Article By: Berry Wardlaw
Photos By: Berry & Hackjob Accurate Engineering – www.accurate-engineering.com
Originally Published In The February 2013 Issue Of Cycle Source Magazine
Many people that I have worked with or have observed over the years seem to feel that engine teardown, cleaning and inspecting is a bottom of the barrel job. They want to jump right in and just start tearing the engine apart as fast as they can, as if the faster they can strip it down, the better they are. Nothing could be farther from the truth. What they don’t seem to realize is that this first step is one of the most important parts of the entire engine building process. This is where you see wear patterns, cracks, worn areas, bad threads, incorrect components, improper assembly, misuse and many other details that tell the entire story of the engine’s performance and the work that lies in front of you. This will teach you more about how an engine works and performs than assembling a hundred engines. This is the test score. It is also how you are going to quote your labor and needed components to a customer, so it must be carefully done. You can’t quote what you can’t see. In future articles, we will discuss each of these topics in depth, but for now we are going to talk about the cleaning process, the use of glassbead, aluminum oxide, soda or sand, and interior coatings. We are going to use the crankcases of a 1937 EL Knucklehead for our example.
This is the price you pay when you don’t clean all of the glassbead out of your engine components. We see a handful of these every year. Clean it dammit!
First, we remove the small plug under the cam chest. This is the block-off plug to the air-oil separator channel that runs from the air-oil separator cavity to the rotary breather. This small area between the lower intake hole and the outer plug we just removed can and will hold years of grime, old glassbead, aluminum and other foreign debris we do not want in our newly rebuilt engine. Believe me, not all of the scoring in the rotary breather comes from the crankcase area of the engine, but also from the area we just discussed. Later we will reinstall a plug, tap and install a set screw, or weld the hole closed depending upon the type of build we are doing. The other plugs on the Knuckle oil return and vent can be cleaned without removing most of the time, but there are instances when they will be removed also. Not so in this case.
Blasting the interior of the cases with 120 grit aluminum oxide.
We first scrub clean the crankcases in #142 solvent to remove any oil, grease and grime, and then we blow dry. Then we scrub clean in very hot water, soap and blow dry. When we blow dry these components, we use two types of blow guns. A standard type blow gun is fine for all large exposed surfaces but then you must have a needle blower about 1½” long. We must be able to go to the bottom of every screw hole in the crankcases no matter how small or how deep. Blowing the outside of the screw/bolt holes is not acceptable; we must go to the bottom of every hole. I would highly suggest wearing safety glasses for this. You will feel grit (old glassbead jobs), spongy material (silicone used on gaskets), short holes (broken screws/bolts/taps) and all kinds of other crap. Do not stop blowing, cleaning and inspecting until every hole has been cleaned and visually inspected to the bottom. Please beware that the silicone plug at the bottom of the screw/bolt holes will come out like a bullet. I like to slightly press against the plug and then release repeatedly until the plug dislodges. While cleaning these holes, I would highly suggest you also use a can of brake cleaner and put the tube to the bottom of every hole. If you do not remove the cylinder base studs, you need to blast the undersides of them with brake clean and the needle blower until it inspects perfectly clean. The studs should be removed.
Spraying brake clean into all screw and bolt holes until CLEAN!
We also submerge the cases in a large vat of Berryman carb cleaner if needed. This will loosen all gasket material, silicone, paint and any other adhesives. Then back to the hot water, soap and our cleaning tools. The tools used to clean these antique cases or any other engine component should not damage the base material in any way. Being aggressive with Roloc (Scotch-Brite) wheels, razor blades, screwdrivers, dull metal scrapers and such is not acceptable! We have had to repair many mating and gasket surfaces due to sloppy workmanship. Choose your tools and technique carefully! These are valuable motorcycle parts, not your aunt’s Pinto engine. Quality nylon brushes, tube brushes, toothbrushes, pipe cleaners, new razor blades, various dental picks, Scotch- Brite pads and sponges are some of what you will need. You may also have to use gasket remover or other solvents to loosen or soften gaskets, silicone and adhesives.
Using a needle blower to thoroughly blow out all screw holes and passages.
Once we have washed the crankcases and blown them dry, including every screw/bolt hole, they are going into a preheated oven at 200 degrees F. We are going to attempt to get as much of the oil out of these crankcases as possible. Early sand cast aluminum products have varying degrees of porosity and they trap and hold oils and other foreign materials, and we want that stuff gone. We cannot coat over the top of oil and expect the coating to stick, and we may want to paint or coat the outside of the case for cosmetic and performance purposes. We want as much oil leached out of the aluminum as possible. After the cases have reached ambient temperature, we remove them from the oven and inspect and begin to remove the weeping oil with brake clean and air pressure. We do this until no more oil weeps from the cases.
Using a pipe cleaner with lacquer thinner to clean air/oil passage. All the way to the rotary breather.
