2005 Chris Craft with 2 impellers overheating

[RalphLJ]

2005 Chris Craft Speedster
5.0 MPI Mercruiser
Alpha One gen 2 sterndrive
New to us in May 2020
Overheated in August 2020. Changed both motor impeller (it was trashed) and impeller in stern. It was fine. Yes boat has 2 impellers.
Enjoyed the boat the rest of 2020, 2021 and 1 time in 2022.
Dewinterize last month and it started getting hot quickly. Changed both impellers again. (Both had wear) it is still heating up quickly.
We checked the risers and manifolds (they look great) and changed the thermostat.
We did not change the impeller housings.
We are thinking we should go back in and change the housings and check the status of the new impellers?
The impeller by the motor was in a few large pieces. But we found them and glued it back together to make sure we got it all.
Boat is babied. Kept inside and warm.
Any other suggestions? Would sure like to use it a few times yet this year.

 

[Scott06]

Does this have a closed cooling system with a thru hull Pick up where the supply from the drive T's into the line from thru hull?

 

[alldodge]

Yes boat has 2 impellers.

Something jut doesn't sound right about that. Has a Alpha drive and Bravo or crank mounted water pump?

Which other pump does it have?

My initial thought is motor was getting hot and original dealer had a motor run pump installed. From my thought I would rather see the impeller removed from the drive and use the other

How about a serial number and pic of the front of the motor?

 

[RalphLJ]

Photo of serial number.
The outdrive says Mercury Alpha One

 

[RalphLJ]

Does this have a closed cooling system with a thru hull Pick up where the supply from the drive T's into the line from thru hull?

Closed cooling system
Not sure what you mean by the rest

 

[alldodge]

Photo of serial number.
The outdrive says Mercury Alpha One

Does the more raw water pump run from a belt of off the crankshaft?

Hey @Fun Times can you look up this serial number 0W312448
Looking to see if it came with additional raw water pump

 

[alldodge]

I looked your motor up and both Alpha and Bravo show a belt driven raw water pump (Bravo type). Look forward to what Fun Times finds. I would bet a nickle there should not be a impeller in the drive

 

[ROY WILLIAMS]

the impellers 2 outdrives now today is the china impeller ? also the grease lube impeller is working of the install it ..

 

[Fun Times]

Yes this engine came as a fresh water cooling system in which would come with a bravo style water pump mounted to the engine.

0W312448 = MERCRUISER 5.0L MPI ALPHA FWC DRAIN 5.0L ALPHA MPI.

So being an Alpha drive, it usually takes looking at the water hose behind the bell housing of the outside of the boat to see if it’s been cut so the alpha drive stays cool while running at speed…Also if the hose is cut there ought to be a block off plate inside the boat… Then to run the engine mounted pump there might be a through hull pickup somewhere.

But sometimes that didn’t happen and some tried to run both Teed in together.

See page 6C-3 for an image of the newer water hose Y input fitting that might or might not be on the engine in question.

(PDF) Cooling System - 6C - Models with Closed Coolingdownload.brunswick-marine.com/filereader/file/pdf/5/enen/mer...Models with Closed Cooling ... Section 6C - Models with Closed Cooling - DOKUMEN.TIPS

Models with Closed Cooling 90-8M0086018 AUGUST 2013 Page 6C-1 6 C Cooling System Section 6C - Models with Closed Cooling Table of Contents Specifications.....................................................................6C-2…

dokumen.tips

 

[alldodge]

Yes this engine came as a fresh water cooling system in which would come with a bravo style water pump mounted to the engine.

0W312448 = MERCRUISER 5.0L MPI ALPHA FWC DRAIN 5.0L ALPHA MPI.

So being an Alpha drive, it usually takes looking at the water hose behind the bell housing of the outside of the boat to see if it’s been cut so the alpha drive stays cool while running at speed…Also if the hose is cut there ought to be a block off plate inside the boat… Then to run the engine mounted pump there might be a through hull pickup somewhere.

But sometimes that didn’t happen and some tried to run both Teed in together.

See page 6C-3 for an image of the newer water hose Y input fitting that might or might not be on the engine in question.

(PDF) Cooling System - 6C - Models with Closed Coolingdownload.brunswick-marine.com/filereader/file/pdf/5/enen/mer...Models with Closed Cooling ... Section 6C - Models with Closed Cooling - DOKUMEN.TIPS

Models with Closed Cooling 90-8M0086018 AUGUST 2013 Page 6C-1 6 C Cooling System Section 6C - Models with Closed Cooling Table of Contents Specifications.....................................................................6C-2…

dokumen.tips

ok, I'm old and slow but
are you saying this install should have had thru hull pickups and block off plates, or something else?

 

[Fun Times]

May want to double check the impeller as there have been a few recent reports of the wrong size impeller has been coming in the wrong part number bag/kit In which isn’t pumping water like seen in the image below between the two.

 

[Fun Times]

ok, I'm old and slow but
are you saying this install should have had thru hull pickups and block off plates, or something else?

