engine runs great unless the drive is installed

[davidh86]

ive been trouble shooting a heating problem that required the drive to come off a few times but now when i install the drive the idle gets inconstant and rough and dies out. This wasn't an issue a few days ago, it only happend when i took off the upped unit and reinstalled the other day. i checked the control and shift cable and their perfect and even remover the top cover of the upper unit and the gears had clean sharp edges. Oh this is a 1978 mercruiser 228 with a 305 and it runs great with a hose in the bell housing and a the drive off.

 

[Grub54891]

Re: engine runs great unless the drive is installed

Lets see some pics of them gears,clean sharp edges? As in pointy or just normal.... Also there could be a restriction in the exhaust making er run funny.
Grub

 

[davidh86]

Re: engine runs great unless the drive is installed

Ill try to take pics later tonight but they looked normal and the with it separated from the lower unit i was able to turn the drive shaft and watch them move freely with not much effort. This all started when i was working on a overheating problem and took out the unit off the bell housing to put a hose in the inlet to trouble shoot, i think the engine shifted after the test since the drive was alot harder to re install than it usually is an the boat was shaking in idle. Before i left for work i noticed an engine mount bolt was loose, thats why im thinking an alignment issue.

 

[NHGuy]

Re: engine runs great unless the drive is installed

Well get yourself an alignment bar and use it whenever the drive is off. Don't just run it without being sure it's lined up. If it's run misaligned you'll be buying parts AND aligning it after they are replaced.
You could still have the roughness issue after that, but the alignment has to be right first of all.

 

[davidh86]

Re: engine runs great unless the drive is installed

Well get yourself an alignment bar and use it whenever the drive is off. Don't just run it without being sure it's lined up. If it's run misaligned you'll be buying parts AND aligning it after they are replaced.
You could still have the roughness issue after that, but the alignment has to be right first of all.

Ill be ordering the alignment tool today since their's a 3 week wait for any half decent marine mechanic now lol.

 

[davidh86]

Re: engine runs great unless the drive is installed

Just got the tool today and noticed when i put the tool through the gimbal bearing it shifts the Bearing at any angle i insert the tool, just wondering if is normal?

 

[achris]

Re: engine runs great unless the drive is installed

Just got the tool today and noticed when i put the tool through the gimbal bearing it shifts the Bearing at any angle i insert the tool, just wondering if is normal?

Yep, that's why it's called a 'gimbal' bearing.

 

[davidh86]

Re: engine runs great unless the drive is installed

ok i guess the engine running fine with the drive off was just a coincidence, i started up the engine other day with the drive off again and it had the same issue as it did with the drive on. Im guessing its the ignition system is the problem since its still running on points and the misfiring /shaking seems to be a symptom of a failing ignition system so i just ordered an electronic conversion and upgraded coil. The only reason i dont think its more serious issue is because i performed a compression test and got about 140 psi per cylinder.