Alternator putting out low voltage/injector replacement

[IDIBRONCO]

This is where I'm leaving it at tonight. As has been mentioned elsewhere, the bolt hole is too small on the 3G. A quick pass with a 5/16 drill followed by a little threading with a 3/8-16 tap and I could use the 1G bolt.
A couple of observations: the boss on the bottom of the 3G alternator was about .003 too large. I took a file and barely knocked it down and it fit perfectly. Also, Mr. Roboto's thread in the tech articles mentions he used a 2 mm shim under the pulley on the 3G alternator to have it spaced correctly. The difference between the two alternators I have was less than 1/2 mm, so I'm just gonna run it. If it throws the belt I'll shim it out.

That sounds about like the experience I had when I installed mine.

The top bolt hole was M8x1.25 and I just used a new bolt, after cleaning the threads up with a tap.

Except for the tap, that's what I did when I installed mine. Of course I do have a decent selection of metric bolts sitting around due to me playing around with ATVs.

 

[BrandonMag]

I got the 3G alternator installation completed along with cleaning up all of the wiring in the engine bay (I had forgotten how time-consuming pulling out unnecessary wires, cutting out extra wire length and sleeving all of the exposed wires with split loom is). I don't like seeing colored wires in the engine bay, it's gotta be all black to look decent to me. (The white wire will be covered by the air cleaner.) I haven't yet started it to see the difference in voltage output; tomorrow I'll be installing freshly rebuilt injectors with new fuel return lines and caps. If everything goes well I'll start it tomorrow afternoon.

 

[ROCK HARVEY]

What are you guys doing for a wire harness if you order the 3g alt online? I can get a 3g alternator and harness at a junkyard, but I’d prefer a reman alternator if the harness is easy to make.

 

[BrandonMag]

I've got a lot of wire laying around; I just crimped female disconnect terminals on some wire.

 

[IDIBRONCO]

What are you guys doing for a wire harness if you order the 3g alt online? I can get a 3g alternator and harness at a junkyard, but I’d prefer a reman alternator if the harness is easy to make.

I just ordered a new regulator plug off of Ebay. It had a few inches of wire on it. From there, I just ran my own. It was pretty simple.

 

[BrandonMag]

As far as I'm getting today. This was the first time I've removed and replaced injectors in the truck. It wasn't hard (the order of operation is self-explanatory), but it sure takes some time. It took a couple of hours just to clean the caked-on yuck in all of the injector bores. (I'm not as young as I once was and laying on the engine took it's toll.)
Best helpful tip I found on OB: if a copper washer is stuck at the bottom of the injector bore use a 5" or 6" long 5/16" lag bolt. I simply threaded the bolt into each of the five stuck washers about three turns and used a slide hammer to yank them out. I'll have the caps and lines installed tomorrow and then I'll see what the voltage output of the 3G alternator is.

 

[Brian VT]

Great tips. Thank you.
Can you give any advice on cleaning "...the caked-on yuck in all of the injector bores."?
Don't want that yuck in there after pulling the injectors and then muck around in there to get the washers out, right?

Side note, my Benz has weep holes at the bottom of the spark plug bores. Nice idea from when things were built by engineers and not by accountants. ;-)
I can blast brake cleaner down there and it runs out the weep holes and takes most of the crap with it.

 

[BrandonMag]

Can you give any advice on cleaning "...the caked-on yuck in all of the injector bores."?
Don't want that yuck in there after pulling the injectors and then muck around in there to get the washers out, right?

Sure: after I removed the injectors, I soaked the carbon deposits left behind in the injector bores with Free All and used an assortment of bent screwdrivers, picks and small bent pieces of drill rod to carefully scrape off the significant quantity of built-up carbon deposits. I then used a shop shop vac (with a small tube I taped into the nozzle) to clean everything throughly. Cylinders 7 and 8 were a *****; they're so close to the firewall that I couldn't see directly down them, so I used a mirror and flashlight to identify where the build-up was. Since I don't have three hands, I would put the flashlight down, pick up the pick (or screwdriver or bent drill rod, depending on what particular tool configuration was needed) and mostly blindly attempt to scrape some of the carbon out of the bore. As you can imagine, it was a time-consuming process to get just those two bores completely clean. (All of this was done while laying on the engine, which after not very long gets uncomfortable.) I had five copper washers stuck after I removed the injectors; on most of those bores I cleaned the carbon out before I removed the copper washers, but not all. I think I pulled two of the washers before I had completely cleaned the bores out. (Both methods worked equally well.)
I chased all eight injector threads with an M24 × 2.0 tap to make sure the injector installation would go as smoothly as possible. Surprising fact: the burr on the edge of the valve covers (left over from the stamping process) protruded ever so slightly (around .010) into the circumference of the injector bores. This made it impossible to thread in the tap, so I gently used a punch and a small hammer to gain the clearance needed. (The threads of the injectors are shorter than the long tap I used; the valve covers were not in the way when I removed the injectors.) The valve cover clearancing took awhile because the angles necessary were difficult to achieve with the injector lines in the way.

