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Old 04-08-2018, 16:23   #16
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Re: Removing raw water deposits

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Just exactly what material are the tubes in question? I had based my previous reply thinking you wanted to clean the engine as well which I had assumed would be cast iron (block and head) but perhaps you are only cleaning the tubing (???).

While not part of your question, I'm curious to know what arrangement/engine has eight zincs?
Its a Yamaha ME180... a clunky 36 hp three cylinder engine they made for third world fishing dories in the seventies. Hand starting if necessary, easily dismantled with a couple of spanners. Three separate heads each of which has a zinc plus another three in the exhaust manifold plus a couple more in the block. Good cruising engine, repairable in remote villages and very tolerant of abuse. Had a few probs with injectors originally until I sorted out the fuel filtering and supply system. Only major drama in 3 decades has been the gland on the water pump">raw water pump leaking and letting water into the sump.
regards and thanks to all for your advice.
PP
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Old 04-08-2018, 16:24   #17
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Re: Removing raw water deposits

sorry.. yes its all cast iron.
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Old 04-08-2018, 17:06   #18
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Re: Removing raw water deposits

Thanks PP, I have heard of but never seen a Yamaha ME180 in the flesh, sounds like a very engine to have. Sort of like a Yanmar 3ES I guess but maybe better.

I don't think you could go wrong using vinegar or hydrochloric acid to descale a old cast iron engine. My guess is that newer specialist descaling products are probably safer around alloys and outboards etc.

My method when using vinegar was to remove the zincs and thermostat and plug the thermostat bypass assuming the engine has one (most raw water cooled engines do have one) and circulate say 8 litres of vinegar though the engine using a small bilge pump. Let it run overnight (or longer) then flush with some fresh water and finally reconnect everything.

I'm not saying this is the best way, just my ad hoc way.
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Old 04-08-2018, 17:19   #19
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Re: Removing raw water deposits

thanks Wotname sounds good. Just getting the manifold off should give a good look at most of the likely areas so we'll see whats needed.
regards
pete
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Old 04-08-2018, 19:35   #20
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Re: Removing raw water deposits

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IMO, they should be removed before any treatment is started.

Yes. They will be consumed and will slow the process.


The article I linked to above gave relative removal and metal corrosion rates.


Don't waste your time and money on vinegar. It is common and feels cheap and safe, but it is barely anything and is proportionately quite corrosive to most metals, and is actually expensive is measured in terms of results..
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Old 04-08-2018, 21:08   #21
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Re: Removing raw water deposits

Are you converting this engine from raw water cooling to a closed circuit unit with a heat exchanger?
I've done this to several engines over the years.
The best solution I've found is to use muriatic acid through all the water passages that salt water had previously touched. Even on iron blocks, otherwise it's questionable that vinegar would do the job. If your looking to convert to a closed system on the engine even the smallest amount of residual salt in the system will cause oxidation over time.
The bronze/brass heat exchanger tubing bundles are also more efficiently cleaned with muriatic acid, just take care in the use and storage of the acid, take all the common sense safety precautions when using it.
If your using it to clear mineral deposits out of an iron block make sure to neutralize the acid and flush with plenty of clean, mineral free water once you've removed the acid, then get your antifreeze/rust inhibtor mixture into it as soon as possible. The newly etched iron will start to rust in short order.
Vinegar is OK for light mineral buildup but wont remove heavy scaling, I use it more for seasonal flushing use on my raw water systems.
One Atomic 4 I rebuilt for a friend had over an 2 inches of accumulated mineral sediment in the cylinder cooling jackets, this means that section of the cylinders was not being cooled, some smaller passages were clogged. Once some physical poking was done it was dipped in muriatic acid, this cleaned it completely. Few other agents would have done the job that efficiently.
If your engine was raw water cooled for 20 years I would suspect it has just as much build up in it.
The cylinder block does not transfer as much heat as the head does, but it still needs complete and consistent cooling as uneven cooling in a cylinder bore can lead to cylinder warping and accelerated wear.
Making sure your cylinder head cooling is free flowing and clean is twice as important, it passes exhaust gasses through the ports and sees a significant heat load.
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Old 05-08-2018, 18:08   #22
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Re: Removing raw water deposits

Hi Wotname and all
thanks for all your advice and great ideas, its now all back together again and running nicely. In the event I chose not to rinse after all. There was only one point of significant accumulation - at the very top of the exhaust manifold where the water exits through a gooseneck elbow into a tube heading for the gearbox oil cooler and wet exhaust. For just a few inches a very heavy buildup whilst elsewhere its just a thin film.
I have a sense that the pressure variations at a blockage may actually accelerate the deposits at that point creating a runaway effect.
The zincs all have a lot of life left...they degrade very slowly in this situation.
A new impellor in the pump is working well. There's a little syphon breaker/pilot tube in downstream end of the system which is visibly squirting nicely once again.
thanks all.
Pete
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Old 05-08-2018, 19:28   #23
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Re: Removing raw water deposits

