'98 Evinrude 15 hp-overheat problem

My impellor plugged with mud, and I had driven about 100 yards or so before I noticed. The motor starts fine, idles excellent, but when I try to give her more throttle-she starts to spit out water from the exhaust. I took off the head and rubbed it on fine sand paper on a flat bench to see if it was warped, was okay. I installed new gasket and fired her up. It seemed like i could slowly increase the throttle a little more but then suddenly the water starts to mist out the exhaust. could be a cracked block?? thanks for any help!!

Re: '98 Evinrude 15 hp-overheat problem

Maybe I miss your point, but the motor is going to spit water out of the exhaust when it is cooling properly. Is the motor overheating -- That is, is the top of the head too hot to touch? That motor also has a tell-tale, I believe -- Is there a stream of water coming out?

Re: '98 Evinrude 15 hp-overheat problem

I realize that water always comes out with the exhaust in the cooling process.But, it comes out normally while idling and as I slowly open the throttle. Then it just spurts out in a huge mist and motor seems to be flooding itself with water. I back off of the throttle and everything is okay again.- The water pump is pumping fine, a good solid, steady stream. The motor also is not any hotter to the touch than it was before. I didn't think I had driven too far with the impellor plugged to do that much damage, but i guess a hundred yards with no cooling is bad enough then.<br />thanks

Re: '98 Evinrude 15 hp-overheat problem

guess it sounds to me like the motor is exhausting more water when you increase speed, which would be normal -- spraying out with more force (as well as volume) with the increased speed. I don't mean to be dense, but this sounds normal to me. Is there another indication that, as you put it, the motor is "flooding itself with water"?

Re: '98 Evinrude 15 hp-overheat problem

Thanks for being patient with me Oldboat. It is a tough thing to explain. But trust me when I say there is Way too much water coming out of the exhaust. When I increase the throttle,(not quite half yet) it runs on 1 cylinder right to full throttle. It's at this time on 1 cylinder that you can really notice more watery mist than exhaust coming out. Does this explain it a bit better? I'm pretty stumped here. thanks..

Re: '98 Evinrude 15 hp-overheat problem

asif2,<br /><br />Ah ha, "running on one cylinder" was the tip off. I'll bet the spark plug for the dead cylinder is real clean?<br /><br />Sounds like you are ingesting water into one cylinder, or both, and it is being expelled under combustion pressure.<br /><br />Two places to check. <br /><br />1. Head gasket.<br /><br />2. Exhaust side cover gasket.

Re: '98 Evinrude 15 hp-overheat problem

I agree with djohns. If you check the plug(s) and find evidence of water in the cylinders, I think I would first retorque the head bolts (You had the head off and installed a new gasket). Then I would take off the exhaust port side cover. There are probably two gaskets, sandwiching a metal plate (too lazy to look up the actual name) -- would help to have a parts manual in front of you. Chances are, you are getting the water leaking into the cylinder(s) by way of the exhaust port. While you are in there, take a look at the water passages to see that they are free of obstructions -- gasket pieces or whatever. If there was water in there, it probably knocked loose some built up carbon/soot and those bits and pieces could also block a water passage.<br /><br />Let us know how you come out -- hope it works out OK.

Re: '98 Evinrude 15 hp-overheat problem

Thanks guys, will check her out tomorrow. I actually did take the exhaust side cover off but didn't pay much attention to it the first time over.

Re: '98 Evinrude 15 hp-overheat problem

Well I tried it! Took the side panel off and blew out the water jackets.--- still getting water blowing out the exhaust..I took the "flush" screw out and the water flew out pretty freely without any water coming out the exhaust. The thing runs nice without the flush screw in!! What is happening here? are the jackets still plugged with mud or is the thing just cracked somewhere up top??

Re: '98 Evinrude 15 hp-overheat problem

I am really confused. How are you runing this motor. Is it in the water, on a trailer useing ear muff, or do you have one of the fusher that bypasses the thermostat???? Do plugs look normal, dirty or clean??? Is the motor overheating, can you hold your finger on the block for two seconds???<br />What you said in first two post is 100% normal if boat is in the water. If it on a trailer and you using ear muff the water normaly comes out the holes above the cavation plate and very little or no water comes out top water outlet. So if it on the trailer useing ear muff and water is coming out top water outlet I would say have some thing blocking water outlet or passage to water outlet. You can put water in top water outlet and it should come out bottom above the cavation plate. Also if can block bottom outlet and put water in there also should come out the top, but this is not so easy. Give all the details and we can help you but can't help much with out some info.

Re: '98 Evinrude 15 hp-overheat problem

I am running the motor on a stand using those muffs. The plugs do look normal, that is to say until the water gets in then the bottom one is a little cleaner. It isn't overheating. I have tried the motor on the boat at the lake and the same thing happens.It starts great, trolls great, but when the throttle is opened up, it cuts down on one cylinder again. Exactly the same as when it is on the stand. I'm trying to explain it the best I can, thanks.

Re: '98 Evinrude 15 hp-overheat problem

On the stand most of the water should come out at bottom just above the cavition plate the holes on both sides. If it comes out the top there must be a blockage. Flush it from the water output holes at the bottom if you can or from top water output hole untill water comes out bottom. Your problem as to why it does not run when open throttle can be several things. It could be weak spark. Make sure you plugs are gapped at .030 or less. It could be a fouled plug. It can be float set too high or too low. Can you tell which plug is bad by pulling each spark plug wire off one at a time. should run on both cly by them selfs. After you find which one is bad swapp plugs, coils and sdee if moves to other cyl.