1992 King Cobra 454 - Overheating and loss of power

[07caddy]

Greetings,
We have a 1992 Four Winns Sundowner 225 (454 OMC King Cobra--not sure if it's the cone or dog clutch model) and put it in the lake today only to have it towed back to the boat launch an hour later.

Background:
We had our boat winterized last year and it sat until today. We put it in the lake and it was hard starting and very sluggish (once started), but my wife got it off the trailer and I went to park the truck and trailer. Got back to the boat and ....

Just as we got out of the no wake zone, gave it a little throttle and the temps immediately shot up to close to 245. Gave it a little more throttle and it wouldn't go above 2K RPM so we backed off and then shut it down. By now the engine was starting (reek is a better description) to smell with a small amount of smoke.

Last year we noticed some high temps when we were trolling and I discussed this with a boat mechanic here in Colorado Springs and he said we should have the water pump replaced because overheating while trolling at low RPMs is a sign of a failing pump.

Given the description of what happened today, I'd rather replace a water pump and not something more significant....unless absolutely necessary.

When we got home I noticed a few pieces of rubber lodged in the water intake holes in the lower unit. That's probably not the technical term for the holes, but that's the best I can come up with without a manual.

Is replacing the water pump and/or impeller a task one with moderate technical/mechanical skills can accomplish in the driveway? Is what I'm describing inline with a water pump that's failed?

I've read a lot of threads about the KC and parts availability, so I'm hoping our troubles can be resolved with a new pump, pump repair kit, and/or impeller...

Any suggestions on where to start are appreciated....

Thanks,
Mike

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

Howdy,


Yours is the cone-clutch model. (take good care of it.....it's a rare one!)

You need to START with replacing the raw water pump. AND if the previous one(s) failed, you need to find all the pieces. They may be plugging up the oil and/or power steering coolers which blocks total water flow.

Is replacing the water pump and/or impeller a task one with moderate technical/mechanical skills can accomplish in the driveway? Is what I'm describing inline with a water pump that's failed?

It's not hard. But to do anything.....get yourself an OEM OMC service manual!!



Oh....Welcome to iboats!



Rick

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Thanks, Rick.

Is the raw water pump in the drive somewhere? Man, I need to buy a manual to find my way around ...

I suppose "rare" is not exactly the best position to be in to buy replacement parts.

 

[sw33ttooth]

Re: 1992 King Cobra 454 - Overheating and loss of power

i believe... the water pump has a belt hooked up to it. dont hold me to that, also i've been hearing get the OEM MANUAL not a climber or other brand

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Looks like I need to replace the impeller. There is a drain hose that's completely rotted as well... Is the raw water pump behind the impeller? Or another way to ask, is the impeller attached to the raw water pump?

Will order a shop manual and figure out how to locate the missing pieces ... Assume the impeller pieces went for a ride somewhere--not good.

Getting dark and no manual, not going to go any further tonight...

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

Nice pictures! In focus too!!

Will order a shop manual and figure out how to locate the missing pieces ... Assume the impeller pieces went for a ride somewhere--not good.

Yeah. Good idea. Don't waste your money on a Seloc or Clymer.....get the real deal.

I suppose "rare" is not exactly the best position to be in to buy replacement parts.

Well.

I hope you know that OMC is a company that has been out of business since 1998. They only made that particular drive from 1990 to about 1995 or so. (maybe 1993 or 94)

It is the "precursor" to the Volvo Penta SX There are VERY few parts available for it.(the drive)

If you have the Spitfire ignition system on your engine (electronic ignition) and it fails, you "junk" it and replace it with a MSD or Mallory marine distributor.

If you break something "big" in the drive, you may be "done" unless you can find another drive......

