'98 Stingray 190LX 4.3 Merc Stuck in Muck Issue

[snipester88]

The other day I was tooling around and managed to get the my '98 Stingray 190LX 4.3L Merc Alpha stuck in some deep mud. I powered my way out of it. Cruising across the lake on my way back, I started to smell burning rubber and came to a stop. I popped the back cover open to a plume of smoke. The boot on the back of the driver side water jacket had melted, split open and was spewing water and hot exhaust gasses.

I'm thinking the water pump is full of muck which clogged the impeller, which ran it mostly dry, and exhaust gasses melted the boot. I won't have time to look at this till this weekend but I'm not super familiar with this part of the boats system. I'm wondering if you guys have any input on this before I start poking it with a stick. Thanks!

 

[Bondo]

Ayuh,...... Welcome Aboard,...... a '98 Alpha should be an Alpha I, Gen.II,......

You'll want to get a raw water pump rebuild kit,.....
You'll have to drop the lower unit to change the pump, so wash all the mud outa the whole casting,.....
You'll need the rubber parts for the exhaust system, not just the one that blew out,.....
The exhaust bellows, might be Ok,.... or not,....
'n I believe the water pipe seal in the upper housin' usually takes a 'ell of lota exhaust heat, when run dry,....

 

[Scott Danforth]

Agree. Impeller kit, exhaust tube, flapper and anything else you find burnt

Also suggest installing a water pressure gauge

 

[Scott06]

Flush the power steering cooler to.
how hot did it get ? Must have been over heating

 

[snipester88]

Flush the power steering cooler to.
how hot did it get ? Must have been over heating

The oil temp gauge never went over 200, but it probably did start to overheat. Water was sizzling off the top of the water jacket. It was ran at about 3000rpm just above plane for a few minutes until I realized what was going on.

Ayuh,...... Welcome Aboard,...... a '98 Alpha should be an Alpha I, Gen.II,......

You'll want to get a raw water pump rebuild kit,.....
You'll have to drop the lower unit to change the pump, so wash all the mud outa the whole casting,.....
You'll need the rubber parts for the exhaust system, not just the one that blew out,.....
The exhaust bellows, might be Ok,.... or not,....
'n I believe the water pipe seal in the upper housin' usually takes a 'ell of lota exhaust heat, when run dry,....

Sounds like a plan, thank you. Is there a good online source for these parts or should I call local?

 

[Scott Danforth]

Without water, the gauge is not accurate. If water was sizzling, temp over 220

 

[snipester88]

Looks like the shifter is all locked up as well. This is not looking good

 

[Bondo]

Looks like the shifter is all locked up as well. This is not looking good

Ayuh,..... Disconnect the lower shift cable, at the shift plate, 'n try the controller,....
If hot enough, the lower shift cable melts where it crosses the y-pipe,....

 

[Scott06]

The oil temp gauge never went over 200, but it probably did start to overheat. Water was sizzling off the top of the water jacket. It was ran at about 3000rpm just above plane for a few minutes until I realized what was going on.

Sounds like a plan, thank you. Is there a good online source for these parts or should I call local?

You may have an issue with head gaskets if it got that hot. Would be on the lookout for water in oil when you get it back up and running.

 

[snipester88]

Looks like the engine is alright. Still 120psi+ on all cylinders and it still turns over strong. The shift cable, exhaust from the water jacket back, and water pump along with the lower unit impeller assemblies are all fried. I am running into an issue where the engine wont fire at all while the Run switch is in the Run position.. however the engine sputters for 2 or 3 pistons when the key is initially turned and the switch is in the Off position. Since I have no shiftthrottle cable, I've tried actuating the accelerator pump and opening the carb manually. I even tried starting fluid but I can't get her to fire up.

 

[nola mike]

Looks like the engine is alright. Still 120psi+ on all cylinders and it still turns over strong. The shift cable, exhaust from the water jacket back, and water pump along with the lower unit impeller assemblies are all fried. I am running into an issue where the engine wont fire at all while the Run switch is in the Run position.. however the engine sputters for 2 or 3 pistons when the key is initially turned and the switch is in the Off position. Since I have no shift cable, I've tried actuating the accelerator pump and opening the carb manually. I even tried starting fluid but I can't get her to fire up.

