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  #41  
Old 05-19-2021, 04:35 PM
Tom Bryant Tom Bryant is offline
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Vehicle: 1986 745 D24T
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Quote:
Originally Posted by RedArrow View Post
Completely off-topic (sorry) ... BUT VERY IMPORTANT:

Be careful what you do in the mornings (even on a warm&sunny Summer morning)! I read words such as `coldstart`, `morning`, `RPM`, revs, `climbing a hill` etc.
I really hope that you normally start the car and let it idle for at least 10-15 minutes before climbing hills or getting on any road that has speed limits above 50KM/H. Raising RPM to 2300 soon after the diesel got coldstarted is NOT OKAY, also equally NOT OKAY even if you simply idled without the car moving. Not to mention attempting climbing a hill with a coldstarted diesel engine at 2300 RPM.
Maybe you missed telling us that you let it idle before taking it on that ``test``.

Driving these cars `hard` when cold, is recipe for serious trouble and recipe for very very premature wear internally and will affect major engine components.
A coldstarted diesel engine will not stay healthy for too long for those who drive their cold diesel too hard or simply too `early` (not waiting for it to warm up which usually takes 5-8miles of **gentle** low-RPM driving OR min 10-15mins of idling (often, even longer stationary idling itself won`t even warm up the car to operating temps), but all of this can vary based on temperatures, climate etc.
<snip>
I beg to differ. Actually, I more than differ. I adamantly state that this is hogwash. I absolutely never idle any of my cars, including my Diesels, before doing any of these "prohibited" actions, and I don't get any premature engine wear either. In fact, it's actually detrimental to many engines to idle them, either cold or hot. Don't do it. Start the car and drive away and don't worry about how you drive it.

Tom Bryant
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  #42  
Old 05-20-2021, 03:28 AM
Tom Bryant Tom Bryant is offline
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Originally Posted by v8volvo View Post
Well said, agreed.



Yes exactly right, the smoke screw gets removed (or at least screwed a long ways out) in order to disassemble the top of the IP/throttle control system. So they would have had to do this during the service that was performed, and then they would have had to get it reinstalled to the same setting it had been.

Normally the way to do this, if one is working on the IP still installed on engine using "seat of the pants" methods, is to very carefully note the position angle of the smoke screw before disassembly, and then count the number of turns required to remove it from the pump upper section housing. Then one tries to reinstall it in exactly the same position and with the same number of turns, so as to have the system work as it did before.
<snip>
There's a much easier way to do this. There is (or should be) a collar crimped onto the fuel limiter screw ("smoke screw" in your terms). And there is a lock nut not far from that collar. Usually there is about one turn (often less) between the collar and the lock nut. Normally, I simply loosen the lock nut, then remove the limiter screw. Later, just install the limiter screw back in the same position. But, if you want to be more precise, you can count the number of turns (or "flats") between the collar and the lock nut.

Tom Bryant
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  #43  
Old 05-25-2021, 12:38 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995

hi tom
after the drama of the injection pump leak which im happy to say is all fixed . the car is running fine engine wise ,the power is back as it should be ,
thanks for your advice on my problems ,
regards jim
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  #44  
Old 05-25-2021, 05:39 PM
jetfiremuck jetfiremuck is offline
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Quote:
Originally Posted by Tom Bryant View Post
There's a much easier way to do this. There is (or should be) a collar crimped onto the fuel limiter screw ("smoke screw" in your terms). And there is a lock nut not far from that collar. Usually there is about one turn (often less) between the collar and the lock nut. Normally, I simply loosen the lock nut, then remove the limiter screw. Later, just install the limiter screw back in the same position. But, if you want to be more precise, you can count the number of turns (or "flats") between the collar and the lock nut.

Tom Bryant
Ive followed your detailed pump overhaul blog.

Regarding the relationship between the fuel limiter screw and idle speed at idle under load my issue is that i get a gray black haze at idle with ac on, ac off and the smoke lessens. The engine is in a conversion and idles around 900rpm in drive ac off. l When i snap the throttle in neutral there is no delay or engine rpm hangup coming back to idle. The crimp collar is still there so its setting is within 1/2 turn of the locknut.

Is this a fueling issue injector wise or does the fuel limiter screw needs backing out with the corresponding idle restored with the idle screw?
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  #45  
Old 05-25-2021, 06:00 PM
Tom Bryant Tom Bryant is offline
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Quote:
Originally Posted by jetfiremuck View Post
Ive followed your detailed pump overhaul blog.

Regarding the relationship between the fuel limiter screw and idle speed at idle under load my issue is that i get a gray black haze at idle with ac on, ac off and the smoke lessens. The engine is in a conversion and idles around 900rpm in drive ac off. l When i snap the throttle in neutral there is no delay or engine rpm hangup coming back to idle. The crimp collar is still there so its setting is within 1/2 turn of the locknut.

Is this a fueling issue injector wise or does the fuel limiter screw needs backing out with the corresponding idle restored with the idle screw?
First of all, your idle speed is a bit high. Spec is about 750 RPM, IIRC. As you seem to be aware, there are two ways to decrease the idle speed:
1. Turn the fuel limiter screw outward.
2. Adjust the idle screw on the inner side of the Injection Pump cover.
Sorry to rain on your parade, but neither of those two adjustments is likely to improve your smoky exhaust. That's because fuel is fuel, regardless of which adjustment is used to regulate that fuel.

It appears to me that you have either bad injectors or bad compression, and from your description, combined with my experience, I'm leaning toward bad compression. So, my recommendation is to check your compression before you try anything else.

Explanation: When you apply more load to the engine, two things happen:
1. The engine slows down.
2. The Injection Pump, via the governor mechanism, supplies more fuel in an attempt to maintain engine speed.
The effect of decreased engine speed, in an engine with compression issues, is for the compression to also decrease. That causes a decrease in combustion efficiency, which, combined with the increased fuel delivery, results in more smoke.

Tom

Last edited by Tom Bryant; 05-25-2021 at 06:10 PM. Reason: To provide explanation.
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