Opportunity for All
The B series Cummins presents opportunity for all shops. Whether your shop works on automotive or large industrial diesel engines or falls somewhere in between, the B Series Cummins presents a good opportunity for any size shop. The B series has been used in many different applications, although the Dodge truck is probably the most well known application for this engine. Millions of these engines have been sold. All shops should be able to handle the B series engines. If your shop is not taking advantage of the opportunities the B series presents, you have to ask yourself why not? If you are an automotive only shop, are you afraid your equipment cannot handle these engines? Are you afraid of diesel engines? If you are a shop working on large diesel engines, are you taking advantage of the opportunities of the B series engine? By the end of this article, if you are not working on these engines you will be convinced you are missing a golden opportunity. If you are already rebuilding or building these engines, then keep reading because there will be a lot of details on this engine that you may not know or have run across.
Where are they used?
You may be curious as to where these engines are used. The most common answer you will get is in the Dodge truck. However, there are many more applications where these engines were used. The Case tractors used these engines for many years. Case tractors were using these engines before Dodge started using them in 1989. Case used the 4 and 6 cylinder engine on their tractors. These engines are also found in air compressors, generators, boats, buses, medium duty trucks, motor homes, mining equipment, military vehicles, back hoes, gravel packers and many other pieces of construction and farm equipment. The applications are very broad for this engine and you may be surprised at where you will find these engines used. There also is a good market for the people doing performance work as many of these engines have been used in mud trucks and drag racing.
Summary of changes to the B series
The B series was originally designed as a 12 valve engine. The easiest way to identify these engines was the individual valve covers. Individual covers were used for each cylinder. In the Dodge trucks, intercoolers were not added until 1991. Bosch and CAV pumps were used early on before the Bosch system became standard. The main changes to the engine up until 1998 were to the fuel system. The basic engine design stayed the same. In 1998 the engine was changed to a 24 valve single camshaft push rod configuration. This form of the B-series used a one piece valve cover. This engine used a Bosch rotary pump with central injectors. This engine was then called the ISB (Interact System B-Series). The block underwent changes also with this change. In 2003 the common rail fuel system was introduced. The head was redesigned and the lower block was stiffened. In 2007 the bore and stroke were increased and the engine then became a 6.7 liter. Also at this time a cooled E.G.R., particulate filter, variable geometry turbocharger and higher pressure fuel system were added to the trucks. The E.G.R. and particulate filter were added to meet emission standards. The 6.7L still used some components from the previous version.
Identifying the engine
Now you have a B-series in your shop and you need to identify it. The first step is to locate the engine serial number and CPL (control parts list) numbers. All Cummins serial numbers consist of 8 digits. The CPL can be 3 or 4 digits. These numbers are located on the engine dataplate. The most common location for these numbers on the B series is on the valve cover or on the left (drivers) side of the rear half of the timing cover. The timing cover consists of 2 halves. The rear half is aluminum and the dataplate is usually attached to the aluminum housing. On the later model ISB engines the engine serial number is also on the ECM dataplate. The tags on the valve cover can become hard or impossible to read because the print can fade with time. The tag on the timing cover can be missing due to the rear portion of the cover being replaced and the dataplate not transferred to the new housing. If this happens, look on the block on the top of the oil cooler housing and you will find the serial number stamped there. With the serial number anyone with access to Cummins Quickserve can provide all the information from the dataplate. These numbers will aid you in obtaining the proper replacement parts for your engine. They also can help you identify which version of the engine you are working on. If you do not have a manual for this engine, use these numbers to order the proper manual. I highly recommend you purchase a manual for any engine you work on as they can save you from a costly come back. If you cannot locate the serial or CPL number, having the original piston number can help in locating the parts for your engine.
Tear down time
So now you are ready to tear down the engine. Once again, I must emphasize that this can be the most important part of the whole engine rebuilding process. I always preach that the engine is trying to tell you a story. If you read it correctly, it can make the difference between a successful rebuild and a failure. Other components may have caused the failure and if not corrected, the same damage may occur again. So if you think whoever is doing your tear down is not important, you may want to reconsider your position on this. AERA has a new on-line certification program and part of this program is proper tear down and inspection procedures. If you have not considered this for your shop personnel, you may want to consider the value this can bring to your staff. For those shops just entering the diesel market, the tear down is basically the same as a gas engine except for the weight of the engine and its components. You look for the same issues in regard to damage and wear. When the head is removed, look for identifying marks on the original head gaskets. On the ISB engines, there are different head gaskets and are identified by a tab with holes in it. Some have holes close together and others have the holes farther apart. The Cummins service manual states that different head gaskets are required in certain applications if oversize pistons are used and if the block has been sleeved. So pay attention to your old head gasket and choose you replacement carefully.
