How to tell if blown headgasket?

[jamminmaz]

Hi,<br />Motor is 1972 Johnson model number 100ESL72R, 100 hp.<br />Last season i was running in the driveway, in a bucket, and I guess i wasnt deep enough so the overheat horn went off. in a panic i shut down, slapped the muffs on, an turned on the hose (stupid i know) i heard a sizzle noise midway up the LU. I posted a while back and most of you guys thought it would probably be fine, but that i may have popped a head gasket, and the signs would be less power etc. Took it to a lake, and i did have less power, but this lake was also 2400 feet higher in elevation, than the usual 5000ft elevation shes used to, so the power loss may have been from that. it ran fine though, and didnt overheat all day. Is there a way to find out if I blew the head gasket without taking anything apart? The exhaust at this 7400 ft lake, smelled kind of different and farty, but i think that mihgt have been the altitude?<br /><br />Thank you very much!

 

[WillyBWright]

Re: How to tell if blown headgasket?

That was the altitude, but it's easy enough to check. Take the sparkplugs out and have a look at them. If one or more is significantly cleaner than the others, that might indicate a headgasket leak. Typically you'll get water entering the combustion chamber and messing with the burn. The effects are usually fairly obvious. Sometimes the sparkplug will be very clean, other times the residue left will be spotty rather than shaded. If they're all burning nice and brown and slightly damp looking, your head gasket should be fine.

 

[jamminmaz]

Re: How to tell if blown headgasket?

Perfect answer, Thank you very much WillyBwright!!!

 

[Walker]

Re: How to tell if blown headgasket?

Unless I'm trying to diagnose, I never run an outboard in a bucket or trashcan or barrel. The water will heat up and then doesn't do the proper job of cooling the engine

 

[DJ]

Re: How to tell if blown headgasket?

Willy is right.<br /><br />Wow, 7400 feet! I'm surprised it had any power. I know I would be weazing.

 

[jamminmaz]

Re: How to tell if blown headgasket?

Yeah, i actually took the cover off to make sure the throttle was opening all the way!!!<br /><br />this would be a pretty hot little motor at sea level.

 

[ledgefinder]

Re: How to tell if blown headgasket?

If you shut it down when the alarm went off, my guess is you didn't blow the gaskets, particularly if you were just idling in the driveway. Hovever you can always check with a compression test. Re-torque the head bolts first.<br /><br />The water pump is actually a few inches above the junction of the lower unit & midsection, so the motor has to be fairly deep into the barrel or no water gets to the pump. Something like 6-8 inches past the junction. I learned this from experience, toasted the pump on a 125 myself, as a matter of fact, plus a 9.5hp and a Merc 65hp. Beyond that Walker is right anyway; it's real marginal running a 125 in a barrel. It'll heat the water up in a hurry, plus it'll fill the water with bubbles. <br /><br />BTW, you likely did some damage to the water pump impeller. It ought to be changed, and if you can't right away, in the meantime watch that overheat alarm like a hawk. Really iffy.<br /><br />Depending on what level of maintenance is right for you, you might want to buy some new head gaskets and pull the heads for a look. Pulling the heads on one of those 125s is a very minor procedure, and aftermarket head gaskets are about $12-15 a piece (try here at iboats.com; if they don't have them you're local NAPA will, or try boatfix.com.<br /><br />Post back if you need any help with the compression test, re-torquing, etc..