Yanmar 4LHA-STP aftercooler service in place

Hey All,

I need to service my aftercoolers on my 4LHA-STPs. I've seen the videos on seaboard marines site, and they all pull the entire cooler. I started to do that, but quickly ran into snags with frozen bolts etc.

On the other hand, it seems to me that I can easily reach the end caps on both sides. Can I just pull off the end caps, push out the core, clean it, grease it and reassemble, replacing all gaskets? Or do I have to pull the whole cooler?

Thanks,

If you have frozen bolts I suspect the core will be in there good and tight too.
But yes, you can do as you stated, if you can do as you stated

Disclaimer; I never worked on that model, but the other Yanmars on which I have came apart that way.

OK, I'm going to give it a try, I can always pull the entire thing if needed, right?

Plus, the bolts aren't so much frozen as super tight and hard to get a wrench on. My motors are very clean with no corrosion. Or t least none visible. LOL.

Shamelessly BTTT. I was hoping for more replies on this one.

Thanks.

WHat is the service interval on those on that engine? I owned one and admittedly never did it...

Does it need it? Here is a shot of the core, it's super clean.

My motors run at 170 to 175 degrees at 2,900 rpm. About 165 at 1,800.

The Port cooler is leaking a little around the aft cap, maybe I could just pull the caps, grease, and replace the gaskets?

Thanks,
Doug

Edit. I can never get pics to upload, it always says "the png image has the incorrect file extension" any advice?

Thanks

Dougcole said:

Edit. I can never get pics to upload, it always says "the png image has the incorrect file extension" any advice?

Thanks

Click to expand...

Do you start by pressing "Manage attachments"???

We just use a descaler solution to clean out the salt water side and turbo wash procedure for the freshwater, eventually will replace complete unit when reaches 20 year.

Dougcole said:

Does it need it? Here is a shot of the core, it's super clean.

Click to expand...

Is this shot to be, of the core after it has been removed? If so great, that means that you don't have any oil or soot on the air side of the tubes.

But if it is of the tube sheet only and you haven't seen the air side, you may be in for a surprise. So yes it needs it.

You remove the core so you can clean the air side. But more importantly by removing it you can see if there is any corrosion that could compromise the core to shell joint. If it leaks, it can trash your engine.

Always pressure test after reassembly.

David

djmarchand said:

Is this shot to be, of the core after it has been removed? If so great, that means that you don't have any oil or soot on the air side of the tubes.

But if it is of the tube sheet only and you haven't seen the air side, you may be in for a surprise. So yes it needs it.

You remove the core so you can clean the air side. But more importantly by removing it you can see if there is any corrosion that could compromise the core to shell joint. If it leaks, it can trash your engine.

Always pressure test after reassembly.

David

Click to expand...

Thank you for your reply, David, very helpful.

Yes, the pic is of the end plate of the bundle, it is very clean but I think I understand now what you are saying about the air side and the seal between the bundle and the shell.

Question though, is there a way to pressure test the cooler after reassembly without pulling it?

It sure would be a lot easier to just pull the core, well within my abilities.

I got a quote from my mechanic on pulling both coolers and servicing them. $1,000 just for labor. Ouch.

I just spent $2,300 on a brain box for my stb micro commander controls, so my boat bucks are used up for a while.

Baker said:

Do you start by pressing "Manage attachments"???

Click to expand...

Yes, I did. I then browsed, found the file, and tried to upload it, that's when I got the error message. It happens every time I try to upload a pic on the site.

Dougcole said:

Question though, is there a way to pressure test the cooler after reassembly without pulling it?
It sure would be a lot easier to just pull the core, well within my abilities

Click to expand...

Maybe. I am not really familiar with the 4LH but from pics I have seen, the after cooler is just a simple round shell and tube heat exhanger and is not tightly integrated with very short hoses like the 6LY is. You have longer hoses on the 4LH that can be removed to access for pressurization.

So, maybe you could pull the core with the shell in place, clean it inside and out and reassemble with new o-rings and lots of grease. Then remove the r/w hoses and pressurize the tube side with with pipe plugs or whatever and hold the pressure for 15 minutes to see if it drops.

$1,000 for labor to do two after coolers is not a bad estimate. It took me 6-8 hours to do one after cooler with complete removal. And as I remember you have some problem bolts to deal with.

David

Try....
Go Advanced (button on bottom of quick reply box)
Hit the attachment button (paper clip) not the Insert Picture button
Select your ,png file (make sure it is not larger than 195 kb)
Hit upload and wait until it is finished uploading.
Close the window and select 'preview' to ensure all is as you would like it and then submit.