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Indmar 409 winterization - question - draining block

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I have a question about draining the block on the Indmar 409. I winterized today and there are two shorter hoses on each side of the engine block located next to the knock sensors with a brass cap. They drained a lot of water, assuming these are the drains for each side of the block and it is not necessary to remove the knock sensors like you have to do on the 350? Are there any other hoses I need to disconnect to drain out? I did blow out the heater core lines.

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I'm no expert and not familiar with that engine, but are you sure those hoses are coming from the block and not the exhaust risers / manifolds?

On my 350 Monsoon there is a similar set up with two hoses and a "quick disconnect" and they are for the exhaust. These will drain a lot of water.

Again, I'm not certain, but I think you need to remove the knock sensors & drain plugs as well.

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Don't need to touch the knock sensors, the short hoses with the brass fitting and end cap

is you block drain. I also pull the hoses off the bottom of the cats, exhaust headers,

transmission cooler, heater hoses, pull the cap off the raw water pump, good time to inspect

the impeller, and blow out the shower.

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I've only had the 350, so I don't have any input. When you drain the hoses, does any sediment/oxidation/etc make ut out of the hoses? I am always surprised at the amount of sediment/oxidation that comes out of the block on the 350's especially after sticking a screwdriver in the hole of the knock sensor. I even got a few really small rocks out of the block this year.

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I agree with the sediment issue...

The manual for the Indmar Monsoon recommends using a "stiff wire to poke around in the drain hole to ensure that any rust of scale is broken apart and the engine drains completely."

That said, regarding the Indmar 409. I wonder what Indmar would advise, as ShawnDoggy's link above makes no mention of scale.

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With this engine, how do you fog the engine? I have herd you spray into the spark plug holes and crank the engine. How do you crank the engine?

Dealer tolled me not to bother, as you can gunk up the injectors. as there is a fine film of

oil over the cylinders walls all should be good. No different then parking a car over a few months.

But personally, I'm still not completely convinced even though I don't spray the cylinders, and also not

sure how to crank the engine over without having it fire.

Any one else fog there 409??

Edited by Dare2goBare
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I don't fog, but I also live in a relatively mild climate for winters. We rarely see freezing temps. My friend in Utah has a 409 and he uses anti freeze in block and heater core. He also does not fog the engine. He never has had any issues firing up in the spring.

  • Like 1
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To crank without spark, simply disconnect the emergency lanyard and turn the key. I don't fog, but it works great to help remove the raw water impeller.

Had to laugh when I read this, Never thought to use the key.... :Doh:
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  • 1 year later...

Hate to bring up such an old thread, but does anyone have any suggestions for running antifreeze through?  Or can anyone suggest a pump? I couldn't get gravity to pull enough through.  Thanks




 I have an extra ballast pump sitting around, would this give me enough pressure?

Edited by hunter77ah
New Idea!
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@hunter77ah:  If you are trying to get antifreeze in the block, you might fill via the hose off the top of the engine water circulation pump.  Remove hose and pour antifreeze down the hole, or is that what you are doing and can't get gravity to cooperate?  If that

is the case, maybe the inlet hose on the same pump needs to be removed to act as a vent, and you will have to cap when the antifreeze gets there.

Engine picture might be of some help:




Edited by Woodski
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I was using a fake a lake to try to get the impeller to suck the antifreeze through everything- gravity alone wasn't giving it enough pressure to allow the impeller to draw it up.  Think a crew member is going to hook me up with a flush pro and I am hoping that will work. 

Thanks for the help @Woodski!

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@hunter77ah:  If you don't get the flush pro, you can simply get some plumbing components at your local hardware store to adapt a garden hose to the inlet hose.  Don't forget to pull the impeller and store loose (in a sealed baggie) when you are all finished, fairly common practice to extend impeller life.

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  • 3 years later...
1 hour ago, Rednucleus said:

Until you have a power failure during the coldest week of the year ...

Generator backup?

Exactly.  Related, we had a 10 hr power failure one winter when I was 7 hours away from the cottage and it was -15F.  The hot tub called me and said "too cold".  Like how am I supposed to get there, and more importantly, how do I drain and dry it at those temps?  Luckily the power failure ended soon after and thengs went back to normal.  I no longer run the hot tub all winter long.

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