Motor overheating when trolling

[fishin2]

I have an I/O and when boat is idling along when trolling my motor is overheating. Replaced the thermostat and thought the water pump was bad, but when I pull my poles in and just idle her up a little, it cools right down, any suggestions. Any help is appreciated, Mike

[Fish Tales]

Check the impeller in the seawater pump.

[wakina]

Check the impeller in the seawater pump.

I believe Fish Tales has almost certainly found your problem!

In case you have never had to change one before here is where they are located. If it is an Alpha 1 Generation 1 or 2 the seawater pump is in the lower unit! If it is a Bravo drive of any series 1, 2 or 3 the sea water pump is located on the bottom of the engine most often on the starboard side at the front! I have no experience with the OMC drives so cannot give any advise on them!

[LOWE LIFE]

Its your impeller in the lower unit. Mine did the same thing while its apart you will want to check everything Bellows, Shift cable, bearings, anodes,ect... Better to do it all at once then to have to tear it all apart again.. Takes about a day to do all the work.

[skipper9]

Yeap I agree its the impeller. ..

[fishin2]

Impellar is new, maybe an obstruction ? She cools right off when idled up a touch. Might go the new impellar route again, maybe something not right, thanks, mike

[aerocraftmach2]

Did you get the new housing and all with the impeller? I had one still get hot after putting a new impeller in and once I got the new housing it was fine. Also just last night I put one in and the seal for the copper tube in the upper unit was smashed causing it to leak around it.

[fishin2]

No, did not replace the housing, might not be sealing well, might just go with a total rebuild kit for the impellar. really don't want to resort to an outboard on the rear of the boat. Motor is a Mercruiser, I/O. Thanks all, mike

[stubby]

No, did not replace the housing, might not be sealing well, might just go with a total rebuild kit for the impellar. really don't want to resort to an outboard on the rear of the boat. Motor is a Mercruiser, I/O. Thanks all, mike

you must check the housing and especially the cover with a straight edge. usually the covers wear concave and at times can be sanded with a glass plate and some compound if the plate is thick enough.....fwiw.....good luck

[skipper9]

Was the old impeller missing any arms.. I have had some of the rubber arms blocking some passage ways I. The past.