Universal M35B vibration at less than 1000 rpm

Apr 2, 2015
25
Catalina 36 MK11 Dana Point
I have a 2002 Universal M35B diesel engine on my Catalina36 MK11. when the engine is in neutral and rpm is below 1000 there is what I consider to be excessive vibration . As soon as I go above 1000 and for the full range of the engine it is very smooth. Does any body have this same problem ?
 
Feb 26, 2008
603
Catalina 30 Marathon, FL
The tachs on these diesels are notoriously inaccurate.

I advance the throttle slightly until she idles smoothly.

Motor mounts can also be an issue. If yours are worn, Vetus mounts are much smoother than the stock mounts.
 
Apr 2, 2015
25
Catalina 36 MK11 Dana Point
The tachs on these diesels are notoriously inaccurate.

I advance the throttle slightly until she idles smoothly.

Motor mounts can also be an issue. If yours are worn, Vetus mounts are much smoother than the stock mounts.
Thanks, I thought that the Tach might be off. I have used the transmission at what the tach calls 1000 and it seems to shift smoothly . For peace of mind I will check the real rpm .
 
Apr 2, 2015
25
Catalina 36 MK11 Dana Point
I think you might be asking a little too much. What's wrong with idling at 900 or 1,000 if it's within the range given by your manufacturer?
The problem is when I am docking,mooring & anchoring I have to shift in and out a lot , if I don't want vibration . I am going to fast at the 1000 rpm. Just trying for a perfect world , maybe its not attainable. I was asking the question thinking there may be a fix like less restrictive fuel filtering ,I am at 10 microns. Or are the injectors in need of service etc.
 
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Apr 2, 2015
25
Catalina 36 MK11 Dana Point
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
There are some things you can do to reduce idle somewhat:

Valve clearance, fuel pump timing, injector pattern. The closer the adjustments approach factory values the lower you can press the idle speed. You might see 900 ish and smooth if these adjustments are all optimum.

Obviously clean air filter, clean fuel filters, are worth doing as well.

Charles
 
Apr 2, 2015
25
Catalina 36 MK11 Dana Point
There are some things you can do to reduce idle somewhat:

Valve clearance, fuel pump timing, injector pattern. The closer the adjustments approach factory values the lower you can press the idle speed. You might see 900 ish and smooth if these adjustments are all optimum.

Obviously clean air filter, clean fuel filters, are worth doing as well.

Charles
Thanks.
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
Be grateful our motor idles at 1000-1200. We stern in essentially always so I hear you on shifting a lot.

On the 10 micron filter, the manual calls for the prefilter to be 20 micron, IIRC.
 
Nov 5, 2009
3
tanzer 22 mainadieu
Lot's to think about. Here is one more...
I have the same boat, same problem. Turns out the plate damper, which is essentially a shock absorbing plate between engine and transmission was worn. Lot's of info on the Catalina owners site including pic's on how to change it( relatively simple).
When I replaced mine, I noticed that the spline gearing on the damper was worn, which would result in the damper plate vibrating when the engine wasn't under load, (low rpm...). This would occur because the spline was no longer snug and the wear allowed for some slack between the teeth. Thus all fine when under load backward or forward keeping teeth firmly together, but when not under load, like at low rpm, the teeth don't mesh tightly, and thus you get "rattlely vibrations"
 
Apr 2, 2015
25
Catalina 36 MK11 Dana Point
Lot's to think about. Here is one more...
I have the same boat, same problem. Turns out the plate damper, which is essentially a shock absorbing plate between engine and transmission was worn. Lot's of info on the Catalina owners site including pic's on how to change it( relatively simple).
When I replaced mine, I noticed that the spline gearing on the damper was worn, which would result in the damper plate vibrating when the engine wasn't under load, (low rpm...). This would occur because the spline was no longer snug and the wear allowed for some slack between the teeth. Thus all fine when under load backward or forward keeping teeth firmly together, but when not under load, like at low rpm, the teeth don't mesh tightly, and thus you get "rattlely vibrations"
Thanks , i will check that out. Do you have to pull the trans to fix ?
 
Jun 25, 2013
2
Catalina 36mkII St. Clair Shores MI
Likewise experiencing this on my 36 MkII. So far I have adjusted for higher idle. Under load there is a band of very rough vibration while maneuvering which I compensate for with higher rpm's and gear shifts.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
The problem is when I am docking,mooring & anchoring I have to shift in and out a lot , if I don't want vibration . I am going to fast at the 1000 rpm.
The transmissions are good up to 1,100 to 1,200 rpm.
 
Nov 5, 2009
3
tanzer 22 mainadieu
Ref: Transmission Damper
You do have to pull transmission. Very easy, few bolts and uncouple your driveshaft. Lots of pictures and guidance on the Catalina forum.