MerCruiser 496 HO 2008 - Engine Alarm (constant sound)

[RubyLily121]

Hi All

So boat is amazing after the new Fuel Rail and Injectors.

Ran it for 1 hour and then the engine alarm sounded. Had to back right off the throttle and put to the Marina.
Here are some gauge snaps and the exhaust that was smoking. Any suggestions?

Feel like I should have a mechanic on a retainer fee!

Any thoughts greatly appreciated.

 

[tpenfield]

How 'bout that oil pressure.

 

[paulswagelock]

Looks like a manifold over temp alarm. Gauges could read ok temperature or slightly high, manifold temp is not displayed. Bad impeller, clogged water inlet, bravoitis, clogged heat exchanger, - lots of potential causes.

 

[alldodge]

Agree, looks like exhaust over temp alarm
Need to get the motor scanned

If the smoke is only seen on one side it's probably a head gasket

Edit: The volt meter showing below 14V so if its accurate then there is another problem

 

[Lou C]

In that pic of the gauges is your engine running? If so I’d be concerned about low oil pressure and low charging voltage. The engine temp isn’t too high but it looks like either you have low water flow to the starboard exhaust or the elbow is clogging on that side…

 

[RubyLily121]

In that pic of the gauges is your engine running? If so I’d be concerned about low oil pressure and low charging voltage. The engine temp isn’t too high but it looks like either you have low water flow to the starboard exhaust or the elbow is clogging on that side…

Thanks Lou - yep that’s the engine on after running for about an hour with no issue. Mechanic finished putting the fuel rail and injectors in the day before. Oh and 2 new batteries- so your question on the Volts has me wondering. What should the Volt’s be at whilst on with two batteries? I keep thinking when we start the boat it no longer turns over first time - maybe there is more than one issue going on.

 

[RubyLily121]

Agree, looks like exhaust over temp alarm
Need to get the motor scanned

If the smoke is only seen on one side it's probably a head gasket

Edit: The volt meter showing below 14V so if its accurate then there is another problem

It was both sides. On the 14 V just replied below. Yep that’s the Volts on and after 2 new batteries. What would I expect it to sit at?

 

[Scott Danforth]

a running motor will have between 13.7 and 14.4 volts

your oil pressure is low

the steam coming from the exhaust is concerning as you should have lots of water spraying out the exhaust

you have more than one thing going on.

 

[Lou C]

You will charge batteries faster if you are just keeping it on either #1 or #2 otherwise you are asking the alt to do a lot all at once. Having said that though normal charging is approx 14V. Oil pressure, while some may say the Chevrolet small block only needs 10 psi per 1000 rpm, that is pretty low, what oil are you using? If you're using a 5w-anything or 10w-anything that is not syn, I'd change it to the Merc syn blend 25/40. Even my old 4.3 at the lowest is 20 psi at idle and that's only after coming off plane, as the oil cools off its back up at 40 psi idle speed.

 

[Scott Danforth]

rule of thumb is the minimum is 10 psi per 1000 RPM. however the stock Gen VII oil pump has a 75psi relief spring in it. unless the oil has the viscosity of fuel, the oil pressure should be much higher on the gauge.

 

[QBhoy]

Oil pressure is a concern there. If it’s genuine. Mine never drops below around 35-40 psi

 

[Gazcar]

Hi All
View attachment 356432
So boat is amazing after the new Fuel Rail and Injectors.

Ran it for 1 hour and then the engine alarm sounded. Had to back right off the throttle and put to the Marina.
Here are some gauge snaps and the exhaust that was smoking. Any suggestions?

Feel like I should have a mechanic on a retainer fee!

Any thoughts greatly appreciated.

How did you end up getting your fuel rail I have the same problem on my 496 I’m in Australia also

 

[RubyLily121]

How did you end up getting your fuel rail I have the same problem on my 496 I’m in Australia also

Hi there
Through this forum I was connected to Raylar Engineering https://www.raylarengineering.com/ Larry Hofer in Sam Diego. He had some 2001 fuel rails that along with that and some new 42lb fuel injectors we had it shipped here into Sydney. Our mechanic in Sydney then fitted the rail and injectors. Not a lot of options globally I spent hours and hours looking. It cost about $1300 USD (including the 8 injectors). Was worth every cent as you could feel the difference in performance. I would definitely contact Larry and see if he can help. Regards

 

[Gazcar]

Hi there
Through this forum I was connected to Raylar Engineering https://www.raylarengineering.com/ Larry Hofer in Sam Diego. He had some 2001 fuel rails that along with that and some new 42lb fuel injectors we had it shipped here into Sydney. Our mechanic in Sydney then fitted the rail and injectors. Not a lot of options globally I spent hours and hours looking. It cost about $1300 USD (including the 8 injectors). Was worth every cent as you could feel the difference in performance. I would definitely contact Larry and see if he can help. Regards

Thanks for the response I have a 2004 model and will follow up on the rail, we had it cleaned and replaced a couple of injectors in about 2015 and need to do a better fix this time thank you cheers

 

[nola mike]

Hi there
Through this forum I was connected to Raylar Engineering https://www.raylarengineering.com/ Larry Hofer in Sam Diego. He had some 2001 fuel rails that along with that and some new 42lb fuel injectors we had it shipped here into Sydney. Our mechanic in Sydney then fitted the rail and injectors. Not a lot of options globally I spent hours and hours looking. It cost about $1300 USD (including the 8 injectors). Was worth every cent as you could feel the difference in performance. I would definitely contact Larry and see if he can help. Regards

So like, are you going to leave us hanging on this thread?