Long shot, 28 hp engine = we have the official manuals but the illustrations don't show the part of the block I need to see.
Drivers side, the top two bolts attaching the gearbox to the block, there Is a coolant leak which seems to be either from the bolt or the block mating face. the core plug just above the area is good and the leak does seem to be long established. the area has been scanned with a camera probe and no obvious cause seen, the flow definitely from below the bolt and flange.
At the front of the engine there is an expansion plug at the same level, which in the cut away view looks to be actually a drain at the bottom of the water jacket, is this plug repeated at the rear?
Short of taking the engine out I don't see a solution - pointers please, the truck is now fully restored and should be attending its first show - not risking it on the road until this leak is traced and sorted.
It would benefit from a carb - a non original one is fitted and its knackered!
