Perkins M50 Overheating

[patkt]

I have recently bought a Moody with a Perkins M50 engine.
At any speed over 1800 rpm the overheat alarm sounds.
I therefore have to reduce engine speed to 1700 or below.
This gives me a boat speed below 5 Kn which is too slow for situations of strong winds or tides.
The exit water is not very hot but I cannot put my hand on the engine so clearly the engine is not cooling effectively.
Has anyone had a similar problem and if so how did you solve it?
Thanks in advance for your response.

 

[Hoolie]

We have the same engine on our Gib'Sea but it's only overheated when the raw water intake was blocked with weed on the French canals.
Assuming the coolant level is OK and the raw water flow is good, I think you might check the heat exchanger thermostat. They often fail open but sometimes they can remain shut and engine overheats. If you don't have a spare to hand you can try taking it out to see if the engine temp reduces.

 

[Gerry]

We have an M50 and every 6 months or so it gives us a scare by overheating. We now go through the following routine.

1. Check the raw water intake, even a leaf can strangle the water flow.
2. Is there sufficient water exiting the exhaust system at the rear of the boat? Should be a good strong flow.
3. Check the impeller. We have found that they last on average 6 months.
4. Do you have a mechanical fridge? If so check the cooling water bypass valve for blockage by old bits of impeller.
5. Check the tension on the fan belt(this is our most usual cause of overheat).
6. Rod through heat exchange valve for bits of impeller.
6. Unique to the M50 the adapter plate from the overhead camshaft to the raw water pump. This wears over time and compromises the water flow quite considerably before it finally fails!!
We have just changed ours for the second time in 12 years.

After lots of nasty panics we find that it's most often a simple solution, impeller or fan belt.

Best of luck!

www.gerryantics.blogspot.com

 

[patkt]

Perkins M50 0verheating

Thank you both for your response.
We will follow up your suggestions and hope it resolves the problem.

patkt

 

[Phoenix of Hamble]

just for completeness, so that readers aren't left worrying about M50s.... the M50 is a very solid and robust engine generally.... and benefits from being able to source parts cheaply, as it is the engine developed for the Montego 2.0 diesel....

 

[Hoolie]

just for completeness, so that readers aren't left worrying about M50s.... the M50 is a very solid and robust engine generally.... and benefits from being able to source parts cheaply, as it is the engine developed for the Montego 2.0 diesel....

Agreed - I have a complete spare engine, bought on eBay for £100. I hope I never have to use it