Boat trouble starting... (1985 Monaco)

muskokamarc

muskokamarc

Member
May 28, 2018
200
Muskoka
Boat Info
1985 Sea Ray 210 Monaco
Engines
230HP Alpha One
So over the weekend I took my 1985 SeaRay Monaco out for a drive. I drove for a solid 30-40 minutes, turned the boat off in the middle of the lake and went for a swim with some friends...

When I went to start it back up to leave, it was turning over strong, but not starting. The engine was very hot so I decided to let it sit for a little while and after about say 45 minutes of sitting in the open water I was able to start it with a bit of throttle. (Note: battery voltage was strong).

I can't tell why the boat is getting so hot and why it won't start up. Perhaps this is a thunderbolt ignition problem? Ignition is mounted to the exhaust manifold. See photo. The temperature gauge may not be too accurate and I forgot to bring my laser thermometer, but the manifolds were hot to touch.

I brought it home and tried to start later in the day when it was cooled off and again it was turning over strong but it wouldn't start.

Note: I had impeller serviced early July and rebuilt the original starter in June and two brand new charged batteries with more than enough power.
 

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Same here. If this is a carbureted engine, vapor lock is quite common when things get good and hot. It is also easy to flood the engine when the engine is hot.
 
If you advance the throttle to full, crank the engine and it starts you may have a problem with the well plugs in the bottom of the quadrajet leaking and flooding the engine. You Tube will have videos of the way to fix it.
 
hottoddie said:
If you advance the throttle to full, crank the engine and it starts you may have a problem with the well plugs in the bottom of the quadrajet leaking and flooding the engine. You Tube will have videos of the way to fix it.
Click to expand...
Tried advancing throttle all the way forward (in neutral obviously) and it wouldn't start either.
 
Ike said:
Same here. If this is a carbureted engine, vapor lock is quite common when things get good and hot. It is also easy to flood the engine when the engine is hot.
Click to expand...
Any suggestions to deal with vapor lock?
 
Possibly choke open - because engine still hot but not hot enough ( too lean)
Giving it extra throttle, like you did, would start it

Sounds like everyone pointing to fuel/ carb issue. I seem to have to fiddle with my choke a little too much. Especially in early spring and fall.
 
I had a vapor lock issue with my 88 240 sorrento with merc 5.7. You could actually see the fuel being pulled back to the tank in the clear filter. Buddy of mine who built race cars told me to install an anti syphon valve at the tank. This fixed the problem. Said they are put on old hot rods due to the heat of the motors
 
So update... communicated with the marina who did the impeller service and he said it’s likely one of these issues:

1) failing thermostat (I have my doubt it’s this as my friend replaced this for me a year ago)
2) exhaust port blockage - sometimes the older boats will rust off there exhaust flappers and they get caught, this restricting exhaust water flow
3) manifold coolant passages plugged up with rust - this is tougher to rectify (why would this be tougher to rectify?)
4) an internal crack in the engine block (does this mean entirely new engine necessary?)

I have a funny feeling it’s #4 as it may have not been winterized properly one year. I cannot be certain though. Either way, a crack in the engine block would likely mean a new block is necessary? I won’t let go of this boat and I guess I will be forking up some cash if that is the issue...

I will be bringing the boat back to the marina once the ice clears out on the lake. I appreciate anyone’s advice on how you think I should proceed.
 
Verify choke operation. That vintage carb has a bi-metal coil that controls the choke operation and the coil will fail with time leaving the choke in the closed position.
 
Wanderer 290 said:
Verify choke operation. That vintage carb has a bi-metal coil that controls the choke operation and the coil will fail with time leaving the choke in the closed position.
Click to expand...

Is it possible that the 'flap' is staying closed even when the engine is running and that is what's causing the boat to overheat and then have trouble starting? How do i verify the choke operation?

I was watching this video to try and learn about it:
 
Does it start? Do you have spark when it wont?
Thunderbolt Diagnostics.jpg
 
Typical choke operation is the butterfly will close about 60% when the engine is cold on a 70* day and possibly up to 95% on a below 50* day. The colder the engine the more it closes and when the engine is at normal operating temp the choke should be fully open.
No a closed choke will not cause an engine to run hot.
As mentioned above check for spark because a failing coil will begin to fail as it gets hotter as will a fuel pump also.
Basically, an engine needs air, fuel and properly timed spark to run.
The choke could be restricting air, the coil could be failing... And if the fuel pump is failing or vapor lock is a condition a lean burn condition would cause the engine to run a little hotter.
You may have multiple failures.
The number one thing that causes overheat is lack of raw cooling water.
 
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