[/quote]it's not wrong at all. Lou is set in his ways and believes HIS methods are the only ones to use. I believe he thinks he sleeps better knowing he used the backfill method. Who knows for sure. There is nothing wrong with the back fill method, and 10 years of sucking AF through the drive has never failed me once. So either method will work IMO. It's up to you really. This debate comes up every year, and you will find proponents of both methods.[/quote]
Well, Captn, it's not really MY method per se, but it's the method you will find if you look in recent Merc shop manuals that real marine mechanics use, and it's also in the OMC shop manual I have used since I have owned my boat. Neither one suggests using the suck the AF up the drive method. I looked at a Volvo owners manual and did see that they do suggest using that method. I have to say, after reading their owners manual, that it is very poor, vague, poorly translated and is likely to cause a relatively inexperienced do it yourselfer to make an expensive mistake. To clear up a few things here, you need to understand how raw water cooling works. This doe not apply to closed cooling engines which can use the suck up the A F method without any problem. Your raw water cooled engine has an impeller that pumps water to the engine and a circulating pump that circulates it through the block and heads. When the engine is cold, the thermostat SHOULD be closed, that causes the raw water to go out the manifolds, but the water in the block does not exit, until the thermostat opens. You run your engine on the water hose, it's about 50* out. The temp gauge reads normal temp (let's say 160). What you may not know, is the thermo may not open enough running at idle, on a cool day, with cold water coming it, to allow the raw water OUT of the block. If you use this method and do not check the block drains to make sure AF comes out (and I'd drain a bit into a paper cup and stick it in the freezer, if it freezes, no good, drain it all) you could have a nasty surprise come spring. If everything works exactly right (the thermo closes all the way, the engine warms up to normal temp, and the thermo opens all the way, and the owner runs through enough AF of the -100 variety), it can work. It can also work if the owner drains the block first. But if the thermo is a bit sticky and does not close all the way, the engine will never warm up enough to open the stat all the way, yet the temp gauge may read normal or close to normal. If the impeller is not perfect (on Volvos and Bravos this can be an issue because of the long run from the drive to the impeller) it may not suck up the AF and the engine can overheat. AF is more dense than water and is harder to suck up. Sticky thermostats are a fact of life in brackish/salt water, I wind up replacing them each season, I could post pix so you can see what they look like...freshwater maybe does not share this issue... I have had 3 experiences that make me think this is too risky. One was the first time I winterized, I used that method and then checked the block drains. What came out looked like rusty water. So I had to drain and backfill. Next spring I had the boat in the shop for some work (carb rebuild). The shop ran the engine on the hose long enough to adjust the carb, points and timing. When I got the boat back, I figured I'd drain the block because it was getting cold again. Thinking there was water in the block, imagine the surprise I got when there was still AF in the block from the previous fall. The thermo did not open enough to let the AF out and the raw water in, and they probably ran the boat at least 1/2 hr. Then just recently someone on this board or iboats, I forget which, asked about doing this, I offered my warning, he drained out a cup of liquid from each side of the block and put it in the freezer and it FROZE. He drained and backfilled, lucky that it did not freeze on him. And lastly my mechanics (best sterndrive mechanics in Western Suffolk County) also do not recommend that method. So there you have it, I am not so rigid, I am merely summarizing Mercs and OMC's methods, and I will respectfully disagree with Volvo, and suggest that whoever writes their owners manuals should be fired......
_________________ 88 Four Winns 200 Horizon 4.3 OMC Cobra-4bbl 2002 Walker Bay 10/2012 Suzuki 2.5 2008 Walker Bay 8
1998 Jeep Grand Cherokee 4.0/Selectrac 2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II
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