Tell Your Friends!
Mercruiser - Flushing Your Engine
As I have stated before, the lack of maintenance that can easily be performed astounds me when I am sometimes called to help out with a problem. Simple procedures can and will avoid costly mistakes. On the water this can go beyond the failure of a crafts mechanical systems and involve human lives. Ironically failures due occur in even the best of maintained equipment, however having done due diligence will ensure that you have done your best to avoid such issues and statistically will ensure a long and useful service life of your unit. I have even in my own boat have observed sand and fine debris when the boat has been near such materials. Many who beach their boats have found themselves with high engine temperatures as a result of clogged cooling systems. Keep in mind that this falls true in all crafts with all types of cooling regardless of fresh or closed water systems. However one system over the other might be more forgiving than the other, in any event they are all susceptible.
Simple as it is, it’s always advisable to run your engine before docking or loading if you are in good water and not in shallow depths. Towing your unit is an ideal situation to run your engine out of the water and utilize a flushing device. Boats taken out of the water however are susceptible to dry out and thereby allows the materials like sand to cake up in the cooling system.
An important note: Never run your boat out of the water for any period of time without a sufficient supply of water drive, damage occurs even if you’re just turning the engine over. I have replaced countless pumps for owners that were just simply turning over the engine. The impeller in your unit turns over when you turn over the engine, thus it can and will get to the point where I have replaced the entire pump housings that had become distorted due to temperatures. Impellers can become distorted and destroyed in less than 30 seconds, housings can distort from heat in minutes and you stand a good chance of destroying the seals in your outdrive. It is also prudent to remove your prop while running your engine out of the water. I have seen some disastrous results even with experienced mechanics as a result of becoming too comfortable with their trade so to speak "complacent" and in too much of a hurry, basically "Lazy" In either case accidents can and will happen, however working safe is a mindset and not an excuse for disaster.
Thus boats that are taken out of the water are prone to dry out whereby boats in the water are keep wet in most of the passages. Not to mention, boats kept in the water are more often run due to the fact they are in a world that allows a boarding and a simple turn of the key rather than the timely process of towing, launching and all the other factors that come into play. However boats in the water do in fact run into some serious conditions by doing so like Zebra mussels, galvanic corrosion, marine life, just to mention a few. I have seen Zebra mussels build up on intakes in a matter of weeks, thus having to pull the unit and thoroughly service the intakes. As bad as this sounds it’s a rare situation whereby that takes place when the craft has not operated over lengthily period of time, for the most part they don’t migrate beyond this point due to the high temperatures of the engine. Ironically, all is not a perfect world as to when I was a witness to a drive in salt water that had grown to become its own sea creature. The unit was covered with barnacles, and things I cannot describe other than that it looked like a statue from Davie Jones locker. This unit had to weigh twice its weight, and had holes craved out where the intakes are on the drive, leave it to American manufactures to build a unit that still runs under these conditions. In any event as to this unit, I have no comment!
Also a good back flush by pulling your hoses from the engine is always a good idea, especially since some debris do in fact get clogged in smaller passages and will not pass forward. This is especially true in your oil coolers and such as to the larger feeds into small tubes. Take a moment to pull the hoses from coolers and such to inspect them for clogging. You might be surprised to find them plugged to some extent. However if you are experiencing higher than normal temperatures and you know your pump/pumps are good one of the first places to check is in such places. I personally do a back flush via the hose from the oil cooler to the engine first. Then proceed with the drive off to completely do a flush and ensure that I have good flow throughout the entire block. Don’t forget to open up the drains at the bottom of the block one at a time and observe clean water existing from the same. This is important due to the fact that the debris do settle in the bottom of the block.
Take a moment and look my set ups for flushing/water supply to drives. The first one is for utilization while the drive is in place and is a beefed up unit for delivering enough water to supply the most demanding of engines. It’s based on a rectangular muff that has had the hoses removed and replaced with larger clear tubes, that helps verifying antifreeze delivery for winter lay-ups. The larger rectangular muffs provide a better coverage over the intakes as well as those seal much better than the round units. The second unit is used during flushes when the drive is not on the boat. This allows me to run the water continually while the engine is off or on. The draw back if the engine is not running is that it does not reach the upper elbows since the thermostat is closed. You can however overcome this issue by running the engine. This set-up allows for troubleshooting engine issues over periods time that cannot be accomplished with the drive in place.
Cooling system cleaners: If you are experiencing issues with what you might think is related to a dirty cooling system, I use my 5 gallon winterization kit to fill the system with a cooling system cleaner that is designed for on the road engines.
Note: Do not use automotive cooling system cleaners on engines while your drive is installed or with intake impellers that are not metal in composite I.e... Closed water systems, inboard engines etc., for the most part the cleaner can and will destroy your intake impeller. There are specialty cleaners specifically, formulated for this use, however they are extremely expensive to use as directed. As always, I cannot stress the importance of obtaining a manual on your unit, obviously the best manuals are from the manufacture; however some information can be obtained on the internet. Everybody including myself has an opinion, but the factory has the last word.