2006 200 Select overheating - Merc 5.0 MPI (305ci)

[Coconuts]

So been reading multiple threads on this and it seems everyone has different versions of cooling systems. Mine appears to be raw water cooled as I have no coolant tank. I also do not have this so called "poppet" valve. Instead I have this setup.

I pulled the top plug, and it was just dry and rusty - not sure what it is and where to even start.

At idle my PSI is like 0.0 - I have to idle up to about 1500 RPMs just to get psi to 1.5 to start cooling back down. Any ideas?

 

[JimG]

First place to start is the impellar in the outdrive.

(Your pictures don't show up)

 

[scoflaw]

Do you have maintenance history ?

 

[Lazy Daze]

Can't see your pics, either.

But, yes, replace the impeller and (possibly) housing. If there are missing vanes of the impeller... you'll need to find those somewhere in the cooling system. Follow the intake hose from the transom.

I'm surprised you're not getting an alarm at the dash for low PSI. Does your alarm sound when you first turn the key on?

 

[Coconuts]

no alarm for low PSI - but I get an alarm when it overheats - just ordered a new impeller - will install tomorrow and see how that goes..

I have some maint history, but it's all general - nothing serious has been replaced that I can tell - all original...

 

[Lazy Daze]

Don't forget the housing - you may need that. If there is even the slightest bit of scoring it needs to get changed.

 

[Coconuts]

Don't forget the housing - you may need that. If there is even the slightest bit of scoring it needs to get changed.

ok - ya, I'll have to get it pulled and look - anyone have that youtube link that shows how to replace it?

 

[Lazy Daze]

ok - ya, I'll have to get it pulled and look - anyone have that youtube link that shows how to replace it?

I'm sure there's plenty of videos out there easy find. But what "it" are you referring to? If it's the housing, you would already have that removed since you need to do that to get to the impeller. From your previous post it sounded like you were already good to go on replacing the impeller?

But... what part of this (if any) do you need more clarification on?

 

[Coconuts]

I haven't pulled the water pump yet - just pre-emptive order of the impeller. The outdrive has a brand new pump/impeller in it from last Oct. So this is the on-engine sea water pump...looks like it shouldn't be too bad to get too.

https://www.marineengine.com/parts/...m300000-thru-0m599999/sea-water-pump-assembly

 

[Lazy Daze]

I haven't pulled the water pump yet - just pre-emptive order of the impeller. The outdrive has a brand new pump/impeller in it from last Oct. So this is the on-engine sea water pump...looks like it shouldn't be too bad to get too.

https://www.marineengine.com/parts/...m300000-thru-0m599999/sea-water-pump-assembly

You don't have an on-engine sea water pump since you have an Alpha. A Bravo would haver that. It's an either-or thing, not both.

 

[scoflaw]

A little history would help. First you said no maintenance records, now you say it's got a new pump last year. So did it run fine after the new pump install? When did this problem arise? All clues help

 

[Scott215]

I have a 2006 MPI with an alpha in the water pump is in the outdrive not attached to the engine

 

[Coconuts]

There's a new impeller in the outdrive unit - that was just replaced. So I have the standard easy drain cooling system:
https://www.marineengine.com/parts/...cooling-system-alpha-single-and-3-point-drain

 

[Scott215]

Sounds like you could have some pieces of the old impeller stuck somewhere in the cooling system preventing water flow in. Others will chime in

 

[Coconuts]

I have a 2006 MPI with an alpha in the water pump is in the outdrive not attached to the engine

Correct - my mistake on all this - so I have replaced that - it actually has a newer, rebuilt lower on the outdrive with all new pump assembly - and ever since, I have overheat problems on idle only.

 

[Coconuts]

hmm - wonder how to clean the system out? any easy way??

So more info on the issue - idle, it overheats pretty quickly. If I leave it in neutral and rev engine up to about 1300 RPMs, the temps start to drop - it's not in gear so boat is not moving at all... what am I missing here?

 

[Scott215]

What temperature does your boat run at when you rev it up to $1,300 RPMs

 

[Coconuts]

It will drop to the 150's - but idle, it only takes a few minutes and it's hitting 190 plus - and my PSI gauge shows 0.0 psi at idle - but only around 2-2.5 PSI at 1300rpm.

 

[scoflaw]

Is there a poppet valve on that motor? Change your t-stat it could be sticking. Your psi sensor could just be faulty, they fail all the time

 

[techmitch]

It will drop to the 150's - but idle, it only takes a few minutes and it's hitting 190 plus - and my PSI gauge shows 0.0 psi at idle - but only around 2-2.5 PSI at 1300rpm.

Is there a poppet valve on that motor? Change your t-stat it could be sticking. Your psi sensor could just be faulty, they fail all the time

A PSI sensor/gauge on a Alpha?