B series Cylinder Head
Now that the engine has been disassembled, it is time to look at the cylinder head. Having worked on many of these engines through the years let me share some items we have seen with these heads. On the 12-valve heads, the injector has a ball which sits in a groove above the threads in the head. In many industrial and some truck applications, the injector can be stuck and hard to remove. If the person trying to remove the injector tries to turn it instead of pulling straight out, the ball on the injector can damage the cylinder head. We have seen this type of damage to the point that it cracks the head and leaks coolant on top of the injector. There are tools available to remove the injectors. We have also taken the end fitting off of an old injector line and welded it to a nut that fits our slide hammer. This makes a great injector removal tool at minimal cost. The 12-valve heads used a positive type valve stem seal. These heads were prone to cracking in the spring seat area. It is important to pressure test these heads and inspect for cracks in this area along with the rest of the head. Another common problem with the 12-valve heads is they crack in the seat area. Most cracks you will see are running through the face of the seat. We like to machine the head, cut out a new seat and then pressure test the head for leaks. If no leaks are found, we install our new seats and pressure test again to verify no leaks. If your shop has never done diesel work, these heads can be built using all of the same tooling you use on gas heads. The cylinder head is only 30 inches long and should fit in most machines you already have in your shop. The valve guides are an integral guide on these heads. It has a 0.314 valve stem and the guides can be replaced by the same methods used on cast iron heads for years. There are aftermarket companies offering valve guides for these heads. When it is time to resurface the head, take a good look at the exhaust manifold side of the head. It is common to see some damage to the head around the exhaust manifold gaskets. This is an excellent opportunity to resurface this surface and do your customer a favor by solving the exhaust leaks he probably has fought for awhile.
The 24-valve head came about in 1998. This was a major change to the head. The fuel injector uses a fuel connector to deliver fuel from the line to the injector. This connector must be removed before the injector is removed or the connector will be damaged. The 24-valve head uses crossheads to open each pair of valves. Each exhaust and intake pair is operated by one rocker arm pushing on the crosshead. The rocker arm is operated by a push rod working off of a gear driven camshaft and a mechanical cam follower just as the 12-valve used. The crossheads have a round and an oval hole. If new crossheads are being installed, they can be placed in any position. If the crossheads are being reused, it is recommended to mark them when removed and install in original position and orientation. When rebuilding these heads, it is very important to maintain proper valve recession and stem heights. It is also recommended to check stem height variance, especially on each pair of valves. If stem heights vary between the two stems of a pair, the crosshead cannot compensate for this and could cause early valve guide failure. The valves on the 24-valve head have the same head diameter for intake and exhaust. The angle on the intake valve is 30 degrees while the exhaust is 45 degrees. The exhaust valves have a flat surface on the head of the valve and the intake valves have a dimple on the head. Always verify the proper valve is in the proper location. The valve stems are a 7mm stem. When these heads first arrived in our shops, it was very common to find these integral guides worn beyond specifications. That situation posed a challenge as 7mm tooling was not a common item in our shops. The tool suppliers have done a great job of keeping up with our needs and you can now buy tooling to install replacement guides with a 7mm i.d. and ½ inch o.d. The intake and exhaust seats are of the same dimension but are not made of the same material. The seats are not cast as part of the head and can be replaced with oversize seats. Another critical step when rebuilding these heads is to verify injector tip protrusion. PRO-SIS from AERA or the service manual will provide this important specification.
If you are not using PRO-SIS, let me take this opportunity to recommend it. PRO-SIS will provide specifications and bulletins to help you complete your rebuild and provide a quality, trouble free product to your customer. We use it in our shop on a daily basis and could not imagine performing our daily tasks without the valuable accurate information PRO-SIS provides.
The Cylinder Block
The blocks for the 12-valve engine stayed basically the same. When the first 24-valve engine was released, it used a totally new block. These blocks were known as STORM blocks which stood for “straight thread o-ring metric.” When the motor was changed to the common rail system, a block change occurred again. A stiffening plate was added to these blocks to strengthen the bottom end. All of these engines can be bored. Pistons are available in .50mm (.020) and 1.0mm (.040) for all engines up to the newest 6.7L engine. The 6.7L can only be bored to .50mm (.020). All of the blocks up to the 6.7 can have a sleeve installed in them. It is basically the same procedure used when installing a sleeve in an automotive block. Bore the cylinder to size for your sleeve leaving a ¼ inch lip at the bottom of the bore. Freeze the sleeve and then put a coat of Loctite 620 on the top of the cylinder bore and press the sleeve in. Finish to the proper size just as you would any other sleeve you install. The oil coolers used on these blocks can be very confusing. The oil pressure relief valve is in the oil cooler housing which mounts on the right front side of the block. The first blocks dumped the oil from the relief valve back to the oil pump. It was changed to dump the oil back to the oil pan. When this change was made the oil pump and coolers were redesigned. When rebuilding this engine, verify that the proper oil pump, cooler and cooler gaskets have been used. Most gasket sets come with more than one oil cooler gasket in them. These engines use only one camshaft bushing in the front of the block. The cam bushing was changed starting with the STORM blocks. The later block’s cam bearing bore were increased in size. All of these engines use a plastic nozzle for oil to be directed onto the underside of the piston. This nozzle is inserted under the main bearings. There were two different nozzles used. The early engines used a short nozzle and a change was made in 1991 to a longer nozzle. Along with this change, the oil pump was changed to a higher volume pump. This change also occurred at the same time as the oil cooler dump was redesigned to dump in the pan.
