Help, Man engine problem in Bahamas

Did you look at your starboard impeller to ensure it is not worn?

Check coolant level........ if I remember correctly there is also a shrader valve near the expansion tank on man's that if you take some things apart, that you have to pump up to a certain pressure with a bicycle pump. I cannot for the life of me remember anything more than it was on MAN's and a 10 cylinder man if I remember correctly.....I wasn't the one that pumped it up.......look in your owners manual.......I wouldn't worry about the coolant pressure alarm as long as your temperatures are within spec......I would get it fixed, but I don't think it would cause a big issue.......

There is a sensor on the expansion tank, looking from the front it is on your right, pull the wiring connector off to identify the correct one by watching the engine control display. Did you get an engine slowdown from the controller?


Call Jeorge S at Hugo Stamp in Fort Lauderdale, he can help you with part ID and replacement.

As long as coolant temperature is fine, I don't see having lower pressure as hurting anything. I had a set of mans like yours do the same thing, and it ended up being that alarm board as bad, and it was around $2k for the part.

Since you have checked the standard stuff, and the running temps look OK, I would run the motors pretty easy (well off of standard throttle, maybe 50-60 % load if possible) in case there really is a pump pressure problem, you dont want to get any local hot spots in your engine. I would also keep a very close eye on the actual temps with a pyrometer. Pick several locations (block and heads) to monitor and compare between both engines, you should get a good read this way if there really is an actual pressure problem or not.

Low coolant pressure is an indication of a fresh water pump failure.

CSkipR, I have MAN's on my boat as well, 1100 CRM's.......same system as your 900's.

The coolant pressure at water pump with the engines running at 1800rpm is 3.4bar (49psi).......had a look at it yesterday.

The coolant pressure in the expansion tank must be 0.7 bar - 0.9 bar.

MAN operating maunal states the following: "To operate the hot engine without an alarm a pre-pressure of 0.7 bar must be present in the cooling system. To achieve this, a pressure valve is fitted to the expansion tank. A pump can be connected to the pressure valve and the system be pumped up to 0.7 bar".

If you had the coolant drained, you must also do the following when refilling the coolant:
- The water cooled exhaust manifold and the rear intercooler must be vented during the filling process. The exhaust manifold and the intercooler are fitted with vent screws which must remain open until the coolant flows free from bubbles or until the coolant reaches the filler neck.
- Re-fit the plugs and run the engines to 2000rpm for 15 minutes.
- Switch off the engines, carefully remove the filling cap and check the coolant level.


I would re-check your cooling system for trapped air by bleeding it again and ensuring that a pre-pressure of 0.7 bar is present in the cooling system.

Hi,

There are a lot of bike pumps that can pump different types of valves on the market with built in gauges like this one: http://www.argos.co.uk/webapp/wcs/s...nline Shop for Bikes, cycling and accessories.


Failing that use a normal pump that will go on the valve and a tyre pressure gauge .7 bar is equal to 10.29 psi so 10 psi should be just fine if you can get the pre charge to there.

Once you have the expansion tank pressure adjusted to 0.7 bar with the external hand pump, you will also read approx. 0.9 bar (Expansion Tank Pressure) on the boat's MAN managment computer display which is probably mounted at the helm when the engines are running.

It is possible to have an air bubble in the cooling system which moved during the operation of the engine and has caused an air lock preventing continuous coolant flow. Therefore, I would suggest bleeding the system again through the exhaust manifold and intercooler to ensure the removal of any trapped air.

Good luck.....

CSkipR, were you able to rectify the alarm?