Coolant in my truck versus my tug

[Hydraulicjump]

Just did the 500 hour service and my mechanic noted that Yanmar seems to want you to change your coolant pretty frequently, as in every two years, even with these new long-life coolants. So I dragged out my 2004 Dodge 3/4 ton diesel manual and noted that they only recommend changing coolant every 60 months (5 years). It seems to me that the coolant in the truck gets worked much harder than the coolant in the boat, but I realize that it is really the breakdown of ethylene gylcol over time that is the concern. Still, is changing your coolant every 24 months overkill?

Jeff

 

[sheral]

All I know is that a friends heat exchanger went on his R21and Yanmar attributed it to the wrong coolant / too long of an interval. It was an expensive fix for him.

 

[Boatagain]

It seems to me that boat motors work much harder than truck or car motors. Pushing through water is much harder than pushing through air.

 

[knotflying]

I use long life prestone and it is approved in a bulletin by Yanmar. I change mine every year because I only get half of it out using the petcock. It is really not expensive and an easy job so once a year is no big deal.

 

[Snug Tug]

Most truck engines have a cast iron exhaust manifold bolted to the side which is hot enough to burn you if you touch it. On a Yanmar marine diesel, the exhaust manifold is made of aluminum and is immersed in coolant in the heat exchanger to keep it cool. An aluminum exhaust manifold would melt through if it wasn't water cooled. Anyway, exposure of the coolant to the direct heat of the exhaust manifold causes the coolant to break down faster. Also, the hot aluminum is sensitive to corrosion if the coolant anti-corrosion additives are degraded by high temperatures. Bottom line: It's Yanmar's use of an aluminum water cooled exhaust manifold that is the issue and that's why the coolant should be changed more often.

 

[Hydraulicjump]

Thanks. That is a great answer. Which is why this site is go useful for us.

Jeff

 

[knotflying]

Mack Boring sells an additive that replenishes the special additives in the antifreeze, but as I said in my earlier post draining from the petcock and adding new antifreeze each year is probably one of the easiest projects encountered on the engine.

 

[Kaisardog]

yanmar also will deny certain claims otherwise covered under warranty if you have not used the appropriate recommended coolant. the yanmar boards are full of stories about such things; check out the reads at boat diesel.com .