How bad did I break it?

NiagaraChillin · **Posted:** Mon Jul 30, 2012 8:44 am

My happy ending;

Installed the new impeller, tested it with the muffs, ran fine, still smelled a little burning plastic tho. So I shut her down and let her cool. Crawled around and viola! found that the hour meter wiring harness and fallen from its plastic clip and was laying across the exhaust, yep it had melted. A quick cut, splice, tape and zipstrip job and all is well. Checked the exhaust while I was down there and everything checked fine, dodged a $$$ bullet this time.

Was out all day yesterday and not one problem....well, except for the sunburn.

ric · **Posted:** Mon Jul 30, 2012 8:57 am

The exhaust shouldn't be nearly hot enough to melt plastic

LouC · **Posted:** Mon Jul 30, 2012 9:02 am

Sounds good, you will know for sure when you back it in the water and start er up because with the muffs, the water pressure forces the water into the drive, in the water, the impeller has to be able to suck the water all the way up to the front of the engine.
Invest in an IR heat gun if you don't have one, they are pretty cheap and you can then have a baseline of what your real temps are, when everything is OK. Then if something changes, you can tell if its a problem or not. I found that normally, my temp gauge runs between 160-172 or so, when I come off plane it will go up to 175 for a minute and then cool off. But using the IR gun to shoot the area under the thermo housing, it ranges from 155-160 even when the gauge says 175. Water temp can be higher than the cast iron. The manifolds, run at 95-110 at idle. After running on plane they will be 130-135 tops. My exhaust tubes are cooler, like 100-120, the Y pipe, the same. That is warm but you can keep your hand on it. I have fond that is its too hot to keep your hand on it the temp is more than 140.
I had a blockage in the thermo housing a few weeks back. I knew something was up because the engine temp was 10* hotter warming up. I checked the manifolds and they were close to 160* at idle, much hotter. So I cleaned out the thermo housing and all was fine after that.

NiagaraChillin · **Posted:** Mon Jul 30, 2012 9:15 am

Ric, the wire had melted when my impeller went and my temp pegged at max (earlier post). I guess when I was testing it after new impeller install, the residual smell was still lingering, or the melted portion got hot again and gave off a little odor, or I just had my head too far in the engine compartment and my big nose caught a whiff.

Lou, I did have it back in the water, and everything is working fine. (ain't gonna say that again, lest I jinx myself)

LouC · **Posted:** Mon Jul 30, 2012 9:58 am

One thing I have noticed is that with engine mounted pumps the impeller and housing/wear plate have to be in very good shape for it to pull water up form the drive. now with an Alpha, or outboard with the impeller in the lower unit, the pump is in the water and it just has to push the water up to the engine. Same with my Cobra except the impeller is in the upper gear housing but always in the water when the boat is not on plane.

The upshot is just replace the impeller and wear plate at least every other year, and inspect the passages in the Thermo housing and manifolds/risers every 4-5 years and you should not have problems

ric · **Posted:** Mon Jul 30, 2012 10:10 am

LouC wrote:

One thing I have noticed is that with engine mounted pumps the impeller and housing/wear plate have to be in very good shape for it to pull water up form the drive. now with an Alpha, or outboard with the impeller in the lower unit, the pump is in the water and it just has to push the water up to the engine. Same with my Cobra except the impeller is in the upper gear housing but always in the water when the boat is not on plane.

The upshot is just replace the impeller and wear plate at least every other year, and inspect the passages in the Thermo housing and manifolds/risers every 4-5 years and you should not have problems

I personally won't own a boat with an Alpha for that very reason. Bravo or Volvo Penta only for me. There's a flaw to my logic though, because if an Alpha drive ever broke.. they are cheapest dang things in the world. You can buy a good leg cheaper then the waterpump for a VP.

650Guy · **Joined:** Tue May 22, 2012 7:15 pm **Posts:** 47

NiagaraChillin, Congrat's!! glad you had a happy ending!

My impeller had eat'n a blade, and cracked two more. Not as bad as I thought it would be but i'm guessing bad enough to heat my engine up. and of course, nobody carries "king Cobra" parts, so there my boat sits, out of the water. I'm sure by the time rain moves in, my part will come with it.

I'm still hoping it was just the impellor, no internal damage, and no blockage. Any suggestions on how to assure I flush the system and have no blockages??

