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Old 04-06-2022, 03:09 AM
Kaptin Kaptin is offline
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Default Injector pump idle screw location

Hi all,

After fixing the power issue, I have been messing with the LDA pin, however I now need to adjust my idle, as cold idle is 2600rpm... I have seen the idle screw referred to here many times, but never with an image/description. I know I will also need to adjust the cold start idle ball, but that looks like it might be easier.

Does anyone have an image, or can describe where the idle pin/screw is?

Many thanks!
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Old 04-06-2022, 09:57 AM
ngoma ngoma is offline
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Highly doubt you were "messing with the LDA pin" but here is a diagram clearly showing the idle speed adjustment screw, however: the labels for idle speed adjustment and max peed adjustment are reversed from our application (diagram is from dieselbombers.com, hence the "reversed" Dodge Ram/Cummins orientation) (also note that this diagram shows an IP w/o LDA)

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Old 04-06-2022, 01:22 PM
v8volvo v8volvo is offline
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To add to the image above -- just posted the below in your other thread, pasting here as well for future reference, although at the risk of redundancy.

Bottom line -- the idle speed screw you are asking about and that is referred to in the diagram above will adjust WARM idle (with the caveat mentioned below about the linkage rod from the throttle spool that may need to be changed also in order to get you full adjustment latitude on the screw). That warm idle adjustment can be made after the engine has reached full operating temperature and the cold start advance system has therefore fully backed itself off to the warm position.

COLD idle is set by the position of a ball stud on the top of the cold start advance arm (side of the injection pump), which contacts the throttle lever and kicks up the idle speed when that cold advance lever is being pulled on by the cold start thermostat. So you will need to move that ball stud back to reduce how much the CS arm pushes the throttle lever forward when cold.

Both warm idle and cold idle, with these two separate mechanisms, will need to be re-adjusted anytime the smoke screw position has changed.

NOTE! You want to adjust the BALL STUD POSITION ONLY on the cold start advance arm. Don't disassemble the end of the cable that moves the entire CS arm or try to adjust things by changing anything about that cable. If you do, then you change not just idle speed but also cold timing advance (which you don't want to affect), and then the cold start system (theoretically) needs to be re-set on a Bosch fuel pump calibration bench.

Quote:
once you have the smoke screw set to where you want it, you will need to make two other adjustments: one to the position of the low idle throttle lever stop screw (see photo and info ngoma posted), and additionally you will need to adjust the position of the ball stud on the cold start advance lever that kicks the throttle lever up to a fast idle position when the cold start advance system is in "cold" position. It will need to be loosened and adjusted towards the rear of the car. This will probably take a few days of cold starts to get where you want it, aiming for about 1000 rpm idle IIRC when cold and then 750-850 when warm.

Further -- and this part is specific ONLY to Volvo cars, unlike the steps above that apply to all engines using the Bosch VE IP -- you *may* also need to adjust the length of the turnbuckle style linkage rod that runs from the bottom of the throttle cable bell crank spool back to the actual throttle lever (and/or, adjust the position of the ball stud on the throttle lever that that rod attaches to). This is because, as you turn the low idle adjustment screw outward to reduce low idle speed setting, eventually you may reach a point where the throttle mechanism is no longer resting against that screw and instead being stopped by the throttle bell crank rotating to its minimum stop position. This is not desirable - you want the low idle screw, not the bell crank, to set low idle speed and you want an air gap clearance at warm idle between the bell crank and its stop. The factory greenbook gives a clearance spec for all this. It's due to Volvo's funky two-part progressive throttle control mechanism that they adapted to VW's engine, resulting in the additional fiddly adjustments, but it all works very nicely provided you get it dialed in.

