My engine is getting too hot.. - Page 2 - SailNet Community
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post #11 of 31 Old 08-27-2007
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Groundhog...

You might have built up a rust sump in the barrels. Take the wee drain plugs out of the bottom of the barrels ONE AT A TIME!!! (replace them each in turn) and run the motor for a wee while to pump the water.. don't run it for long as the cooolant flow will be disturbed, and your exhaust will be under-cooled.

Often, the wee holes are in a rust sump, and need to be poked with wire to flush out the rust. That might help, though I am still puzzled as to why you are overheating.

Try this too.... take out the thermostat and check that it is opening.... it is under the cover at the fwd end of the manifold. Just boil the thermostat in water and you will see it open. If it does not open, and you don't have another one, don't despair... just bash the middle out of the thermostat to leave the outer seal ring, and re-assemble without the thermostat mechanism.

This will have the effect of allowing cooling circulation all the time. I really cannot see how you could be overheating then. You should be over-cooling then, and the motor will take that for a fair while... certainly better than overheating.

Are you pumping enough water from your coolant pump? Have you checked that enough comes out with the exhaust?

I have had a love/hate relationship with that MD17C over the years. The motor is very strong indeed when set up right and maintained, but the price of spare parts is absolutely shocking.

I went to the west of Scotland earlier this month, a round trip of 180 miles, about 160 of it motoring. An engine mount slacked off a wee bit and had to be tightened, but the motor ran fine, and used very little oil. I took off the engine panels to allow instant checking and access, the idea being that it would encourage inspection and warn me of impending faults. The engine room is like a wee submarine... panels and lights and fuel pump. It's a bit noisy, but so be it.
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post #12 of 31 Old 08-27-2007
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Before you take the wee plugs out, tie some cord around them as they are very easy to drop. If you have a deep bilge like mine, you won't see them for years.
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post #13 of 31 Old 08-27-2007
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Quote:
Originally Posted by wumhenry View Post
Is acid treatment recommended only for engines with raw-water cooling, or also for engines with heat exchangers?
I didn't mean to imply that it's a recommended approach. To the contrary, I've never heard a diesel marine mechanic who's opinion I respect recommend muriatic acid treatment. One major reason is that there is no definitive interval before which acid MAY affect seals and rubber parts while still doing anything effectve to break up caked material which is not porous enough to allow penetration of acid beyond it's surface layer. What I suggested is that If someone wanted to try it and was concerned about the acidic effect of parts, dilute it slightly but that only minimizes the efficacy of the acid making the process that much more futile.
The only was to KNOW is to remove the suspect part(s) as the original poster implied he did and inspect the cleaning process result. Using vinegar which is about as acidic as soda pop is a feel-good approach only.
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post #14 of 31 Old 08-27-2007
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Thumbs up

http://www.trac-online.com/barnacle-buster.html

This product worked very well for me...it basically fixed my running hot issue, as I did not want to remove the exchanger if I didn't have too because its a SOB to get off.

I let it sit as opposed to using the cycling method they prefer...however I believe the active ingredient, Phosphoric Acid, is easily obtained from a hardware store.

before after
(photos are from the website, not actually my exchanger)

Cheers,
Shawn

S/V Windgeist
1982 Tartan 37C

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post #15 of 31 Old 08-27-2007
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FWIW...we used the muriatic acid treatment on a Yanmar Diesel w/ heat exchanger. We had NO problems whatsoever with it and our engine AND the treatment was recommended by a guy who was Yanmar certified. I would imagine leaving it in the engine long term would not be helpful but again...it only stays in for a few minutes and then is thoroughly flushed out by the engine running.
Won't help remove rubber impeller pieces from the heat exchanger but does a good job on scale.
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post #16 of 31 Old 08-27-2007
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Second Cam's experience. Our Yanmar raw water cooled generator was overheating. Confirmed all components were operable and on advice of trusted Yanmar mechanic did the muriatic acid routine. Sucked it in through the raw water pump, let it sit 15 minutes, reconnected raw water intake to thru hull and flushed. All ended well, no gasket failures or impeller problems upon subsequent inspection.

Ike
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post #17 of 31 Old 08-27-2007 Thread Starter
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Well, it sounds like what I should do is:
1.) Apply barnacle buster and flush.
2.) Pull the wee plugs and dig out remaining rust, which is probably there.
3.) Change thermostat.

On the thermostat.. I do believe I put the old thermostat back in thinking, "they always break open don't they?"

I also do remember my temperature gauge going down quite rapidly a couple of times and then gradually rising back up (Sunday).

Does that sound like a plan?
Thx,
gh
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post #18 of 31 Old 08-27-2007 Thread Starter
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oh..
4.) Flush with that barnacle buster again somewhere in there.
gh
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post #19 of 31 Old 08-27-2007 Thread Starter
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There is also a product for fresh water cooled engines..
http://www.defender.com/product.jsp?path=-1|10918|309314|311419&id=750278
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post #20 of 31 Old 08-27-2007
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Groundhog...

If it's going up and down there Groundhog, the thermostat is working.

Typically it climbs slowly, then dips quickly. It should not rise to beyond 12 O'Clock on the wee Volvo temp guage (on mine anyway). If you put your hand on the coolant pipe after it leaves the engine, you will feel it heat and cool alternately as the thermostat opens and closes.

How are you judging the overheating?
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