Side note, my Benz has weep holes at the bottom of the spark plug bores. Nice idea from when things were built by engineers and not by accountants. ;-)
I can blast brake cleaner down there and it runs out the weep holes and takes most of the crap with it.

That is a very good idea indeed. Leave it to the Germans; I've never seen that on an American or Japanese vehicle.

 

[Brian VT]

How do you stop the crap from getting into the engine when you're cleaning the injector bores?

 

[BrandonMag]

How do you stop the crap from getting into the engine when you're cleaning the injector bores?

Time and patience: I'd scrape a little, vacuum, scrape some more, vacuum, and repeat until finished. I used two tubes taped into the vacuum nozzle to get into the pre-cups and I found that there was a little bit of carbon that got into the injector nozzle holes. I read a recommendation to use grease to cover the nozzle holes, but that would have made a mess and taken even longer than it did. (On reflection, a better method would have been to put something like a dime down the bores to cover the nozzle holes.) Was it an absolutely perfect method? No, but I'm confident that I was cautious enough to prevent any large chunks of carbon from getting into the cylinders. If there's an issue that I notice I will definitely post it here; making mistakes and sharing that information is how I learn what not to do.

 

[DaveBen]

Crank over the engine, with the injectors out, to blow out any garbage left in the cylinders.

 

[Nero]

What I do on the big rigs I work on any time we replace an injector, blow the area clear, use a cloth rag on a wire brush that has your favorite brake cleaner on it, and then clean the hole out. I put mine on a little 3/8 drill so it cleans it out well and barely anything falls in. So far no leaks or toofed engines.

 

[Brian VT]

Good idea. Maybe a Dremel tool with a flexible extension for the hard to reach ones.

 

[BrandonMag]

I got all of return caps and lines installed, double-checked everything to make sure I hadn't overlooked anything obvious, hooked up the battery and gave it a crank. Surprisingly, it didn't take that much cranking (maybe 10 seconds) and it fired up. After a few seconds of rough idling it smoothed out. I was pleasantly surprised, there was an improvement in the sound at idle... smoother, I guess? I let it warm up for a few minutes and observed a noticeable improvement in voltage output: there's a full volt more than the best reading I observed with the 1G alternator! I am very pleased with this result! (Also, I waited for a few hours after my test drive and checked the resting voltage of the batteries: 12.65 volts. My experience says your batteries really need that extra volt in order to stay fully charged.) My takeaway: if you're having a low voltage output with the OEM alternator, upgrade to a 3G. It's a noticeable improvement.
Also, the fuel injector replacement was a great upgrade as well. I had a noticeable improvement in throttle response and power. There's a hill about a mile north of my house that's roughly half a mile long. Before the replacement, if I was traveling 60 MPH when I began to climb it, by the time I got to the top (with the pedal to the floor) my speed had dropped to 55 MPH (with the truck unloaded). Now, traveling at 60 at the bottom of the hill, I was able to accelerate to 65 MPH by the top of it. I certainly won't be winning any races, but the condition of the truck is moving in the right direction. There's still a fair amount of work to do, but I am very happy with both the 3G alternator upgrade and the fuel injector replacement. I still need to get it timed, so I have one of the DTI timing sets from eBay on the way. It's supposed to be here between Wednesday and Saturday of next week (hopefully Wednesday). Once I get that accomplished I am confident she'll be running great... and maybe then I'll turn up the fuel.

 

[IDIBRONCO]

The only time that the needle on the factory ammeter in my Blue Truck moved was after I did the 3G swap on it. So it does make a BIG difference.