NiagaraChillin · **Posted:** Mon Jul 30, 2012 2:02 pm

650Guy, if you only missing one blade, it should be easy to find. Just make sure to take all applicable water hoses off and shake em/ or flush them with a water hose. Also do the same with your thermostat (T-Stat) housing, might as well change the T-Stat while your doing all this. Check inside your water neck (where the T-Stat housing bolts on.

Best case, you find that blade in a hose or the T-Stat housing, worst case its been carried into the exhaust manifolds/risers and is stuck there. If it is worst case, thats where my limited experience ends, but some of the more experienced guys here can help ya with that....

LouC · **Posted:** Mon Jul 30, 2012 2:39 pm

ric wrote:

LouC wrote:

One thing I have noticed is that with engine mounted pumps the impeller and housing/wear plate have to be in very good shape for it to pull water up form the drive. now with an Alpha, or outboard with the impeller in the lower unit, the pump is in the water and it just has to push the water up to the engine. Same with my Cobra except the impeller is in the upper gear housing but always in the water when the boat is not on plane.

The upshot is just replace the impeller and wear plate at least every other year, and inspect the passages in the Thermo housing and manifolds/risers every 4-5 years and you should not have problems

I personally won't own a boat with an Alpha for that very reason. Bravo or Volvo Penta only for me. There's a flaw to my logic though, because if an Alpha drive ever broke.. they are cheapest dang things in the world. You can buy a good leg cheaper then the waterpump for a VP.

But ric all outboards use that exact same design as an Alpha, and you have to admit, it makes more sense from the point of view of physics, to PUSH water from a pump that's under water than it does to SUCK water through a pump that is 5 feet forward of the transom. Usually the raw water intake lines are below the waterline but it's still harder for that pump to suck the water all that way.
So what you do is learn how to drop the lower unit every other year and replace the impeller, it helps to avoid having the bolts that hold the upper and lower together from seizing and also from the driveshaft splines from seizing. I have not had to split my Cobra in a long time but last year I backed out all the bolts and coated them in OMC Gasket Sealer just to keep from having a problem when I do take it apart.

IMHO, the best impeller design is the Cobra, it primes easy because the pump is in the water but its much easier to replace than the Alpha/OB style. 3 bolts the top plastic cover is off 3 more the impeller housing is off. You could even do it in the water with the drive trimmed all the way up if you are careful.

ric · **Posted:** Mon Jul 30, 2012 2:48 pm

It makes sense to me that I can replace it while the boat is in the water in under 20 minutes and not having to take the drive apart while the boat is on a rack/trailer.

650Guy · **Joined:** Tue May 22, 2012 7:15 pm **Posts:** 47

Thanks LouC and Ric!

My impeller kit should be here tomorrow. I'm slightly more intimidated than previously. My simplistic mind had some idea of muffs, running water, and boom, if water flowed... I'm a happy man (and if it didn't i wasn't willing to think about that). I now see, well, there is a little more than that.

So if I understand this correctly I have a bit more work ahead of me?

NiagaraChillin · **Posted:** Mon Jul 30, 2012 6:43 pm

650Guy, I posted a thread about my impeller change with a couple of pics if that helps any. http://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=9886&p=95514#p95514

It really isn't that difficult, take it from me, I am as new to this as can be....just take your time and make sure to do it right the first, second and maybe fifth time :shock:

LouC · **Posted:** Mon Jul 30, 2012 7:17 pm

650Guy wrote:

Thanks LouC and Ric!

My impeller kit should be here tomorrow. I'm slightly more intimidated than previously. My simplistic mind had some idea of muffs, running water, and boom, if water flowed... I'm a happy man (and if it didn't i wasn't willing to think about that). I now see, well, there is a little more than that.

So if I understand this correctly I have a bit more work ahead of me?

Naw, King Cobra, is like the plain Cobra, easy job, just make sure you get the housing gasket in right. I use OMC gasket sealer on he housing gasket and bolt threads.

650Guy · **Joined:** Tue May 22, 2012 7:15 pm **Posts:** 47

I know pulling the impeller was easy as can be, Did you coat your impeller with grease?

to flush the system, I was thinking all I had to do was hook up the hose and muffs and see if the water came out is that it?

NiagaraChillin · **Posted:** Mon Jul 30, 2012 9:08 pm

Not grease...use the glycerin that comes with the kit (all of it). After you have it all buttoned up, throw on the muffs and closely monitor the pump area and engine for leaks and such, annnd the temp gauge for sure. If everything is working, take it to the water and start it while in the water, again closely monitor everything just to make sure.

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