Go here to find part numbers


Cheers,


Rick

 

[Lou C]

Re: 1992 King Cobra 454 - Overheating and loss of power

the impeller is the raw water pump...that one looks like it was used at least one season too long, but you want to try to find all the missing parts of the old one or else you can have a blockage that will cause continued overheating. I'd try removing the raw water intake hose at the thermostat housing, pull off the housing, look in there and in the hose, then take the raw water intake hose and back flush the hose to force out any pieces that may be in it, or the power steering cooler....you might also want to check the rubber exhaust hoses and the exhaust flappers in this pic

http://www.dougrussell.com/partscat...,1131,1132,1133,1134,1135,1136,1137,1138,1139
in this pic, the thermostat housing is part #31, raw water intake hose is part #34

http://www.dougrussell.com/partscat...,1131,1132,1133,1134,1135,1136,1137,1138,1139

in this pic, the power steering cooler is part #17, and that raw water intake hose from the thermo housing is part #4, this cooler is way back on the rear of the engine, the other end of the cooler has a holes on it that goes to the transom, the water pumped in by the impeller goes through that hose, then through the cooler, then through the raw water intake hose, then to the thermo housing. Impeller fragments could be anywhere upstream of the impeller. BUT since you have it off now, if you remove the raw water intake hose at the thermo housing, and stick a hose nozzle in it, have someone turn on the water, it may force pieces out of water ports that are usually covered by the impeller. If that does not do it, then you have to take off the hoses and cooler and get those pieces out....

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Lou,
Thanks for clarifying the raw water pump/impeller. I noticed another missing piece/torn hose and it looks to be an exhaust tube or bellow (too dark to take a pic now). Well, the only thing left is the clamp and just enough material for the clamp to hang on to.

Thanks for the links and I'm looking forward to get the boat back in the water by the 4th -- as we have camping reservations and don't want to canx.

Another question...after I get it put back together, and hook up the muffs, should water come out of the prop with the engine running?

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

If you saw smoke, and you ran the engine very long with no water flowing into the exhaust system, you may have cooked the rubber parts(#3 & 18 below) of the exhaust system. So check them carefully.

If you have thru-prop exhaust, there's also exhaust shutters(#28) that you have in the y-pipe (#40) that might have gotten a little cooked. If they were cooked enough they might get stuck open and won't be doing their job of preventing water "back-flow" during rapid deceleration. That could damage your engine if it happens.....


You may or may not see water coming out of the prop but you WILL see water at the transom (relief ports) and under the bellows. (the exhaust bellows may have slits in it.....which is normal)

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Inspected some of the rubber in and around the exhaust and didn't see any obvious signs of cooked rubber. My inspection has only been visual (exterior of the hoses) because I haven't been able to actually disconnect a hose after loosening a clamp.

There must be some sort of ninja skills to remove the hoses because they are a PITA.

Just placed an order from Doug Russell for water pump repair kit and gasket and hope to have it here in a few days.

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

First shot of theromstat housing after removing the raw water intake hose Lou C recommended I check out, note the rust.

I haven't been able to disconnect the other hoses, but i'm working on it.

Should I just replace this housing and go from there or remove and inspect completely?

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

A rusty t-stat housing doesn't automatically make it "the cause"......

You should however check the rest of the cooling system.

Absolutely replace the raw water pump, search for (impeller)pieces, remove the manifolds and risers (break them apart) so you can inspect and replace the riser gaskets.

It might even be a good idea to have a look at the circulating pump if it's the original one....

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

A rusty t-stat housing doesn't automatically make it "the cause"......

You should however check the rest of the cooling system.

Absolutely replace the raw water pump, search for (impeller)pieces, remove the manifolds and risers (break them apart) so you can inspect and replace the riser gaskets.

It might even be a good idea to have a look at the circulating pump if it's the original one....

Thanks for the advice, Rick. You guys are a wealth of knowledge and experience, no question about it.

Still waiting for a manual but anxious to tear apart the manifold and risers without it...

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

Removing the manifolds and risers doesn't take any sort of special skills.....remove the nuts on top and pry them apart.

You don't absolutely have to remove the manifolds from the heads, but it might be good to look in the exhaust ports for evidence of water(rust) Also, you'll need to scrape the riser-manifold surfaces and you'll not want that stuff dropping into an open exhaust valve.