Crankshaft and Camshaft
The crankshaft journal dimensions have basically gone unchanged even with the crankshaft changes that have occurred. The noticeable changes were on the snout and rear of the crankshaft. If you are replacing cranks, verify that you have the correct crankshaft, as some engines used a sensor ring. On some later ISB cranks there were two dowel holes on the rear of the crank. The camshaft originally had a press-on gear. It later was changed and a bolt and washer were added. To change the gear on either style, the gear must be heated. The gear should be heated to a temperature no higher than 350 degrees. Verify the timing mark is facing away from the camshaft. The gear can be installed backwards. The cam can be installed with the gear backwards but the engine will be out of time and valves will contact the pistons. The connecting rods have seen changes in design through time. The first rods were tongue and groove at the parting line and used the same upper and lower bearing. The last design rod was a cracked cap rod and the upper and lower bearings are different due to the location of the bearing tabs.
If your shop has experience with gas engines only and you think timing the injector pump is a reason to not work on these engines, you will be surprised. There were a few different pumps that were used but they were all gear driven. For several years there was a common drive gear used with different letters stamped on it. You had to know the engine type and certification to know which letter on the gear to time with the cam gear mark. This information is on the dataplate that was discussed at the very beginning of this article. These pumps had a key on the shaft so once the gear was in the proper location you just had to stab the pump into the gear and tighten to specifications. The later engines used a Bosch in-line pump and the shaft was a taper shaft with no key. These were a walk in the park to time. The engine has a pin on the backside of the timing cover that fits into a dimple on the backside of the gear. Take a lesson from experience here on this timing pin. It is made of plastic and has a small end that fits into the gear. It can be hard to tell when it is in the gear. Turn the engine slowly and put pressure on the timing pin. You will feel it when it goes in the dimple. The pump has a large nut covering the timing pin on its side. Remove the nut and you will pull out a plastic pin. Turn the pin over and insert into the hole on the pump. Turn the pump shaft slowly until the pin goes in. When the engine and pump are pinned, install pump and tighten nut on end of pump shaft to specifications. Now here is a lesson I learned the hard way. Both pins are made of plastic and you must remember to disengage the engine timing pin and remove the pump pin and insert back in pump with the long side out. I promise if one or both pins are still in place, the engine can be turned by hand and the plastic pins will break.
Opportunity for Performance Shops
So you say all your shop does is performance work and there are no opportunities with the B series Cummins? The same work you do to your performance engines can be done to the B series engines. Think of all those Dodge trucks running around. You know many of those owners want to go racing in their truck or go play in the mud. Many of them know there is opportunity to get more power from their B series engine and you can be the shop to help them get it. From helping the customer choose a camshaft to doing your magic on the cylinder head there is an abundance of profitable opportunity waiting for you.
I hope everyone realizes that opportunity abounds with this engine. In this age of machine shops, it has become really hard to turn away any customer saying we do not work on those engines here. The successful shops have stayed abreast of the engines as they change and are not afraid to dive in. Always remember that not only do we have to adapt to our customer base and what they bring through our doors, we have to make a profit on the job. Information on an engine you are not familiar with is readily available. If you are not a member of AERA and not using PRO-SIS, then you are missing out on one of the best sources of information available to you. AERA provides technical support to all of its members. I hope this summary of our experiences with the B series Cummins gives you courage to say “yes” the next time a customer approaches you with an engine you not familiar with. I will leave you with this philosophy we have at our shop — “If it runs on fuel and we can get it in the door, we will work on it.”
Dwayne J. Dugas is the owner of Dugas Engine Service and holds the position of first vice chairman on the AERA Board of Directors. He has also been involved in the ASE Machinist Certification Program for the last 11 years. Dugas Engine Service was started in 1969 by his father, Cloures Dugas. He opened a parts store in 1966 and then started rebuilding heads in 1969. He progressed into a full engine rebuilding shop and in 1979 sold the parts business to concentrate on the machine shop. Dwayne bought the business from his father in 1999 and although his father retired after that, he still comes to work — at age 77, he still does all the crank grinding.
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