mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

[Boatch]

I have a mercruiser 888 (ford302) have cooling issues,raw water cooled,replaced impellar and housing,lower unit shaft seal.....any advice would be greatly appreciated...im stumped at this point?

 

[alldodge]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

No guru here but how do you know your getting air into the inlet cooling hose?

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

Water pocket cover?

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

No guru here but how do you know your getting air into the inlet cooling hose?

Common fault-findering trick... Put a section of clear hose in the inlet line....

 

[Another retired guy]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

I have a mercruiser 888 (ford302) have cooling issues,raw water cooled,replaced impellar and housing,lower unit shaft seal.....any advice would be greatly appreciated...im stumped at this point?

Don't know if the air bubbles are a problem or not, but have you checked the thermostat? If not, remove the cover and test it. Also look for rust debris etc. that may be partially blocking a water passage.

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

I also checked water pocket cover,looks ok?took out to lake today and at idle no air bubbles,but when I throttle up large amount of air bubbles coming in.....

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

I have also checked flow at manifolds in and out=good elbows=good t-stat housing =good no debris....

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

The cover can 'look' fine, but the gasket leaks, displaying EXACTLY the symptom you have. Pull the drive, split it and pressure test the cover. 10 to 1 on it's leaking....

You'll find that those bubbles are actually exhaust gas....

Chris........

 

[trevtt600]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

Had the same issue on my boat last year with both motors. One was the water pocket cover seal, and the other was the seal on top of the water pump housing that slides down the impeller shaft and seals the shaft on top of the housing. It was not completely down on the housing. It could also be a leaking gasket in the impeller housing, or a warped impeller housing base.

 

[Bt Doctur]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

water pocket leaks reduce the flow not produce bubbles.i would drop the lower unit, put the muffs on it and see if the pump base is leaking.the base is the suction side where you would suck bubbles .bubble only appear when the pump is out of the water so to speak.
Under way at speed the cavity only has exaust gas and discharge from the risers.Slow speed the pump is covered by water.

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

thanks for tips guys!!! just a FYI I have new impellar and housing and base with gaskets,but I am gonna check all those things tmrw when I pull outdrive...question=what is the best way to pressure test water pocket cover and water pump assembly? thanks again for help...

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

Have a read of this post I did a while ago for someone else. It details how and why exhaust gas can be pushed into the cooling water, and how to check the water pocket cover...

http://forums.iboats.com/mercruiser...s/im-running-hot-help-556903.html#post3825409

Chris.........

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

ok guys...I did the pressure test on the lower unit and water is pouring out of the base took apart inspected and all looked good?? I think I might have wrong water pump base?Any info would be appreciated...my 888 is a 1972 with the preload pin on top of shaft....

 

[Bt Doctur]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

#22 Sterndrive Exploded Views D : MerCstuff.Com
use contact cement/bellows adhesive where the water inlets are .

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

The correct part number for the water pump base in all MC-1 drives from 1970 to 1982 is 46-57234A1...

Chris.......

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

thanks for tips...isn't my drive an "R" drive its 1972 outdrive serial # is 3421801....and my water pump base has a 1/8 hole in the front of it.Is that the right base?

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

R drive started in 1982, not 72.... You have an MC-1....

 

[Boatch]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

Ok,thank U....Do u have any idea about hole on my water pump base?

 

[haulnazz15]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

The hole in the water pump base is only needed if you have the motor flush adapter hole on the lower unit. If you don't have that flush hole, you should be using the MC-1/Alpha I water pump base that doesn't have the hole. You may be able to just epoxy over than hole if you have the wrong base, but I'd wait for the someone here to confirm if that's an option.

 

[achris]

Re: mercruiser 888 overheating...air bubbles in water inlet hose from outdrive

You need the water pump base for MC-1/R, NOT MR/Alpha One, they are different.

And yes, the hole in the side is for the very old MC-1s with a flush attachment hole in the side of the gear housing.

What is the part number of the base you put in? (and did you use the right gasket?)

Chris.......