Now it’s off to the blast room. These cases will be getting a glassbead exterior finish at low pressure as to get them back to their original look but the inside of the cases will get blasted with a 120 grit aluminum oxide. We use this blast media because it is best for the preparation of our internal coating. Once the blasting is finished we blow the cases off in the blast cabinet! Once removed from the cabinet, we blow the cases off again and using the needle blower we blow out every hole again. Now we wash the cases with hot water and soap, drying as before, including those doggone bolt/screw holes. Why so much damn washing? If you review what we are doing, we are trying not to contaminate each following step. If we put filthy components in our glassbead cabinet and blast them, then the crap we just blasted off contaminates the glassbead. When we go to get a nice final finish it will look dull and have blotches from the dirty glassbead. This final wash I just mentioned is only a preparation for our ultrasonic wash. We have a special cleaning solution made for us and it is fairly expensive so we want it contaminated as little as possible. What we are doing is giving the crankcases deep cleaning.
Using a bottle brush to clean cylinder base stud threads.
Ultrasonic cleaning uses heat, special water based solution and high frequency sound waves to remove foreign matter hidden in porous material, blind holes, oil galleys, compound holes and even embedded impurities on solid surfaces. Ultrasonic cleaning along with hand cleaning will also remove polishing compounds. We are using this technique to remove the broken pieces of glassbead, and any other contaminate left behind. We want our engine clean! Before we coat our crankcases, let’s have a little lesson on glassbead, aluminum oxide, other blast media and polishing compound. These products are nothing more than abrasives. Abrasives that, over the years, have brought us a lot of work because a previous engine builder did not know enough, have the right equipment or take the time to clean the components properly. We have rebuilt more “rebuilt” engines due to glassbead, blast media and polishing compound contamination than you would ever believe. Once that abrasive has scored that new component there is no going back. We have included a picture of a stepped crankpin from a very expensive “rebuilt” Big Twin Flathead ULH that was sent to us. This engine had been built with very good components and came from a fairly competent engine builder. The basic assembly of the engine was good, as was the machine work. Glassbead contamination and polishing compound killed that engine. We are talking less than 1000 miles. When we began our teardown, cleaning and inspection process, it was surprising how much glassbead was still in this engine’s screw holes, porosity holes and the damage the glassbead had done to brand new components. It was very hard to believe that the engine builder could not feel this stuff in the bearings when he rolled the engine around with the rods during assembly. What is worse is maybe he did. Polished engines are also very popular, and while they do look good, if they are not clean, clean, clean, then you just pissed your money down the drain. I cannot express enough how important cleanliness is in engine building.
Spraying brake clean beneath cylinder base studs. This is a must if you don’t remove the studs! You won’t believe what you will find.
Now that our crankcases have had the ultrasonic bath, it is back to the hot water and soap bath, a good blow dry, and of course those pesky screw holes. Every area must now be perfectly dry including the bolt and screw holes. Finally, we are through cleaning these darned cases, you say?! Nope! With our clean hands we move our lovely crankcases to the paint room. We get our lint free towels and begin to wipe the cases with lacquer thinner until the towel wipes clean. These cases were cleaner than many engine builders ever get their engine components, but look in the photos at those towels. That is nothing more than broken down glassbead, very fine, but glassbead none the less. Now we wipe the interior of the cases with a wax and grease remover using our lint free towels. There is nothing quick about engine teardown, cleaning, inspection and preparation. It is actually a large percentage of the labor time in engine building. When done properly the rewards are huge. Okay, we are ready for coating!
Notice the porosity holes right next to the oil return hole. Coating will help seal these types of areas off.
Cast aluminum components are very prone to porosity. Harley-Davidson components are a true testament to that. This would also apply to many other motorcycle manufacturers. We’ve all seen it. Many of you have seen the red paint inside of H-D crankcases. This is a product called Glyptal 1201 Red Enamel. It is an insulating paint and is resistant to oil and water. It is used to seal the porosity in the castings, promote oil shedding, and in some cases hold small casting slag in place. I used this product before I started using coatings and still do if the customer requests it. What I use on a regular basis is a thermal dispersant coating.
You just think it’s clean! Wipe work down with lint free towel and lacquer thinner.
I have been applying coatings since 1990 and have stuck with the same company I started with. They have added many products over the years, but the main products I use are the ceramic, dry film lubricant, thermal dispersant and thermal barrier coatings. Each coating has its place, but the one we will be using on these EL cases is the thermal dispersant. These coatings are not Band- Aids, and will not help an engine that is not built properly, but they will enhance a well built engine if used in the proper way. There are similar products that have Teflon in them, but Teflon is a thermal barrier and we want to use a thermal dispersant. The purpose is to transfer heat from the oil to the crankcases and the outer engine surface area so to aid in the cooling of the oil and the engine. We also want to seal the porosity of our crankcases so the oil doesn’t impregnate our super clean cases and to seal the tiny holes so foreign matter and byproducts of the engine don’t have as many areas to get trapped. This thermal dispersant coating goes on very thin and produces a very slick surface to aid in oil shedding. This helps us get the oil back to the pump and on to the filter and oil tank for cleaning and cooling. It could also be used on the flywheels but we did not do that in this case. I have used it for that purpose in the past with excellent results. This coating is also an excellent corrosion inhibitor and greatly reduces oxidation on aluminum.
A piece of slag to the right of the penny. This is just one of the things you look for when inspecting and cleaning. That little piece had barely hung on since 1937 just waiting for a trip into the oil pump. Look carefully!
This little ’37 EL is cleaned, sealed and ready to assemble. Damn, that’s neat!