Engine shuddering - Anyone heard of this?

[roland stockham]

Sods law says always assume a fault starts withe the last thing touched until you prove otherwise. So engine mounts, could be miss-alignment, could be over-tightened or could be shot all three can make the engine shudder and reduce power.

[MV Wanderlust]

Originally Posted by donradcliffe

Alignment should be done in the water.

I doubt the Gendinning failed--they are usually pretty reliable. Did you move the slave throttle to max after you turned it on??

Thanks, Don. Yes, I did... and it caused the slave engine RPMs to increase. The pilot light comes on but the slave throttle doesn't seem to give up control. I need to find some time to check if the solenoid is, in fact, clicking and disengaging the slave throttle cable. If it is, Glendinning said the clutch may need to be adjusted. Just need to get some time to check it.

[MV Wanderlust]

Originally Posted by Cadence

It should be done in the water and doesn't take much more than feeler gauges and acquiring a few more gray hairs however have someone do it if you haven't. JMHO

Originally Posted by a64pilot

Engine alignment is easy to check, dead easy. Little more to aligning though, but it's just trial and error from what I can tell, no real Science.
You won't really know if it's right or not if you pay someone. I did, and later found out of course that it wasn't in alignment, after pulling my hair out, cause I knew it was aligned, I just paid to have that done.

Thanks, Cadence and pilot. I'll discuss this with my local mechanic. Would rather watch it done the first time.

[MV Wanderlust]

Originally Posted by roland stockham

Sods law says always assume a fault starts withe the last thing touched until you prove otherwise. So engine mounts, could be miss-alignment, could be over-tightened or could be shot all three can make the engine shudder and reduce power.

So that's what Sod's law says?

Hmm... hadn't thought about over-tightened engine mounts. Interesting. Or the mounts on that engine could be bad. Okay. Proper use of a torque wrench will take care of any potential over-tightening. Is there an easy way to check for weak or bad mounts?

[hellosailor]

The people who make those engine mounts (Gates, Goodyear, etc.) will all tell you to check them the same way. With a calendar. Five years old? Time to change them. I know, most of us never do or will, but their policy is based on the fact that these are rubber (elastomer) parts, which harden and fatigue and age from simple heat and oxygen and chemical aging, not just from work stress. Given that you've probably got the originals, new mounts should make it smoother if nothing else. And much less likely that one of the old ones will fail at some exceptionally inconvenient time. FWIW.

[MV Wanderlust]

Originally Posted by hellosailor

The people who make those engine mounts (Gates, Goodyear, etc.) will all tell you to check them the same way. With a calendar. Five years old? Time to change them. I know, most of us never do or will, but their policy is based on the fact that these are rubber (elastomer) parts, which harden and fatigue and age from simple heat and oxygen and chemical aging, not just from work stress. Given that you've probably got the originals, new mounts should make it smoother if nothing else. And much less likely that one of the old ones will fail at some exceptionally inconvenient time. FWIW.

Thanks, sailor. A valid point.

[Cadence]

I went back and read your original post. Just as an off beat chance, check to see if he didn't just neglect to tighten down what he loosened to get that 1/4 inch. It could be over thinking a simple oversight.

[MV Wanderlust]

Originally Posted by Cadence

It could be over thinking a simple oversight.

And it wouldn't be the first time that's happened to me. Good suggestion. Thanks.

[tkeithlu]

If you tackle alignment, think about the ways the engine can be off. It can be tipped too much or too little (gap at top or bottom, while the flanges basically match all the way around). It can be too high or too low (flanges don't match but gap is same all the way around). It can be canted, with port or starboard mounts higher than the other (gaps different on the two sides, or flanges don't align side to side). This last one is because the shaft coming out of the transmission is not directly between the mounts, so raising one side of the engine does not just rotate everything in place.

Then, your working adjustment is in the lower nuts; you loosen the top ones, align, and tighten the top ones. It takes only a partial turn to make an obvious difference at your feeler gauge, although actually, you'll probably see it. Think of the process as aiming the first shaft at the second shaft.

You can do this with, as mentioned, only a few more gray hairs. I'm sorry the bottom nuts apparently weren't left in place when the engine was lifted - having them basically right makes the job a lot easier. While your doing it, consider the advantages of soft shaft connections - they absorb minor misalignments.

[MV Wanderlust]

Originally Posted by tkeithlu

If you tackle alignment, think about the ways the engine can be off. It can be tipped too much or too little (gap at top or bottom, while the flanges basically match all the way around). It can be too high or too low (flanges don't match but gap is same all the way around). It can be canted, with port or starboard mounts higher than the other (gaps different on the two sides, or flanges don't align side to side). This last one is because the shaft coming out of the transmission is not directly between the mounts, so raising one side of the engine does not just rotate everything in place.

