over heating issue

[billy boater]

i have a 17 foot boat with a ford 2.3 in it with a omc outdrive(p.o.s) any way the problem im haveing is if i let the boat sit in the water and idle it will overheat or if im in a no wake zone just putting along it overheats as well. but if i am at quarter throttle or better the boat runs cool as can be. ive gone thru about 6 impellers in two summers and housings.if the boat is idling and u grab the hose coming from the outdrive to the t stat housing its hot but if ur going quarter throttle or more its cold. i replaced the t.stat i did a compression test on the motor and it had good comp in all 4 cylinders.any ideas????

 

[slasmith1]

Re: over heating issue

you have an air leak somewhere check the seals (orings or gaskets) pump housing pin hole in a hose maybe.

 

[havasuboatman]

Re: over heating issue

Back flush the waterline back through the P/S oil cooler. You may have a piece of old impeller caught in there restricting water flow.
Did I read this correctly? The inflow of water from the drive is getting hot at idle?

 

[slasmith1]

Re: over heating issue

when I had my omc I had the same issue the one time I paid someone else to change an impeller. they inserted an extra gasket between the oring on the pump housing and the drive caused neither to fully seal and created an air leak. The motor speeds the impeller up enough to compensate at higher rpm's I would check all seals and hose connections.

 

[billy boater]

Re: over heating issue

thanks for the info i will go over it one more time. i have flushed and flushed it thinking the same thing. but yes the inlet hose coming from the outdrive to the motor gets hot at idle

 

[a70eliminator]

Re: over heating issue

What ate up all those impellers or are they burning up? Check the raw water feed hose, follow it up to where it connects to the through transom nipple, I had one that was torn right there near the transom nipple at the clamp, it looked like the clamp itself cut through it because the hose makes an unatural bend sort of twist in that area, this was on a Cobra drive with a v-8 though.
http://forums.iboats.com/attachment.php?attachmentid=5896&d=1190320038
It was actually the stainless ground cable that cut the hose like a cheese cutter, the clamp was out of position as you can see from where the patch is, in fact it wasn't even slid up onto the nipple.

 

[rockyman]

Re: over heating issue

you may want to check the lowwer unit water pump where the plastic tube goes into the steal tube could be a problem if its not right,while your there you may want to check the stael tube for cloggs.

 

[slasmith1]

Re: over heating issue

you may want to check the lowwer unit water pump where the plastic tube goes into the steal tube could be a problem if its not right,while your there you may want to check the stael tube for cloggs.

It is an omc it doesn't have a pump in the lower unit it is in the upper.

 

[THE BEEF]

Re: over heating issue

Go to the hardware store and get a clear plastic hose .Hook it up for the feed water and see if you have air bubbles. That will let you see whats happening.
Beef

 

[billy boater]

Re: over heating issue

the impellers melt like they are getting run out of water.

 

[Bondo]

Re: over heating issue

the impellers melt like they are getting run out of water.

Ayuh,... Then that's probably exactly what's happening....

 

[searay3]

Re: over heating issue

No experience with an OMC..however, you say the pump/impellor is in the upper.
It has to draw from the lower....must be clogged between the pump and the lower where the water pickup is...

 

[a70eliminator]

Re: over heating issue

Water enters through the screened intake of the lower unit, it travels up the water tube connecting to the upper, the pump has a rubber vent line which purges the air from within the pump upon submersion.
If your intake screeen is out of place then debri could have gotten pulled up into the water tube, also when up on plane the pump could be pulling air if the o-rings are bad on either end of the watertube, but that doesn't seem to be the issue as you say it overheats while idling and below planing speed. Hmmm, you replaced the impeller about six times including cage at least once, did you do it by the book or did you just assemble the cage and impeller the way it came out, maybe it was assembled wrong like upsidown or backwards and you keep doing this over and over?

 

[rockyman]

Re: over heating issue

the problem is in the lower because the impeller is melting due to heat due to no water and the water must come through the lower to get to the pump,

 

[a70eliminator]

Re: over heating issue

If the vent tube is plugged up air pockets will form in the pump cavity and the impeller can't pump air.

"Make sure vent passage is clear, it ensures quick pump priming by preventing air pockets from forming." (exact quotes from OMC service manual)

Easy to check just pull the access cover to reveal the pump, the vent tube is right there pull it off and blow through it both ways and see if it's clear.

 

[billy boater]

Re: over heating issue

i havent got it outa storage yet due to crappy weather in minnesota but as soon as i do i will check that lower. im just lookin for some ideas. i know i have been installing the impeller correctly tho cuz a a tech from a marina showed me how its done when i bought the last 3. i have been reading alot of posts with guys having the same problems but have not been able to pin point it yet