2001 f100 Overheating

[Sandbarjonny]

Motor overheating at midrange to full throttle.Removed lower unit check w/p
impeller looked newer,housing looked ok.Replaced w/p & housing & thermostat.Checked popit clean working ok.Tell tale weak.Back flushed motor with lower unit off.Installed lower unit flushed again still weak tell tale.Test run overheating 180 to 190 with temp gun.Boat bottom clean no restrictions in front of lower unit......

[CatCam]

What does your tell tale do when you hook up a garden hose to the flush port?

If it is the same weak flow I'd try to blast the tell tale with 150 PSI air and see what happens. Sand, mud daubers, critters, everything likes to plug up the tell tale.

[FabricGATOR]

I might pull the thru cowl nozzle for the tell tale and ensure that it is clean and clear, but it is just that, a tell tale to show cooling water is flowing.

Maybe inspect the thermostat and water jacket by peering in thermostat hole with a flashlight.
If restricted by salt and oyster shells, I had inconclusive results by recirculating RidLyme through the engine with an old fresh water washdown pump.

I dropped the lowerunit, and hooked the hose directly to the waterpump outlet tube up to the engine block. I caught the overflow fluid as it came out of the engine and recirculated it through for 6 hours.

RidLyme representative said it dissolves salt, calcium, and lime like a cough drop dissolves in warm water.

http://www.apexengineeringproducts.com/

Good luck!
Regards,

[99yam40]

I had inconclusive results by recirculating RidLyme through the engine with an old fresh water washdown pump.

So you did not have good results?