Jet Slicker
New Member
Hey everyone. I have a 1998 Challenger 1800 with the twin 787's. The boat actually had decent jet performance and only mild cavitation after I bought it. Stock impellers. I really could have left it alone, but I always want things to be the best they can be, lol. So I purchased brand new Solas Concord impellers (Stock pitch), new wear rings with the lip (Titan 757 Performance), and new neoprene seals. I found an OEM service manual for the boat too.
Removing the pumps, everything looked pretty decent. There were NO neoprene seals or RTV though. The wear rings that were on the boat did have the lips, and seemed to seal well since there was only mild cavitation at most. Also, the port side driveshaft was much more wobbly in the PTO than the starboard side. I see that they are supposed to wiggle though. I just don't know how much.
I installed the new parts 100% to spec and torqued everything down with quality torque wrenches to factory specs. When torquing the pump to the hull (24ft/lbs), there was creaking/cracking noises coming from the plastic jet pumps. I was a bit worried, but continued anyways since I was doing everything to factory spec. The port side creaked/cracked more than the starboard side. I did not find any actual cracks or stretch marks on the pumps.
I put the boat in the water, confident I will have perfect propulsion now. But NOPE, there is extreme cavitation and the boat struggles to plane out... The port side has worse cavitation than the starboard side. If I go full throttle, the port side goes right to rev limiter and really only starts providing thrust over 25mph. The starboard side isn't much better..
Pulling the boat back out of the water, the impellers have worn into the left and right sides of the wear rings, but NOT the top or bottom at all. The sides have been shaved down like 1/16th of an inch, and the top and bottom look brand new. The port side has shaved more away than the starboard. It seems that the sides are way too tight. Maybe the pump warped/bent when torquing? I loosened the nuts on the port side pump, down to maybe 15ft/lbs, and it changed nothing with cavitation.. There was no uneven wear on the stock setup I pulled off of the boat.
I see these boats do not come with a neoprene ring from the factory, but everybody seems to put them on. Could the ring have provided too much gap that the pump needed to make up, so there ended up being more torque to the pump mounts to meet the hull and it bent the pump in? Or what on earth could make this happen?
For now, I bought some used large hub pumps and matching Solas impellers. I also went with new carbon seal kits and driveshaft bumpers. I plan to reinstall without the neoprene seals. Before I potentially destroy another set of pumps, does anybody know what happened here? Any help is appreciated!
-Randy
Removing the pumps, everything looked pretty decent. There were NO neoprene seals or RTV though. The wear rings that were on the boat did have the lips, and seemed to seal well since there was only mild cavitation at most. Also, the port side driveshaft was much more wobbly in the PTO than the starboard side. I see that they are supposed to wiggle though. I just don't know how much.
I installed the new parts 100% to spec and torqued everything down with quality torque wrenches to factory specs. When torquing the pump to the hull (24ft/lbs), there was creaking/cracking noises coming from the plastic jet pumps. I was a bit worried, but continued anyways since I was doing everything to factory spec. The port side creaked/cracked more than the starboard side. I did not find any actual cracks or stretch marks on the pumps.
I put the boat in the water, confident I will have perfect propulsion now. But NOPE, there is extreme cavitation and the boat struggles to plane out... The port side has worse cavitation than the starboard side. If I go full throttle, the port side goes right to rev limiter and really only starts providing thrust over 25mph. The starboard side isn't much better..
Pulling the boat back out of the water, the impellers have worn into the left and right sides of the wear rings, but NOT the top or bottom at all. The sides have been shaved down like 1/16th of an inch, and the top and bottom look brand new. The port side has shaved more away than the starboard. It seems that the sides are way too tight. Maybe the pump warped/bent when torquing? I loosened the nuts on the port side pump, down to maybe 15ft/lbs, and it changed nothing with cavitation.. There was no uneven wear on the stock setup I pulled off of the boat.
I see these boats do not come with a neoprene ring from the factory, but everybody seems to put them on. Could the ring have provided too much gap that the pump needed to make up, so there ended up being more torque to the pump mounts to meet the hull and it bent the pump in? Or what on earth could make this happen?
For now, I bought some used large hub pumps and matching Solas impellers. I also went with new carbon seal kits and driveshaft bumpers. I plan to reinstall without the neoprene seals. Before I potentially destroy another set of pumps, does anybody know what happened here? Any help is appreciated!
-Randy
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