Sunday, January 11, 2015

Real time vehicle to manufacturer communication coming soon

Hello, everyone and welcome to The Toolbox.

I just read a news article that tells of GM plans to connect the vehicle via the 4G Onstar link and provide prognostic information to the customer. Click on the link below to see the article.

GM prognostic link

The parameters monitored will be limited but it is a matter of time before things like emissions and performance information is included.

After this it is hard to imagine that heavy truck dealers won't soon start a similar program on trucks.


Sunday, December 21, 2014

Maxxforce DT with Injector Sleeve Issue

            Hello everyone, and thanks for checking out this post. I recently worked on a customer’s 4300 that was burping coolant out of the expansion tank. It is a 2005 EGR motor with 500,000+ miles that is kind of a frequent visitor to the shop. We have replaced 5 of the injectors, the radiator, and a fuel transfer pump over the past few years, but it remains a fairly good running truck. The customer delivers a product requiring a special cargo lift to a large geographical area, so their trucks tend to be in service a long time and repairs must be turned around as quickly as possible.
            The truck actually came in with an injector miss in #4 cylinder. After a road test to confirm that repair, I saw coolant escaping from the fill cap. When the radiator cap was loosened immediately after the drive, several gallons of coolant exploded out of the reservoir. The problem was not accompanied by overheating at least not for the limited drive I took, but it was obvious I was getting excessive pressure in the coolant system.
            Having seen this happen if all the air isn’t purged from the system when filled with coolant, the first thing I did was to ensure the system was filled and no air was trapped. The upper radiator pipe going across the front of the engine has an air bleed on it that must be loosened while filling. Most trucks will have a petcock like a radiator drain on the system high spot, but this model has a plug sealed with an O-ring and these will usually seize and won’t loosen. As a consequence they often aren’t bled properly when filled. As the truck recently had a hose replaced on the road, I needed to be sure there wasn’t an air bubble causing the problem. I warmed up the bleed fitting boss with a torch, twisted the plug out, welded a nut to it, then reinstalled it with a new seal and some anti-seize so it could be easily removed next time.
            Of course the same condition was present after another drive, so work continued. I replaced the reservoir cap with my pressure tester and found the pressure built at idle at a rather alarming rate. After eliminating the air compressor by clamping its coolant hoses and idling again, I used a test kit to check for combustion gasses in the coolant, which confirmed the pressure was coming from a cylinder. Assuming I had a head gasket problem, pitted liner, or a head crack, we got the OK to pull the head. The rest of this post will illustrate the danger of making assumptions, even after years of working on a particular engine.
            Normally I remove the injectors when pulling a head. It is just too easy to damage an injector tip when removing or installing the head, not to mention the care that needs to be taken when cleaning or moving the head around. It just isn’t worth the trouble. I also usually pull the injectors fairly early in the head removal process, in order to catch any injector, cup, or head issues early in the job. However, we had replaced 3 of the injectors in the past couple of years and didn’t see any of these problems, so I waited until the end of the day for injector removal. When I went to pull the #1 injector, I found it stuck. Unlike the earlier DT, the injector hold down in the EGR (2004-and up) motor extracts the injector as the hold down bolt is loosened. This one however, didn’t move and the effort required to turn the hold down bolt after the first few revolutions told me there was a problem. I tried to pry the injector up with a pry bar, but it only moved a fraction of an inch. Assuming the injector was coked in with carbon, I poured a little intake system cleaner around it and let it soak overnight. At least it looked like I found the problem and the head probably wouldn’t need to come off.
            The next day I managed to get the injector pried out with a large ladyfoot pry bar, and it was indeed coked up. If for whatever reason the injector doesn’t seal to the bottom of the sleeve, combustion gasses will enter the sleeve and the carbon and soot will accumulate and harden around the bottom of the injector. This can make the injector very hard to remove. The problem can be caused by the injector not being seated properly when installed, an improperly torqued or broken hold down bolt, a missing or damaged injector tip sealing washer, or a leaking sleeve. In this case the hold down and bolt were ok, torque seemed good, and the metal bottom seal was in place, so the cup was suspected to be damaged and leaking. The lower injector O-ring, which seals the fuel passage from the sleeve and coolant area, was in bad shape from the heat and pressure it had been subject to, and it would probably have failed before long.
            The injector sleeve needed to come out, but the problem was that the sleeve remover we had for the DT 466/T444/7.3 would not work in the Maxxforce, as the sleeves are different size. We actually only found 1 source for the correct remover/installer kit, and it was expensive. Some research however revealed that the DT365/Ford 6.0 engine uses the same cup as the Maxxforce, and 6.0 tools are easy to come by, and cheaper. Maybe tool manufacturers don’t want us to know that the tools for both engines are interchangeable. One manufacturer actually lists a separate part number for each of the two kits and they are on the same web page, with no indication that they would each work on both engines. Not having the two injectors available for a side-by-side comparison I can’t say the two don’t differ in length or some other trivial dimension, but since the cups (sleeves) used are the same, the tools for all practical purposes are interchangeable. The short story is that we got a kit for the 6.0. and it worked.
            When the sleeve was out there was an evident track where it looked like combustion gases had been passing from the injector tip hole and across the bottom of the sleeve. The sleeve didn’t appear to be cracked or otherwise damaged. This led me to believe that the sleeve had lifted a little in the bore, causing both excess pressure in the cooling system as well as the coked-in injector. At least that is what I hoped. Whenever I have a problem like this I like to find something I can point to without a doubt as to the cause of the problem, but I was not truly comfortable with the injector cup as the solution. Still, I wasn’t ready to entertain the likelihood of two contributing problems at the same time, and needed to move forward with the job. Thus I was disappointed that the problem still existed when the engine was run again, but not completely surprised.
            At least now I could be sure the problem was the head gasket or liner problem, or a cracked head. At any rate the head needed to come off. Once the head was off, inspection of the gasket clearly showed an area about 1 1/2 inches long on the #2 cylinder where combustion gas was escaping. The head gasket has a metal fire ring on each cylinder. The ring sits on top of the cylinder liner and is compressed when the head is torqued. A ring that has been sealing properly will have a shiny silver circle all the way around it where it was in contact with the liner and on the other side, the head surface. A place that was leaking will have a dull, brown or grey appearance, and you can usually see a track where the combustion gasses went past the gasket to the nearest coolant passage. Liner protrusion always needs to be checked in this case, at the very least on the cylinder that was leaking. A liner with too little protrusion will not provide enough crush on the fire ring, and it will fail to hold compression. Other causes can be improperly torqued head bolts or a warped head.

            In this case the head was flat, liner protrusion was ok, so the engine was reassembled and now passed the road test.  With 20/20 hindsight, I wish I had gone ahead and pulled the head after seeing nothing absolute with the injector sleeve, but at the same time, one doesn’t want to waste time and customer money looking for a problem you’re not sure is there. Sometimes a job just does that to you. Explaining these things to the customer is the hard part.  Many don’t understand that repair is not always a cut-and-dried, point A to B process.  

Tuesday, October 28, 2014

Rolling Stones Mobile

Hi, everybody. I subscribe through Gmail an alert for truck technology.
This week's assortment of articles included one about the mobile studio the Stones had built in 1970.
The studio was used for recording much of "Sticky Fingers" and parts of other albums.
Other bands including Deep Purple, Led Zeppelin, and Iron Maiden also recorded in it.

Click this link to read the article    RSM