Gone_Fishin_
Recruit
- Joined
- Apr 28, 2011
- Messages
- 2
Hello,
A friend and I purchased a 16' 1970 Hourston Glasscraft that had a 1977 70hp Johnson on it, we recently put a jet pump onto the motor and within a few weeks had the motor blow a whole in the block on the lower 3rd piston. Now the motor was previously used in salt water for years and the owner never bothered to clean or take care of it. We got this for very cheap and we were kind of expecting it to crap out as it was severly pitted and worn out.
We have found another 1977 70hp Johnson that was in a fellows garage for 5 years, was taken off and stored properly. We did a compression test and it ran at 115 in all 3 cylinders. We installed our jet pump and went to try the motor. It started up perfectly fine and had no idle problems or anything else that we can see.
At idle the motor wants to push real good, has strong thrust and seems to run very well. When we excellerate the motor sounds really strong and like it is runnning at full rpms but it will not move the boat well, it bogs down the rear end of our boat and is like were getting no thrust. The jet pump worked perfectly fine on our other motor and put the boat on plane very nice. (we did raise the motor so the pump foot is 1/4inch below hull) we are not having cavation problems and the dump is not flipping up and causing reverse/forward thrust. We have pulled the jet pump completely apart (more then once), checked the bearings, replaced the seals and adjusted the shims correctly.
The pump is working just fine (we believe), idles nice and really wants to push us along. When we give the motor throttle it again sounds perfectly fine and revs right up but we seem to be losing thrust and not moving anywhere. Is it possible were not running on all cylinders? do we need to do a carb rebuild kit? we have the other cracked block motor that has decent looking carbs/parts on it. The spark plugs all look good, it is not missing, idles perfect, throttle works good, just no go !
If anyone can please help us as we are completely stumped on where to look or what to check. We can not finacially bring this into a repair shop and are both very mechanically inclined at fixing things and such, but have not worked on boat motors in the past so were not sure where to start.
If someone can help it would be greatly appreciated, thank you for your time and consideration in reading this post.
Happy boating and tight lines to all !
A friend and I purchased a 16' 1970 Hourston Glasscraft that had a 1977 70hp Johnson on it, we recently put a jet pump onto the motor and within a few weeks had the motor blow a whole in the block on the lower 3rd piston. Now the motor was previously used in salt water for years and the owner never bothered to clean or take care of it. We got this for very cheap and we were kind of expecting it to crap out as it was severly pitted and worn out.
We have found another 1977 70hp Johnson that was in a fellows garage for 5 years, was taken off and stored properly. We did a compression test and it ran at 115 in all 3 cylinders. We installed our jet pump and went to try the motor. It started up perfectly fine and had no idle problems or anything else that we can see.
At idle the motor wants to push real good, has strong thrust and seems to run very well. When we excellerate the motor sounds really strong and like it is runnning at full rpms but it will not move the boat well, it bogs down the rear end of our boat and is like were getting no thrust. The jet pump worked perfectly fine on our other motor and put the boat on plane very nice. (we did raise the motor so the pump foot is 1/4inch below hull) we are not having cavation problems and the dump is not flipping up and causing reverse/forward thrust. We have pulled the jet pump completely apart (more then once), checked the bearings, replaced the seals and adjusted the shims correctly.
The pump is working just fine (we believe), idles nice and really wants to push us along. When we give the motor throttle it again sounds perfectly fine and revs right up but we seem to be losing thrust and not moving anywhere. Is it possible were not running on all cylinders? do we need to do a carb rebuild kit? we have the other cracked block motor that has decent looking carbs/parts on it. The spark plugs all look good, it is not missing, idles perfect, throttle works good, just no go !
If anyone can please help us as we are completely stumped on where to look or what to check. We can not finacially bring this into a repair shop and are both very mechanically inclined at fixing things and such, but have not worked on boat motors in the past so were not sure where to start.
If someone can help it would be greatly appreciated, thank you for your time and consideration in reading this post.
Happy boating and tight lines to all !