Outdoor Power Equipment and Small Engines - Compression Test

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jsouth
05-28-07, 04:16 PM
Just curious I have a B&S MAX 3.5 H.P. snapper push mower model #90708 type 0071 I check the compression shows 30# on my gauge,I put about a teaspoon of oil in the cylinder,compression showed no change.It starts on the first pull,my question is has anybody had this low of compression on a mower to have it to start.This is my first most of the other mowers shows 55 or above.I know about the compression release but I still get above 55# on other mowers.Also do the flywheel rebound to check compression.Year is a 89 model.

Thanks,
Jerry

repair_guy
05-28-07, 04:45 PM
Jerry,Like you I stell rely on a good old fashioned compression gauge.But at 30 Lbs. and the engine cranks???I think that there's something wrong with your gauge.Normanly that fiding would mean that the rings was shot.

And yes flywheel rebound is supposed to check compression on newer engines.(1990 + up to today) so they say.
jsouth
05-29-07, 01:09 PM
Repair guy the gauge is new just bought it,I did check it with my old gauge and it showed the same reading,I did check other mower tvs 90 3.5 horse power and it showed 55# don't figure.

Jerry

puey61
05-30-07, 03:34 AM
Compression that low, and start? Sure, but I'd bet your down to about 1 1/2 or 2 horsepower though!
jsouth
05-30-07, 07:51 AM
puey61 never thought about that,mower still seems to be running strong.

Thanks,
Jerry