May want to finish final adjustments to the smoke screw before undertaking all this. (aiming for just at the point of a slight puff of smoke as you push pedal to full load, and then it should clear up entirely once under steady full load, don't want any continuous black smoke) Since any further tinkering with that smoke screw will cause you to have to redo your adjustments to idle speed and related parts again.
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Old 04-08-2022, 12:29 AM
Kaptin Kaptin is offline
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Nguma and V8Volvo,

Thanks a lot for the info! I also found the useful cummins link you posted in a sticky nguma - it was invaluable, and looking at the pump and thinking logically for just a few seconds and it's obvious how it all works.

(To prevent redundancy, will talk about both posts here!)

V8Volvo - timing belt all done! All moving parts changed at the same time. Also did the IP belt, and IP all back together. Then came the fuel pin (NOT LDA, I was mistaken with thinking it was the LDA pin as you stated) adjustments!

However, I have a problem...

The low idle screw is completely siezed, any screwdrivers I got on it instantly started to crush the screw end. Is this common, is there any way to get around this? I can't take the pump off, so I have to try to sort it in-place. But it's already starting to chew, and if I just do the same I will round the screwhead off. I don't really want to grab the threads on the other end with a vice-grip either, for fear of damaging the threads - but if that is what needs done, so be it.

Any ideas of what to do? I completely pulled the cold start ball away, so that I can sort the warm idle first, then try to place it correctly.

As an aside - it's so much fun to tinker with compared to any modern junk - this is how modifying should be! I work in computing and programming, however this is better than a laptop I feel.
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Old 04-08-2022, 05:26 PM
ngoma ngoma is offline
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Quote:
Originally Posted by Kaptin View Post
...timing belt all done!
Congradulations! You sure took care of that quickly! Especially for a first timer!
Just out of curiosity, what is your mechanical background, and did you already have the (what the greenbook calls) Special Tools handy?

Quote:
Originally Posted by Kaptin View Post
The low idle screw is completely siezed, any screwdrivers I got on it instantly started to crush the screw end. Is this common, is there any way to get around this? I can't take the pump off, so I have to try to sort it in-place. But it's already starting to chew, and if I just do the same I will round the screwhead off. I don't really want to grab the threads on the other end with a vice-grip either, for fear of damaging the threads - but if that is what needs done, so be it.
It is a long screw that threads through two threaded bulkheads cast into the IP top cover. Also it has a jamnut tightened against the forward bulkhead. (Hopefully you already loosened the jamnut before attempting to turn the screw. )
Can you visually tell if there is corrosion of any kind at either of these three threaded portions? If so, try applying some good penetrant for a few days before trying again.

Also, tapping the screw with a light hammer, or hammer/punch combination can help free stuck screws. Sometimes tapping the end of the screwdriver while trying to turn the screw can free the screw.

That location can have limited access to get good purchase with a screwdriver. You may be able to doublenut the screw to get better leverage for turning it. Yes, thinking about this now, there should be just enough threads available to get another nut up against the one jamnut already there on the slotted end of the screw to doublenut it for removal. Well not removal but to free it up for further adjustment. So try doublenutting before resorting to visegrips, etc.

Be aware that both the IP top cover and the screw are not especially strong alloys.
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Old 04-14-2022, 12:51 AM
Kaptin Kaptin is offline
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Hi Nguma, apologies for the delay in getting back to you.

Just a hobbyist really, but have help from my father, who owned a garage for 30 odd years - rather useful for a first TB on a new engine to me. He has a D24 too, so has done multiple. I've done a couple on my D5252T (2.5 TDI 5 cylinder V70), but never on the D24. No special tools, all done manually, admittedly IP was not properly timed, as whilst I had access to a dial gauge, I did not have access to an adaptor. Timing was set on the advanced end of the scale as I will be pulling power from the engine.

Yep, I found it, it appears to just be stuck, there isn't corrosion but there is 275k of grime. I'll try penetrating oils and a little smack, I just definitely don't want to risk damaging the threads. Tried adapting the sandwich plate which touches the screw, which worked but didn't give that much movement. For now I turned the fuel back down, and have a 600rpm idle, which sounds so great!

