Heat exchanger repair yanmar 4jh3-te

[drtsr1]

The end caps are leaking on my yanmar heat exchanger, I also want to clean the the exchanger at the same time. Thus removing the core, it has not been cleaned or inspected since 1999.

I would also like to flush the green coolant and put the yanmar fluid in at the same time. How do I get all the fluid out of the engine and the water heater?

Has anyone done this before or know of a step by process to complete these tasks?

Also what hoses, gaskets, sealer, and antifreeze I would need?

Thank you

 

[Bill Roosa]

When you pull the core the green antifreeze will drain so all you really have to do is drain the block and water heater. There should be a petcock for draining the block and draining the water heater is just a matter of taking the hose off and letting it drain (into a bucket of course) then go to the engine side of the water heater hose and (after building up a good layer of spit on the lips) blow in the hoses to get that coolant out (also into a bucket)
To refill just mix a 50/50 mix of anti and water and pour it in through the "radiator cap." Fill the overflow tank to "full hot" and run the engine to check for leaks and to bring it up to temp. After shutting it down and letting it cool check the over flow and top it off to the "full cold" line. Repeat filling the overflow tank till the level stabilizes (2-3 times as you normally use the engine and always when cold). The small amount of air in the engine after the first refill will not hurt anything nor will the small amount of old anti in the hoses or heater.

The core pulls out after the end caps are removed. Note the alignment of the baffle on the end caps as that is important to making the fluid flow twice/three times through the heat exchanger.
good luck

 

[drtsr1]

Thanks..!!

Would have a picture of the baffle on the end caps you are talking about?

Not sure what they are.

 

[Bill Roosa]

Just look at the back of the cap. It will have either a "wall" going all the way across the diameter (two way flow) or a set of three "walls" at 120 degrees all meeting in the center of the cap (three way flow)
You have to get the gaskets and ends back on in the right places or the flow of raw water will not work. There is a front and rear cap and while you can put the front on the rear the water will not flow correctly if you do so.
It is pretty obvious once you have them in your hand.

 

[KD3PC]

D

IF you are not going to have a shop dip and clean the exchanger....I would mark it with a permanent marker, as it comes off the Yanmar. IF you are going to take it to a shop, I usually lightly notch the end cap and the exchanger where it goes, so when they dip it, I still have a registration mark.

Some use the phone camera to take a pic and then make sure it looks right when you put it back together.

I was going to give you my process, but Bill did such a clear and easy job of it, I just added the above