October 2009 - Performance Zone
COSTLY REBUILDING MISTAKES
By Performance Specialist Bruce C. Mallinson
I recently received two phone calls from owner operators with Cat engines that were the victims of failures associated with poor engine rebuilds. I also currently have a truck in my shop with a KTA Cummins that also got a bad rebuild. But these three failures were not because of faulty parts – they were caused by carelessness and/or poor decisions made by the mechanic performing the rebuild. If you’re wondering, both of the owner operators with the Cat engines went to a “qualified” shop – one was a Caterpillar distributor and the other was a Western Star truck dealership. The Cummins, well, maybe it wasn’t such a reputable shop.
Let’s start with the MBN Bridge Cat that was rebuilt by the Cat distributor. By now, we all know that the 2003 and early 2004 Cat “Bridge” engines have a lot of problems – namely, poor performance and poor fuel mileage. Also, because of low liner protrusion, the MBN Bridge Cat tends to blow head gaskets. This engine was the victim of Caterpillar trying to meet the EPA’s air pollution requirements for 2003 before they were actually ready. Cummins, Detroit, Mack, Mercedes and Volvo all went with EGR systems, but they aren’t much better (the good engines, the ones that run forever and give you great power and fuel mileage, went away in 2002).
The owner of this Cat Bridge engine had replaced the Bridge ECM a few years back with our performance ECM to “un-bridge” the engine, which then ran great and got better fuel mileage. However, when he took the engine to the Cat distributor for a rebuild, he let them put the Bridge parts back into the engine. At that time, he should have had them eliminate the rest of the Bridge parts that make up the MBN Bridge Cat engine. To make this engine a “real” engine, the pistons, camshaft, injectors and turbocharger should have been changed. With those improvements, fuel mileage, longevity and power would have all improved. Besides, these parts had to be changed anyway, so why not install the correct parts to go with the un-bridged ECM?
The reason this owner operator went to the factory Cat House was because he was in a hurry to get the truck back on the road. Gentlemen, in my 31 years of rebuilding engines, I have heard this statement over and over again, but there is never any time or the right time to rebuild your engine. Everyone is always in a hurry to get their truck back on the road, so poor decisions are made. When you have a breakdown, you must ask yourself what happened, what your options are to fix the problem, and where you should take it to get fixed. You might even consider fixing it yourself if you have the time, expertise, knowledge and tools to do so.
Maybe you should take one day and think about your engine problem, do some research, make some phone calls, and talk to a few good mechanics that you know have a great reputation for rebuilding engines. In fact, you should have a plan in your head as to what you’re going to do when/if your engine fails (breakdowns rarely occur close to home or near the shop you would prefer rebuild your engine). Did you ever think it might be more economical in the long run to have a friend with a retriever, low boy or drop-deck trailer come to where you are and haul your truck to your preferred shop?
Anyways, back to this Bridge Cat at the Cat House. With the rebuild complete and the Bridge Cat parts re-installed, the mechanic started the engine and realized that it was out of time and would not run correctly. But instead of removing the front cover of the engine and putting the cam gear in the correct spot, he made up the difference with the Bridge ECM. He even told the owner that he was one tooth off with the timing gear, but that he was able to make it run okay being out of time. Then, the owner took his truck home and re-installed his un-bridged Cat ECM, but then the engine wouldn’t run right because of the timing gear. So, the owner had to take the truck to another shop and pay to have them retime his engine and his ECM. This is a minor problem compared to the next problem I’m going to tell you about.
Another owner operator took his 3406E Cat to a Western Star dealership for an in-chassis rebuild, but guess what the mechanic failed to do – check the liner protrusion. He never cut the upper counterbores to install the stainless steel shims that raise the liners and hold the head gasket. Needless to say, the head gasket failed in two months. So, back to the Western Star dealership he went for the warranty work, only to find that they had gone bankrupt and were out of business. So, off to the Caterpillar distributorship went his truck to have the head, cylinder packs, and oil pan removed so the upper counterbores could be properly cut. This is everything you have to remove to do an in-chassis rebuild, so now he is paying for the labor twice in a 60-day period.
