suggestions for 4.3 flush before winter storage

[JackBronson]

2008 Mercruiser 4.3 Alpha 1. After reading the spirited conversation in the "Just draining block is not enough", I am pondering my situation. I've had the boat 2 seasons, 240 hours on the engine. First 8 years she was moored in fresh water, last 2 seasons (80 hours total) she has been trailered to salt water.

I'm assuming the motor has never had a good probe and clean out - when I removed the blue plastic drain caps this week I got some good dirty water out of it.

So, my first question is if I was going to flush it with say oxalic acid (as was suggested), how would I do that? Mix up the solution and feed it in the intake with the muffs and a large funnel?

Then I pull off all the various cooling hoses and let them all drain, and then using tools (coat hangers? small metal picks?) I go to town trying to get any and all crud out of the passages?
My concern on this last part is what if I end up loosening up some big stuff that doesn't end up making it out of the engine through the exhaust? Could I end up creating a blockage?

Last step will be cleaning up the mess I create in the bilge, which will be excellent because only a contortionist can actually reach into the tight space with this hull.

Thanks in advance for the advice.

 

[Lou C]

Mine's been salt water (moored in it 6 months/per season) for 15 years and I've never done that, thought about it though. I think flushing it and manual draining is less risky from the point of view you mention, you can if you want back fill with either -100 Marine AF or mix up 4-5 gallons of Sierra brand PG antifreeze (at least 50/50 if not 60%AF/40% water) which will work fine as well. 50/50 on the Sierra gives you -25* freeze temp. Keep in mind that the other marine AFs list burst temp not freeze temp. I measured the -100 (bust temp) and got a -45*F freeze temp which is more than adequate....here, the -25 from the Sierra is just fine and its cheaper to mix that up, than to buy -100.

I use a small screwdriver or a pick to rod out the holes.

 

[achris]

Bear in mind that if you add AF, any small pockets of water that would otherwise have been harmless, will further dilute the AF and may push it to freeze, as if it was water only, leading to a cracked block.

Normally any small puddles of water left in the block would be able to expand into the air above them, but by adding AF, especially diluted AF, you remove that air space and the expansion has nowhere else to go but out to the sides, and that's what causes a crack...

If you do choose to add, drain the block first, probe those drains, drop the big hose off the water pump and drain that, and add it by removing the thermostat housing and pouring it in. Sucking it up with drive pump is not a good idea and just adds to that dilution... Due to water left in the pump and all the cavities and hoses between the pump and the engine. That could be as much as 3 litres (a gallon)... If you have a power steering oil cooler, remember to drain that too. Later ones have a drain plug you can remove....

Once you're done with the engine, remove the drive. That should allow the hoses and cavities to drain naturally. Drain the drive oil, split the drive and service the water pump ready for next year and that takes care of any water left in the pump housing... Add oil to the drive and you're good for the long sleep....

JMHO...

Chris....

 

[JackBronson]

My plan is to NOT go the AF route. Drain as much as possible for me.

How about getting out of the engine what may be there from 10 years of use? I'm going to assume that not much has ever been done to this engine in the way of flush or getting rust/scale/crud out of it.

 

[achris]

Apart from stripping the engine and having it acid bathed, not much you can do. I haven't tried these products but people are talking about 'Salt-away' and the like... Those might be worth a try...

As far as the winterizing, as long as you poke and probe those drains, and make sure you have little or no water left in the engine, you should be fine.

My engine's 12 years old and never had any scale or rust flush. It's fine. Never had a problem getting all the water out when I needed to.

 

[Rick Stephens]

iBoats has a descaling wash from Starbrite.
https://www.iboats.com/shop/starbrit...tar-brite.html

I found a hose attachment that I used for Salt Away after every trip into the brine (I have an aluminum intake on a freshwater boat). StarBrite makes one as well, although I couldn't find either on iBoats. Works great and looks like this:


I used the attachment to add salt away and washed my boat and trailer with it as well. Nice little tool to have. I might have to try the Descaler linked above. It seems to get good reviews. Might have to pull my thermostat housing or exhaust elbows to see how well it works.

 

[JackBronson]

Rick, you used this to flush the motor? via the muffs?

 

[Rick Stephens]

Rick, you used this to flush the motor? via the muffs?

Yah! I hauled the boat to Monterey Calif, and everyday I pulled the boat out, hooked up the hose to the flusher and hooked that to the muffs. Flushed my motor a couple times through. The cup doesn't hold a lot, so I refilled it and ran it again. Super easy. Both Salt Away and Starbrite make this type of attachment. I used Salt Away product as the cleaner. Then pulled the flusher off the muffs and used it as a nozzle to spray off the trailer and hull. Took all the salt sticky away.

 

[JackBronson]

So today I rigged up a big funnel and the muffs, brought the engine up to operating temp with the hose, then filled the engine with an oxalic acid solution via the funnel and let it sit. Did this twice. Then ran the motor with the muffs and clean water to let it flush.

Removed the drain on the starboard side front and got some good murky/rusty water out of it. The port side forward drain yielded black rust bits. The port rear drain I didn't get a lot of water out of and was surprised, so I stuck a screwdriver in there and yep, it was plugged. Out came the rush of water. Thank God I did that because I would have parked the boat for the winter with that water still in it.

Overall, a worthwhile effort if it means I may have saved myself a cracked block.