Compression steps. boat out of water. need help

[Puppet boat]

Compression test <br />1 mark all wires and unplug (ground wires)<br />2 take out spark plugs<br />3 spray WD40 in each hole (3 to 4 Sec)<br />4 take off air filter, open carb <br />5 unhook gear cable <br />6 turn motor clock wise (facing motor)<br />7 test compression. <br /><br />Should I spray WD40? I have read on this site not to, but I was told I should because the motor is dry as it has not been started in two years.<br /><br />Are these steps correct? <br /><br />thank you.

 

[sculbert]

Re: Compression steps. boat out of water. need help

I would also hook up water to the outdrive. your water pump will be dry also. <br /><br />As for the WD40 that is a little thin for a fresh spin. I would look for a little heavier lubicant. if you took a little few cc's 10 w 30 and poured in each cyliner and let it sit a little first then spin it over a little would be good. You don't want much sitting on top of the pistons though because it will miss lead the compression readings. You want to use the starter to test the compression and read it in two steps. Spin motor over and give close attention to going through one single spin to the compression stroke and read the level of compression. Then spin it over a couple times straight through and check for max compression. First compression will be lower on first stroke and then build up. The compression will vary depending on your engine. If you get above 75 psi on the first stroke you are probably okay as long as it pumps upto atleast 150 on multiples. all cyclinders should be close to each other. If you have one or two that are out of range by more than 15% you might need to be concerned about them.

 

[Puppet boat]

Re: Compression steps. boat out of water. need help

The outdrive is off the boat.<br /><br /><br />Thank you very much.

 

[sculbert]

Re: Compression steps. boat out of water. need help

Then you good to go! Just don't worry about the Water Pump.

 

[Puppet boat]

Re: Compression steps. boat out of water. need help

compression test has been done.<br /><br />Ford 302 175Hp OMC outdrive (Outdrive is not on)<br />Low 125 <br />High 150<br /><br />Question. Would the compression be much higher if I was running the motot before doing the test? <br /><br />As the boat is out of the water and without the drive on, I just turned over the motor three times and took the readings.<br /><br />Is this accurate reading?<br /><br />Now. Trying to start the boat. Does anybody have advice.

 

[sculbert]

Re: Compression steps. boat out of water. need help

My mercruiser manuals don't cover forod engines. But from my history as a mechanic I would say you are probably okay. You have acylinder or two that are a little low but not bad enough to warant a rebuild. <br /><br />Make sure your drain ports are closed.<br />Hook up water<br />fuel in carburetor<br />fire it up<br /><br />You should be good to go for cranking it up. I would put the plugs back in make sure you have water running to it. find your input hose from the leg and connect a water hose to it. Pour a cap full of gas in the carburetor the first time and fire it up!

 

[Puppet boat]

Re: Compression steps. boat out of water. need help

Thank you.<br /><br />I can't find input hose. Where should I be looking? <br /><br />And I can't find my manual..... turned my garage upside down looking for it. <br /><br />Can I start the motor without water, run for a few minutes (just to get it running)

 

[Lou C]

Re: Compression steps. boat out of water. need help

NO you will ruin your exhaust and then the engine!<br />Water inlet should be at the rear of the boat, transom shield. Or you can follow the hose that goes from the outdrive to the thermostat housing, and try to tie your water hose into the nipple on the thermo housing that the hose from the OD is connected to, that is the water inlet to the thermo housing.<br />You will get more valid comp test readings with a hot engine.