Generally yes for block offs and through hull but it depends on who and how they set it up as I have seen both before. This is more of one of those you don’t know until you physically see it typed deals.

 

[alldodge]

Generally yes for block offs and through hull but it depends on who and how they set it up as I have seen both before. This is more of one of those you don’t know until you physically see it typed deals.

Thanks
What do you or anyone think about removing impeller and restriction plate in pump and allow it to just flow thru like the Bravo?

 

[RalphLJ]

This is exactly what we have We truly believe it is factory. It is super clean. No cut hoses. I was able get several part numbers off of parts that are on the motor. They all match up to these

 

[alldodge]

Agree, but we need to know is it the Alpha to Bravo connection which is causing the overheat, or something else

I actually think it would work fine to remove the drive impeller and plate so water flows freely, but has not been tested that I know of

 

[muc]

I worked for a Chris Craft dealer back then, That's a drop dead gorgeous boat. First year of them at the boat show, sales put one out on the point and everybody stopped and drooled. We sold every one we had on order. I was a twin engine boat tech so I didn't get to spend anytime in one until the 4th one, had sold to someone that already owned a big boat. I got to do the rig and delivery. Man that's one sweet hull. We had ordered it raw water cooled and he was going to ship it down to FL. to use as a tender for his yacht, So I installed the freshwater system on it.

From your picture, I only see one garden hose. This boat will have 2 water pick ups. The one in the Alpha drive like normal and another thru hull or transom pick up. Are supplying water to both when you run it out of the water? If you don't it will burn the engine mounted impeller.

Yes this boat needs 2 working impellers. There should be a "Y" fitting right before the Engine mounted pump intake. This engine has a brass engine mounted sea water pump, if you have burned a impeller in it. It probably has grooves in the brass, especially at both end of the impeller. Might want to check that when you replace the impeller. Also MerCruiser wanted a seacock installed on the thru hull intake. Make sure it didn't get shut by mistake.

 

[RalphLJ]

I worked for a Chris Craft dealer back then, That's a drop dead gorgeous boat. First year of them at the boat show, sales put one out on the point and everybody stopped and drooled. We sold every one we had on order. I was a twin engine boat tech so I didn't get to spend anytime in one until the 4th one, had sold to someone that already owned a big boat. I got to do the rig and delivery. Man that's one sweet hull. We had ordered it raw water cooled and he was going to ship it down to FL. to use as a tender for his yacht, So I installed the freshwater system on it.

From your picture, I only see one garden hose. This boat will have 2 water pick ups. The one in the Alpha drive like normal and another thru hull or transom pick up. Are supplying water to both when you run it out of the water? If you don't it will burn the engine mounted impeller.

Yes this boat needs 2 working impellers. There should be a "Y" fitting right before the Engine mounted pump intake. This engine has a brass engine mounted sea water pump, if you have burned an impeller in it. It probably has grooves in the brass, especially at both end of the impeller. Might want to check that when you replace the impeller. Also MerCruiser wanted a seacock installed on the thru hull intake. Make sure it didn't get shut by mistake.

Thank you for your reply. It is so good to hear that it is how it is supposed to be. We will change the motor impeller and the brass housing and put it in the lake to test it. I’ll update afterward. Thanks again.

 

[RalphLJ]

Yes this engine came as a fresh water cooling system in which would come with a bravo style water pump mounted to the engine.

0W312448 = MERCRUISER 5.0L MPI ALPHA FWC DRAIN 5.0L ALPHA MPI.

So being an Alpha drive, it usually takes looking at the water hose behind the bell housing of the outside of the boat to see if it’s been cut so the alpha drive stays cool while running at speed…Also if the hose is cut there ought to be a block off plate inside the boat… Then to run the engine mounted pump there might be a through hull pickup somewhere.

But sometimes that didn’t happen and some tried to run both Teed in together.

See page 6C-3 for an image of the newer water hose Y input fitting that might or might not be on the engine in question.

(PDF) Cooling System - 6C - Models with Closed Coolingdownload.brunswick-marine.com/filereader/file/pdf/5/enen/mer...Models with Closed Cooling ... Section 6C - Models with Closed Cooling - DOKUMEN.TIPS

Models with Closed Cooling 90-8M0086018 AUGUST 2013 Page 6C-1 6 C Cooling System Section 6C - Models with Closed Cooling Table of Contents Specifications.....................................................................6C-2…

dokumen.tips

Agree, but we need to know is it the Alpha to Bravo connection which is causing the overheat, or something else

I actually think it would work fine to remove the drive impeller and plate so water flows freely, but has not been tested that I know of

Thank you for your reply. It is so good to hear that it is how it is supposed to be. We will change the motor impeller and the brass housing and put it in the lake to test it. I’ll update afterward. Thanks again.

Where would we connect the 2nd hose?

 

[Scott Danforth]

one to the thru-hull pickup with a fake-a-lake adapter, one to the outdrive on muffs.

 

[alldodge]

Where would we connect the 2nd hose?

Look under the boat for a intake. MUC said there should be a Y connection so go from the brass pump and follow the hose back to the Y and then see where the 2 hoses go