Then, your working adjustment is in the lower nuts; you loosen the top ones, align, and tighten the top ones. It takes only a partial turn to make an obvious difference at your feeler gauge, although actually, you'll probably see it. Think of the process as aiming the first shaft at the second shaft.

You can do this with, as mentioned, only a few more gray hairs. I'm sorry the bottom nuts apparently weren't left in place when the engine was lifted - having them basically right makes the job a lot easier. While your doing it, consider the advantages of soft shaft connections - they absorb minor misalignments.

I love this forum! Such a wealth of great knowledge. Thanks, tkeithlu.

[topmast]

It's possible to align an engine and have the weight uneven Or even being held down on one corner and up on the diagonal opposite. Engine can then rocker(shudder) on the others and it won't show on the feeler. .some intuitive nut turning is helpful.Waste of time if condition of mounts is doubtful. For starters though, how about giving the messed with mount a bit of up (remember how much) and have all the top nuts slacked back . Try running ,Shudder? Aligning is only tedious Up in front causes down in back Flanges must centre and be parallel (same friction on the feeler gauge all round) Then check centres again .Soon is easy Remember to tighten all when finished

[Sailorbob8599]

I agree with those who tell you to go back to the last thing done. You did not say, & I know one should never assume ... however, I'm thinking if the problem did not exist prior to the mechanic loosening the mounts, then it most certainly is related to that procedure. If you are certain it is not a pre-existing condition, I would call the mechanic back, tell him of the new problem that has developed since he performed the impeller change & ask him to check to see if it is related to his previous work. Any mechanic worth his salt will be glad to check it out knowing every one of us are capable of 'missing' something. Be very polite in the manner in which you handle this as it is always possible something brand new has developed that was ok as long as it remained undisturbed.

[MV Wanderlust]

Originally Posted by Sailorbob8599

I agree with those who tell you to go back to the last thing done. You did not say, & I know one should never assume ... however, I'm thinking if the problem did not exist prior to the mechanic loosening the mounts, then it most certainly is related to that procedure. If you are certain it is not a pre-existing condition, I would call the mechanic back, tell him of the new problem that has developed since he performed the impeller change & ask him to check to see if it is related to his previous work. Any mechanic worth his salt will be glad to check it out knowing every one of us are capable of 'missing' something. Be very polite in the manner in which you handle this as it is always possible something brand new has developed that was ok as long as it remained undisturbed.

Morning Bob,

Thanks for the suggestion. The mechanic who did the impellers is about a four hour drive where our boat's new home. He did the work and then we left out on a repositioning trip. I called him and gently discussed the situation. He said... and this is nearly a quote... "I don't want to tell you what I think it is because I don't want you to spend three or four thousand dollars if I'm wrong." He refused to say any more. Whatever. Not the first time he pulled that secretive thing. He's too far away to use him on a regular basis, anyway.

We have a local mechanic that we have come to trust. We have relayed all of the info from these posts and he's going to take a look.

[ontherocks83]

Originally Posted by JohnEasley

We have a local mechanic that we have come to trust. We have relayed all of the info from these posts and he's going to take a look.

Oh Jeezum you didn't ,

I can assure you (ask me how I know, and no I'm not a mechanic) there is nothing more a mechanic hates more then someone asking for them to fix something and then providing recommendations from a bunch of internet experts.

I mean nothing demeaning towards CF because I love this forum and the info it provides, but Mechanics can be, lets call it "sensitive"

At my work we have people constantly coming in saying "well on line I heard this is a problem so I want you to fix that". Usually we convince them to let us do our job and diagnose, then repair it but.................every now and then if they are being extra ornery and I mean REALLY ornery (i'm talking they really have to earn it) we will fix "that" at their cost and when it doesn't fix it start over and they end up paying more in the end.

[MV Wanderlust]

Originally Posted by ontherocks83

Oh Jeezum you didn't ,

Oh Jeezum, I did.
This mechanic is a pretty good guy and doesn't seem to really be the type that would be offended. That being said...

Originally Posted by ontherocks83

At my work we have people constantly coming in saying "well on line I heard this is a problem so I want you to fix that". Usually we convince them to let us do our job and diagnose, then repair it but.................every now and then if they are being extra ornery and I mean REALLY ornery (i'm talking they really have to earn it) we will fix "that" at their cost and when it doesn't fix it start over and they end up paying more in the end.

Mine's the same way and we've done the same thing on more than one occasion for those that really earn it.