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NissanDiesel
LD & SD series Nissan diesel engines, and the people who love them
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asavage
Site Admin
Joined: 26 Nov 2005
Posts: 4648
Location: Port Townsend, Wash.
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 Posted: Thu Feb 14, 2008 10:31 pm Post subject: |
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Sorry, I am not available at all times, and I don't answer every Q anyway, because we have so many folks who can do that besides me.
| goglio704 wrote: | | I thought a VE pump injects at about 5,000 PSI, but I don't know for sure. |
The injector pop-off spec is within 10% of 2000 PSI. Figure spikes and peaks and such, and 2500 would be a reasonable guess.
However, reading the Bosch VE-style IP book (the "Yellow Book"), it's clear that the fluid dynamics involved preclude anything like a union in the IP line, so scratch that. It will run, but not as Bosch designed. Like two-stroke exhaust expansion chamber design, there are reflected waves back toward the IP when the injector closes; the delivery valves are designed with that in mine. Change the shape of the interior of the injector line, and that throws it all off.
And, as time goes by and I work on more and more VE IPs, I have begun to strongly suspect that pretty much all of our IPs are worn out, in the sense that the hydraulic timing system is probably not functioning anywhere near spec. That is a guess, but a pretty well-educated one at this point. The advance mechanism cannot be tested for proper hydraulic advance functioning via the Tach-N-Time, because there is a Torque Control mechanism that retards the timing under light load/high RPM even if the hydraulic advancer would normally advance the timing based solely on RPM.
I do not make this up, only a German could come up with the mechanism. It is explained in the "Yellow Book".
My own '82 shows 8° BTDC at idle, and pretty much 8-10° BTDC at 4000 RPM. Is this correct? Or does it prove my "non-functional advancer" theory? Who knows?
Add'l variable: the newly-rebuild VE-style IP I installed on Tom Sigmond's Toyota diesel PU showed this data: IP set mechanically per Toyota spec got about 3.6° BTDC at idle; at 2800 RPM and above, I saw ~12° BTDC.
That's only a single data point, but it does reinforce my "LD28 IP non-functional-advancers" theory. Obviously, we need more data (or more-educated forum members).
All this is prelude to me stating: one car's "EGT @ some degree base advance" may not translate at all to the same result on another vehicle, due to differences in the internal advancer's performance.
Bear in mind that the advancer piston is only the part being acted upon; the true wear item is likely to be the vane lift pump, is my guess.
Many repair manuals warn specifically against bending injector lines, and you will note that all diesel injector lines are always of the same length, even when this means making extraneous loops for the injectors that are close to the IP.
| Quote: | | I have had similar thoughts about using EGT as an indication of timing. Until it produces high EGT, advance is a good thing isn't it? There is also an emissions issue related to advanced injection timing. High levels of something. NOx or some such. |
If the goal was power & economy, one could do a good job of adjusting the timing using a variety of feedback metrics (dyno, EGT, consumption equipment). But that's not the whole goal, at least it isn't for me. And there is a limit to the number of hours I am willing to spend trying to optimize better than Bosch's engineering staff 
| Quote: | | I think the goal of static timing has always been that it would be a good baseline reference. If two or three cars could be static timed and then shot with a timing light, we'd have reference points. Once the data was collected, no more need for static timing. |
That is where I think we should concentrate timing efforts. I am ashamed to say that I have not gotten around to this, but in my own world, where for much of the time I do not drive my Maxima, it just doesn't get to the top of my To-Do list. Here's hoping someone else will take up the challenge. Every time I start to try to mechanically time mine, I bounce off the project and end up doing something else. Turns out, buying the equipment and tools was the easy part. 
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Regards,
Al S.
1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey.
