Water pump issues, 3rd times a charm

[okeechobee]

This is my 3rd attempt to post a new thread. The other 2 are out there in cyper space somewhere. Anyway, I hope somebody can help me with this issue. I have a 1999, 90 hp, 2 stroke, Yamaha outboard engine that has always ran great. I put it in the water last weak and while it was sitting idling in the water the overheat alarm went off. I shut the engine down, let it cool, checked the water intake ports in the lower unit and everything looked good. I fired it up and the alarm stayed off. The stream of water coming out of the head seemed a little weak but the alarm did not sound again. I ran it for probably 12 miles total and no alarm. I went back in and while running slow approaching the dock the alarm went off again. I inadvertently put it in reverse the water stream was much strong and the alarm went off only after a few seconds. So, the water pump seems to pump enough water at a high speed and while in reverse. It doesn't when running slow or idling. Does this sound like the impeller or something else. Thanks in advance for any help you could give me.

Okeechobee

[DennisG01]

You impeller spins just as fast in fwd as in rev. In other words, it always spins the same way - the only variable to it's rotational speed is RPM. From what you've posted, it sounds like you got weeds or something caught on the gearcase intake when traveling slow. When you went into reverse, the weeds were forced off. That's my best guess based on the info!

[robert graham]

Same exact year and model motor as mine....assuming your water pump is in good working order, then it's very easy to remove/inspect/clean/replace the thermostat and/or the pressure control valve(black plastic X shaped item) under that square cover on top/back of motor....4-10MM hex head bolts. It's a good idea to check these about once a year or so anyway...

[99yam40]

Low RPM overheats can be caused by a PRV sticking open.

It would be best to inspect your cooling system to make sure all is in good order

[TownsendsFJR1300]

Basic's first..

As noted, the "water flow seemed a little weak".

When was the last time the water pump was replaced?

As your not over heating at speed, I doubt the PCV is leaking, simply NOT enough water flow to the power head. Same for the thermostat.

Doesn't hurt to inspect (basic maintenance actually) but my $'s on the impeller (un-less it was changed within a year).


.

[99yam40]

Basic's first..

As noted, the "water flow seemed a little weak".

When was the last time the water pump was replaced?

As your not over heating at speed, I doubt the PCV is leaking, simply NOT enough water flow to the power head. Same for the thermostat.

Doesn't hurt to inspect (basic maintenance actually) but my $'s on the impeller (un-less it was changed within a year).


.

strange input there Scott
usually a stuck open PRV over heats a low RPM not at high RPM, because at high RPM the PRV is already forced open by the extra flow/pressure and has plenty of water to fill the power head

[TownsendsFJR1300]

The WP is about the most neglected part of the cooling system...

It was not mentioned when it was last serviced / replaced.

I suspect on that engine, it's easy enough to check.

My engine has never over heated but when my WP is about 3 years old (and the F150 impeller is VERY STOUT), I can see the pisser fluctuate. A new WP kit fixes that fluctuation. The vanes are there, just have a set (not a lot) from old age..

IMO, un-less that impeller is fairly new, it's the first thing I would replace (not just check but replace as your already in there).

*Especially on the smaller machines, how many impeller vanes have broke off and got INTO the block. A fair amount of failures posted on this forum alone..

(Still won't allow you to make spaces in-between sentences??)

[okeechobee]

Water pump issues continued:

Thanks to all that responded. I decided to go ahead and change the impeller. I have only had this boat for a few seasons. Regular maintenance has been performed on a regular basis but I have not changed the impeller.

When I removed the lower unit there was pretty fresh grease on all the end of the bolts. The impeller vanes where certainly bent but they were not cracked or broken. I have to put it back in and try it in the morning but it seemed like a pretty tight fit.

We are in a canal of the rim of Lake Okeechobee. There are really no weeds to speak of, checked for weeds both times the alarm went off, there were no weeds on the intakes and nothing on the intake screens.

I am not real familiar with the parts on an outboard motor, so, the abbreviations do not mean much to me. I understand what an thermostat is but what is a CPV, etc. Again, thank you for your help.

Okeechobee

[TownsendsFJR1300]

I gather you meant to write "inspected it", not replaced it with new.

We now know the water pump impeller has a SET (bent vanes) in it, it NEEDS REPLACEMENT (2-3 years old).

The rubber hardens up and does not flex nor pump as well as a good (or new one) will. It Will make a difference (and very likely is your issue).

Also inspect the housing for any distortion, confirm all seals are there.

You can look up in the parts section above (in RED), bring up your engine, and see what's where, seals, assemblies, etc. I'd get the kit, not just the impeller (not much more $ and worth it.

The PCV is the Pressure Control Valve. It is a spring loaded "valve" that releases block water pressure when the pressure gets too high.

Part #41, on this 1999 90 HP (I don't know your model #) is the PCV:http://www.boats.net/parts/search/Ya...ASE/parts.html

A cover, spring, plastic valve and a rubber seal (grommet) that sits in the block. That same cover (on that model) also houses the thermostat (zoom in on the picture).

Being your in brackish water (I'm guessing by your user name), corrosion is less of an issue for you. Salt water causes much more issues with thermostats /PCV, etc...




.

[rodbolt17]

brackish water smakish water.
if you can catch a crab the motor is in salt water.
whdda mean water pumps,fuel pumps,thermostats and needle valves wear out after 10+ years?
poor design?
its called maint.
do it and all you will do is read posts.

[TownsendsFJR1300]

brackish water smakish water.
if you can catch a crab the motor is in salt water.
whdda mean water pumps,fuel pumps,thermostats and needle valves wear out after 10+ years?
poor design?
its called maint.
do it and all you will do is read posts.

I (and many members) do JUST read posts (and I learn as well) and add info occasionally. You will NOT find many posts from me for lack of maintenance. Balancer, starter relay, etc..

That's what I posted... R&R the WP on the Op's engine, it's way over due..



BTW, I don't believe you'll find any crabs in Lake Okeechobee, it's a fresh water lake.

As they dump excess FRESH water in the river (and canals especially in rainy season-summer), there is NO salt in the water. The river water goes from greenish blue to BROWN as the fresh water flows down to this side of the state, (50 miles away) and out into the Gulf of Mexico..

No salt but nasty looking...

.

.

[okeechobee]

Water pump issues continued:

TownsendsFJR1300, you are absolutely correct on Okeechobee and the Rim canal, as it is referred to. I did inspect the impeller and decided to go ahead and replaced it. It is at least three years old. That part is finished and I will give it a shot this afternoon. I hope you are right. Thanks again and I hope i become just a post reader. This boat did not get a lot of attention from the previous owner other than putting gas in and running it hard. It is a great engine and I hope to give it the attention a motor needs. It still runs good but needs a few things that have been neglected. Thanks again to all that have responded.

[TownsendsFJR1300]

Please post if the new impeller fixes your issue (or not )

[okeechobee]

Water pump issues continued:

I will post the result but it may be late afternoon Thursday, it is supposed to be 33 degrees in the morning but it will be 70 by afternoon. Thanks again.

[TownsendsFJR1300]

Yea, nay?

Lost at sea?