5.0 overheated on muffs

[randolf]

Hi guys, I just bought a Maxum 2100 sc with a 5.0L Merc, Alpha 1 drive, freshwater cooled (full system I think).
I had it out on the lake yesterday and all seemed good except halfway through my Tach, speedo and voltage gauge stopped working. As I was trying to troubleshoot in my driveway I had muffs on and the beeper by the dash started going on. I turned off the boat since its either high oil press. or temp. The engine feels pretty hot so Im assuming it overheated. It wont start again, just clicks (could be a thermal protection on starter?

Im used to dealing with a Bravo 3, so heres my two part question. Is there an impeller in the leg that means the drive has to be engaged to circulate water when Im on land?
There is a hose that goes to what looks like a water pick up under the boat close to the rear routed to a 2nd water pump?

I guess Im wondering if there are 2 water pumps, the big one on the block and a raw water one that sucks in from under the boat? If so is there any point to putting muffs on the rear while running as it seems like the water just goes in and shoots back out.
Ill attach a pic, the bottom left side (behind the fuel hose) is the under boat pickup pump im wondering about.
Thanks !!

 

[tpenfield]

Re: 5.0 overheated on muffs

The alpha drive has the impeller in the drive unit. So, dis-assembly is required to change it.

 

[Bt Doctur]

Re: 5.0 overheated on muffs

appears to be an engine mounted raw water pump for the freshwater cooling setup. unless you had the hose there, that impeller
is trashed now from no water. The alpha drive has a impeller in the lower unit,most times it supplies water to the engine unless the hose was cut. you need it working cause it helps cool the drive.In most cases the impeller is not sufficiant enough to supply the vol. of water needed for FWC system.
You need 2 water sources, one for the drive and one for the engine mounted one.

 

[randolf]

Re: 5.0 overheated on muffs

Thanks Doctur, so are you saying the main water circulation pump on the block is for the coolant only and it should still be good and the other one on the bottom left is to pull through the heat exchanger and manifolds etc and is likely cooked?

I would guess the one in the leg circulates through the leg only then?

 

[Bt Doctur]

Re: 5.0 overheated on muffs

the engine circ pump only handles the A/F in the engine
the raw water pump on the bottom left pulls in water , sends it thru the heat exchanger to cool the A/F and then the water goes out the risers. without water to the impeller it is most likely destroyed .

 

[randolf]

Re: 5.0 overheated on muffs

Can I just confirm that since there is an intake at the bottom of the boat, I dont need to have muffs on the leg while running and not in gear? Or do I need a bucket and a hose for driveway running?

 

[Fun Times]

Re: 5.0 overheated on muffs

If that black water hose hooked up to the brass fitting with the orange handle goes to the back side of the lowest pulley on the left in the photo, then in order to run you're engine, you would need an item nicknamed fake a lake. It looks like a toilet plunger,
http://www.westmarine.com/webapp/wc...toreNum=50366&subdeptNum=50396&classNum=50401

Or you could install something like this,
http://www.iboats.com/Flush-Pro-trade-Inboard-Flush-Valve/dm/view_id.39356

Also your stern drive may have an impeller so you would need to run a second garden hose to the drive to keep that impeller in good shape as well.

 

[randolf]

Re: 5.0 overheated on muffs

I've added a T fitting on the top of the heat exchanger, would that be sufficient to circulate water if I close the seacock valve, even if it's after the raw water pump or would it have to be per-pump?
Also I thought all Alpha 1s had an impeller, I assumed that in my case it would only cool the drive leg so I'd only need it if I was in gear?

 

[Bt Doctur]

Re: 5.0 overheated on muffs

water supply has to be on the suction side of the pump to lubricate the impeller.outdrive impellers turn as long as the motor is running, nothing to do being in or out of gear.