Compression Test

[Ken Juul]

I don't seem to be making as much power and getting a lot of black smoke at full throttle.  Think I need to do a compression test.  Should I remove the glow plug or injector for the gauge?  Anybody know what size it is?

[lucky]

remove nozzles and check thread size at a store that sells only bolts and nuts.black smoke is not lack of compression,that should be blueish white smoke,pull oil fill cap and look for blow by.GOOD LUCK
lucky
hull 13

[Paulus]

Ken,  Went through the same process.  In 2013 realized that I did not have as much power or speed, a lot more black smoke. In 2014 I noticed a significant about of loss and a lot of black smoke.  This lead to a rebuild transmisson.  I did have my compression checked.
Easy way to check if it is the transmission:  secure it in the slip and start the engine and have someone put it in forward increasing the throttle as you watch to see if the shaft turns faster. (probably not very scientific)
Paul

[Ron Hill]

Ken : Black smoke usually means the engine is being overloaded for the amount of fuel. Overload (dirty bottom/prop) Insufficient air (restriction), Excessive fuel (defective injector/s)

Hope this helps!!

[Paulus]

Ken, let us know what you find.
Thanks,
Paul

[sailaway]

Another way of compression test is to use a temp sensor gun when the engine has been running for awhile shoot all the cylinder heads they should be the same temp. Not as good as a compression test but a good start.  A lot of the engine survey are done this way now. Charlie

[Ken Juul]

I don't normally clean the engine air filter until the foam filter on the outside needs to be changed.  Thinking about what Ron and Lucky said, I decided to pull the unit and check it.  Surprise!  The stainless steel wool inside is beginning to flake and the screen in the bottom was almost completely blocked.  Another chore to add to the spring recommission checklist!  Started the engine, at the dock in gear can get 2700 rpms at full throttle, normal underway is 2900 so I think the problem is solved.  Used the temp gun to check all the cylinders, they were within 3 degrees of each other so I think other than having 2200 hours on it all is fine.

[KWKloeber]

The stainless mesh can be replaced with roller store stainless steel pot "scrubbies"

kk

[Ken Juul]

Thanks Ken, I was going to look at Ace but the roller (Dollar?) store is closer.

[KWKloeber]

Darn Siri is just not cooperative at all'


NAPA has small engine foam filters that fit, though I don't know the p/n.


kk

[Stu Jackson]

NAPA has small engine foam filters that fit, though I don't know the p/n.

http://c34.org/bbs/index.php/topic,7370.msg50214.html#msg50214

[KWKloeber]

Stu


Interesting, but I'm a little confused by your prior post. Could you clarify because I suspect this will pertain to my engine also?


You say you had the old, round style, no air horn?  That originally came with A foam a pre-filter.


You said you replaced it with another? Round?. Are you saying a whole new housing?
Or just a filter that fits inside the round coffee can? Or simply replace the  foam outside?


Thanks
Ken

Our 1986 M25 came with the "old style" round filter, no snoot.  We replaced it with the new style with the foam filter.  That filter can be replaced at Napa auto with a Briggs & Stratton filter piece.  Napa 7-02278 Pre-filter, replaces B&S 270782, 271794 pre-filter for 7-02210

« Last Edit: June 30, 2015, 01:05:14 PM by Stu Jackson »
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

[Noah]

CD sells both the full can kit and the foam sleeve, if you want to go that route.

[Stu Jackson]

You said you replaced it with another? Round?. Are you saying a whole new housing?
Or just a filter that fits inside the round coffee can? Or simply replace the  foam outside?

Old style vs. new style was inscribed in the parts manual from our local Universal dealer when I bought the new filter in 1999.   My filter is horizontal on our M25.

[KWKloeber]

 Very interesting Stu. Do you happen to have a photo of that?