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fj45lvr
Active Member
United States
10 Posts |
 Posted - 02/21/2007 : 12:36:40 PM
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I have a 1985 rig with 8.2L Turbo detroit that may have a problem with an injector....I bought an unopened "powerpak" that includes 8 injectors I wanted to know something about them:
They are packaged in boxes labeled 4C65 (which is the right ones for me) then they have another number 4229915 (don't know what that is) then they say CALIBRATION and on each box there is a handwritten fraction that is shown 68/18 (6 injectors) 68/19 (1 injector) and 66/20 (1 injector) the fraction is written on the injector as well with pencil. What are these fractions in relation to anything? if the upper half represents the measured output in CMM what is the smaller number? can any of the set be installed anywhere? I am assuming "yes" but I wonder why they wrote this information down.
Also wanted to know how important reaming the injector tube the manual mentions doing so with a specific tool which I don't have so I wanted to know if I need to hunt one down.
Do you think it is fine to replace only one or a couple of injectors rather than them all?
I remember someone said something about the injector liner tubes but I don't want to take off the head...I should be able to inspect these visually for any cracks??
I had a problem with hearing a knock that a friend believes is from an injector. though it may turn out to be something else I am sure I can at least eliminate the injector as the possibility (while at the same time doing a base circle tune-up).
thanks for assistance |
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wagonmaster
Top Member
USA
2298 Posts |
Posted - 02/23/2007 : 05:11:57 AM
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Suggestion:
If you have an 8.2 Detroit and have never worked on it or been trained n it in any way DON"T attempt an injector replacement. It's not rocket science, but it is a complicated procedure. See if a tech from your local DD dealer will do some "side" work for you. Might just need the one injector,maybe not. At any rate, this is not a task for the uneducated on DD engines and should not be taken lightly.
Good luck! Aren't many folks left that can do what you need since these engines have been out of production for over two decades! |
Joe
Land of the Free, because of the Brave! |
Edited by - wagonmaster on 02/23/2007 05:12:19 AM |
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IBTMech
Top Member
USA
973 Posts |
Posted - 02/23/2007 : 6:29:46 PM
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8.2s...... good riddance...... a 100K engine.
If you're determined, follow Wagonmaster's advice and find someone familiar with with the base circle timing procedure. It's not for the lighthearted or the amateur.
Better still, depending on the mileage, look for a reman. |
If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years. |
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International-9.0
Advanced Member
USA
459 Posts |
Posted - 02/23/2007 : 7:37:25 PM
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Better still, put in a 9 Liter.  |
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ModMech
Top Member
USA
948 Posts |
Posted - 02/24/2007 : 6:50:49 PM
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| If you don't have the timing tool ($800+), DO NOT bother. There is nothing you can do with the injectors, unless you have that timing tool. |
If you want customer service, you NEED an International! |
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Brad Barker
Administrator
USA
874 Posts |
Posted - 02/26/2007 : 12:23:21 PM
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In most cases that I am personally familiar with the injectors came out clean. I only had to run a tube cleaning brush into the injector tube to clean it up before installation of a new or rebuilt unit.
Like Wagonmaster says, if you are not familiar with running the overhead on an 8.2 DO NOT attempt it. Even the experienced can screw up once in a while. I did. I had a helper working with me one day and got distracted. The fuel control rods got locked in the full fuel position without realizing it. When I started it the engine overrevved and almost blew up before we got it shut down. NOT a fun experience. Fortunately I had an emergency intake plate ready to throw over the intake but it still would not fully shut down until we removed the fuel filter. |
Brad A. Barker |
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fj45lvr
Active Member
United States
10 Posts |
Posted - 02/26/2007 : 10:27:55 PM
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I have the timing tool already and the detroit manual.
the base circle timing seems pretty easy....just wanted advice as to injectors and hearing a knock based on people's experience...I suppose my issues with unburned diesel (white smoke) and the knock could be several things at a minimum I will just do the tune-up and was thinking I would slip in the rebuilt injectors on the side I percieve the knock is on to see if it doesn't quit one cylinder at a time.
thanks for tip as to being able to brush and on the over-revving with fuel control being locked...
