ProfPinz I Need your help on heat exchanger

[milesdzyn]

Peter....Couldn't find your post relating to cutting open the outer shell of the heat exchanger. How did you cut it open, the weld seems to be along the top edge, but for rewelding it seems that cutting it along the flat just below the edge would be a better rewelding point. Just not sure of how deep off the top edge the weld has penetrated, thinking that 3mm should be right. How did you do yours?

Looking inside it looks like one of the heat fins has broken off and someone tried to reweld it in place through the outlet hole and really buggered it up. Are the fins made of weldable material?

For those of you not getting enough heat this may be some of the problem. The heat fins are critical for pulling heat away from the exhaust tubes, more surface area to pull heat off from.

Miles

[Profpinz]

G'Day Miles

How did you cut it open, the weld seems to be along the top edge, but for rewelding it seems that cutting it along the flat just below the edge would be a better rewelding point. How did you do yours?

It's going back a few years now since I modified it (11+ years) so I can't remember exactly how I "opened it up", but I think I just ground/cut the original welds with an angle grinder .... plasma cutters weren't readily available back then

Once I had "opened it" I ground the edges flat and smooth, but left a raw edge....it doesn't matter if there is a gap between the two halves when you put them back together.
I then folded a 30mm wide steel strip (1.2+ mm guage) down the centreline to make a slight angle, then hammer formed the strip around the curves of one half to make a "perimeter" .... as per the cross-section sketch below.
After that I spot welded this "perimeter" strip to the outside of one half.
Next I put the other half in position then drilled holes through the "perimeter strip" and into the half....about every 40mm.
After that I put M4 nutserts in the half using the previously drilled holes as pilots.
There are also two "baffles" in the casings that I re-fabricated and at the same time, made "screwable in position"
Finally I had the two completed halves powdercoated inside and out.

Now, I can now unscrew the M4 stainless steel bolts, remove the casings, and clean out the mud and gunk that gets inside.

Looking inside it looks like one of the heat fins has broken off and someone tried to reweld it in place through the outlet hole and really buggered it up. Are the fins made of weldable material?

My guess is that the manufacturer of the exchanger simply sand cast aluminium alloy around the pipes.... there were cold flow lines on mine on parts of the casting and a couple of the fins were short-shots, both symptoms reminiscent of this method.
I would simply MIG / TIG weld the fins back in place once the casings were removed and the part was thoroughly cleaned / sand-blasted.

You'd be surprised by the ammount of mud that builds up inside these units.... after I clean it out (every one or two years) the extra ammount of heat that comes through the heater is amazing!

Hope the above helps!

[milesdzyn]

Thanks Peter Makes sense to have it removable for cleaning.

Miles

[Kiwibru]

Peter, nice details. My H.E. has a major dent up front and I am getting ready for a new muffler / flex pipe install so this is looking like a do-able chore also.
How does mud get in the H.E. to begin with? Unless the flex hose pipes are not attached I just can't figure out how it would get in! Hmmmm...

[David Dunn]

You'd be surprised by the ammount of mud that builds up inside these units.... after I clean it out (every one or two years) the extra ammount of heat that comes through the heater is amazing!

Hope the above helps!

Peter, you wouldn't have to clean it so often if you didn't "play" U boat commander in the mud pits...
Remember, I have some DVDs of some of your outings, and can clearly hear you shout " Going to periscope depth !"

Dave Dunn

[Profpinz]

How does mud get in the H.E. to begin with? Unless the flex hose pipes are not attached I just can't figure out how it would get in! Hmmmm...

In actual fact the heat exchanger leaks like a sieve!
For interest sake, and to see how much, pull a pipe/flex off one day and fill the unit with water .... so when your driving through any dirty water/mud it gets in, then "bakes" onto the hot metal components ..... and this cycle continues over and over.
If your doing lots of muddy 4WDriving this only takes a short while, but if your not doing much it may take years to happen.
I contemplated sealing the HE to make it less suspectable to this condition, but then I figured that any muck that did find it's way in, wouldn't be able to get out, so I might make the situation worse.

....and Dave, with the water situation in Aus at the moment, those muddy puddles are becoming rare and valuable water assets, so I've packed-up the periscope for the time being