mrsaundep
Seaman
- Joined
- Jun 9, 2009
- Messages
- 55
Hi,
I am new on here. I bought a boat 2 years ago with an existing engine problem. It has the following drive;
Engine
Make Mercruiser
Model MCM 140
Serial number 5568367
Displacement 181 CID
Stern drive
Make Mercruiser
Type Alpha 1
Serial number OB656591
I rebuilt the ignition system and replaced the HT leads as the old ones were cheapo auto parts, reset the timing, tuned it up as per the manual, and have had two years trouble free running from it since.
I lifted her out of the water this month to strip the outdrive for an inspection and to change the water pump impeller. (I also need to remove the engine (not had time to get it out as yet) to change the front crankshaft oil seal (leaking) and the engine mounts (as they are worn)).
I have the correct manuals (#3 for the sterndrive and #6 for the engine), and am buying (or making) special tools as I go.
The oil level in the outdrive was correct before I pulled it and there were no external leaks. The oil was a very nice dark grey (not quite black) colour, with no emulsification at all. The magnet on the drain plug was clean (save for some very small particles. The gears engage nicely and the drive shafts turn freely with no abnormal noise. I pulled the outdrive and split the upper and lower units.
I stripped out the water pump, rebuilt it with a new overhaul kit including impeller, body assembly, face plate and associated gaskets etc.
I did note that with the water pump off, the drive shaft in the lower unit (the shaft with the impeller on it) had quite a bit of axial movement, which I later measured to be 1.4mm.
Before reassembling, I made a rig up and pressure tested the upper and lower units separately, to 15psi, whilst turning the drive shafts. The upper gear housing was fine and passed the press test.
The lower gear unit (prop shaft) was found to be leaking from the water pump through the top of the pump body between body and shaft (beneath the rubber slinger). I pulled the pump body and water pump base plate, so I could see the oil seal, applied air again, and it is definitely leaking through the shaft seal. Pulled the shaft seal, the seal looks good, lip not worn, still supple, and the spring is intact. The shaft is not worn or grooved where the seal sits on it. I will buy and a fit a new oil seal (2 seal and an ?O? ring).
I prised the top race of the tapered roller bearing assembly (item 21) off, the inner bore of this is smooth, all the rollers are intact, and the bearing looks good. Apart from the fact that it has an axial clearance of 1.4mm side to side. I can also lift the shaft up by approx 0.5mm.
So, my question is, do I need to replace the tapered roller bearing, or is the apparently excessive clearance normal?
I am new on here. I bought a boat 2 years ago with an existing engine problem. It has the following drive;
Engine
Make Mercruiser
Model MCM 140
Serial number 5568367
Displacement 181 CID
Stern drive
Make Mercruiser
Type Alpha 1
Serial number OB656591
I rebuilt the ignition system and replaced the HT leads as the old ones were cheapo auto parts, reset the timing, tuned it up as per the manual, and have had two years trouble free running from it since.
I lifted her out of the water this month to strip the outdrive for an inspection and to change the water pump impeller. (I also need to remove the engine (not had time to get it out as yet) to change the front crankshaft oil seal (leaking) and the engine mounts (as they are worn)).
I have the correct manuals (#3 for the sterndrive and #6 for the engine), and am buying (or making) special tools as I go.
The oil level in the outdrive was correct before I pulled it and there were no external leaks. The oil was a very nice dark grey (not quite black) colour, with no emulsification at all. The magnet on the drain plug was clean (save for some very small particles. The gears engage nicely and the drive shafts turn freely with no abnormal noise. I pulled the outdrive and split the upper and lower units.
I stripped out the water pump, rebuilt it with a new overhaul kit including impeller, body assembly, face plate and associated gaskets etc.
I did note that with the water pump off, the drive shaft in the lower unit (the shaft with the impeller on it) had quite a bit of axial movement, which I later measured to be 1.4mm.
Before reassembling, I made a rig up and pressure tested the upper and lower units separately, to 15psi, whilst turning the drive shafts. The upper gear housing was fine and passed the press test.
The lower gear unit (prop shaft) was found to be leaking from the water pump through the top of the pump body between body and shaft (beneath the rubber slinger). I pulled the pump body and water pump base plate, so I could see the oil seal, applied air again, and it is definitely leaking through the shaft seal. Pulled the shaft seal, the seal looks good, lip not worn, still supple, and the spring is intact. The shaft is not worn or grooved where the seal sits on it. I will buy and a fit a new oil seal (2 seal and an ?O? ring).
I prised the top race of the tapered roller bearing assembly (item 21) off, the inner bore of this is smooth, all the rollers are intact, and the bearing looks good. Apart from the fact that it has an axial clearance of 1.4mm side to side. I can also lift the shaft up by approx 0.5mm.
So, my question is, do I need to replace the tapered roller bearing, or is the apparently excessive clearance normal?
