470 causes boat owner to go postal (overheated after changing power steering hoses)

Here it is late July and we haven't been out on the boat once. A couple of months ago we were planning to go boating, but a rusty power steering line started squirting fluid at me. Other than that, it started on the first try and ran fine. In fact, the boat ran great all last year. We put over 20 hours on the boat with absolutely no problems.

So I broke out another $300 and replaced all the power steering lines.

I checked all the fluid levels, hooked up the muffs, and started it. It ran really, really roughly and was belching blue smoke. After a couple of minutes it steadied out. I checked oil pressure: good. I checked engine temp. Not even off the peg. I verified that water was coming out of the lower unit at a normal clip. Everything looked okay. I figured it was running roughly because the engine got rained on while I went to the store this morning.

Then I noticed that there was smoke coming from the rear of the exhaust elbow. It was scalding hot! The rubber bellows that connects the exhaust elbow to the exhaust pipe was also too hot to touch. The bellows adhesive was bubbling out from under the bellows.

I quickly shut it down. It only ran for about six minutes.

All the cooling system hoses were warm, but not hot.

I'm assuming that the blue smoke was the rubber exhaust flapper burning up.

The boat has been sitting up since May because I had to do two timing belt jobs and go camping a couple of times...oh yeah, and work.

Does anyone have any ideas?

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Simplest explanation: For some reason your seawater flow has stopped, or is greatly reduced. Easiest to check, is the driveshaft turning? Next, check the impeller, maybe it has failed?

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Solved. I found fragments of the cooked flapper all under the outdrive, including half of the metal plate. The exhaust bellows split open last year, so it fell out. I also found that the fresh water hose had pulled off the bell housing, so that water coming out of the lower unit never made it to the heat exchanger.

So here's the deal. I was going to take my daughter tubing for her 15th birthday, but can I drive it without an exhaust flapper assuming I slow down gradually to prevent the stern from being swamped? The wife wants to know if there's a possibility of getting stranded if a rogue wave does swamp the stern.

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

My flapper has been gone for as long as I've had my boat (with 470) - hit by waves, stopped dead from WOT, you name it - never had a problem...

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

dn010 said:

My flapper has been gone for as long as I've had my boat (with 470) - hit by waves, stopped dead from WOT, you name it - never had a problem...

Click to expand...

You'd think that the pressure of the exhaust gases would prevent water from coming up into the engine.

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Like you said, slow down slowly, let the engine idle down , then shut it off, The worst danger i believe is if ya have a back fire. Then ya can suck a cylinder or two full of cold lake water, potentially causing a hydro lock bent connecting rod and other $$$ havoc.. if your engine is running well, that danger should be minimal...

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

I think you'll be fine as long as you don't shut the engine down from anything above idle, and also never while the boat is moving at anything above idle speed. Exhaust gases will prevent water from getting into the engine as long as the engine is running. If your boat for some reason has inadequately high risers or the engine is mounted too low - both of which could lead to water sloshing into the exhaust valves - then you should be very careful. Some designs are like this due to mfr's poor planning, most are not.

DougM

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

This was an unbelievable day! I got up at 5:30 a.m. so I could put this sucker back together (after replacing PS hoses/tubes and fixing a minor alternator issue) in time to be out on Santa Rosa Sound pulling some kids on a tube before it got to rough. Had the water hose issue, fried an exhaust flapper, then found a leaky PS tube which required a partial disassembly of the power steering booster thingy. Finally, I got all that crap squared away and it looked like I could salvage the day with some later afternoon tubing.

We launch the boat and the damned thing would not start!!!! It would trim up and down, but nothing at the key. Pulled it out and went home.

Turned out to be a loose wiring harness connector. J.H.C.! Why is it that a boat will run great in your driveway, but take a crap when it's stern hits water??? Why is it always so easy to troubleshoot in the driveway, but impossible at the boat launch with 12 trailers in the queue?

I decided to end this miserable day by getting drunk. Not quite there yet, though. Five beers and I'm barely buzzed. Gonna hafta step it up to bourbon.

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Ah man. And I was pulling for you. Last night got my cockpit seating and pads screwed back in place with a flashlight in my teeth. Torqued the outdrive properly, then at 7am this morning put it back into the water after some major crisis work on my part. Turned out well and literally only minutes to spare as we got the last trailer parking spot at the ramp and spent the day out. Hope you don't have a headache this morning.

Get that thing tightened up and take it for a test spin with just you and a buddy or similar on a weekday evening so there's no pressure.

DougM

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Doug's right, fix it & try it without the kids hanging by. Even if they are being patient they will add pressure and make it miserable. You can't hurry careful. It's got to be right after all.

Re: 470 causes boat owner to go postal (overheated after changing power steering hose

Yeah, it seems obvious now. I disconnected that big round electrical connector just below the 50 amp circuit breaker and it wasn't fully seated when I reinstalled it. Should have thought about that, but yes, the pressure, the pressure!

It's running fine now. We'll go out this Saturday. Thanks for the moral support!