Double nut does sound like the best way, there are definitely enough threads for it, however I can see getting spanners on being a challenge...if I'm able to get them to line up just right, I think a deep 10 may be able to go over both and move it. I shall give them all a try, thank you!
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Old 04-16-2022, 01:53 PM
v8volvo v8volvo is offline
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Quote:
Originally Posted by Kaptin View Post
I've done a couple on my D5252T (2.5 TDI 5 cylinder V70), but never on the D24. No special tools, all done manually,
Be careful with that way of thinking. Are you familiar with how tight the torque on the front crankshaft bolt needs to be (much like on the D5252T which is highly similar) and what happens if the bolt is installed at insufficient or excessive torque? It is not something you want to be uncertain of. No tool other than the factory setup or an exactly similar homemade copy can get it torqued right. An impact gun, even a massive one, cannot necessarily do it because the crank is not held perfectly still thus the force of the impact is absorbed by movement in the crank. You may *think* it is tight enough -- many have! -- but it might not be. Similarly if you somehow manage to overdo it and make it too tight, that can lead to the same kind of disaster if it pulls threads or stretches/breaks the bolt. You cannot use the transmission to hold the torque on a standard trans car because the clutch can't hold 340 ft-lb and will slip, and if you try to use a lever against the flywheel ring gear, it'll break off the teeth. That is the kind of force we are dealing with on this bolt.

This is just simply a part of the engine that you really don't want to roll the dice with. It's no great challenge to get it right, but a world of pain if you don't. Read others' experiences with the sad consequences of anything short of perfection in terms of the installation of this fastener before you decide you feel lucky.

Same goes for the cam and IP timing. You can hope you got lucky but you will never know for sure and in the meantime damage could occur. And what is the benefit of the gamble? Doing these things the right way with the right equipment is easy and satisfying, you would probably enjoy the peace of mind knowing it's right!

Quote:
Originally Posted by Kaptin View Post
admittedly IP was not properly timed, as whilst I had access to a dial gauge, I did not have access to an adaptor. Timing was set on the advanced end of the scale as I will be pulling power from the engine.
A little confused here -- how do you know the timing is on the advanced end of the scale if you did not have the timing tools to know what the timing setting actually is?

How do you know it is not overly advanced? Too much advance leads to extreme peak cylinder pressures and internal stresses on the engine and can get you into deep trouble quickly. Headgasket, pistons, rings, connecting rods, bearings, etc can all suffer avoidable damage. All the more so if you are aiming for increased power.

Beware that if you are assuming that the timing is set advanced based on observed positions of the crude visual marks on the IP and its bracket, those in fact tell you nothing on this particular engine design. This is because the rear cam gear is not keyed to the cam and can be installed in any position (this is intentional -- how the timing process is accomplished when done correctly). Thus it could "look" like the timing is set advanced based on the relationship of pump to bracket, yet have the actual timing be far retarded, OR vice-versa. So if your timing guesses are based on that, then watch out, you might be making a false assumption. The only way to have know is using the dial indicator and rod/holder set. Those tool sets are ubiquitous on UK ebay for 50 GBP or less. Not expensive.

Quote:
Originally Posted by Kaptin View Post
Yep, I found it, it appears to just be stuck, there isn't corrosion but there is 275k of grime. I'll try penetrating oils and a little smack, I just definitely don't want to risk damaging the threads. Tried adapting the sandwich plate which touches the screw, which worked but didn't give that much movement. For now I turned the fuel back down, and have a 600rpm idle, which sounds so great!

Double nut does sound like the best way, there are definitely enough threads for it, however I can see getting spanners on being a challenge...if I'm able to get them to line up just right, I think a deep 10 may be able to go over both and move it. I shall give them all a try, thank you!
Sometimes can be helpful to remove the tripod stand that holds the throttle spool assembly to the top of the IP for easier access to the adjustment screws. Then you can do all the setup of idle speeds using those screws, with the throttle spool assy removed from influencing the engine speed, and last of all reinstall it and get it dialed in where it needs to be once you know the pump base settings are as you wish.
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