2004 Classic 60hp 3 Cylinder Overheated

[Willyclay]

I was with my neighbor last fall when we ran up on a sandbar. He tried backing off before shutting down the motor. After restarting in deeper water, there was no flow from the tell-tale outlet. We checked the lower unit inlets for blockage but found nothing. We ran at low RPM's(1000-1500) for a hour heading back to the landing and the tell-tale never flowed or even dripped but the engine did NOT overheat. We verified the alarm function by turning the ignition key off and on. Shortly before reaching the landing, we ran it at WOT and normal cruise(3500RPM) and did not experience any problems, overheat alarm, etc. When we returned home, I removed the tell-tale outlet and checked it for blockage, then back-flushed the motor through the tell-tale hose while the motor was off. After reconnecting the tell-tale, we started the motor and everything seemed normal. We had good flow from the tell-tale and no problems observed. Yesterday, prior to launching his boat for the first time this spring, we started the motor on muffs and had ZERO tell-tale flow. After waiting a couple of minutes for the thermostat to open, we noticed smoke from the top of the engine block and shut the motor off. While no decals peeled off and I think the smoke was from silicon spray, the top of the block was too hot to touch. The ONLY water exiting motor was from exhaust relief port immediately below lower cowling. I felt warm AIR flow from the tell-tale outlet just before we shut it down. FYI, boat is stored in closed garage and we have no manual. Would appreciate comments on this situation so I can give my neighbor some guidance and a clue of what to expect. Thanks!

 

[Windykid]

Re: 2004 Classic 60hp 3 Cylinder Overheated

You need to replace the impellar and probably inspect the housing to see if it is scarred up and in need of replace.

 

[Texasmark]

Re: 2004 Classic 60hp 3 Cylinder Overheated

That engine should have a stat probably opening at 120 (my 90 does) and a bypass valve. At your 1500 rpm's you were running on the stat. Up around 2500 or if you get the boat on plane and get some water pressure into the lower unit the bypass valve opens, bypassing the stat. Nice thing about that is that if your stat sticks closed (as mine did) you can get up to speed, force the bypass open in the process, get the horn to go off and make it home.

The pee probably comes directly from the exhaust manifold (like mine); has nothing to do with the stat. That engine should pee within a minute from turn on. Should run about 5 psig at idle and 10 or so at WOT so the pee stream gets stronger the harder you run.

I agree that the impeller (in the water pump....see archives for how to replace) needs a looking at and while you are there you might as well replace it. You can flush out the water passages too while you have her apart.

If you really want to go nuts, you can pull the cover off the stat/bypass, pop both of them and check for flow thru there too while you have the hose running. Then look on the pellet of the stat for the temp, put it on the stove in a slowly boiling pan of water with an adequate thermometer and see if it starts to open when it's supposed to (# marked on pellet).

The stat and bypass valve are under a cover on the rear of the block, on the head's water jacket, close to the plugs. Two bulges on one cover, one about the size of a nickle, the other a quarter. If you prise it off carefully, you can use some blue RTV and stick her back on when finished, or go to a dealer and get another. I used RTV and never had a problem.

Iboats sells stats if she doesn't open; about $10. Make diagrams of the part assemblies you remove so that you can get them back in place correctly.

Mark

 

[Willyclay]

Re: 2004 Classic 60hp 3 Cylinder Overheated

Thanks to Windykid and Texasmark for the feedback. Without a manual, I am hesitant to start pulling things apart since it is not my motor. Will post results.

 

[Willyclay]

Re: 2004 Classic 60hp 3 Cylinder Overheated

Neighbor decided to let selling dealer do the work. Three weeks and several hundred dollars later, we had NO flow from telltale but NO overheat on muffs. Removed telltale plastic nozzle and cleaned blockage by large grain sand. Also, back-flushed motor with water hose through telltale hose. Started it again on muffs and had good flow. Replaced plastic nozzle and launched it in the river. Drips only from telltale but no indication of overheat. Also, no power at WOT and engine bogging badly, max 3000RPM. Back in the driveway, removed telltale plastic nozzle which was AGAIN blocked by large grain sand. Since fuel was last fall's fillup of built-in tank with stabilizer, put fresh gas in a remote tank and went back to the river. Same results, little or no flow from telltale and switching tanks made no difference with WOT performance. Pushing the choke/primer button DID make the motor run smoothly to 4000-4500 for briefing intervals. Next day, we cleaned the high speed jets with aerosol carb cleaner, adjusted the carb linkage to get WOT as original link&sync had throttle butterflies far from fully open/horizontal. Great design by Mercury making the jets accessible! Also, did NOT replace telltale plastic nozzle but extended telltale hose through lower cowl. Back in the river, had good flow from telltale and WOT picked-up 500 RPM's over previous best performance. Thanks to all, especially TD, for troubleshooting procedures learned from this forum. Maybe now my neighbor will buy a manual!

 

[Texasmark]

Re: 2004 Classic 60hp 3 Cylinder Overheated

Glad you got her fixed.

Mark