The exhaust outlet was heavily corroded and I noticed a crack had appeared in it - time for replacement.
|Finally got the old elbow off leaving three broken bolts in situ.|
The fixing bolts were M8 mild steel and might as well have been made of chocolate as three of them sheared off as soon as I put the spanner onto them. After a bit of sawing and hacking I got the elbow off.
|Remains of the elbow after my hacksaw had done its stuff|
The reason why the corrosion was so bad soon became apparent; the heat exchanger and elbow are made of aluminium alloy and were jointed by a copper-faced gasket.. doh!
|Copper faced gasket had been used on original assembly|
I had to remove the whole heat exchanger from the engine and put it on the bench to tackle the removal of the broken bolts. It was assumed that these would need to be drilled out and the trashed holes would need to be 'Helicoiled', however, to my surprise I got all four out and cleaned up the blind holes with a tap. A new elbow and joint gasket were sourced from Beta Marine - the new gasket was fibre. Instead of using new bolts I 'Locktighted' M8 threaded studs into the holes in the casting and bolted it up with nuts and washers - hopefully making it easier to remove next time.
|Studs fitted once mating face had been cleaned up|
|New elbow fitted to heat exchanger|