Overheating

[Bruening40]

1987 omc cobra is still overheating is have replaced both water pumps cleaned out exhaust manifolds it works great with the hose in the front yard but when I put in a bucket it won't suck water to impeler pump. I also tool lower unit apart to blocks double checked seals on water tube it all looks fine but can't prime itself any hints.

 

[xdgt03]

Re: Overheating

Bump. I have the exact same problem. New impeller. With muffs on it pumps water just fine. Put in a bucket there is no water circulating. There does not seem to be any blockages anywhere. Might this be the water tube or seal in the lower housing? Can I separate the lower unit to get to this tube without draining the lube? I have the OMC manual but it is a little vague to me since I have never worked on an outdrive unit.

 

[Randy J]

Re: Overheating

hi since took lower unit apart did the O ring for the water inlet stay or is it missing. 2nd thought what shape is your thermostat in????

 

[sea wolf]

Re: Overheating

Check the 0-ring gasket on the impeller housing. Make sure it is in the groove. Also, pull the metal backing plate & put a straightedge across it. If the plate has any warpage in it the housing will not seal, causing the pump to suck air resulting in an overheat. Forget about putting the drive in a bucket & expecting it to pump water. The impeller housing must be submerged for the pump to draw water.

 

[HT32BSX115]

Re: Overheating

Forget about putting the drive in a bucket & expecting it to pump water. The impeller housing must be submerged for the pump to draw water.

Absolutely. The pump is pretty much submerged when the boat is in the water!

It's a VANE-type impeller pump. They're not self priming.

 

[xdgt03]

Re: Overheating

Trying that right now.

It is a new housing, impeller, rubber gasket, etc... It overheated and cooked the impeller and housing. I put a new one on and it pumped with the muffs on but overheated (not ruining the impeller or housing this time) so I put it back in the driveway and thought it may be the tube seals.

I'll check again if it doesn't work this time but I've had this apart several times and I'm pretty good at getting on right but ill check .

As always, thanks for your sage advice all.

 

[xdgt03]

Re: Overheating

Works perfect. Thanks again