Cobra drive cooling problem

[Len2020]

Okay so Omc outdrive model 983842 and serial number T0434818. With outdrive on hose, no water pressure from the in let to motor. I’ve pulled honeycomb (ps cooler) out and is clear. line is clear, also I backwash thru the line inside boat and blows thru water pump outlet fine. If I squeeze the earmuff it comes thru the inlet good. Motor and outdrive brand new water pump full assembly’s. Problem- no water sucking up even when It’s in bucket. It came up one time when throttle motor up then worked for few minutes then motor overheated. It doesn’t want to keep sucking it up. Pulled little line out when running and has suction. (Line under the cover) run hose on motor works great. Also ran water down the inlet hole and comes out great. should I put the boat in water and try because I’m out of solutions.

 

[southkogs]

Impellers don't suck water up per se. It's more of a circulation pump. Running the stern drive in a bucket smaller than a large pasture pond won't work. You've got to have muffs on the stern drive when you're out of the water.

If you put it in the water, you should have different results.

 

[Scott Danforth]

unless your bucket is big enough to have water a few inches over the raw water pump, it wont work. as'kogs mentioned, that is a large pond or a 10,000 gallon swimming pool.

raw water impellers pumps only push water. they need to be submerged to prime. then when your boat is moving, water is forced up the casting to the raw water pump when on plane

so since you tried to suck water up from a bucket, you have toasted your impeller, and because there was no water flowing you over-heated your motor, and burned the insides of your rubber exhaust hoses and burned your flappers.

 

[Lou C]

OK keep in mind that the Cobra impeller is in the upper gear housing, about 18" above the level of the water intakes there is no way on earth it will prime in a bucket, garbage can, etc. That will only work with outboards were you can submerge the lower unit BELOW the level of the impeller. Remember for an impeller to prime and move water, it has to be in deep enough water for all the AIR to get displaced, impellers do not move air.
For the Cobra...you can have a problem with it sucking up water if:
the internal water grommets for the water transfer tube got melted due to a previous overheat
or, if there is marine growth or other crud on the internal water screen.

I would first try better muffs, the best ones I have used are the Merc/Quicksilver ones that have the metal rod clamp. These use soft rubber that conforms to the lower unit shape better than the Tempo rectangular dual inlet ones I used to use.
If after using the better muffs, you still don't get the impeller sucking up water it could be the water tube grommets. You have to pull the drive and split the upper and lower gear housings.
Also, when you replaced the impeller what did you use? OEM or Sierra? Did you replace the cage and wear plate too?

on my Cobra used (and moored) in salt water I had a chronic problem with marine growth growing on that damn plastic screen, finally I split the upper and lower housings and removed it, and cleaned out all the crap in the water passage, after that no more problems with water flow.

 

[Lou C]

https://www.dropbox.com/s/ysj65t93un...0hose.MOV?dl=0

see the water exiting under the transom mount, that shows you are getting good flow through the system. I can idle it on the muffs as long as I want it will hold 160* exactly on the temp gauge.

 

[Len2020]

Last night I hoped ears backup and boat did not overheat sucked up the water no problem tomorrow morning 10:00 a.m. Eastern time will take a video and posted on YouTube of the results being in water at the dock. The buckit was completely submerge the bottom lower unit and it worked but didn't hold pressure for more than 4 to 5 minutes. I do have the rectangular ears with dual feed and not sure how I like them also I did install Sierra parts I believe Also I think the boat is running rich or it is overheating with the brand new engine I think it's possible the head gasket may of went. The smoke is not thick white smoke seems like it's rich smoke I will post a video as well I am also temperature to pull lower unit off and re do all the seals