EXHAUST ELBOWS on Ford Lehman 120s

[JESSEDIVER49]

I've owned my 1984 GB Classic 42 for 9 yrs and although I had no signs of pinhole leaks, I recently changed the exhaust elbows on both my engines. I did so because of the "recommendations" from several sources that this should be done about every 5 yrs. I do not know for certain when the elbows had last been changed. Upon removal of the old elbows which again were 9+ yrs old, I could see no evidence of a thinning wall of any significance or a failure suspect area internally. My question to forum is this: has anyone had exhaust elbow failures on elbows less than 10 yrs old? And is the corrosion rate affected only by age or also by engine run time?

 

[Mike GB32]

I just happen to have removed the elbow from my FL120 because it was leaking from a crack in the casting. I believe it's been on the boat for about seven years (2 of those years with the previous owner). One of the bolts broke in the exhaust manifold so I cut the flange off the elbow and bolted it back on to use the flange as a guide to drill out the bolt.
Anyway... here's a picture of the flange. One portion of the casting is pretty thin from corrosion. No way to see that from the outside of the elbow. I'm in the north east and the boat has only been used seasonally.
View attachment elbow.pdf

 

[TJM]

I just had a failure in one of mine after 12 yrs. Rusted thru at the scallop areas where the bolt head sits. Last summer, on a long transit, 8 hrs midway we saw some salt crystals gathering on the exhaust hose. Luckily we had spares and changed it upon our arrival.
Of course, last week I changed the other elbow and snapped off two of the lower bolts, UGH !

 

[Mike GB32]

TJM-
If I may- I mentioned cutting the flange off to serve as a guide to drill the broken bolt...
I have access to a small lathe so I drilled the centers of three 3/8" bolts. One with a 1/8" hole, one 1/4" and one 5/16". Cut the bolts down to half inch long and inserted them one at a time to into the flange to act as a drill guide. Drilled with a cobalt bit and I was left with a perfectly centered hole and only had to clean up the threads with a tap. Worked perfectly. Couldn't wait to share.
Sorry about the thread creep!

 

[Cigatoo]

TJM-
If I may- I mentioned cutting the flange off to serve as a guide to drill the broken bolt...
I have access to a small lathe so I drilled the centers of three 3/8" bolts. One with a 1/8" hole, one 1/4" and one 5/16". Cut the bolts down to half inch long and inserted them one at a time to into the flange to act as a drill guide. Drilled with a cobalt bit and I was left with a perfectly centered hole and only had to clean up the threads with a tap. Worked perfectly. Couldn't wait to share.
Sorry about the thread creep!

Nice! Great solution!