Heat Exchanger

[gpd955]

Hello. Me again. After a productive day of prep I went to check my zinc and when I pulled the cover off of the heat exchanger, what appeared to be fresh water came out.

Should I check anything in particular to make sure damage was not done over the winter? It was a small amount of water (maybe 1/4 cup or less).

This was the first winter with a diesel engine (former boat had an A4) and I figured all the water was replaced with anti-freeze when I winterized. Did not realize there was a separate drain for the exchanger.

I plan on replacing the exchanger gasket an o ring since the gasket had gray paint on it which leads me to believe it is 10 years old.

 

[Stu Jackson]

Do you have an M25XP? If so, just take the HX off and look it over.

Reply #1 has a resource for new gaskets, you don't need, or want, an O ring.

http://c34.org/bbs/index.php/topic,3744.0.html

 

[Raftco]

You should check your zincs or zinc in the heat exchanger and replace. You can also service your heat exchanger by pulling it off and hosing it out with fresh water to wash out any residue. The small holes can be cleaned out with a welding rod if you have barnacles or anything else stuck in there.

Remember, anything that makes it to the heat exchanger will be travelling through the rest of your engine so keeping your coolant system clean is a priority.

 

[Snotter]

If you go through the hassle of removing the HX and/or the stack, take it in to a radiator shop and have it pressure tested; the price is neggligable then you will know for sure.

 

[JK_Boston_Catalina310]

I asked some of the same questions of Mainesail.

 

[gpd955]

I asked some of the same questions of Mainesail.

Perfect. Thanks.

 

[gpd955]

You should check your zincs or zinc in the heat exchanger and replace. You can also service your heat exchanger by pulling it off and hosing it out with fresh water to wash out any residue. The small holes can be cleaned out with a welding rod if you have barnacles or anything else stuck in there.

Remember, anything that makes it to the heat exchanger will be travelling through the rest of your engine so keeping your coolant system clean is a priority.

That's what my original task was until I decided to open up the cover to make sure it was clean inside. It was still about 75% intact but I ordered a bunch of zincs and a new cover/gasket since it appeared that the one on there was the original. Other than the zinc pieces, it was clean inside.

 

[Maine Sail]

This was the first winter with a diesel engine (former boat had an A4) and I figured all the water was replaced with anti-freeze when I winterized. Did not realize there was a separate drain for the exchanger.

I guess the question becomes how did you winterize the engine? If done properly you should not need to drain off the HX.. How many GALLONS did you sick through, two, three, four, five? One gallon will not cut it on most motors and can leave you frozen solid. PG should not be diluted so unless you drain off the fresh water first you will get dilution if only sucking though a bare minimum. If you add engine driven refrigeration and its HX you're upwards of four to five gallons to have it test the same freeze point as it went in, as measured at the water lift muffler..

 

[Maine Sail]

Remember, anything that makes it to the heat exchanger will be travelling through the rest of your engine so keeping your coolant system clean is a priority.

The HX isolates the engines fresh water/antifreeze side. Anything passing through the HX winds up in the wet exhaust not in the engien cooling pathways.

 

[rardiH36]

The HX isolates the engines fresh water/antifreeze side. Anything passing through the HX winds up in the wet exhaust not in the engien cooling pathways.

Hi Mainsail:

Something I always wondered ... if the HX becomes breached due to pin holes between the separate engine coolant and raw seawater pathways ... what's more likely ... will the raw water migrate into the engine circuit... or will the engine coolant be lost into the raw water circuit and out through the exhaust elbow?

Obviously its best to ensure that the heat HX never corrodes enough to develop pin-hole leaks.

 

[gpd955]

I guess the question becomes how did you winterize the engine? If done properly you should not need to drain off the HX.. How many GALLONS did you sick through, two, three, four, five? One gallon will not cut it on most motors and can leave you frozen solid. PG should not be diluted so unless you drain off the fresh water first you will get dilution if only sucking though a bare minimum. If you add engine driven refrigeration and its HX you're upwards of four to five gallons to have it test the same freeze point as it went in, as measured at the water lift muffler..

4 gallons. And I did run the engine until water stopped coming out of the exhaust before I put the anti-freeze in. The amount of water that came out of the HX was very little. I did start the engine for a few seconds the other day and it started nicely and purred like it did before she was winterized. The boat is still on the hard so I couldn't run it for long.