Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-07-2015, 20:02   #16
Guy
Registered User

Join Date: Feb 2013
Location: So. Oregon, USA
Boat: Seafarer36c
Posts: 4,308
Re: Wobbling crankshaft??

Bummer. The front seal has no real pressure on it, just crankcase pressure, which should not be much.
__________________

__________________
Guy is offline   Reply With Quote
Old 26-07-2015, 20:13   #17
Registered User

Join Date: Jun 2015
Posts: 16
Re: Wobbling crankshaft??

Yep. Stinks. Eating into my re-fit budget for the rest of the work needed. Everyone I talk to says the same thing; "welcome to boating". Its to be expected I guess.
__________________

__________________
Ten87 is offline   Reply With Quote
Old 27-07-2015, 17:59   #18
Registered User
 
MBWhite's Avatar

Join Date: Apr 2012
Location: Illinois
Boat: Hurley Alacrity
Posts: 370
Re: Wobbling crankshaft??

So how did the crankshaft get bent, lightning?

Let me preface this with the fact that I am on dial up at the moment and the browser bounces around a bit so apologies if I post something already written as it is hard to read the entire thread continuously.

Anyway, crankshafts do not just bend by themselves. So it either got bent somehow or the crank pulley is not on straight and the wobble is from the misalignment.

A couple of ways to figure it out, simplest but least accurate is to remove the pulley and replace just the bolt, turn over the motor and see if the bolt is spinning centered or moving around in a circular motion. If it is wobbly there then you can decide whether to see if you can straighten it yourself of if you want to send the crank out for professional straightening, rebalancing, and new bearings with a possible crank regrind. If money is a minimal obstacle to you that is what I'd suggest doing.

If worn bearings are the cause of your wobble I'd still strongly recommend sending the crank out for an inspection for any journal out of roundness and possibly magnafluxing for cracks.

However, if the crank has been bent due to abuse either by dropping something heavy on it or more likely someone using a hydraulic jack to lift the engine up and either overdoing it or forgetting to loosen a motor mount AND funds are short at the moment or you are in the middle of nowhere, it is possible to use a jack to carefully bend the crankshaft back to center. You will need to borrow or purchase a dial indicator with a base, but magnetic base indicators are available on ebay for $15 and up.

Straightening a bent crankshaft is not an undertaking to be casual about but it is within the abilities of most people who can pay attention to detail.
__________________
MBWhite is offline   Reply With Quote
Old 28-07-2015, 05:49   #19
Registered User

Join Date: Jun 2015
Posts: 16
Re: Wobbling crankshaft??

Thanks for the reply:
It doesnt appear the crank is bent or wobbly as the tech put it; but after further investigation, doing exactly what you suggjested with just the bolt in the crank, its walking forward and aft, as well as while removing the balancer I could feel excessive vertical movement. Also no oil pressure. Motor scheduled for rebuild Aug 8th. Pulling it out this week. My guess is the crank will have to be machined or replaced at the least. Im sure a spun bearing or two has scored the journals along with other probable damage that a machine shop will have to handle. If i dont have it gone thru, I would never have confidence in it.
__________________
Ten87 is offline   Reply With Quote
Old 28-07-2015, 11:20   #20
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,645
Re: Wobbling crankshaft??

Quote:
Originally Posted by Ten87 View Post
...Motor scheduled for rebuild...My guess is the crank will have to be machined or replaced at the least...
Now you are getting up to speed.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 28-07-2015, 11:47   #21
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,037
Re: Wobbling crankshaft??

Not the best thing to do, but I have replaced worn bearings on cranks before.
Pop off the cap, install a cotter pin in the oil hole in the crankshaft, when you turn the crank this will roll out the top half of the bearing shell. Polish the bearing journal on the crank with crocus cloth and insert the bearing shell covered in white lithium grease of your favorite pre lube.
I've done this on farm tractors where to remove a crank means spitting the tractor in half, course they were wet sleeved so I could replace the pistons, rings and sleeves with the block in place too.
If it starts well, the top end isn't hurt, and by all means while your there replace the rod bearing too, and think about a new oil pump.
Best to remove the engine and do a complete overhaul though
Course if it has spun a bearing your screwed, spun bearings though are pretty rare, often means engine seizure and a ruined crank
__________________
a64pilot is offline   Reply With Quote
Old 28-07-2015, 15:58   #22
Registered User
 
MBWhite's Avatar

Join Date: Apr 2012
Location: Illinois
Boat: Hurley Alacrity
Posts: 370
Re: Wobbling crankshaft??

Quote:
Originally Posted by Ten87 View Post
Thanks for the reply:
It doesnt appear the crank is bent or wobbly as the tech put it; but after further investigation, doing exactly what you suggjested with just the bolt in the crank, its walking forward and aft, as well as while removing the balancer I could feel excessive vertical movement. Also no oil pressure. Motor scheduled for rebuild Aug 8th. Pulling it out this week. My guess is the crank will have to be machined or replaced at the least. Im sure a spun bearing or two has scored the journals along with other probable damage that a machine shop will have to handle. If i dont have it gone thru, I would never have confidence in it.
Do you have an idea how many hours are on the engine? I totally understand the need to have confidence in an engine so I will just bring this to your attention and then you can form your own opinions-

It sounds like your problems are confined to the bottom of your engine. Before you remove it you may want to take compression readings on your cylinders. If compression is within specifications it is not necessarily mandatory to do rings and valves. Leaving the top end alone will not only be cheaper (may or may not be an issue) but it will definitely get you back on the water faster. Regardless of what you choose to do, as mentioned already plan on replacing the oil pump as that is a smart thing to do on most any engine that has had lubrication issues.

Good luck!
__________________

__________________
MBWhite is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Crankshaft replacement, does it need balancing? surfmachine Engines and Propulsion Systems 23 31-07-2012 13:33
Turning Crankshaft by Hand S Y Tuppenny Engines and Propulsion Systems 4 03-02-2012 18:49
Want To Buy: Perkins 4.154 Front Crankshaft Pulley hummingway Classifieds Archive 0 05-10-2011 17:22
Wanted Perkins 4-108 Crankshaft. sailboatvern Engines and Propulsion Systems 1 21-07-2008 21:04
Wanted Perkins 4-108 Crankshaft. sailboatvern Classifieds Archive 1 21-07-2008 16:26



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:05.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.