2001 50 hp bigfoot cooling problem

[rob johnson]

I was trying to help a friend with her boat and something is wrong. She complained about a cooling alarm and diminished output from the tell tale. I installed a new waterpump, t-stat, backflushed, spark plugs, engine oil and gearcase oil. Everything seemed alright in the driveway with the engine on muffs; good output from the telltale (still diminished in her opinion) and no alarm. When she ran it tonight she got the alarm again and still complained of diminished output from the tell tale. When I backflushed through the thermostat, everything seemed to run clear. I am lost. I can't think of what else could cause this. Please help!!!!!!

 

[Indian Ground]

Re: 2001 50 hp bigfoot cooling problem

Is the water pickup somehow out of the water or catching air when you run it in the lake?

 

[rob johnson]

Re: 2001 50 hp bigfoot cooling problem

not that I know of. It is on a pontoon boat over here in the indian river lagoon. Are you afiliated with MMI? As far as I know it it trimmed down all the time, all the way.

 

[MercFan]

Re: 2001 50 hp bigfoot cooling problem

A common suggestion I've seen given here, though I'm no expert, especially on your engine, is the poppet valve. But I'm sure one of the experts will point you in the right direction soon.
The old impeller wasn't missing a blade when you took it out?

 

[rob johnson]

Re: 2001 50 hp bigfoot cooling problem

What is the poppet valve????

no, the impeller was intact just old. I am really at my wits end here. literally losing sleep over this, I mean it can't be that difficult. Thanks for all help

 

[MercFan]

Re: 2001 50 hp bigfoot cooling problem

I'm not clued up on the poppet valve since my engine doesn't have one. Apparently it's casing looks like a figure 8. It's meant to dump excess water at high rpm. It's a spring loaded assembly, but doesn't jump out at you when you remove it from the engine. So my guess would be if the poppet valve is stuck in the open position that it would dump water instead of sending it to the head while at idle. As I said, all this is guess work as I'm not familiar with your engine at all, or poppet valves for that matter.

Edit:
Another trick could be to remove the t-stat and run it like that to see if you have different output from the tell tale and if the alarm persists.