How do you do a leak down test on 717 motor
- Thread starter rkkoeb
- Start date
I did a leak down test on my 717 with help from Mikidymac, I took the carbs off, used a piece of old inner tube to sandwich between the carbs and the intake manifold, took the exhaust off at the exhaust manifold and again sandwiched inner tube in there, and then pressurized to 6 pounds I believe, I would have to have a look at the manual or my HX thread to be sure on the psi, pressurize through the pulse fitting on the crankcase
BrianMoore
Member
Both replies are absolutely correct. By the time you get the carb and exhaust off, you are a lot of the way to having the engine out.
"trying to get a 717 motor to run right" ?
We got a 1997 GTI 717 for $1 a couple years ago. Owner had it professionally maintained, it only ran in fresh water, and it looked perfect. 2013 it wouldn't start and it sat until the son-in-law bought it in 2021. It was a clogged fuel filter in the carb. Engine had never been touched. It would do about 40 MPH and it pulled a tube with two people no problem. It did take quite a while for it to start when cold. Started OK when hot. It had a 1/4 throttle bog. I wanted to do a top end. My son-in-law's plan was run it until it died. Myself I an not a fan of swimming to shore. The condition of the engine as we bought it was low compression. Pistons rattled around in the cylinders and the ring end gaps were huge. Cylinders still had some rust after running it for a season. Rotary cover was worn to .020 and pretty chewed. I tried a pressure test with it still in the boat. I used some plywood and inner tubes as blockoff plates. I used a bicycle pump for pressure and got it to 8 PSI but it immediately dropped. Leaked to 3 PSI in about 30 seconds. That is a long winded way to say the engine was beyond tired. Now I have only this boat as experience. But this boat was running acceptably with all those problems. I put in a BRP re-manufactured short block and new rotary valve cover so it is basically completely new. It accelerates a tad harder now and it does 5 MPH more now. I would be really surprised you could have a bad enough lower seals that it would be very noticeable.
"trying to get a 717 motor to run right" ?
We got a 1997 GTI 717 for $1 a couple years ago. Owner had it professionally maintained, it only ran in fresh water, and it looked perfect. 2013 it wouldn't start and it sat until the son-in-law bought it in 2021. It was a clogged fuel filter in the carb. Engine had never been touched. It would do about 40 MPH and it pulled a tube with two people no problem. It did take quite a while for it to start when cold. Started OK when hot. It had a 1/4 throttle bog. I wanted to do a top end. My son-in-law's plan was run it until it died. Myself I an not a fan of swimming to shore. The condition of the engine as we bought it was low compression. Pistons rattled around in the cylinders and the ring end gaps were huge. Cylinders still had some rust after running it for a season. Rotary cover was worn to .020 and pretty chewed. I tried a pressure test with it still in the boat. I used some plywood and inner tubes as blockoff plates. I used a bicycle pump for pressure and got it to 8 PSI but it immediately dropped. Leaked to 3 PSI in about 30 seconds. That is a long winded way to say the engine was beyond tired. Now I have only this boat as experience. But this boat was running acceptably with all those problems. I put in a BRP re-manufactured short block and new rotary valve cover so it is basically completely new. It accelerates a tad harder now and it does 5 MPH more now. I would be really surprised you could have a bad enough lower seals that it would be very noticeable.