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14-Jul-07
1981 720 SD22 (scrapped 04-Sep-07)
1983 Sentra CD17, 255k, bought 06Jul08 |
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Carimbo
Joined: 27 Nov 2005
Posts: 362
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| Posted: Thu Feb 14, 2008 11:11 pm Post subject: |
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| asavage wrote: | | The advance mechanism cannot be tested for proper hydraulic advance functioning via the Tach-N-Time, because there is a Torque Control mechanism that retards the timing under light load/high RPM even if the hydraulic advancer would normally advance the timing based solely on RPM. |
Chassis dynomometer would allow this high load/ medium RPM test. Sorry, this didn't really advance our cause; I know nobody here has access to a dyno.
| asavage wrote: | | Many repair manuals warn specifically against bending injector lines, and you will note that all diesel injector lines are always of the same length, even when this means making extraneous loops for the injectors that are close to the IP. |
AND they stress importance to replace all hi-pressure injector line clamps (although this more to minimize metal-fatiguing vibrations).
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S. Caxambu
'82 Maxima Diesel
Seattle WA |
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LD28 Owner
Joined: 14 Oct 2007
Posts: 34
Location: Olympia, WA
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rlaggren
Joined: 03 May 2007
Posts: 362
Location: San Francisco
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| Posted: Tue Feb 19, 2008 1:23 pm Post subject: Dyno availability |
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Wouldn't the chassis dyno at emissions testing stations serve? Even if you don't have a "friendship pass" many offer "pre test" screening for $30 which could be probably be enhanced by a quantity (or curiosity) discount. But I've never used the pre-test so I don't know if there may be bureaucratic requirements there.
Rufus
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82 Maxima wagon |
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rlaggren
Joined: 03 May 2007
Posts: 362
Location: San Francisco
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| Posted: Wed Feb 20, 2008 1:49 am Post subject: |
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Interesting take on the IP's, Al. You're saying the vane pump has sliding surfaces that wear even under good/excellent maintenance (I'm vague on pump design)? Does anybody here have a rebuilt IP with, say, less than 50K on it?
Case pressure seems fairly critical. Does the book have any pressure/RPM specs? Is there a way to measure it directly? .
It's past my bedtime but I'll look at the Toyota IP thread tomorrow and see if I'm missing something.
Rufus
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82 Maxima wagon |
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dieseldorf
Joined: 03 Jun 2007
Posts: 119
Location: PDX/Vancouver Pacific NW
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dieseldorf
Joined: 03 Jun 2007
Posts: 119
Location: PDX/Vancouver Pacific NW
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dieseldorf
Joined: 03 Jun 2007
Posts: 119
Location: PDX/Vancouver Pacific NW
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| Posted: Sat Jan 24, 2009 1:08 pm Post subject: IP Timed |
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I bought this adapter set from Ebay (ZDMAK Tools) It is made in China (what's not) but the quality is acceptable. The plastic set-screw is crap, so I replaced it with a metal one. Kit comes with two extensions and two plungers. An indicator dial with 8mm shaft is needed.
First, I attempted to use the short plunger. No luck, it was still to long. Could not attach it to the IP.
The plunger needs to be shortened. So I made a new one, keeping the original unchanged. I took a steel rod 1/8" dia, 1.5" long (welding rod) and made a 3mm thread on one end. Still no go. Then I assembled the whole set and inserted into the IP keeping the set-screw loose. Turning the extension I could screw the set into the pump and secure it. As you can see all the injector tubes have to be removed.
I could set the timing to factory spec. of 85mm @ TDC (86mm for 1983) after disangaging the CSD.
Then I checked the markings on the IP and the engine front cover. They aligned perfectly. This is probably the case if you have a new IP belt, as I do. As the timing belt wears out, the timing is slightly delayed and the pump needs to be turned CCW in order to advance it.
With all the right tools, the job can be done in 3 HRS
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Astro Van project with LD28 propulsion
'86 Ford Escort Wagon Diesel MT Sold 07-17-08
Last edited by dieseldorf on Tue Aug 11, 2009 7:18 pm; edited 2 times in total |
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rlaggren
Joined: 03 May 2007
Posts: 362
Location: San Francisco
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| Posted: Sun Jan 25, 2009 2:06 pm Post subject: |
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Very nice.
