compression on rude?

TDuck · Nov 14, 2003

took my engine to a mechanic 1995 45 hp 2 cyl., he took a compression test ad the top cylinder had 125psi bottom had 135psi, he acted like this was a big difference, and something was bad wrong, is this correct, i just dont want to pay for a lot of work i dont need

ob · Nov 14, 2003

Re: compression on rude?

Those readings are acceptible.You could run a shot of OMC engine tuner (as per can instructions)through the valve on the primer solenoid and be good to go.In short,you don't have a problem.

Cricket Too · Nov 14, 2003

Re: compression on rude?

Yeah I agree with ob, those compression readings sound good to me, engine tuner would be a good idea. If I were you I wouldn't go back to that mechanic, he's either scammin you or he actually thinks that compression is bad, not sure which one is worse. Good Luck.

TDuck · Nov 14, 2003

Re: compression on rude?

my outboard motor seems to have a small problem, it is a 95 45 hp 2 cyl. the motor went dead at wot after restarting there was a rattle,after the motor cooled down and was restarted the rattle was much less distinct, took to a mechanic and had the compression issue i spoke of a few posts down, called him earlier and he said he didnt here a rattle in the tank. im afraid this guy wants to rebuild the motor and charge me an arm and a leg when the problem is minor....also there was water on the plugs...i talked to aomeone else and they said it might just be the head gasket....any thoughts or suggestions....how should i approach this mechanic to either get my boat back or make sure he fixes only whats needed?

JB · Nov 14, 2003

Re: compression on rude?

Hi, Trey. With the compression you reported it isn't likely to be a head gasket. Water may have gotten into your fuel system or engine some other way and ended up in the cylinders. Good luck.

rodbolt · Nov 14, 2003

Re: compression on rude?

hello pull the head and have a look. it quick easy and painfree. the fact that you were running when it quit is a concern. classic overhaet or piston sticking symptoms. in anycase have a look at the head for surface trueness and the cylinder walls for scuffing. gastket is abot 16 dollars, piece of mind is priceless. 125 to 135 is almost to much. I would do a leakdown test at a minimum. good luck and keep posting

TDuck · Nov 14, 2003

Re: compression on rude?

do you have to torque the bolts to a certain psi on the heads, also is there a certain pattern to torque like on a car motor?

Solittle · Nov 14, 2003

Re: compression on rude?

Yes to both questions. My V4 requires 18-20 ft lbs and torque sequence pretty much the same as an auto.

ob · Nov 14, 2003

Re: compression on rude?

Trey, If you look close at the head cover there may be torque sequence numbers embossed into the head material.Another possible source of water intrusion into a cylinder is the exhaust cover gasket.If you choose to venture into the job yourself ,I recommend obtaining a service manual to help you along with the finer points.In any case , good luck and keep us updated on your findings.

TDuck · Nov 19, 2003

Re: compression on rude?

mechanic pulled head and informed me the bottom piston was scuffed and had shavings in the cylinder, said the top cylinder had water in it, gave no thoughts on why the water was in there, now wants to rebuild motor, i havent looked at it yet thinking about paying him for the work so far and taking the boat for a second opinion, any ideas or suggestions?

Solittle · Nov 20, 2003

Re: compression on rude?

You need to eyeball this one first hand and take along a friend who knows outboards to look over your sholder. If there are shavings and "bad" scuffing you are in for a rebuild. If you don't see any shavings and the scuffing is "relatively minor" (might have been in the scruffed condition for ages) you might pay for the work to date and take it home, put a new head gasket in it and hope for the best. If you do that you need to find the source of the original problem - overheating or running lean due to crud in the carbs or ??? - - You did not give us much info to go on.

compression on rude?

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