Draining blocks

Hi guys, first year winterizing the 2005 280 twin 4.3s alpha 1 gen 2. My old 1984' I used to take out all four blue plugs, thermostat housing and fill block with antifreeze. 2005 seems to have one central valve on top of motor to drain blocks. I can not find any blue plugs. Is this the solution for draining the block? Would still like to remove thermostat housing and fill with antifreeze, does this make sense to everyone? Thanks ,Tony

thats a single point drain system that ONLY works when the boat was brand new. in time the block drains will clog with debris and you wont know it.come springtime you will find the block cracked because it didnt drain correctly. it has been recommended to remove the block drain hoses and fittings from the block and install regular drain plugs and just plug and cap the hoses and let them just hang.the 1 inch hoses on the manifolds dont seem to have the clog issue being 1 inch in dia.

I have an 03 5.0MPI Alpha drive with the single point drain system. This is the second year I've had this boat and just finished my winterize routine. My concerns last year were the same as this year, am I really draining all the areas of the engine? I felt reasonably comfortable last year when I was able to add almost 4 complete gallon of the pink stuff down the thermostat housing....it must have been empty to hold this much. This year I decided to take it a little further and investigate this single point system. After a view of the diagrams on some Internet parts web sites and an extensive down in the bilge painful examination with a light I felt more comfortable with this single point only if you pay close attention to the temperature of the rubber hoses as it drains!!! I agree with the above post by Bt Doctur, the small hoses coming from the block to the drain collector would be the problem with blockage, it's very unlikely the larger hoses would clog up. I ran my engine up to temperature for a few minutes and shut it down. After feeling of the temperature of each hose going to the collector at the bottom near the valve I determned most were warm except two, the large ones coming from the exhaust manifolds were still cold. Apparently there is absolutely no water flow in these hoses as the engine runs but there may be some in all the others since the hoses get warm to the touch. Now my next step was to open the handle valve, and then within 30 seconds take out the blue plug on the thermostat housing like the instructions in the owners manual dictates. As the system drained, I again felt of all the hoses coming to the collector near the valve at the bottom of the engine. All were hot. Even those that were warm before draining were now hotter than before. I paid special attention to the two small ones that drain the block. They too were very warm. The water poured out for a long time and I left the drain open overnight. I will now add antifreeze to the thermostat housing after removing the thermostat and monitor how much it takes. I assume it will take 4 gallons again. Now I have more confidence in this single point system. As the engine ages it will begin to accumulate rust in the block and the passages coming out of the engine block drain will have more of a tendency to clog. They did on my 86 Sea Ray and I always pushed a small piece of coat hanger into the hole to be sure they were not clogged. Occasionally I would have one plugged up and when pushing the coat hanger in the water would suddenly gush out. I hope my experiences and research on my engine helps others who have this single point drain system. If it works properly it must be the best thing Mercruiser has ever done to make things easier on these engines in cramped conditions.
It's so simple it makes you feel like you are cheating. I don't miss all those years trying to reach the drain cocks on my old block that I could feel but not see.

I would not trust the single point drain. It seems every yeay i have one that does not drain and needs to be poked open with the wire. It would be ok if they each had a single hose going to a manifold of sorts so you could verify flow.

LK

I truely believe I have verified flow by using the method described. If there was no flow I can't see why the hoses became much hotter when I opened the valve. I will be in a better position to know for sure when I add the antifreeze today. If it holds 4 gallon or more I will be confident. Last year it held 4 gallon and I experienced no freezing in my engine. Since it was the first year I had winterized this engine I felt a little uncertain as to how much it should hold. Will update this thread later.

Hi guys,
thanks for all of the responses. I think that the above posts are all correct. I will check the hoses, but even if one is clogged and does not let all the water drain out, by filling up the block with antifreeze by the thermostats housing wouldn't that mix with any water that was in the block and prevent it from freezing anyway? Thanks.

tony

Last Dollar said:

I truely believe I have verified flow by using the method described. If there was no flow I can't see why the hoses became much hotter when I opened the valve. I will be in a better position to know for sure when I add the antifreeze today. If it holds 4 gallon or more I will be confident. Last year it held 4 gallon and I experienced no freezing in my engine. Since it was the first year I had winterized this engine I felt a little uncertain as to how much it should hold. Will update this thread later.

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Ok, I'm a coward. After reading the posts above it really generated a questionable doubt in my mind about the block draining completely through these two little 3/8 hoses. Yes they got hotter when I opened the single point valve but did they flow for a while and then clog with rust particles that always exists inside these cast iron blocks? How would I know, blockage could have occured just after I felt of the hose at the collector. So after listening to a lecture from my son who also has a Sea Ray I decided to take his advice and ideas to heart. I disconnected the two 3/8 hoses that come from each side of the block and put a brass ball valve on each hose. The other hoses on this single point system are 3/4 inch or more and I really doubt they would clog. I then pluged the two empty ports on the collector with just a U shaped piece of 3/8 hose connecting them together. Remember there is some water flow in this collector any time the engine is running. After removing the thermostat and filling the block with probably well over 4 gallons of antifreeze (had some spillage and cannot be sure how much I used) I considered the job done. As per my son's recomendation, I opened each valve on the new block drains and collected a little antifreeze, just to be sure it had rich color and was not diluted. My single point system is still a great feature, I just have two more valves to open and can actually watch the water pour out of the block, what a great feeling to know that block is draining!!

has anyone had a similar concern with the 3 point drain system?

Since nobody responded to your concerns on the 3 point system I would just comment that you need to research how the block drains and pay particular attention to the diameter of the tubing used to drain the block. I personally believe 3/8 diameter could clog especially at the fitting on the side of the block where the tubing attaches. My experiences each Fall in winterizing my old 86 Sea Ray with a 4.3 leads me to believe that blockage can occur and unless you are watching the water or listening to the water pour out of the block it is impossible to be certain all the water drained. I ran a piece of coat hanger in each side and on more than one occasion this enabled a little more water to drain. On one occasion when I had first purchased the boat nothing came out of the hole until I pushed something in it. With the current design on the single point system I now have, I would totally be unable to monitor what was coming down to the collector/valve assembly. Engine blocks are not cheap folks and very hard to install !!