here we go again, your opinion

[dave2092]

I think I might be narrowing the problem. First thing Mercury xr6 150 (1993). I had and oil line problem (fixed), water leak in hose (fixed), fuel problem (fixed). Did compression test showed #3 cyl. not good reading almost zero. #1 around 95psi all the rest around 120's. thought had busted rod turned out ok no visible damage to piston no holes ect... Now heres the thing my warning alarms do not work did not know that. boat is over heating. when at idle runs good but pee'in really hot. when on plane @ 3/4 throttle will just die. assuming from overheat. I will check thermostat but I assuming it works because it pee'in. I had noticed some wire coverings starting to melt lightly probly from overheat. Now my question.the poppet valve on the block seems to be pooling water could seal, gaskets be bad causing the motor to overheat when at wot? could the overheat caused the headgasket to blow causing low if no compression in #1 and #3 cyl's . just need a few opinons before I take it to mech. by the way anyone know were I can better diagrams on motor. Got the selco online not very good in my opinion. Thanks again guys.

dave

 

[Dukedog]

Re: here we go again, your opinion

Number 3 is dead meat no mater what tha head gasket problem turns out ta be. Running it that way will present and cause a host of other problems with/to tha motor. Get your pocket book out....................

 

[saumon]

Re: here we go again, your opinion

Number 3 is dead meat no mater what tha head gasket problem turns out ta be. Running it that way will present and cause a host of other problems with/to tha motor. Get your pocket book out....................

What he said! Sorry but i think you tackle it backward. On any engine of unknown history, the more efficient approach was to check, IN THAT ORDER, for:

1- good, even compression on all cylinders (over 100 psi and within 10%)
2- strong (blue, crisp) spark at all cylinders (jump at least a 7/16 gap)
3- fuel system checkup (from the tank pickup up to the carbs with everything between, including the fuel lines, the primer bulb and the fuel pump)

Trying to adjust timing, changing fuel lines, cleaning & adjusting carbs or throwing costly electronics on an engine with a bad, scuffed cylinder is a waste of time and money, as you'll never be able to get it running right...

So, take it to the shop or, if you want to do it yourself, get a real OEM service manual. Not that hard to do. Two holes at least will probably have to be bored oversize with matching pistons. If you're lucky, the others can be ok with only a honing and new rings but, anyway, you'll have to open it to assess the damages...