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PERA'S Core Corner: When It Comes To 'How Clean,' Do You Really Know?
By Roy Berndt
Ever notice how many commercials there are in our environment about cleaning? Cleaning your floors, toilets, counter tops, disinfecting everything and anything that you come into contact with. In fact even the air that we breathe needs to be cleaned.
Spin that out to the vehicles that we drive. You know they have to be clean as well, and not just clean on the outside but emissions clean.
Now just because I shave my head does not put me in the Mr. Clean category and we all know that cleanliness is next to godliness. So, depending on who you talk to or what study you believe, the original start up of a remanufactured engine can result in half or more of that engine's total life cycle wear.
In an attempt to combat premature wear there are oil additives, EP assembly lubes, synthetic oils and a host of other wear combative type products, most of which are excellent. But the bottom line is; the cleaner an assembled engine is, the less likely premature wear and/or possible premature failure will occur.
The same holds true for the installer. Failure to properly clean any bolt-on components will result in a catastrophic failure of that remanufactured engine, cylinder head assembly or crankshaft kit. I would be remiss if I did not mention the kiss of death for more engines than we can count: the use of composite metal finishing discs. Realize that these are a good product in the hands of a professional, but you need to clean very thoroughly after using them.
So is there a way to quantify how clean your machined engine components are? Can you tangibly indicate how clean a given block is prior to being assembled? Your cylinder head? Crankshaft or connecting rods? How about that new oil pump that you installed: how clean is it?
Do you know? When was the last time your spray washer was cleaned - is it leaving any contaminant residue? Are your oil passage brushes doing the job? Again I ask, do you know?
What is the consistency of your cleaned parts from day to day? Week to week? Month to year? Do you know? You suspect, you believe, you think - but do you know?
Unless you are doing "sediment testing" you cannot answer any of these questions with any certainty. You can profess, you can claim, you can even believe but there is no possible way to quantify and verify how clean your components are if you are not sediment testing.
So how do you sediment test? Well, that has almost as many answers as all the questions proposed herein. Let's start with basics and then move into the variables.
Individual automotive engine components or assemblies to be sediment tested are cleaned with an emulsion detergent solution which is collected in a controlled environment and vacuum drawn through a filter medium. That medium is then dried and weighed in milligrams for one complete engine.
That means that you will take all the individual pieces or component assemblies and sediment test them for one engine assembly. If there are six connecting rods, that is the number you test. Twelve rocker assemblies, two cylinder heads, one camshaft - you get the picture. Even bearings can come into play in sediment testing. When is that last time that you cleaned bearings fresh out of the box prior to installation? The racing industry does.
The goal is to determine a collective number for all of the components in an engine that contact oil. You are not concerned about coolant ports of castings: oil passages, yes; coolant passages, no.
So how and with what do you test these components to determine a sediment reading? There are different ways in which you can determine sediment and there is no school of thought as to which may be better or worse just different.
One method is the pouring method in which you will pour a pre-determined amount of solution into a stainless steel retention resource. That can be a tray that holds the components (see Figure 1) rockers and/or crankshaft) or a manufactured stainless booth. The booth, of course, is much more expensive and is custom built. However, it also requires an enclosure so that it does not become contaminated while not in use.
The liquid medium that I found to be the most popular among remans and OE's alike (such as Ford and GM) is the brand name product Citrikleen. It is a powerful, water-soluble detergent solvent leaving little or no residue. It is only available from the design company Penetone Corp., Carlstadt, NJ.
For sediment testing, Citrikleen is used as a 1 to 3 parts water dilution mixture. I have been told that the waste by-product of Citrikleen is an excellent grease cutter for floors and is an excellent general cleaning product so there is literally no waste.
The sample solution is drawn into a receptacle through a 10 micron filter (see Figure 2) via a vacuum pump at 15 inches of vacuum (Figure 3).
The filters must be dried in an oven (Figure 4) at 150-180 degrees F, both before and after the sample solution. The dry filter paper is weighed and recorded before and after which gives an accurate weight differential in milligrams (Figure 5). To give you a reference of what a milligram is, a common paper clip weighs in at 1,226 milligrams. Notice that in the picture the scale is encased in glass since even a room breeze can affect the accuracy.
Now for the hard part. Now that you have a weight number, what do you do with it and what does it mean? The numbers for a V6 are not the same as a V8 or an inline. Aluminum numbers are different than cast iron so how do you know? If there was a standard a recommendation or even an industry practice you could go to, you could determine if you are on target.
At the OE or PER level there are large quantities of parts to test and to determine a "mean" weight. From there the idea is to constantly improve and continue to bring the number down by refining and honing the procedures and practices of operations.
A determination of a reject limit is also put into place. Therefore if any individual component or assembly is beyond limits things stop. Are all those in that cleaning batch then pulled and cleaned again? Why is the number high? Is it isolated to one component? Is there something in the process that has changed? Is there a breakdown in the system?
One company I spoke with found that they had a significant drop in sediment testing numbers simply by covering everything remaining in assembly for the next day with plastic before they left each night.
Remember that random testing is done of all components everyday, and determinations of procedures are made based upon those numbers.
Just so that you have some idea, the following numbers are reject limits in milligrams:
351 Ford Block 16.0;
Chrysler 318 cylinder heads 24.0;
262 Chevrolet camshaft (new) 8.0;
Chevrolet con rods Gen I and II 20.0.
The actual numbers recorded for the above components were less than 25 percent of the reject numbers and these are what actual contaminated filter papers look like (Figure 6).
There is another thing some are doing as well. They will take the 10 micron filter papers and put them under a microscope, import that image into a computer and then place a electronic grid over the top that will actually allow them to measure (in microns) the size of the sediment particles and determine what they are as well. This determination allows them to isolate where the contaminants came from and what corrective course of action needs to be taken.
One caution: there is a common factor that may be a cause of false readings, however. The water you use may be the culprit. It can and will give you false readings that can change from month to month and season to season. Sediment testing of your water supply is imperative to determine if you will need to use distilled or RO water for your testing and rinsing process.
Sediment testing can be done for as little investment as $4,000 or you can spend as much as you like when getting into the exotic. Like buying a 50" plasma screen or a 20 person custom built private home theater, they'll both show you the movie.
The bottom line, if you're looking to verify the consistency of your cleaning process in your organization, sediment testing is the only way to obtain quantifiable data.