Reply
 
Thread Tools Search this Thread
 
Old 12 July 2009, 14:48   #1
Member
 
Country: UK - Scotland
Town: Queensferry
Make: Northcraft/Osprey
Length: 5m +
Join Date: Jun 2009
Posts: 31
Suzuki DT4 (2-stroke) strange noise.

OK...how do I describe a strange noise??

Engine starts and runs fine, but if opened up past about 1/3 throttle, it starts making a horrible noise/vibration. Goes away when throttle closed.
A number of knowlegeable people have listened, and declared that it was most likely a problem with the main bearings.
I dismantled the engine, replaced the bearings and started it this morning.

Same noise...

I now get the impression that it could possibly be coming be from the lower leg, and suspected it was coming from a partially engaged gear. (It's that sort of noise....like in a car when you try and engage gear with the clutch not fully depressed)
Checked the rod adjustment, and tried the gearshift in various positions...no change.
Set it up in a big water tank, and tried it in gear. Prop turning fine, and same noise.

Has anyone experienced anything like this?
__________________

__________________
Douglas C is offline   Reply With Quote
Old 12 July 2009, 17:57   #2
Member
 
Country: UK - Wales
Town: West Wales
Make: Vipermax 5.8, SR4.7
Length: 5m +
Engine: 150 Opti, F50EFi
Join Date: Sep 2005
Posts: 6,298
Could be a knackered (tech term ) bearing on the bottom of the driveshaft, or on the propeller shaft.
__________________

__________________
Downhilldai is offline   Reply With Quote
Old 13 July 2009, 01:55   #3
Member
 
Country: UK - Scotland
Town: Queensferry
Make: Northcraft/Osprey
Length: 5m +
Join Date: Jun 2009
Posts: 31
Quote:
Originally Posted by Downhilldai View Post
Could be a knackered (tech term ) bearing on the bottom of the driveshaft, or on the propeller shaft.
Bottom unit coming off tonight.
Driveshaft more likely than the propellor one, as it makes the noise in neutral.
__________________
Douglas C is offline   Reply With Quote
Old 13 July 2009, 08:20   #4
Member
 
Country: UK - Wales
Town: West Wales
Make: Vipermax 5.8, SR4.7
Length: 5m +
Engine: 150 Opti, F50EFi
Join Date: Sep 2005
Posts: 6,298
If the lower unit is at fault, this may be of interest to you:

http://cgi.ebay.co.uk/SUZUKI-4HP-GEA...A3%7C294%3A100

__________________
Downhilldai is offline   Reply With Quote
Old 20 July 2009, 16:02   #5
Member
 
Country: UK - Scotland
Town: Queensferry
Make: Northcraft/Osprey
Length: 5m +
Join Date: Jun 2009
Posts: 31
Ok,
Think i've diagnosed the cause.
Discovered that a rubber bushing about half way up the driveshaft had dropped down. The driveshaft had a mark where it had rubbed against the lower leg casting where it passes through the hole where the bushing should be.
I can only assume that the driveshaft starts vibrating and flexing at a certain engine speed, causing the horrendous noise.
Stuck the bushing back with silicone to see what happened....no noise.
Will get a new one soon. :-)

Douglas
__________________
Douglas C is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:23.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.