They're heavy though.........don't hurt yourself.

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Are the risers #48 in the diagram you posted yesterday? I suppose I'll need new gaskets once I remove, inspect and replace and will have to order replacements as well?

Wish some of these parts were common gm parts, but I guess marine grade stuff isn't readily available at Autozone or Advanced

 

[HT32BSX115]

Re: 1992 King Cobra 454 - Overheating and loss of power

Are the risers #48 in the diagram you posted yesterday? I suppose I'll need new gaskets once I remove, inspect and replace and will have to order replacements as well?

Wish some of these parts were common gm parts, but I guess marine grade stuff isn't readily available at Autozone or Advanced

Yes. You need #8 in that drawing.

Autozone or Advanced, not normally (although I was able to buy a mechanical (marine) fuel pump from Autozone right out of their Airtex catalog...........)


You can however, go to NAPA though. They have a Marine line (Sierra).....Riser gaskets are fairly easy to source.

Otherwise, you'll need to get them from an online source like iboats!!

http://www.iboats.com/OMC-Sterndriv...7380947--**********.488805949--view_id.270043

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Thank you, sir.

BTW, I'm retired AF! I think I read in one of your posts that you are as well.

Mike

 

[Lou C]

Re: 1992 King Cobra 454 - Overheating and loss of power

You don't have to replace it unless you see big chunks of rust coming off inside. You can remove it (good time to check the thermostat) and look through all the openings, to make sure they are not getting necked down with rust. If so you can clean it out with a big machine screw or similar. When you reinstall, use some OMC gasket sealer on both sides of the gasket and the bolt threads, that helps em not corrode in place. If the hoses won't come free, get a hair dryer and heat em up a bit, just enough to get them to loosen a bit. I put a bit of grease on the necks each one fits on when I winterize. You get rust under there and the hose gets kinda welded on. Same thing happens with exhaust hoses, remember that when you check your manifolds. On my old 88, I had to slide the lower exhaust pipe down to get the manifold off, because it's the one piece manifold/riser design. Here are few pix, this is what a new one looks like and one use in salt water for 5.5 seasons.....

The engine pic shows you want you want to see....no rust in the exhaust ports, no rust on the exhaust valve. If the gasket between the manifold and riser leaks, you can get rusty exhaust valves which will cause a miss and low compression, and if you get a big leak from a rust hole in the manifold, you can hydrolock the motor. Probably rare in freshwater but common in salt.

 

[07caddy]

Re: 1992 King Cobra 454 - Overheating and loss of power

Lou,
Thanks for the pics and tips on removing hoses that seem welded on. I'm not brave enough to take off the thermostat housing, manifolds and risers without the manual, gaskets and sealer on hand. The OEM OMC manual is not cheap nor easy to come by. In the scheme of things, cheap compared to $90/hr for someone else to work on it.

BTW, I removed more of the hoses attached to the thermostat housing and the water that come out was rusty with a few rust bits spilling out as well.

Question: When I flush out the raw water intake hose from the thermostat, where should I expect to see any bits of the impeller? Would they be captured at the steering cooler or further back?

The hose attached to the bottom of the steering cooler and heading to the transom has been extremely difficult to remove (not on the cooler side as those hoses were easy to remove). In fact, I'll try the hair dryer to see if that works...

 

[Lou C]

Re: 1992 King Cobra 454 - Overheating and loss of power

Well if you're lucky, they might come out the water passages that are covered by the impeller,(leave the impeller off when flushing) if so then great, if not then I'd try removing the hose to the transom, from the cooler, and try to flush it there, then remove the thermo to cooler line and flush it, then flush the cooler with both lines off. That transom hose is in a real bad spot, I don't think I'd try getting off the end of it that goes into the transom mount unless you have to.

Oh and don't be afraid to remove the thermo housing, just take a quick digital pic of how everything is hooked up. It's very easy to remove, I have even had to replace thermostats with my boat in the water on the mooring. And Im in salt water as you can see from my manifold pix...