???Engine gets hot at idle???

[blairjbyrd]

I have a mercruiser 7.4 and at idle speed the tempature guage starts climbing. When im at cruising speed the temp is normal. I am guessing that the impeller needs to be replaced. I'm I correct in asuming that? also is the impeller locate in the outdrive or on the side of the engine block?

Thanks in advance

 

[Matt89GT]

Re: ???Engine gets hot at idle???

Id start by replacing the impeller, doesn't sound like its able to push enough water at idle, If its cooling at higher RPM's most likely its just the impeller, it's located in your outdrive, I think it's easier to pull the whole outdrive then seperate the halves, install it, grease u joints, check alignment, throw it back together and go boating.

 

[HT32BSX115]

Re: ???Engine gets hot at idle???

I have a mercruiser 7.4 and at idle speed the tempature guage starts climbing. When im at cruising speed the temp is normal. I am guessing that the impeller needs to be replaced. I'm I correct in asuming that? also is the impeller locate in the outdrive or on the side of the engine block?

Thanks in advance

Howdy,


I seem to remember you have a Bravo I drive on that thing...... If it's an Alpha, the raw water pump is in the drive.....(Bravo~Sea Water pump IS on right side of engine (front))


If you haven't checked the impeller .............You'll need to pull the discharge line from the pump, and clear any impeller pieces from this or previous impeller failures that may have happened.

You should also have a Power steering cooler AND/or an Oil Cooler.

The PS cooler sometimes will pass small impeller fragments. The oil Cooler will not.

So you'll need to pull the oil cooler and clear out any debris in it.


Lastly, what is your drive ratio, prop pitch, MAX speed and RPM?

(did I ask this before?)

Nothing like a Liberator!!


Cheers,

Rick

 

[blairjbyrd]

Re: ???Engine gets hot at idle???

Thanks

gear ratio is 1.50 max speed somewhere between 40-45 (not for sure havent gps it in awhile) pitch is 19.

how hard is it to change the impeller? Is it a couple hour job?

gotta love them libs

 

[HT32BSX115]

Re: ???Engine gets hot at idle???

Thanks

gear ratio is 1.50 max speed somewhere between 40-45 (not for sure havent gps it in awhile) pitch is 19.

how hard is it to change the impeller? Is it a couple hour job?

gotta love them libs

That's a Bravo right?

If so, the pump is in the lower right hand front area of the engine.....(belt driven).....your fuel pump may also be driven on the raw pump bearing housing...........It also doesn't hurt to check that there's oil in the fuel pump drive.....(that thing costs a fortune!)

You'll (carefully) pry/ pull the 2 hoses from the pump (note where they go.

Then remove the housing (5 bolts)

You may have to replace the housing if it's in bad shape....... The whole kit is only about $60

Here's the kit I used.

If you have had impeller disintegration now or you suspect it in the past, you should remove the hoses connected to the oil and Power steering coolers and ensure that there's no impeller parts crammed up in them.

My oil cooler was completely crammed full of the last impeller failure!!!


Regards,


Rick


Libs......Yeah, I only like the Four Winns kind!!!!