Why, why, why 496 HO overheating?
 

I've got a big investment in a 28 Daytona with 496 HO's. It's a 2001 and had 10 hours on it when purchased. I had both sea pump impellers replaced at start of season and one engine keeps running near 180 deg. when boating on the Missouri river, but runs fine at lake of the ozarks. The engine goes into guardian mode and loses power at the 180 deg point. Is this really that hot on this engine? Are these sea pumps really that unreliable? What else might be the problem? When I look at the through hull exhaust, there's plenty of water circulating, just as much as the other one. I'm getting very frustrated that I spent !@#$% on a boat and I have to worry about overheating.

Any ideas or input would be appreciated. Could it be something else?

Re: Why, why, why 496 HO overheating?
 

So you are seeing a engine temp difference between the two bodies of water? On both motors?

Re: Why, why, why 496 HO overheating?
 

How were the impellers you pulled out? If one was missing parts they could be clogging somewhere in the system. Try backflushing.

Re: Why, why, why 496 HO overheating?
 

Caincando1- I have analog gauges, so as far as I can tell the engine that's fine runs about the same at lake or river.

obnoxus- The engine that overheats had the impeller that had all the veins missing, but the guy that replaced it said he backflushed everything out. You know how that goes though.. What's the easiest most effective way to back flush to get the crap out if something were still in there? Where would be the most likely place that something might be stuck? I need to get this prob fixed.

Re: Why, why, why 496 HO overheating?
 

Theres your problem, backflush and I bet your fine. Start pulling hoses and flushing water through them. Its a pain in the ass.

Re: Why, why, why 496 HO overheating?
 

Harper, I am in St. Charles whats the guys name that did the work. I have a 496HO I just got installed and no problems so far. If you need someone else to look at it PM me I got a guy that is really good with that engine.


Rich

Re: Why, why, why 496 HO overheating?
 

The way I did it was to pull the hoses and flush them then pull the thermastat and flushed from the bottom drain plugs on the block, made fittings to connect to my garden hose, got nothing at first so I connected a air hose with 100 psi to the bottom drain plugs and shot that for 30 sec. then did the water again and the pieces started flowing out.

Re: Why, why, why 496 HO overheating?
 

i pitchure PIECES somwhere too,my .02

Re: Why, why, why 496 HO overheating?
 

Ok, here is what happened to my 496 ho today. The port motor kept going into gardian mode and alarms ringing, all gauges were ok. This would keep happening intermitently. I used the scan tool and found that port motor, port exhaust manifold ran at 106 degrees, starboard ex man. port motor 205 dg., hooked it up to the starboard motor and both manifold ran 105 and 106....... all manifolds felt same to the touch..... I took both temp senders out of starboard manifolds of both motors and switched them and problem moved over to starboard motor.....the sender looks to be the problem, will change it tomorrow and will post the results. only 30 hrs on motors.....

Re: Why, why, why 496 HO overheating?
 

Rich- A guy that works for Boat Docs at LOTO changed them. He seemed to know what he was doing, but then we're all human. I keep the boat where I live in SW Iowa near Omaha, so you're a little ways away. I wish there was somebody decent to look at it around here. I won't deal with the Eliminator dealer just 15 miles away. Don't even ask..

Backflushing sounds like a good place to start and by the sounds of it Tricky is on to something. I actually talked to a few others and the senders were brought up as a possible problem.

Are the senders capable of sending a false temp reading to the ecm and triggering a false alarm? I guess it makes sense..

Thanks guys