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CurlewIII
07-14-2015, 02:01 PM
I have a Sabb diesel from '67. It's a 10 hp, one cylinder, model GG, with saltwater cooling.


Basically, every time I turn on the engine, it runs fine for a few minutes, and then the cooling system gets blocked up.


I was confused about why the system keeps getting blocked up, but after removing blockage after blockage, it seems to be that the things causing the blockages are little pieces of scale, presumably coming from inside the engine. The engine had been sitting unused for three years before I acquired it, and it seems likely that some rust occurred inside, which is now getting picked up by the water and getting trapped, usually in the thermostatic valve on the top of the cylinder head.


I was wondering where I should start in fixing this? How do I remove the scale, and where would be a good place to start removing it from? I'm a total novice at this whole 'mechanics' thing so any help would be very appreciated!

Thanks so much,


Maya, and Curlew III :)

Garret
07-14-2015, 02:20 PM
Welcome to the forum!

No fun. First off, do you have a raw water strainer on the water coming into the boat? That's a must - particularly with a raw water cooled engine.

If it is caused by scale loosening from inside the engine, I don't see any thing short of a teardown fixing it. Even then, getting at all of the cooling passages will be tough. It's possible that running a powerful radiator cleaner (read mostly acid) through it, but you'd have to isolate the incoming & outgoing water to a barrel or some such - as it has to circulate through for a while (1/2 hour or more) & can't be diluted too much. That would be hard to do with the boat in the water - unless you run temporary hoses to a barrel in the cockpit. You'd want to be really sure not to spill any of the solution on the boat - as it'd mess up wood, varnish & paint.

Another thing is that if there is a lot of scale, it could mean that the walls of the water jacket have deteriorated to where they are very thin & could potentially break through. Not saying that to scare you! Just a warning.

Raw water cooling in salt water is not a good thing...

George Ray
07-14-2015, 02:25 PM
A strong flush would be the ticket.
Any good radiator shop should provide the details.
Many different things have been used over the years such as Muriatic Acid (HCL), Vinegar etc but I can't recommend any chemical in particular or the concentration or time.

It's been a long time since I talked the US Sabb parts people and hope they are still in business.
Give them a call and ask for suggestions.

USA SABB America East
119 Lake Shore Circle
Leesburg, FL 34788-8967
(1)3525892882
(1)3525897722
sabbamerica@aol.com


p.s. GO SABB!!!!
http://i.ytimg.com/vi/tByjGFTpQi4/hqdefault.jpg

CurlewIII
07-14-2015, 05:42 PM
Hi there! Excellent suggestions, thank you very much. I'm thinking of rigging something up with some hoses and a bucket to circulate through the engine and see if that does anything. Fortunately, the engine doesn't have to be running to do that, all I have to do is turn it over with the decompression lever out of place, and the water will pump through. That means I can disconnect the exhaust and just run a circuit through with a barrel of some sort to collect it all.

As as for the raw water strainer, I actually don't have one. I thought that was the problem as well, and I shall certainly install one soon, but it seems like the actual blockages are invariably caused by pieces of scale rather than marine flotsam.

Thank you so very much for your help, I really really appreciate the timely and very helpful response! And please, if anyone else has suggestions, feel free to send them my way, I need all the help I can get haha!

CurlewIII
07-14-2015, 05:45 PM
It's been a long time since I talked the US Sabb parts people and hope they are still in business.
Give them a call and ask for suggestions.


p.s. GO SABB!!!!

I sent them an email ages ago and they never responded. I'll try calling! I've been ordering parts from sleek an and harken in the UK. Thanks so much for your help!

skaraborgcraft
07-15-2015, 02:55 AM
All of the above regarding flushing the system, thats the only in-situ way attempting to clear any blockages other than a full strip down. The Sabbs run at a lower temperture than some modern diesels, so salt deposits dont "cake" as badly, though its not unknown for an old engine to have the walls eaten away after 20+ years. The water strainer is something you should definately consider, the water pump diaphram can be easily clogged/ruptured.

CurlewIII
07-15-2015, 09:41 AM
All of the above regarding flushing the system, thats the only in-situ way attempting to clear any blockages other than a full strip down.

I was talking to my Dad about all this and he sounded wary of doing a system 'cleanse' with muriatic acid or the like. What are the dangers of doing such a procedure? Strong acid in the engine seems bound to lead to trouble if not done correctly.

Garret
07-15-2015, 02:12 PM
I was talking to my Dad about all this and he sounded wary of doing a system 'cleanse' with muriatic acid or the like. What are the dangers of doing such a procedure? Strong acid in the engine seems bound to lead to trouble if not done correctly.


http://www.race-mart.com/product.asp?itemid=322893&gclid=CjwKEAjwiZitBRCy0pb3rIbG9XwSJACmuvvzDnMooN4t p5gsntzwTy1CjIFvCmvcNLqr5uUW6OiRzxoCtUnw_wcB

http://www.permatex.com/images/stories/virtuemart/product/80030.jpg

It's got acid in it, but specifically formulated for radiators.

Figment
07-15-2015, 02:22 PM
The dangers of doing the muriatic acid procedure are more of a danger to the person doing the procedure than they are a danger to the engine.

The acid doesn't stay in the engine for very long. It's cheap enough that you can do it several times but start conservatively. Do a 10-minute soak, and if that doesn't do the job, do a 15-minute soak, etc.

Read here.... http://www.moyermarine.com/forums/showthread.php?t=127
(the scale and the acid don't care who made the motor, the process is the same)

Jim Ledger
07-15-2015, 02:39 PM
Over time a lot that scale and sediment falls to the lower reaches of the cooling passages and just stays there, in this case around the bottom of the cylinder. If the engine was out of the boat with the cylinder head off you could poke a wire down the passages and pull out a steady rain of rusty junk. I doubt any kind of flush would remove it all, considering the low pressure that can be brought to bear on the cooling passages. Engine rebuilders can boil a block and head, which might do a more thorough job. The problem is that after all your efforts the remaining iron might be salt-soaked, weak and porous.

Fifty years of salt water cooling is a lot...even for a Sabb.