Overheating!!!!

[20pilot]

Hi, I just purchased a Baja 272 with a Mercruiser 454. The boat has 213 hours on the engine. I just changed the oil/filter and the fuel filter. Took the boat out and it started to run hot, so went right back to the trailer. I then changed the impeller and Thermostat. The impeller was dry rot and all cracked up. Inspected the hoses and did not see any missing fins so put it back together. Took the boat out again, ran strong for 10 min then shutdown due to overheating. Is there an impeller in the lower unit that needs to be changed? Or is there something else I should look for?

 

[bspeth]

Re: Overheating!!!!

Post you serial numbers and im sure one of the clan can help you out. Bravo drive?

 

[Scott Danforth]

Re: Overheating!!!!

we need to know what drive you have. year and serial number are helpful as well.

also, what the history on the boat is. 213 hours is meaning less if it sat in salt water and the manifolds are rusted solid.

when you changed the impeller, did you back flush the lines, or just look in them.

 

[Bondo]

Re: Overheating!!!!

Hi, I just purchased a Baja 272 with a Mercruiser 454. The boat has 213 hours on the engine. I just changed the oil/filter and the fuel filter. Took the boat out and it started to run hot, so went right back to the trailer. I then changed the impeller and Thermostat. The impeller was dry rot and all cracked up. Inspected the hoses and did not see any missing fins so put it back together. Took the boat out again, ran strong for 10 min then shutdown due to overheating. Is there an impeller in the lower unit that needs to be changed? Or is there something else I should look for?

Ayuh,.... I'm gonna Guess ya got a Bravo drive,..?? If so, no impeller in the drive,...

When ya had the motor driven raw water pump apart, were there fins missin' or not, ya said ya looked,..??
Did ya back-flush out through the drive,..??

As noted, 200 hours don't mean squat, what's yer serial numbers, what vintage,..??

Ya gonna test to see whether water is gettin' In, 'n if so, can it get Out,...

If the impeller pump is Pumpin' In,..?? Are the riser passages clear, so's the water can get Out,..??

Doesn't yer boat have a heat gauge,..?? Why'd ya Run it, til auto-shutdown,..??

 

[cr2k]

Re: Overheating!!!!

Well if there are or ever were missing impeller pieces they could be stuck in the plumbing. Best to back flush from where the water enters the block with the pump un hooked.

 

[tpenfield]

Re: Overheating!!!!

+1 time to backflush the intake hoses from the thermostat housing on back. Usually stuff gets clogged in the oil cooler from a bad impeller.

 

[tazrig]

Re: Overheating!!!!

As others have suggested back flush the line from the pump to the drive and remove and inspect the risers to see if they are rusted out. Everything else can be perfect but if the risers and or manifolds are clogged and the water can't get out you will still overheat.

 

[20pilot]

Re: Overheating!!!!

The boat has a Bravo One drive. I did pull the lines off and inspect them and there was no clogs, however there was one small piece from the impeller in there that I did remove. Other than that it all looked good! I was running around 140 when I took it out, it ran good at about 3500 RPM, as soon as I went above 4000RPM the boat started to overheat. I want to say it shutdown at 185.

 

[tpenfield]

Re: Overheating!!!!

I had a similar issue a while back and did all the 'usual' stuff regarding the cooling system to no avail. After the boating season ended and I pulled the outdrive, I found a fairly large barnacle had lodged itself in the fitting of the water intake hose on the outdrive's gimbal assembly. Not sure if you are in salt or plain water, but, if all else fails, maybe take a look inside the outdrive passages for any blockage.

 

[alldodge]

Re: Overheating!!!!

The boat has a Bravo One drive. I did pull the lines off and inspect them and there was no clogs, however there was one small piece from the impeller in there that I did remove. Other than that it all looked good! I was running around 140 when I took it out, it ran good at about 3500 RPM, as soon as I went above 4000RPM the boat started to overheat. I want to say it shutdown at 185.

The two hoses attached to your raw water pump one should be hard, as in real stiff and cannot be compressed by your hand. The other will be more pliable, is this the case?

 

[20pilot]

Re: Overheating!!!!

I will have to go back to the boat and check the hoses. I have the boat on a lift now, so to check the outdrive I would have to put it back on the trailer. I was hoping to rule the engine out before doing the outdrive.

 

[tazrig]

Re: Overheating!!!!

If you're focusing on the motor for now then pull off one of the risers and look to see if it is clogged with rust. If it is you'll need to replace both risers. While you have the riser off you might also want to drain the block and inspect the manifolds for rust clogging as well.