Cobra water circulation problem (Video and pics added)

[Fix'em]

So I finally got around to firing up my freshly rebuilt 4.3 and when I did I noticed a concern with the water circulating through the stern drive.

The impeller is in good shape and flows a good volume up to the engine and into the exhaust manifolds, but it doesn't seem to exit properly. According to the manual, the exaust/water mix should exit through the propeller. However, in my case, I don't get any flow there at all. It is all pouring out around the large zinc anode at the front edge of the drive. This can't be normal.

I've poured through the manual and can't seem to find a "troubleshoot" for this type of problem.

Any suggestions. It's a Cobra drive on an 87 Thundercraft.

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Oh, and I did notice that the water coming out at the anode was warm water so I assume that everything is circulating properly around the engine.

 

[PINESOL]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

EXACTLY ...its probably just a torn exhaust bellows ... your drive doesnt even need it .. some people use an exhaust tube . which doesnt mate to the drive at all ..

 

[Rat Capri]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

some Cobras had perforated exhaust bellows to reduce back pressure at idle. Look on the bottom side of your exhaust bellows for oval cut-outs going down the lenght of it.

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

I don't think I have any cut-outs or holes in the exhaust below from what I remember. Just a couple of days ago while the drive was still off, it had rained outside and there was quite a bit of water accumulation inside both the drive and exhaust belows. I had to tilt the housing down to drain it and use some rags to soak up the rest.

Is there anywhere else it could be coming from? It seems to come out of the housing with a bit of pressure. It sprays out significantly from around the anode.

Is there any possibility of water getting somewhere it shouldn't? I checked the oil level after it ran for 5-10 minutes and it was ok so it's not getting into the lower unit.

 

[Rat Capri]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

I don't think I have any cut-outs or holes in the exhaust below from what I remember. Just a couple of days ago while the drive was still off, it had rained outside and there was quite a bit of water accumulation inside both the drive and exhaust belows. I had to tilt the housing down to drain it and use some rags to soak up the rest.

Is there anywhere else it could be coming from? It seems to come out of the housing with a bit of pressure. It sprays out significantly from around the anode.

Is there any possibility of water getting somewhere it shouldn't? I checked the oil level after it ran for 5-10 minutes and it was ok so it's not getting into the lower unit.

it's either leaking around the exhaust bellow or you have a leak in the water hose in the gimbal housing

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Is either one of those possible leaks critical? Or can I wait to investigate the next time I have the drive removed for service?

 

[Rat Capri]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Is either one of those possible leaks critical? Or can I wait to investigate the next time I have the drive removed for service?

i just noticed you said warm water, so it's probably your bellows....in my opinion anything amiss needs to be properly attended to, however it's your boat

 

[bruceb58]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

It is all pouring out around the large zinc anode at the front edge of the drive. This can't be normal.

It's actually very normal. That is where the exhaust exits at idle. If all was required to exit the prop at idle, you would have too much exhaust back pressure for the engine to idle properly.

 

[mkast]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Oh, and I did notice that the water coming out at the anode was warm water so I assume that everything is circulating properly around the engine.

Normal.

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Excellent. Good to hear. Thanks guys.

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Myself, I would check to see if there is something in the drive blocking exhaust flow. Something = flapper remains.

Hadn't thought about possible debris. Hmmm. Good idea. Worth checking I guess. Maybe I'll just take a few minutes and drop the lower unit tonight to have a look.

 

[Fix'em]

Re: Cobra water circulation problem

Re: Cobra water circulation problem

Just an FYI: Water running out around the zinc is not uncommon, *IF* its just running out. However, if its "squirting" out, as in its under pressure then you have an issue that must be addressed. If its under pressure it will surely back up into the exhaust manifolds.

Being under pressure indicates the normal exhaust path is blocked.

Well, I wouldn't say it squirts out too badly. It more or less pours out around the zinc. It falls straight to the ground other than the bit of spray that comes out when the water initially hits the zinc. I'll try to get a video of it if it persists.

 

[Fix'em]

Re: Cobra water circulation problem (pictures added)

Re: Cobra water circulation problem (pictures added)

Well, didn't get a video, but here is a picture. The red arrows point to where the water comes out after circulating through the motor. I checked the exhaust bellow and it is fine. The water gets into the drive, but comes out still around the anode and also some comes out of what I think is an exhaust relief maybe? on the transom area right above the water drain hole.

 

[Fix'em]

Re: Cobra water circulation problem (pictures added)

Re: Cobra water circulation problem (pictures added)

Bubba1235. Any thoughts?

 

[md-lucky]

Re: Cobra water circulation problem (pictures added)

Re: Cobra water circulation problem (pictures added)

Fixem:

I have a 87 Thundercraft with a Cobra drive also. I don't recall the water ever coming out of either of those spots in nuetral. I'm fairly sure mine comes out of the prop.

It may be a little while before I hook up the muffs again, but I will be sure to check the very next time I have them hooked up and report back!!

 

[Fix'em]

Re: Cobra water circulation problem (pictures added)

Re: Cobra water circulation problem (pictures added)

Thanks Md-lucky. I'd appreciate that.

 

[Fix'em]

Re: Cobra water circulation problem (pictures added)

Re: Cobra water circulation problem (pictures added)

I found this on youtube. http://www.youtube.com/watch?v=jEkfzbkdIFc

This is pretty much what mine does. See where the water is flooding out of on the video. Only thing is that this guy gets a little squirt every now and then out of the prop. Mind you, my boat is pointing downhill a little and this one seems on level ground.

Any thoughts?

 

[sea wolf]

Re: Cobra water circulation problem (Video and pics added)

Never mind.

 

[Fix'em]

Re: Cobra water circulation problem (Video and pics added)

Never mind.

so you figure this is normal? I'm only concerned because I have never ran this boat before. I bought it with a blown motor and just got it running this week for the first time. If this is normal, great! It's just that I've only ever had outboard before, so I am going by the manual and it said that it comes out the prop. If this is ok, then I'm thrilled. LOL I'm going out then on the water for the first time this weekend with it.