I realize that this engine is obsolete, "throw away" and pretty much bad mouthed already but it happened to be in the vehicle when I bought it so I'm just goin to use it till it dies (who knows when??). Odometer doesn't turn over anymore and is on 238k right now...probably close to the end but some owners say they were happy and got 400k and there are hit and miss reports whereas if they do work they are hard to kill (as long as you don't overheat). |
Edited by - fj45lvr on 02/26/2007 10:30:46 PM |
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wagonmaster
Top Member
USA
2298 Posts |
Posted - 03/02/2007 : 09:57:15 AM
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quote:
some owners say they were happy and got 400k
Sorry. I don't buy that! If an 8.2 DD was pushing a golf cart it wouldn' go 400k! Not to rain on your parade, but don't believe everything you hear! If that was a 6V92 or an 8V92, no problem, but no way for an 8.2 to go 400k. Sorry..... |
Joe
Land of the Free, because of the Brave! |
Edited by - wagonmaster on 03/02/2007 09:57:55 AM |
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ModMech
Top Member
USA
948 Posts |
Posted - 03/02/2007 : 10:33:29 AM
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I don't know of even one example of an 8.2L OVERheating, in fact GM and Ryder spent many hundreds of thousands of dollars trying to get them to heat AT ALL in the northern areas of this country. They had no success.
If you have the books and tools, then it is not a very difficult project. The injectors should be set to the "industrial setting" for peak performance and fuel economy (although not optimum for emissions).
The 8.2L DD makes a GREAT marine engine.... when it dies at least you have a worthy boat anchor. |
If you want customer service, you NEED an International! |
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International-9.0
Advanced Member
USA
459 Posts |
Posted - 03/03/2007 : 09:32:31 AM
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I have yet to understand how the fuel injection works on a 8.2. I know it's a "rack unit injection" type system as opposed to an injection pump. I've been told (correctly or incorrectly) that the throttle actually directly controls the amount of fuel injected and that the throttle setting is only over-ridden when the engine drops below a minimum or goes above a maximum.
The best understanding I have of my 9 Liter (be it correct or incorrect) is that the throttle controls a spring in the govenor/injection pump, and the position of the throttle along with the engine rpm determine how much fuel is injected. Even at full throttle, as rpm increases from peak torque (1200 or somewhere in there??), the amount of fuel is slowly cut back until the last 1-300 rpms before no-load high idle. At this point the drop off of fuel delivery is very sharp. Mine will run out at about 3150 rpms. Anybody have insight as to how correct or incorrect I am? |
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ModMech
Top Member
USA
948 Posts |
Posted - 03/03/2007 : 10:02:52 AM
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| All mechanical (non-PT) diesel fuel systems control the fuel rate in exactly the same way - with a helix. The position of the Helix determines how long fuel is injected for, a short helix will not inject fuel for as long as a longer helix. The main difference is the with the DD engines, the helix in in the injector, instead of in the injection pump. In any event, there is one helix for each cylinder. |
If you want customer service, you NEED an International! |
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Thomas Ford 85-16
Top Member
USA
4177 Posts |
Posted - 03/03/2007 : 10:05:00 AM
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quote:
Originally posted by International-9.0
I have yet to understand how the fuel injection works on a 8.2. I know it's a "rack unit injection" type system as opposed to an injection pump. I've been told (correctly or incorrectly) that the throttle actually directly controls the amount of fuel injected and that the throttle setting is only over-ridden when the engine drops below a minimum or goes above a maximum.
I'm probably the one who messed with your understanding there. I know we've talked about this in the past. Out in the open here, perhaps some mechanics can clear up any misconceptions.
