paradak
09-24-2022, 09:25 AM
I decided to tear down and rebuild my 1985 2.4L vertical reed chrome bore 175. While it seemed to run strong, I heard piston slap that concerned me. After tear-down I found it needed 6 pistons/rings. I think I tore it down just in time as I believe it would have self destructed if I had run it as is. I did the following:
Complete disassembly of powerhead
Verified all bores are original standard size chrome cylinders, no sleeves.
All pistons were scuffed quite a bit and the rings were shot.
Bores were acceptable in their current condition. I could not justify the cost of sleeves or re-plating for this boat.
Removed aluminum from the chrome bores with muriatic acid, cleaned the bores with scotchbrite pad
Verified out of round and taper to be less than 0.006". Worst case was 0.004 out of round just above the ports. At the top of the cylinders, bores were 0.002 or less out of round.
Cleaned the whole block with soap and water paying special attention to sealing surfaces.
Installed 6 new pistons (standard size), rings, connecting rod upper and lower bearings, top and bottom crank seals, upper and lower cap O-rings all rod bolts.
Crankshaft and Crankshaft bearings looked fine.
Reeds looked fine.
I had previously rebuilt the carbs, fuel pump, poppet valve, removed the oil injection and idle stabilizer so no new work there.
I also had the heads milled just enough to ensure flatness (not to increase compression)
Verified all check valves in the reed block were operating properly
Replaced all bypass lines with Tyvek tubing
Compression on all cylinders was 125PSI upon installation and prior to starting. I could not even discern a 1 psi variation. The motor fired right up the first time. I had to reseat the poppet valve (slight leak from the weep hole) but other than that, all seemed to be OK.
Here are a few photos taken during the rebuild. It was fun bringing this 36 year old motor back to life. There is also a link to youtube for videos on the lake. Keep in mind this is the first run of the motor other than 5 minutes in the tank so I am taking it easy on it to break it in. More break-in required.
https://www.youtube.com/playlist?list=PLi2Pg9tR0AlLGsrhTn_cmBCk10Dqhki3q
I have lots of pictures taken with the motor apart if anyone needs any specific areas for reference. I will be glad to see if I have them, PM me.
Complete disassembly of powerhead
Verified all bores are original standard size chrome cylinders, no sleeves.
All pistons were scuffed quite a bit and the rings were shot.
Bores were acceptable in their current condition. I could not justify the cost of sleeves or re-plating for this boat.
Removed aluminum from the chrome bores with muriatic acid, cleaned the bores with scotchbrite pad
Verified out of round and taper to be less than 0.006". Worst case was 0.004 out of round just above the ports. At the top of the cylinders, bores were 0.002 or less out of round.
Cleaned the whole block with soap and water paying special attention to sealing surfaces.
Installed 6 new pistons (standard size), rings, connecting rod upper and lower bearings, top and bottom crank seals, upper and lower cap O-rings all rod bolts.
Crankshaft and Crankshaft bearings looked fine.
Reeds looked fine.
I had previously rebuilt the carbs, fuel pump, poppet valve, removed the oil injection and idle stabilizer so no new work there.
I also had the heads milled just enough to ensure flatness (not to increase compression)
Verified all check valves in the reed block were operating properly
Replaced all bypass lines with Tyvek tubing
Compression on all cylinders was 125PSI upon installation and prior to starting. I could not even discern a 1 psi variation. The motor fired right up the first time. I had to reseat the poppet valve (slight leak from the weep hole) but other than that, all seemed to be OK.
Here are a few photos taken during the rebuild. It was fun bringing this 36 year old motor back to life. There is also a link to youtube for videos on the lake. Keep in mind this is the first run of the motor other than 5 minutes in the tank so I am taking it easy on it to break it in. More break-in required.
https://www.youtube.com/playlist?list=PLi2Pg9tR0AlLGsrhTn_cmBCk10Dqhki3q
I have lots of pictures taken with the motor apart if anyone needs any specific areas for reference. I will be glad to see if I have them, PM me.