opening a heat exchanger

[njlarry]

My heat exchanger is showing some corrosion around the end caps. I would like to remove them, clean the area and replace the end rubber gaskets. I know that closing the raw water intake will limit the drainage from the raw water side. Now for a really dumb question. ..what stopes the total loss Of the engine antifreeze when I open the ends up?
The engine is a 2011 universal mb 25xpb with 200 hours so I am not expecting it needs any thing more.

 

[Mark Maulden]

Not familiar with your particular engine, but there should be some drain cocks at the low points. Crack the expansion tank cap for vent. If the HX is high on the engine, it should drain. If it is low, then there is probably some mopping to do.

 

[Davidasailor26]

If the HX is assembled like our old Universal M12 was, then the antifreeze is in a closed loop inside the HX, not in contact with the end plates. You should be able to remove the end plates without affecting the closed loop; it will only drain the raw water side.

 

[njlarry]

Of course, that makes sense. I said it was a stupid question. Don't know what I was thinking. No different than when the zinc is changed.
Thank you.

 

[Johnb]

I have attached before and pictures of my heat exchanger to
1 Show that if you removed the end caps the seal provided by the O ring would leak and the fresh water would probably pour out
2 The shop cleaning was really effective - they refurbished the whole exchanger for $170.

Maybe your question is actually pretty smart

 

[MitchM]

1. on the yan mars be sure you have the factory replacement gaskets . the originals are very thin and can tear .( also keep some Form A Gasket from the auto parts store in your spares kit if you have to do an emergency Ht Ex take apart at sea and don't have the OEM gaskets. ) 2. there will be some antifreeze leakage when you take the hoses off . tie a string around the supply hose, wrap the open end tightly with duct tape then and have a buddy elevate it higher than the level of the antifreeze in the radiator to minimize leakage. 3. you can carefully ream out each ht ex tube with a pipe cleaner. if there's a piece of raw water impeller stuck in a tube, it is amazing how that small blockage will cause your engine to run hot. and if you've changed a raw water impeller and seen one come out missing some impeller blade tips, be sure to see if it's stuck in the heat exchanger. 4. when you re assemble tighten the cover bolts, do so in alternating fashion 1 3 5 2 4 6 etc . don't tighten all one side then all the other or the gasket may leak.

 

[Davidasailor26]

if you removed the end caps the seal provided by the O ring would leak and the fresh water would probably pour out

Where's the fresh water going to come from? Isn't the fresh water on the inside of the heat exchanger element (the part you can't see), and the part you can see is where the raw water runs?

 

[Johnb]

Yes, the fresh water is on the inside but the inside is sealed from the outside by the O rings you can see in the second picture I posted above. When the end cap is removed that O ring is no longer compressed and the fresh water will come micturating out.

 

[odaydokay]

Micturating???? I think he means Mickjaggerating.

 

[Jim 5757]

Universal M20... removing the end cap only exposes the raw water side. Engine coolant circulates around the tubes and is not affected.

 

[njlarry]

The Universal (Westerbeake) is a different design. It has a flat rubber disc with a central bolt holding it on.
Have not opened it so not sure about a o ring being there.

 

[Tally Ho]

Learn something new everyday on this forum !

 

[Capt jgw]

There are drain cocks on the engine so you can capture the coolant. Best not to let it drain into the bilge whether you reuse it or not. The coolant does need to be changed periodically and five years old is probably not too early.

 

[Jim 5757]

No o-ring on ours... just the rubber gasket.

 

[CloudDiver]

View attachment 127463 View attachment 127464

I have attached before and pictures of my heat exchanger to
1 Show that if you removed the end caps the seal provided by the O ring would leak and the fresh water would probably pour out
2 The shop cleaning was really effective - they refurbished the whole exchanger for $170.

Maybe your question is actually pretty smart

I love those pictures... So great to see a well cleaned heat exchanger; Most owners just don't get how much future maintenance costs in parts and labor, avoiding performance loss, and avoiding potential DIW that $170 service can save you.

To the OP, since your engine is a 2011 with 200 hours I imagine that it has never actually had a full heat exchanger service. I would go ahead and fully remove the unit and have it serviced like JohnB did. Here's a tip, take it to a regular radiator shop... they do the job at 'normal' prices where any shop with 'marine' in the name will charge you a 'marine' premium.
You'll have to change out the antifreeze, but its probably due anyway.

 

[odaydokay]

Learn something new everyday on this forum ! View attachment 127468

Yep, that sounds like Mick.........

 

[Padrone]

Having done this on a Universal MXP25, I found that using a suitably sized plug in the end of each of the hose connections is the easiest way to go and minimizes the fluid loss from them. Well worth doing a full removal and endorse the use of a vehicle radiator shop for "de-gunking" (technical term).

 

[Padrone]

Having done this on a Universal MXP25, I found that using a suitably sized plug in the end of each of the hose connections is the easiest way to go and minimizes the fluid loss from them. Well worth doing a full removal and endorse the use of a vehicle radiator shop for "de-gunking" (technical term).