My service manual describes it like you said... The fuel is metered at the injector by way a of a small gear on the outside. A rack with teeth moves back and forth to rotate that gear. That rack is connected to the throttle pedal linkage, and where that connects to the engine is also mounted the governor and the fuel shut-off solenoid. The solenoid is supposed to move the rack to a full-closed position when the engine is shut off, and the governor is supposed to move the rack away from the full-open position when it reaches its governed speed. Additionally, the governor will move the rack to maintain the correct idle speed. I'm told this governor is hard to tune, and I have witnessed many DDAs with an idle that fluctuates over the course of a 15 seconds or so.
John I admire that you find the fuel systems so interesting. Even though I can dive into so many other systems of a bus, I've never found myself to have the mental capacity to remember everything going on in the fuel system.
Edit - sorry ModMech, your explanation seems to be adequate and breif! We must've been typing at the same time. |
Mike's Bus Yard - http://buses.zwebpages.com - Since 1999
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Edited by - Thomas Ford 85-16 on 03/03/2007 10:07:24 AM |
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International-9.0
Advanced Member
USA
459 Posts |
Posted - 03/03/2007 : 1:09:12 PM
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Mike, your post was a little bit more what I was looking for to start. My question here would be: Does this governor slowly cut back on fuel as the rpms increase or does it ONLY interfere when it comes to min and max rpms?
My next question would be to ask, what do the rotating gears connect to? Do they directly control the position of the helix? I think the helix assembly is probably something I'd need to see to understand, but I find this all very interesting. I know that a helix is like a screw or spiral shape, but I cannot totally visualize how it all fits together. Thanks to all the responses! |
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ModMech
Top Member
USA
948 Posts |
Posted - 03/09/2007 : 1:39:41 PM
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The DD govornors, and most others, do both and either. Some are spec'd with "automotive" type Govornors and others just "max RPM" based govornors.
Automotive types will gently maintain a pre-set engine speed within the limits of the engine's output w/o changine RPM.
"Limit" types simply control the minimum/maximum RPM of an engine, and do not come into play in between. |
If you want customer service, you NEED an International! |
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International-9.0
Advanced Member
USA
459 Posts |
Posted - 03/09/2007 : 6:15:28 PM
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Ok, so it all depends how the engine is setup. I'd imagine emissions requirements, turbos, application of the engine, and many other factors would determine how governor is setup and the engine is "tuned." Sometimes I wish mine would fuel a little bit more at higher rpms so I'd have some torque in the upper rpm band, but I suppose that would kill my fuel economy and make it smoke quite a bit more. Thanks for the info.
Jonathan |
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Thomas Ford 85-16
Top Member
USA
4177 Posts |
Posted - 03/12/2007 : 06:41:46 AM
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Sorry that I can't chime in more for you; I'm 500 miles away from my service manual at the moment, so I can only contribute to the general concept.  |
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International-9.0
Advanced Member
USA
459 Posts |
Posted - 03/12/2007 : 7:32:10 PM
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| Well thanks anyways Mike. Everybody's input was useful and I get to learn a little bit more day by day. Today I was under the rear of my bus studying air lines trying to figure out how everything ties together. I think I found my anti-composition valve or whatever that thing is called, but I need to do some more studying. I'd love to watch/help with an 8.2 injector changeout sometime. One of the mechanics we have that used to work for CAT gave me a helical injector to study. (think he said it was off a 3406) I think I finally understand how the capacity is controlled. The rack rotates the plunger inside the barrel. As it rotates away from no fuel position, the effective stroke is lengthened (as the helical cut in the plunger spirals upward). The injection will start at the same point in the stroke, but will go longer before being "cut off" (where the return hole in the barrel is uncovered by the helical cut in the plunger and sufficient fuel pressure to open the nozzle valve is lost). I'm sure they all vary a tiny bit from that, but does that sound about right to those experience mechanics out there? I also found interesting that this particular model required no o-rings. Roger informed me the barrel and plunger are a very very precise bore, to keep fuel form getting in to the oil supply. I'm sure they aren't all the same, but I thought that was interesting. |
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question on rebuilt injectors dd 8.2L and install
