Inboards that start running too hot?

[Scot McPherson]

Originally Posted by AJ_n_Audrey

Another possibility is an undersized pipe or fitting somewhere in the plumbing for either fresh or raw water. I recently discovered a 30-year-old mechanical bulletin that had never been implemented on my Westerbeke that called for replacing some plumbing with larger diameter pipe to eliminate over-heating at higher RPM. Might be worth checking the Yanmar database.

A good idea to do, but still does not address the fact that something has changed. I know I am repeating myself, but this is the _key_ element in the OPs problem.

[ranger58sb]

Originally Posted by Scot McPherson

I want to agree with this because it seems like sound advice, we should always refer to the manufacturer when in question right?

However; I can't in this case.

Regardless of what the specified operating temperature of the engine _should be_, The operating temp of the engine has in fact been whatever it _has been_. If the engine is running warmer now than it had previously, even if that means it's now running within spec, it means something is happening to the cooling system.....

Yep, good distinction. I just meant to hit the high points, but you're right tp point out the sometimes more subtle nuances of troubleshooting...

-Chris

[svseawitch]

Might be something as simple as build up in the heat exchangers. We pull ours ever few years and take them to a radiator shop to have them clean it in their tanks. It makes a noticeable difference....

[boeing1]

how is the water flow from your exhaust, if low..I would check the mixing elbow for condition/ blockage,

[topmast]

A possible plugging can occur in the transmission cooler Tubes are smaller than other orfices and even bark bits and grass can call it home. Just a matter of limiting things.

[sailah]

My Westerbeke 44B was starting to climb in temps nearing 200 degrees after extended motoring. Always pumped plenty of water, new impeller every year.

Finally pulled the heat exchanger last year, 2 years after I bought the boat. Where the hose from the raw water pump came into heat exchanger salt had precipitated out and necked down a 1" hose to an opening about 1/4 of that size.

It was a clay like consistency, and clogged just like I imagine an artery would. I removed the heat exchanger, cleaned everything well including some dilute acid soaking. Reinstalled, temps never climbed above 180.

That was last season. This year I had an unrelated issue which allowed easy access to check that same hose. It wasn't as bad but I could reach in with my finger and feel it starting again. It's now on my yearly maintenance schedule.

I also remove my impeller every fall and replace with a new one. I keep the old ones as spares. My engine has a V drive so the pump is aft and a pain to stuff myself down there to change. I've lost enough of the screws that hold the pump cover on that I bought a box of 50 from McMaster to keep aboard. It's very awkward to reach the pump and you almost have to do it by feel. I ditched the slotted head screws in favor of socket head cap screws that won't fall off the end of my allen wrench when I'm fumbling around.



And i also keep 4-5 gaskets onboard for it because they are one time use only on my pump.

[softdown]

This would seem to be a very common problem after reading these comments. An update on the OP:
*The engine was already pulled. It sits on my garage floor wondering what to do.
*Ordered an impeller and gaskets plus a shop maintenance manual.
*The S2 is a 1978. Yet I seem to have a memory that this Yanmar is a 1980. Visiting the Yanmar web site yielded no way to determine the year of production.
*Having operated in saltwater, it seems like taking the heat exchanger to a radiator shop is pretty automatic. I'm so green that I don't know what the heat exchanger looks like.

[sailah]

Originally Posted by softdown

*Having operated in saltwater, it seems like taking the heat exchanger to a radiator shop is pretty automatic. I'm so green that I don't know what the heat exchanger looks like.

See the black tubular thing going left/right at the bottom of the pic? That's my heat exchanger. My engine is mounted in reverse because I have a V drive so yours may be aft vs forward like mine. On mine the raw water inlet is on the left of the photo below the exhaust manifold.

It's not hard to remove and clean yourself at least mine isn't. Getting it off is 90% of the work. Mine has gasketed endcaps that you unscrew to gain access to the tubes inside. You can easily clean it yourself. I use a aluminum TIG rod to gently go thru all the tubes, you do want to be careful you don't damage them as they are copper. Then I soak it in a dilute acid solution but vinegar works just the same. Then rinse. I painted mine after I was done to make it look nicer as the red paint chipped off a little.

