Runs hot for 30 minutes

[Twalton]

This is my second season with my 1974 C&C 27 on the Chesapeake. My A4 starts right up. Under load it reaches 185 and stays there as long as I don't push too hard. It will run fine for around 30 minutes then die. Then it won't start until another 30 minutes or so passes. I think it has something to do with the high running temperature, but I'm not sure. I have plenty of water flow. I installed a new thermostat (from Moyer) where there wasn't one previously, but it still runs quite hot. I try not to run more than 30 minutes, but sometimes it's necessary. Any ideas?

Thanks so much,

Todd

[Dave Neptune]

More info and ~~~

Todd, welcome to the forum. First how long since a flush? Check for a restriction under the fitting at the end of the manifold where the water exits, this is a common place for clutter to gather.
You can also try restricting the "bypass" line with a clamp unless equiped with a valve. This will force more through the block and can indicate otyher issues relating to flow.
Are you FWC? If not we'll need to look elsewhere.

The engine dying and not starting for a while is indicative of a bad condensor cheap or the coil not to expensive. Did you check for spark when it died?

Dave Neptune

[Twalton]

Thanks, Dave.

I flushed with vinegar at the end of the season last year. I will check for gook in the hose near the manifold. I don't know what FWC is, sorry. Is is possible that the engine running that hot could cause the fuel to vaporize and not burn properly? We had a car that used to do that, they called it vapor lock. Anyhow, the engine seems to sputter a bit before it dies. I will check for spark and let you know.
Thanks again for your help.
Regards,
Todd

[roadnsky]

I flushed with vinegar at the end of the season last year. I will check for gook in the hose near the manifold. I don't know what FWC is, sorry. Is is possible that the engine running that hot could cause the fuel to vaporize and not burn properly? We had a car that used to do that, they called it vapor lock. Anyhow, the engine seems to sputter a bit before it dies. I will check for spark and let you know.

Todd-
FWC is "Fresh Water" or a closed system using coolant.
RWC or "Raw Water" is the stock system using the intake water your vessel is floating in.
IMHO, running at 185° isn't really that high.

Are you using points or Electronic Ignition?
Dave's earlier questions are leading us to the coil as the possible villain here.
A very popular topic lately on our forum.

[romantic comedy]

That temperature is fine for the engine. If you have raw water cooling, it is high because of the salt water, but should not effect performance.

When ever you stall, follow the basics:

Spark? blue spark?
fuel?
compression?

I am wondering if you have a fuel issue. Something like a clogged tank vent?

[tenders]

I would change the points, condenser, cap, rotor, and coil as a matter of course first. Maybe the spark plug wires too. As was pointed out these symptoms are strongly suggestive of a failed condenser or coil and it sounds like 90 minutes of ignition maintenance is overdue anyway.

If that doesn't solve the problem I would guess a failing fuel supply, coming from a weak fuel pump, clogged fuel tank vent, or air leak between the tank and the carb.

[Twalton]

Thanks

Thanks to everyone for the suggestions. I will do some ignition system maintenance and let you know how it works.
Thanks again,
Todd

[Jesse Delanoy]

Also, and it's an off-chance, have you checked your oil pressure. If the oil pressure drops as the engine gets hot, it may go low enough for your OP safety switch to kill the engine. Are you getting fuel flow when it dies?