Is revving engine to clear exhaust enough ?

[BobJohnson]

Want to make sure I get my boat ready for winter the right way, not just the easy way. Rotax engines are close cooled with antifreeze, so the water I need to get rid of is just in my exhaust. I have come across 3 different methods for getting the water out and would love to hear your all thoughts on the different methods.

1. out of water, start and rev engines for no more than 20 seconds to blow the water out of the exhaust.
Pros - easy, clean, no other equipment or tools needed.
Cons - can't or hard to tell if all the water is really out.

2. pump anti-freeze into exhaust system in order to clear it of water and replace with antifreeze. Then rev engines to remove the anti freeze.
Pros - if anything is left in the system, it is antifreeze
cons - not crazy about having antifreeze pour out onto ground while flushing system. Costly. Need pump?

3. Attach pressurized air to the exhaust system up to 100 psi and blow the system clear of water.
Pros- should clear system well.
cons - I don't have a air compressor, so would need to buy or find one to borrow. Also, blowing up to 100 psi of air into system, worries me. just feel like to much pressure could cause harm. to little pressure might not get all water out.

So - # 1 is my prefered option, if it is satisfactory. Around here we can easily see below zero weather for extended periods of time during winter. Want to make sure I am doing the job right, just to easy.

Please let me know your thoughts and what you do.

 

[BigN8]

If it were me I would rev engines out of water for 5-10 seconds. Maybe just 4 quick bump revs with the throttles. Then shutdown, wait a few minutes to let any left over water settle and then start again and bump rev the engines a few more times. That really should be enough.

We have hit single digits here in TX and all I have ever done is rev the engines.

 

[Cobra Jet Steering LLC]

Hook up a wet vacuum to the exhaust port at the rear of the boat, be sure to clean the vacuum first . Disconnect the large exhaust hose at the top of the muffler, vacuum out the muffler and then add some eco friendly antifreeze.
Place a thick piece of plastic like a sandwich bag on the pipe and just slide the large hose back on the muffler without the clamp being tightened this makes a water barrier so vapors can not travel back to the engine, place the kill switch or keys in the engine compartment so you remember to remove the plastic and tighten the clamps in the spring.

 

[txav8r]

I don't think you have to go to the extreme Jeff describes, and he is dealing with skis that those components are easily accessible on, so I get why he does or would do it. I don't do that stuff at all and I can tell you why. The water box (muffler) is a big stainless steel cylinder with convex ends. It will only keep up to about 2" of water in it if that much. With the round shape, water has more than enough room to freeze and expand without any adverse affect on the water box. The real issue is the engine and the rest of the exhaust. You want ALL of the moisture out of it. So it has to be blown out complete, not completely. Revving the engines will expel and dry out the engine and exhaust easily, but the moisture in the water box can still migrate to the open exhaust valves...this is why you want to use Yamaha Ring Free in the fuel, as well as fog the motors periodically. Nothing is going to freeze, it is about keeping it from rusting! And if you have modified your clean out tray to get under it easy, you can remove the big rubber hose like jeff says and vacuum out the water too. Save the effort on the anti-freeze, it won't stay in the engine. If you want to pour some in the bilge, your going to need a few gallons, to suck into the bilge pump lines, go ahead, but that too is a waist...it is self draining. If your worried about the lines, just blow them out. And...this is just my opinion. If I lived in Minneapolis I would do the exact same thing.

 

[tdonoughue]

I do the rev only method, but then again, I am down here in Texas with Mel. Nothing really freezes here (did undergrad in MN and from IL originally, so I know real freeze).

But I do agree it ain't the freeze but the rust that you should be concerned about primarily. You rarely have problems freezing even a 1/2 full pipe. It is the ones that are 90+% full that mess you up. But a pipe 1/2 full of water is plenty to mess up an engine that has not had oil circulated on it for awhile.

 

[GTBRMC]

Keep in mind OP has a Chap with Rotax drive, so approach might differ a bit from Yamaha boats.
Anyone with experience with both care to comment on the differences?

 

[robert843]

I think the boat runs on the same system as the newer Sea Doo skis. If this is the case that system was not designed to rev the engine out of the water even with a hose hooked up. If you do this with in seconds you should throw an engine alarm code due to the carbon seal/ring over heating. I do know this is the case on the skis anyway the boats could be different.

 

[RightStuff]

If your worried about the lines, just blow them out. And...this is just my opinion. If I lived in Minneapolis I would do the exact same thing.

I live near Minneapolis and this is all I have done above #1 and haven't had any issues. Close to -30 last winter too.

Remind me again why I live somewhere that tries to kill us?

 

[KXCam22]

My town hits -35C in the winter. My old I/O got antifreeze (mostly for iron block rust prevention) added but the yamaha just gets reved and the remainder of the water evaporates. There is always a puddle in the bottom of the mufflers but freezing in that spot causes no issues. The engine is designed to drain and it seems that it does. Cam.

 

[buckbuck]

BobJohnson, I live nearby and I concur with the others. Just rev it a few times and fog the intake. The winters here have a low relative humidity and will help dry it out. But, like Mel said, the Yamaha will always have a little water left in the waterbox. I have never had a problem and I store in an unheated barn.

 

[Big Shasta]

My town hits -35C in the winter. ..........

UGH, I'd say move south immediately but I guess there's no reasonable winter in your country.

 

[txav8r]

I stand corrected! I completely missed the fact this was but a Yamaha engine. I love our forum and features, but on my phone, I don't see the profile info unless I hold the phone in landscape view. My mistake. Apologies for not making sure I knew what I was referencing. I was speaking in reference to Yamaha boats, not the Chap.

 

[BobJohnson]

I thought about posting this in the Chap section, but since Scarab, Glastron and SeaDoo have the same engine, was hoping for a more broad look. I am sure most of the process is similar between Yamaha and Rotax. @ScarabMike or any other Rotax owners owners have thoughts?

 

[BobJohnson]

As of now going to go with the pressurized air method. Picked up a 100psi compressor from harbor freight. Plan on doing all my get ready for winter stuff Saturday. Will update back with how it goes.

 

[Matt Phillips]

I don't have specific experience with Rotax close loop cooling, but wouldn't you need to check the cooling liquid in that statement like in a car? I'd like to think there's antifreeze in there. Again, just a hunch

 

[BobJohnson]

Yes there is antifreeze foe engine cooling and I'll be checking it also. The water is for exhaust cooling.

 

[BobJohnson]

Well my cheap air compressor from harbor freight didn't do anything. Wouldn't keep pressure up enough to push water. Ended up running engines a couple times and reving engines. Had wife watching. Said alot water came out first time. Second time little. So hopefully I got enough out.

Washed it. Sprayed all joints with anti corrosion. Batteries are home and will go on trickle charge. Count down is on to April. Until then.... Go Cubs!

 

[buckbuck]

Go Cubs Go...Go Cubs Go...

 

[robbo3]

Well my cheap air compressor from harbor freight didn't do anything. Wouldn't keep pressure up enough to push water. Ended up running engines a couple times and reving engines. Had wife watching. Said alot water came out first time. Second time little. So hopefully I got enough out.

Washed it. Sprayed all joints with anti corrosion. Batteries are home and will go on trickle charge. Count down is on to April. Until then.... Go Cubs!

I took this same approach with my Sea Doo jet ski.