This is for the van, right? I haven't considered doing this (my engine runs good right now) and I'm not sure if the clearance problems you experienced would be the same for the car. Ie. would this tool work for the car considering that we have a firewall and different engine space to deal with? Alternatively, what caused the clearance problem for you?
Thanks, Rufus
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dieseldorf
Joined: 03 Jun 2007
Posts: 119
Location: PDX/Vancouver Pacific NW
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| Posted: Mon Jan 26, 2009 2:45 pm Post subject: |
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The clearance problem stems from the short distance between the IP and the oil filter mount. If you read the beginning of this thread, you will know what I mean
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Astro Van project with LD28 propulsion
'86 Ford Escort Wagon Diesel MT Sold 07-17-08 |
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goglio704
Joined: 03 Dec 2005
Posts: 698
Location: East Tennessee
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| Posted: Tue Jan 27, 2009 6:13 pm Post subject: Re: IP Timed |
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| dieseldorf wrote: | Then I checked the markings on the IP and the engine front cover. They aligned perfectly. This is probably the case if you have a new timing chain and IP belt, as I do. As the timing chain wears out the timing is slightly delayed and the pump needs to be turned CCW in order to advance it.
With all the right tools, the job can be done in 3 HRS |
This is great news, particularly if it will work on the Maxima, but I must point out that timing chain wear will not affect IP timing since the IP belt is driven directly off the crank.
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Matt B.
83 Maxima Sedan, LD28, 5 speed, white, 130k miles. My original Maxima.
83 Maxima Sedan converted from gasser, LD28, 5 speed, 2 tone blue, 230k miles
82 Maxima Sedan, LD28, 3 speed auto, 2 tone Gray/Silver, 140k miles
81 810 Sedan, LD28, 3 speed auto, rust, rust, and more rust!
2005 Jeep Liberty CRD, 85 Blazer 6.2 Diesel |
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rlaggren
Joined: 03 May 2007
Posts: 362
Location: San Francisco
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| Posted: Tue Jan 27, 2009 7:34 pm Post subject: |
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| Quote: | | If you read the beginning of this thread, you will know what I mean Wink |
Guess this thread's lasted longer than my memory. Oh well, just have to struggle on... <g>
Seems like the dial indicator overall length would be an important issue. Since you have on that works, how long is it? I believe there are different standard lengths but I don't know the proper designations.
Rufus
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dieseldorf
Joined: 03 Jun 2007
Posts: 119
Location: PDX/Vancouver Pacific NW
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| Posted: Wed Jan 28, 2009 10:49 pm Post subject: |
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goglio704 wrote:
| Quote: | | This is great news, particularly if it will work on the Maxima, but I must point out that timing chain wear will not affect IP timing since the IP belt is driven directly off the crank. |
You are absolutely right. I was still thinking VW Diesel. I edited that post.
Regarding the Dial size, they seem to be one standard size. I bought a cheap chinese dial at Harbor Freight Tools with same overall dimensions as the VW-set dial I used with one exception however, the shaft was 9mm dia. It will not fit into the extension tube. It has to be 8mm dia shaft.
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Astro Van project with LD28 propulsion
'86 Ford Escort Wagon Diesel MT Sold 07-17-08 |
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Carimbo
Joined: 27 Nov 2005
Posts: 362
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| Posted: Fri Nov 06, 2009 12:16 pm Post subject: Interesting New Approach to Timing VE Pump |
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Wonder if this would work for us?
http://www.vwdiesel.net/forum/index.php?topic=21808.0
Simplicity  , might not even have to remove the injector lines.
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S. Caxambu
'82 Maxima Diesel
Seattle WA |
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rlaggren
Joined: 03 May 2007
Posts: 362
Location: San Francisco
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| Posted: Sun Nov 08, 2009 11:38 am Post subject: |
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Looks pretty good - hope his "production line" works out well. Thanks for the tip.
Rufus
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