compression testing\engine reliability

[garymack777]

hi folks,
great forum,

i have an 1978 mariner 115 2 stroke,shes a 6 cylinder ,she seems to be running ok now after an eventfull year of various problems.
anyhow i believe that to do a compression test on each cylinder will give me an accurate idea of how the engine is running and in turn give me a little more confidence while out on the boat.

i believe that an even compression across all cylinders is the best result is this correct?also are all compression testing guages gerneric.i.e can they be used on
different engines or are they specific to the exact engine?is there any good places to get them online?

finally( i realise im pushing it here)what roughly under normal sea\wind conditions should that engine consume in fuel in gallons\litres??
i know there are probably a lot of variables here so even a rough hint would be great.and any help at all on the above would be fantastic

thanks again for a great site and happy,safe boating!
Gary

 

[Silvertip]

Re: compression testing\engine reliability

A compression test is a measure of the relative quality of the sealing of each cylinder including the ring seal. While it is a general indication of overall engine health, there are many other things determine how well the engine actually runs. Low compression however will prevent an engine from making its maximum power. Compression gauges are generic and are not specific to any engine. You can buy them at virtually any store that sells auto parts. Your engine will burn about 11.5 gallons of fuel per hour at wide open throttle. The general rule of thumb is 10% of rated horsepower and that applies to any outboard -- two or four stroke. The size of the boat, type of hull, load and speed are all factors that affect fuel consumption.

 

[garymack777]

Re: compression testing\engine reliability

thanks for the help!

rgds