Bit late now as i see you've decided not to flush but a guy I know who cleaned his cast iron block to remove liner got great results with CRC rust remover. Just filled his block up & let sit overnite. Had zincs & thermostat out.
I soaked a part of a raw water-cooled engine in white vinegar overnite & it didnt seem to do anything to the encrusted salts.
Sounds like a good engine!
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Old 05-08-2018, 20:15   #24
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Re: Removing raw water deposits

Quote:
Originally Posted by lifeofreilly57 View Post
Are you converting this engine from raw water cooling to a closed circuit unit with a heat exchanger?
I've done this to several engines over the years.
The best solution I've found is to use muriatic acid through all the water passages that salt water had previously touched. Even on iron blocks, otherwise it's questionable that vinegar would do the job. If your looking to convert to a closed system on the engine even the smallest amount of residual salt in the system will cause oxidation over time.
The bronze/brass heat exchanger tubing bundles are also more efficiently cleaned with muriatic acid, just take care in the use and storage of the acid, take all the common sense safety precautions when using it.
If your using it to clear mineral deposits out of an iron block make sure to neutralize the acid and flush with plenty of clean, mineral free water once you've removed the acid, then get your antifreeze/rust inhibtor mixture into it as soon as possible. The newly etched iron will start to rust in short order.
Vinegar is OK for light mineral buildup but wont remove heavy scaling, I use it more for seasonal flushing use on my raw water systems.
One Atomic 4 I rebuilt for a friend had over an 2 inches of accumulated mineral sediment in the cylinder cooling jackets, this means that section of the cylinders was not being cooled, some smaller passages were clogged. Once some physical poking was done it was dipped in muriatic acid, this cleaned it completely. Few other agents would have done the job that efficiently.
If your engine was raw water cooled for 20 years I would suspect it has just as much build up in it.
The cylinder block does not transfer as much heat as the head does, but it still needs complete and consistent cooling as uneven cooling in a cylinder bore can lead to cylinder warping and accelerated wear.
Making sure your cylinder head cooling is free flowing and clean is twice as important, it passes exhaust gasses through the ports and sees a significant heat load.
Hi wotname and all
thanks for all your advice and great ideas, its now all back together again and running nicely. In the event I chose not to rinse after all. There was only one point of significant accumulation - at the very top of the exhaust manifold where the water exits through a gooseneck elbow into a tube heading for the gearbox oil cooler and wet exhaust. For just a few inches a very heavy buildup whilst elsewhere its just a thin film.
I have a sense that the pressure variations at a blockage may actually accelerate the deposits at that point creating a runaway effect.
The zincs all have a lot of life left...they degrade very slowly in this situation.
A new impellor in the pump is working well. There's a little syphon breaker/pilot tube in downstream end of the system which is visibly squirting nicely once again.
thanks all.
Pete

.....
Thanks for your thoughts.... No there's nothing like that buildup of deposits. Apart from one short section mentioned, there's only a thin film.. perhaps a max of 1mm.

This ME180 was designed for primitive raw water use from the outset. About 12 years ago I actually built a heat exchanger thinking that would extend its life but switched back to raw pretty quickly.

What happened was that with the heat exchanger fresh water was circulating at a bit less than 80degrees, which from what I was reading was about right. But shortly afterward one of alloy rocker covers started leaking from a new crack.

So I thought maybe this engine was never designed to run as hot as that. I couldnt see an easy way in which I could get the fresh water to mimic the temperature gradient of the orignal raw water, didnt want to risk the same thing happening with a cylinder head, so went back to raw and I just keep all the anodes working.

I ran with a plywood rocker cover for a while until I could get the original rewelded.
regards
Pete
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Old 06-08-2018, 09:00   #25
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Re: Removing raw water deposits

Rig a fresh water flushing system on the sea water inlet side, and use it very frequently.
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Old 06-08-2018, 16:10   #26
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Re: Removing raw water deposits

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Rig a fresh water flushing system on the sea water inlet side, and use it very frequently.
Thanks, that's not a bad idea.
pete
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Old 06-08-2018, 23:07   #27
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Re: Removing raw water deposits

If you'd like pics and schematic of what I have, you are welcome to PM me.
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Old 07-08-2018, 18:01   #28
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Re: Removing raw water deposits

I 2nd what parkstone bay said. We rigged up a freshwater flushing system ( from a CF contributor tip )for our raw water cooled Yammer & it seems to keep system a lot cleaner as well as extending anode life. Happier leaving it sitting with kinda fresh water in cast iron block when we aren't using it.
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Old 07-08-2018, 19:10   #29
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Re: Removing raw water deposits

Thanks. Yes it sounds like a good arrangement
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Old 07-08-2018, 19:25   #30
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Re: Removing raw water deposits

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I need to remove accumulated deposits from the tubing of an old raw water-cooled engine. Any suggestions for rinsing the engine tubing to remove deposits?

Perhaps heat exchangers have a similar problem of a buildup of deposits.

Suggestions gratefully received.


There are various anti scalents used in HVAC chilled water systems. These chemicals are used to remove build up in heat exchangers a small amount is all that would be needed. Let it soak from r a day and flush it. It will do less damage than acids
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