Caterpillar cut the upper counterbores, installed the stainless shims and raised the liner protrusion and now the head gasket is holding, but the bill was $6,000, which the owner had to pay – not because the parts failed, but because the first mechanic failed to do the rebuild right (I guess there is no need to wonder why they went out of business). There is a saying that is appropriate for this situation: “Why is there never time to do it right the first time, but always time to do it again?” When I asked the owner why he did not tell the mechanic that he wanted .006 liner protrusion, he said, “I assumed they knew what they were doing.” Well, we all know what the word ASSUME means. We have all been guilty of this, and it has cost all of us a lot of money over the years, so don’t do it – never assume!
This last poor engine rebuild is a whopper – $56,000 was spent and the engine is still sitting in the chassis disassembled. Not only is the owner a victim, but so am I. This engine is a 1,150 cubic-inch KTA 600 Cummins, the largest engine ever built for on-highway use. First released in 1974 by Cummins as an experimental product, this great engine is still being manufactured today (it’s now called the QSK) for machinery uses only. When built properly, this engine can develop 2,500 horsepower for truck pulling and drag racing.
Shortly after the first engine builder put this engine together, it went right back to them for no power. Another set of injectors were installed, but still no power. After returning a third time to the original rebuilder, and still no power, the truck was brought to our shop. We found that the turbocharger dated back into the mid 1970’s and would not make enough wind to dry your hair, so an updated turbocharger was installed. Never use turbochargers from the 1970’s on an engine today – they were not very efficient back then. Next, we found the aneroid was partially plugged in the fuel pump and would only allow enough fuel to the engine to develop about 300 hp. After we fixed these problems, the truck left our shop running much better, but not as good as it should. We could not tell by the paperwork what parts had been installed in this engine because there were no part numbers so it was hard to know if it really was fixed.
The owner of this truck, who has had eleven KTA engines so he knows them quite well, complained of a slight “thump” he felt when he let out the clutch (after the rebuild). A couple trips later, the head gasket blew, so we installed a set of steel o’ringed head gaskets to fix this problem. A couple months went by and then the engine started to miss and get excessive blow-by. He towed the truck back to our shop where we found that the #3 piston had debonded, which means the top of the piston broke off down to the first piston ring. Once we got into this engine, we found all kinds of problems.
When our head mechanic Brian removed the #3 connecting rod cap, he noticed a gap between the #4 connecting rod and the crank. He found a .084 clearance (it should have been .008), so he removed that connecting rod cap as well. There was excessive wear, so he checked the end play of the crankshaft and found .030 (it should have been .008 to .016). After removing the damaged piston, we could not determine the manufacturer of the piston so we removed the #4 head to get a piston number, and also removed that damaged connecting rod. What we found was that the first rebuilder had installed the wrong compression ratio pistons (15.5 to 1 instead of 14.5 to 1). Also, the pistons were not Genuine Cummins, they were an aftermarket brand. Always use genuine OEM parts when rebuilding your engine.
The piston failure was caused by too high of a compression ratio, and the slight “thump” the owner heard when he let out the clutch was the end play on the crankshaft, which was a result of the wrong thrust washers being installed during the rebuild. Needless to say, the mechanic who rebuilt the engine did not check the end play. So I called the owner of that shop to discuss the problems we found and he said to me, “So what do you want me to do about it?” I suggested that he help this owner operator and supply him with a new crankshaft and connecting rod, to which he promptly hung the phone up on me.
This engine has only 91,000 miles on it since it was rebuilt by the other shop. Now, it needs a crankshaft, six pistons, six ring sets, a complete gasket set, rod bearings, and a lot of small miscellaneous engine parts, plus the labor to perform an out-of-chassis rebuild, at an estimated cost of about $20,000. So now, when this truck is finished, the total price of the engine rebuild will be over $80,000! You might ask why I am a victim, also. Well, when there is an engine problem and a lot of time is involved, our staff needs to have meetings to figure out what the problem is. A lot of labor is lost and you just can’t bill for the time invested. We are only charging the owner $38 per hour for the mechanic’s time, but $0 for mine, Gary, Pete and Shawn’s time.
As you can see, it’s a loss for everybody when a mechanic does a poor quality job when rebuilding an engine. Don’t be a victim. Take your truck to the best mechanic you know – one who has a good reputation and uses the best parts. Even if it costs a little more, as you can see in these three stories, a little more now is much better than a lot more later! If you have any performance-related comments or questions, contact me at Pittsburgh Power Inc. in Saxonburg, PA at (724) 360-4080 or via e-mail at bruce@pittsburghpower.com.