OMC Cobra-3.0L Slipping occasionally and OVER HEATING

ClaytonAylmer

Recruit
Joined
Jul 5, 2012
Messages
2
Sorry for the long post but all the details are needed!

I just recently bought a 1988 Stratos 1700XL with a Cobra Outdrive. 3.0L-130HP. It needed a rebuilt carb(which I've completed in order to make it start.) Then I took it out for the first time, it would go in reverse (no big deal) so I idled out, and by the end of the no-wake zone it had already reached 200. I put it up on plane and it cooled back down. After about a minute of 3/4 to full throttle it felt like it was missing every other second and started heating up again. So after that, I thought the waterpump was bad so I replaced it. After replacing it, I pulled the hose off the housing to see if water would come out and it does not when dropped into a lake but when the muffs are hooked up to it, it does. When muffs are hooked up it runs like a dream, no over heating at all (even after an hour on the muffs.)

I took it out a second time after having the linkage adjusted so it would go in reverse. Same thing happened, I got to the end of the no-wake zone (on a small lake) and it had already hit 200 degrees. I went 1/2 throttle and no less then 10 seconds in it started to really slip. Almost as if the prop was no engaging anymore. I finally killed it. Started it again, put it in gear, it started to go forward a bit but slipped again and fell out of gear and revved before i put it back in neutral.

What is my problem??? I've read several similar problems and some say it's the engine coupler and others say to check the hub on the prop. My prop, when engine off and in gear, seems fine; so I don't think thats the problem. Could it be something besides the engine coupler?
 

Kainon

Chief Petty Officer
Joined
Sep 13, 2009
Messages
608
Re: OMC Cobra-3.0L Slipping occasionally and OVER HEATING

So you replaced the water pump on the outdrive the impeller? did you replace the housing too ? sometimes they warp and was the impeller broken or complete? could have bits lodged inside. You could also have a blockage in the exhaust manifold or riser.

the slipping can be the rubber dampening in the prop or "could be" the engine coupler. when it slips dp upi smell rubber burning at the back of the engine or do you hear clicking from the outdrive ? could be a lower shift cable or bad gears in the lower from previous owner shifting to slowly.
 

ClaytonAylmer

Recruit
Joined
Jul 5, 2012
Messages
2
Re: OMC Cobra-3.0L Slipping occasionally and OVER HEATING

So you replaced the water pump on the outdrive the impeller? did you replace the housing too ? sometimes they warp and was the impeller broken or complete? could have bits lodged inside. You could also have a blockage in the exhaust manifold or riser.

the slipping can be the rubber dampening in the prop or "could be" the engine coupler. when it slips dp upi smell rubber burning at the back of the engine or do you hear clicking from the outdrive ? could be a lower shift cable or bad gears in the lower from previous owner shifting to slowly.

I replaced the water pump on the outdrive the impeller INCLUDING new housing. The old housing was warped and been burned on the inside. The exhaust comes from the prop and it seems to be coming out just fine from my observations.

I've put the prop in gear (Fwd & Rev) and it doesn't seem to be the hub in the prop.

I wasn't at the back of the boat in order to smell any rubber but, the boat overheats and slips out of gear (doesn't that mean its the engine coupler because of the overheatting?) It could be bad gears because i've read that the OMC gearsets go bad easily but in the upper housing the gears seemed to look fine.

What else could my problem be? Or are we sure its the engine coupler now?
 

ljsweeney

Seaman
Joined
May 23, 2011
Messages
54
Re: OMC Cobra-3.0L Slipping occasionally and OVER HEATING

As far as the overheat condition goes, you can't assume that this is a new issue, since you just recently acquired the boat and got it running. If the old impeller and/or housing showed signs of thermal deformation, it's a good bet the PO did not do a good job on the maintenance, and there may be more hidden damage. You did not state whether or not the new impeller/housing resolved your overheat issues. Did you test water flow at the t-stat housing while the boat was in the water? Testing on muffs will not yield accurate water flow data (your hose is pressurized - the lake is not). If there is not adequate flow at the 'stat (water column roughly 4" high), you are going to have to pull the outdrive, separate the upper and lower units, and inspect the water tube seals. When an overheat condition melts an impeller housing, it is likely that your water tube seals have also melted.

As far as the slipping is concerned, have you pulled the prop and checked the splines? Spinning a prop would be a more common occurrence than a bad coupler. If you've pulled the prop and its splines (as well as the prop shaft splines) are good, then the coupler would be the next place to investigate, provided that you are not getting any grinding/clunking noises from the outdrive when it slips. If you hear grinding/clunking immediately before or during the slipping, your lower unit is on its way out (specifically the clutch dogs).

Chances are you'll be pulling the outdrive next (pending results of water flow test and prop spline inspection). Get an OMC factory (NOT Seloc or Clymer) manual before starting.

Good luck.
 
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