick up the much colder glow plug of a dead cylinder.

Anyways the basis of my approach on a problem like this would be to make sure the engine idle is reasonable and at the higher end of the recommended specification when warmed up. The high end because the engine is older and if it where the solution reduce it a little until just above the threshhold of a maintainable reliable idle with a cold engine is reached.

From experience my 77 300d with a manual idle adjuster in the cab from the factory. Will not stay running cold if the idle control is set to the lowest position of adjustment. I have never checked the rpm spread it controls but perhaps 100-150 variance in rpm may be appropiate. You even have to give it some pedal for it to start with the idle control minumised.

If this is not manageable then first I would be looking for a cylinder or cylinders not firing when the engines is cold. All cylinders firing in the early stage of the testing when cold then move on to simpler possible things.

One important question though to cover before going on. Has or is this engine using an form of alternate fuels. If so the approach would be different in some ways.

Also to give you a break after reading the above. Is there a static bubble only present in the small fuel filter? Or in addition a continious flow of small air bubbles transiting through the filter as well? Air in the fuel could be a contributor. There are a few other things that come to mind but without establishing if all cylinders are firing when the engine is colder they are time consuming and almost pointless to chase until that is known first.

My approach on a problem of your nature is to move quickly and easily over things until some indication of what is wrong is revealed. Only if it is not indicated by this would I start more time intensive approaches.
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  #7  
Old 03-08-2013, 04:59 PM
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Big thanks ya'll

Thanks for the response.

Yanked out the idle adjustment screw/component. Pin and spring were stuck. A little choke and carb fixed that. Put it back in and increased idle a couple of turns. Idled great cold. A slight increase hot. Screwed down a half a turn. Idles awesome hot or cold.
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  #8  
Old 03-08-2013, 05:53 PM
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Quote:
Originally Posted by 82cdt View Post
Thanks for the response.

Yanked out the idle adjustment screw/component. Pin and spring were stuck. A little choke and carb fixed that. Put it back in and increased idle a couple of turns. Idled great cold. A slight increase hot. Screwed down a half a turn. Idles awesome hot or cold.

Nice to see a nice simple not complicated solution to a problem.

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