newbie mistake

yankdownsouth · Jul 6, 2011

I just baught my first boat and was so excited to get it in the water that i didnt mix oil in the gas. im orig from md and grew up on boats but never worked on them , i took the boat out and ran it till it died paddled back in . now im afraid that i perm screwed it up. it isnt siezed up but it still wont start . i mixed the oil and gas and got it to turn over but it wouldnt start. any info on what to do would be helpful... i dont want $2,000 down the drain . go ahead and make jokes about it if ya want . i was mad at first but i have laughed it off by now .

Skifferskipper · Jul 6, 2011

Re: newbie mistake

Check your compression in the cylnder head..

Skifferskipper · Jul 6, 2011

Re: newbie mistake

My guess is you fried your rings and you probably need a hone and a new set of rings but dont get discouraged that is actually really easy..

yankdownsouth · Jul 6, 2011

Re: newbie mistake

how do i go about checking the compression? i can find time to do any work needed im just on a tight

Skifferskipper · Jul 6, 2011

Re: newbie mistake

They sell compression testers at any Autoparts store and most hardware stores for about 15 bucks.. What you can do is Pull all the plug wires off the plugs (Make sure you dont forget where they go) Pull the first plug out and depending on what kind of tester you get Attach the tester to the plug hole and run it untill the tester wont go up anymore then take note of #1 The compression #2 What the spark plug looks like, Fuel, Burnt, ect .. then continue with cyl2 and cyl three. Figure out if you have solid compression I might be wrong but I think its about 115 to 130 for one of those You should look up the manufacturer spec though..

OptsyEagle · Jul 6, 2011

Re: newbie mistake

I agree. You most likely have created a compression loss, most likely from your rings, but wherever it is you will need to verify it with a compression tester. Make sure both plugs are out of the motor when you do the test.

Report back here with the numbers first, but you will most likely have to pull the cylinder head to take a look at the damage. Not a difficult job either, but get the compression numbers first.

By the way, the good thing about that mistake ... you will never make it again. Something positive always comes out of these things.

Also, you should let us know the type of motor, Hp and year you are dealing with.

Skifferskipper · Jul 6, 2011

Re: newbie mistake

LoL I Thought We were working on a 70hp johnson I got this post mixed up with another one I was typing on..

wilde1j · Jul 6, 2011

Re: newbie mistake

The is no "manufacturer spec" for compression. Cylinders should be within 10% of each other. Depending on the motor, over 100 psig for most V4 and V6's, less for pull start motors (>60 psig for them).

jtexas · Jul 6, 2011

Re: newbie mistake

It's best not to leave the spark plug leads hanging, so disable spark by pulling the emergency lanyard, or leave the keyswitch "off" and crank the motor by jumping the solenoid. Either that, or ground the leads to the engine block using jumper wires.

yankdownsouth · Jul 6, 2011

Re: newbie mistake

its a 1975 evinrude 85 hp 4cyl . i can pick one up when i run back in town... i live in the boonies lol. thanks everyone ill post the numbers as soon as i get them

Skifferskipper · Jul 6, 2011

Re: newbie mistake

Okay.. There might not be a manufacturer spec.. But I Have a evinrude 70hp That runs at 115 and a Johnson 75 that runs at 120.. and the safe zone is between 90 and 130 according to my Repair manual..

glengold · Jul 6, 2011

Re: newbie mistake

Nothing is permanent, glad you laughed it off by now.

Don't sweat it, it can be fixed, its just money.

1stgenbird · Jul 6, 2011

Re: newbie mistake

wilde1j said:
The is no "manufacturer spec" for compression. Cylinders should be within 10% of each other. Depending on the motor, over 100 psig for most V4 and V6's, less for pull start motors (>60 psig for them).

Huh. My 18 hp pull start gets 115 psi in each cylinder.

OptsyEagle · Jul 7, 2011

Re: newbie mistake

1stgenbird said:
Huh. My 18 hp pull start gets 115 psi in each cylinder.

He didn't say there was no compression when manufactured, he said that the manufacturer does not issue a specified number for the compression of their motors. Also, since many compression guages will vary from each other, it would be difficult to confirm the number anyways.

I suspect that either both cylinders will be very low (less than 50 psig) and/or vary significantly from each other (difference between them of more then 10%). If this is not the case then it is not a compression problem. We will have to see.

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