98 Force 50 not peeing - how do I backflush

[Rowan]

A friend of mine (really) ran his boat aground in soft, silty mud then powered his way out of it but, surprise, the motor quit peeing. It's a 1998 Force 50, serial number OE318180, he couldn't locate the model number. We've tried to flush it but cannot get any water flow. I read in this forum where you can 'remove the gearcase and backflush through a hole' if you think it's clogged. Can anyone provide more specifics or even better, step by step directions? Please assume I don't know where the gearcase is, where this backflush hole is, etc... If I knew everything I wouldn't be asking on this forum! Thank you!
If this doesn't work then am I right in thinking that replacing the impeller and/or water pump is the next step? If so, do the directions in this forum for "step by step impeller replacement" apply to this motor? because from what I remember from messing with it, this is a two cylinder motor and the directions are for three and four cylinder motors. Thank you for any assistance.

 

[roscoe]

Re: 98 Force 50 not peeing - how do I backflush

Water pump replacement is only slightly different for different models and years.

There is no "backflush" hole.

You can remove the thermostat and that will give you a hole at the top.

I would drop the lower unit. There is a water tube that connects the water pump to the powerhead.

You can try forcing water into the thermostat opening, and up the water tube, to flush out the powerhead and the passages.

You will probably have to remove the waterpump to clean it out.
Might as well replace the impeller.

 

[sentinel]

Re: 98 Force 50 not peeing - how do I backflush

In addition to what Roscoe said, you should check the INTAKE venting passage to the water pump too. It may be clogged with larger pieces of bottom material.

It is difficult to completely flush an engine. Using a hose with a "necked down" piece of clear fuel line tubing helps direct water into some of the smaller ports visible with the head off. You are gonna get wet and your engine is going to get wet. Avoid wetting anything that is electrical or has to do with your ignition or carburation. This may require you to tape a plastic garbage bag "bib" around your engine block before you flush.

You can also (recheck) your passages after the block has drained by using clear tubing placed over passage holes and blowing and sucking air with your mouth. There should be no restriction in either direction noted. This same technique will help isolate & troubleshoot carburation idle, main jet, and float passage problems.

Also carefully inspect your head gasket passages and openings.....head gaskets are often poorly cut out and this can accelerate the incidents of water flow blockages.

As Roscoe said, the water pump should be disassembled and cleaned. The way the impeller blades work does not allow simple back-flushing by way of the output tube or input passages because the blades TRANSFER water a small amount at a time. That is why running an engine is necessary when you use any (yuk!) clamp-on flushing fixture which is really only designed to flush out sea water.

Go slow, and do it right the first time around. Your friend saw the movie "Murphy's War" too many times.....I think.

Larry
<Scuba Diving with water wings not recommended either.>

 

[Rowan]

Re: 98 Force 50 not peeing - how do I backflush

Thanks Roscoe and Sentinel. Looks like I'll be helping to replace an impeller for the first time; gotta start somewhere.