The accelerator pump is activated by the throttle cable, not the shift cable. Please elaborate on what you're calling "run" position. That is different than "start" position.

 

[snipester88]

Sorry, shift cable was a typo in that sentence. I meant to say the throttle cable. The throttle / shifter near the drivers seat is stuck in the forward position, so I disconnected it at the engine in order to manually actuate the carb and attempt to start the engine.

The red switch labelled "Run/Off" near the throttle on the drivers side. I believe this switch controls power to ignition.

 

[Scott Danforth]

150 psi is a new engine
to me personally, 120 psi is where I start looking for a rebuild

however your gauge may be off. what was the spread of the compression numbers? you want only 10% variance

 

[Scott06]

Sorry, shift cable was a typo in that sentence. I meant to say the throttle cable. The throttle / shifter near the drivers seat is stuck in the forward position, so I disconnected it at the engine in order to manually actuate the carb and attempt to start the engine.

The red switch labelled "Run/Off" near the throttle on the drivers side. I believe this switch controls power to ignition.

The red switch is man overboard or kill switch . What you describe kibd of sounds like it is tripped. Try cycling it on snd off snd see if you get spark.
also not gonna help if you cant advance throttle on a could start.that andtnhe choke helps richen the mixture

 

[snipester88]

Not much variance. 120psi was the lowest, the rest were around 125 up to 130. I could probably swing a rebuild, but 120+ should work for the rest of the season I’d think. I tried flipping the kill switch rapidly while starting but it doesn’t seem to help. Is there a way to bypass this switch completely? I‘ve tried advancing the throttle through the linkage on the carb.. no luck. There’s no engine ignition in the run position..

 

[Scott06]

Not much variance. 120psi was the lowest, the rest were around 125 up to 130. I could probably swing a rebuild, but 120+ should work for the rest of the season I’d think. I tried flipping the kill switch rapidly while starting but it doesn’t seem to help. Is there a way to bypass this switch completely? I‘ve tried advancing the throttle through the linkage on the carb.. no luck. There’s no engine ignition in the run position..

Do you have 12 v on positive side of coil when key is in run position?

If not trace back to ignition switch where you are loosing power. If you do have 12 v then diagnose ignition system

Yes compression of 120-130 should run. When you get down around 100 is when you start having dead cylinders

 

[snipester88]

The problem turned out to be the shift interrupter. I disconnected it and the boat fired up immediately while manually running the carb. It looks like since the shift cable is stuck in gear the boat was cutting ignition once it senses the shift interrupter engaged

 

[nola mike]

Not much variance. 120psi was the lowest, the rest were around 125 up to 130. I could probably swing a rebuild, but 120+ should work for the rest of the season I’d think. I tried flipping the kill switch rapidly while starting but it doesn’t seem to help. Is there a way to bypass this switch completely? I‘ve tried advancing the throttle through the linkage on the carb.. no luck. There’s no engine ignition in the run position..

You can bypass the switch by supplying 12v to the I terminal of the ignition switch. It is the switch is accessible you can jump the wires on either side together

 

[Scott06]

The problem turned out to be the shift interrupter. I disconnected it and the boat fired up immediately while manually running the carb. It looks like since the shift cable is stuck in gear the boat was cutting ignition once it senses the shift interrupter engaged

Ok - based on your comments and over heat willing to bet if you disconnect your lower shift cable at the shift plate your throttle cable can freely work.

If you shift cable sticks the shift plate will trip the shift interrupt knocking out the ignition. you can leave it disconnected for the time being. When you get your damaged lower shift cable replaced and are running on land the shift interrupt will never trip. Only on water with a load on the prop should the interrupt get tripped. It unloads the prop momentarily so the back cut engagement teeth on the gears can unload and come out of gear.

 

[snipester88]

Hi all,

I ended up replacing the lower shift cable, the exhaust tube from manifold, the exhaust bellows, impeller assembly, and the water pump. I also rebuilt the lower unit. I just fired up the boat this afternoon and noticed that the drivers side exhaust manifold is getting super hot, while the passenger side remains cool. What could cause this imbalance? I'm running the boat on water muffs for now