Cobra not pulling up water?

[Bigdaveaz]

Re: Cobra not pulling up water?

So.... no water at idle,then you put it in the lake and all was ok? Dave.

 

[jomamma1]

Re: Cobra not pulling up water?

I thought I would chime in. I had a very simular condition on a 1990 King cobra, not sure if the cobra and King cobra have the same pick up tube setup, but, my pickup tube is 1" brass with a rubber gasket at the top(where it contacts the upper drive) and a flange with a rubber seal attached to the bottom(lower drive). This lower flange had melted when a plastic bag snagged on the outdrive and covered the pickup inlet causing an overheating condition(thats another story) Anyway after major repairs I had the same problem you are describing, it would flow water fine when at idle and when running with muffs, but when running on plane it would over heat very quickly. after much fiddling with the impeller and checking of other cooling componets. I dropped the lower outdrive and walla, found my problem. After changing both the upper and lower seals on the pickup tube. No more over heating problems. When the water pick up was blocked the chamber around the pick up tube was over heated by exhuast gas and failed. One other thought, Make sure your impeller is installed correctly! The fins need to be folded slightly in the correct direction to insert into the impeller housing. If the fins are folded the wrong way it may not work correctly. Get a manual and check it out. Good luck! JG

 

[Bigdaveaz]

Re: Cobra not pulling up water?

JG, thank you for the reply, just what I need is someone with the same problem/experience. I am beginning to think my problem is that I think I have a problem that I don't, in that I have been trying to get my Impeller to pick up water from too great a distance( Sorry to all you who have been trying to teach this knucklehead) in the tank and not in the lake! My next test will be in a Lake, I'll let you know what happens. Dave

 

[Coors]

Re: Cobra not pulling up water?

For $50, you get the impeller, liner, plate, and ring, gaskets.
Pull the hose first, hold it level with top of transom bracket, should shoot up 2-4".
Then try clear hose for exhaust or air leaks, as stated.

 

[Bigdaveaz]

Re: Cobra not pulling up water?

Up date on Cobra not pulling water, after much inspection,discussion,depression and gathering information, we put the boat in the lake,water level covers top of drive while sitting,impeller pumps thru engine! Still have and issue in that temp rises at idle,any thing below 1100 rpm, am pulling the ps cooler today prob partially plugged.PO did brake and impeller fin off, did not find it suspect I will when I pull ps cooler! Boat did not sink,drove forward and back and we got her to 3/4 throttle and stayed close to launch, Dave

 

[Bigdaveaz]

Re: Cobra not pulling up water?

bump

 

[Gary H NC]

Re: Cobra not pulling up water?

Very possible there is a piece of that old impeller blocking flow somewhere.
How warm is it getting at idle?
I did not go back and read all the posts again but did you ever pull the impeller back out and inspect it?

 

[Gary H NC]

Re: Cobra not pulling up water?

On another note: I just talked to the guy on Ebay with the service manuals.He said the 87 manual is getting really hard to find and he has only 2 left.Just a heads up if you are going to buy one.
Tell him i sent you...

 

[Bigdaveaz]

Re: Cobra not pulling up water?

Whooeeee! I hooked a garden hose to the hose from the ps cooler, and disconnected the hose from the transom to the cooler, back flushed with a hose over the transom,guess what i found on the driveway, one "fin" from an old impeller. I may have solved the mystery! Dave

 

[Gary H NC]

Re: Cobra not pulling up water?

GOOD DEAL DAVE!! I hope that was it.It makes perfect sense!

 

[Bigdaveaz]

Re: Cobra not pulling up water?

Up date, had the boat out on the lake today for more Sea Trials, much improved! Still may have issue with cooling,at idle temp goes to 170 and stays there, but at low speed,throttle closed in gear, temp goes to 200,is this normal! also one more (I hope) thing,anyone have a trim sender that needs a home? 87 cobra,drive. Dave.

 

[Gary H NC]

Re: Cobra not pulling up water?

Thats still running on the warm side.It should have a 160* thermostat in it.
Mine used to run about 165 to 170 all the time.

May be time to pull the T-stat and test it...

 

[Bigdaveaz]

Re: Cobra not pulling up water?

Forgot to add, I replaced the "T" stat!

 

[Gary H NC]

Re: Cobra not pulling up water?

Maybe back flush the whole thing out again.I bet there is still something restricting flow..
Did you order that manual? It has a cooling system flow diagram and instructions for testing water flow.
I would pull the impeller and the adapter plate under it and flush from the motor back.

 

[Bigdaveaz]

Re: Cobra not pulling up water?

And,what is the vent hole in the Impeller housing for? Read somewhere the hole should not be plugged,I made sure,maybe too sure? Too large a hole? Dave

 

[Coors]

Re: Cobra not pulling up water?

You might install a piece of clear hose to the end of the impeller line to t-stat, and see if it has bubbles.
Sucking air .

 

[Gary H NC]

Re: Cobra not pulling up water?

And,what is the vent hole in the Impeller housing for? Read somewhere the hole should not be plugged,I made sure,maybe too sure? Too large a hole? Dave

There should be a small hose or plastic tube on that hole.Its for the housing to drain.
Did you enlarge that hole? That may very well be the problem.

 

[Coors]

Re: Cobra not pulling up water?

Nah, don't even need the tube.
Without the tube, if the top of the drive is above water, it just sends overflow out the cover, which looks like a leak.
OMC installed the tube after the first units were out-consumers thought there was something wrong, with water spurting out.
I learned this after my vent tube dropped down the drive. And I freaked out.

 

[Bigdaveaz]

Re: Cobra not pulling up water?

When running,water"shoots" out of hole. I have seen covers with a "l" fitting on them,one boat mech. told me you can attach a hose to it and run down to hole in drive just beneath the impeller? Yeas I did make the hole larger!,maybe too large? Dave.

 

[Bigdaveaz]

Re: Cobra not pulling up water?

That s/b "L" fitting! Dave