[sailah]

Yours looks like this, thing that says YANMAR on it. Looks like right side of that is where you unbolt and slide out heat exchanger:

Looks like you'd want to buy the gaskets/O rings ahead of time that way you are prepared when it needs to go back together.

[softdown]

Originally Posted by sailah

Yours looks like this, thing that says YANMAR on it. Looks like right side of that is where you unbolt and slide out heat exchanger:

Looks like you'd want to buy the gaskets/O rings ahead of time that way you are prepared when it needs to go back together.

Thanks!

However I am wondering about the cleaning instructions: "Don't waste your time cleaning it manually.
Clean the core assembly in a neutral pH cleaning bath."

Cleaning is done with pH reactions. Alkalinity is removed with acid. Acidity is removed with alkalinity. Since we have aluminum, we can't use alkalinity. Since we have build-ups of alkalinity (mostly calcium carbonate), we should use acid (such as vinegar).

Distilled water is a neutral pH solution. It likely will not clean much without heat and water movement.

[sailah]

Originally Posted by softdown

Thanks!

However I am wondering about the cleaning instructions: "Don't waste your time cleaning it manually.
Clean the core assembly in a neutral pH cleaning bath."

Cleaning is done with pH reactions. Alkalinity is removed with acid. Acidity is removed with alkalinity. Since we have aluminum, we can't use alkalinity. Since we have build-ups of alkalinity (mostly calcium carbonate), we should use acid (such as vinegar).

Distilled water is a neutral pH solution. It likely will not clean much without heat and water movement.

I would agree with your assessment. I used acid that I diluted. I would think a vinegar solution is mild enough to work just fine. Dunk it in there and monitor, happens pretty fast in my experience. I don't leave it in there for hours. I would agree on the manual cleaning thing as the more manual cleaning you do the better your chances are to break something. However a little gentle mechanical cleaning first means less time in an acid bath.

As usual common sense applies well here.

[softdown]

Where does one get a gasket set for a Yanmar 2GM heat exchanger? Surprisingly they seem to be non existent at Ebay.

[ranger58sb]

Originally Posted by softdown

Where does one get a gasket set for a Yanmar 2GM heat exchanger? Surprisingly they seem to be non existent at Ebay.

Yanmar dealer... or Yanmar certified tech/shop...

-Chris

[sailah]

Try this to start:

http://www.marinedieseldirect.com/ca...ors=&comment1=

24311-000700 (2) & 128695-44070 (2) Gaskets

If you copy the part number and then use google to search by part you'll get a sense as to who has them.

Things like O rings aren't something that Yanmar makes. When I need O rings I use my calipers and find the size. Then I go to McMaster Carr and order the right o ring. Typically you get a bag of 50 for cheaper than 1 would cost you from Yanmar. The gaskets though you'll probably need to get from Yanmar as they will surely be a specific size made for them.

You can also call your local Yanmar distributor, here in MA it's Mack Boring. Often they will have prices better than online at least in my experience.

[softdown]

Originally Posted by sailah

Try this to start:

http://www.marinedieseldirect.com/ca...ors=&comment1=

24311-000700 (2) & 128695-44070 (2) Gaskets

If you copy the part number and then use google to search by part you'll get a sense as to who has them.

Things like O rings aren't something that Yanmar makes. When I need O rings I use my calipers and find the size. Then I go to McMaster Carr and order the right o ring. Typically you get a bag of 50 for cheaper than 1 would cost you from Yanmar. The gaskets though you'll probably need to get from Yanmar as they will surely be a specific size made for them.

You can also call your local Yanmar distributor, here in MA it's Mack Boring. Often they will have prices better than online at least in my experience.

Closest Yanmar "dealer" is over 200 miles away. Colorado is a poor sailing state. This dealer works with industrial engines, I'll bet they have some experience with Yanmar agricultural products. Almost none with marine products.