It has been two seasons since I removed the heat exchangers, plus I didn't know the age of my cast iron exhaust elbow so I decided to take everything apart after I hauled the boat for it's long winter nap.
Engine temps had been running 5 to 10 degrees warmer than normal the second part of the season so something was up.
The exhaust elbow was corroded, but still servicable. However you know it dod not come off easily. One of the 4 bolts broke off with about 3/8 inch sticking out. Trying everything including all of my auto mechanic son's stud removers, I finally had to remove the manifold, which was no easy task. The bolts came out easily, but it was a two person job lifting it out of the enigne room and down off the boat. When my son got a hold of it at his shop, it took him literally only seconds to get it out once he got the torch going.
I had another surprise when I went to remove the main heat exchanger. The bracket had seperated from the shell and only the hoses were holding that thing in place!
So I had that brazed back together and added 2 large hose clamps to help keep the bracket attached.
The tubes were not crudded up, but I ran some muriatic acid thru it to remove anything stuck to the tubes.
On a Lehman the oil and tranny coolers are the same part number, so I installed new ones only because everything else was going to be "new". The old ones were only 6 seasons old, but since I'm going cruising next summer I don't want any surprised along the way that I can prevent. (now I have 2 good spares to tote along
). The oil cooler was pretty crudded up for being only 6 years old with maybe 350 hours on it. So I'm sure that was the cause of my warmer temps.
In the spring I'll install a new impeller and that will make me good to go.
