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5.7 getting hot. Why?

J

jrwoodward

New member
New boater here. I bought a 88 Century 3500 with 5.7 motor. Last weekend I hit something and broke a blade off my propeller. Took it out today with a new replacement prop. Didn't get 1/2 mile and noticed the Temp was red hot. Shut it down. Got it back home and inspected my lower unit. Found a hole IMG_20180805_144743.jpg

Is this the cause of my over heating? I had no Problem before.
 
A lot of things could have happened from ripping a blade off but overheating is not one of them. You could have a damaged water pump
I find it strange you didnt notice the hole when you had it out or the oil slick when you hit the bottom ?
Being an `88 its most likely a Alpha 1 - 1.47/1.50 ratio
 
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Bt Doctur said:
A lot of things could have happened from ripping a blade off but overheating is not one of them. You could have a damaged water pump
I find it strange you didnt notice the hole when you had it out or the oil slick when you hit the bottom ?
Being an `88 its most likely a Alpha 1 - 1.47/1.50 ratio
Click to expand...

I did see oil when I loaded the boat the day I hit something. Honestly forgot about it. But when I removed the old prop and installed the new one I never saw it. Also the day I broke the blade I limped back to the loading ramp. So it never went fast. Today when I took it out I didn't get more than 1/2 mile when I noticed it getting hot.
Could my accident damaged my water pump?
 
You said it operated but ran hot after the strike so no shafts are broken so impeller damage is a possability.
Drop the lower and inspect/replace the mpeller /water pump
 
The lower unit needs to be torn down to inspect gears and bearings.-----The hole needs to be looked at and welded up if possible.----This going to empty your wallet.
 
By limping back home with a hole in the case that large, you have no doubt ruined the lower unit gears/bearings.
It will be cost effective to simply replace the lower gear unit, rather than to have it repaired.
 
water will replace the oil in the drive and will cool as well if not better than oil....however it will trash all the internals in VERY short order.
 
Ayuh,..... Ya might get by with just a lower unit, but My guess is, the entire drive is trashed,.......

SEI is the cheapest way out,.....
 
Lesson #1...Boats are expensive! I think you are at a point where you gotta ask yourself if it's worth putting any more money into this thing. Smacking the lower will cost you another spinny thing. Fortunately there are gazillions of good used lowers out there so you can probably find another one for a couple hundy. The overheating is likely due to the water pump not being serviced. It would't necessarily be related to the prop strike (which must have been a very interesting day). Keep out of the skinny water. That looks like you hit a rock, so stay in the channel if you don't know the waters. If you had it wide open (guessing yes) you could possibly be thrown out of the boat so wear that PFD bud!
Good news is that this can all be put right with wrenches, time and lots of moneeeee.
 
bondo said:
Ayuh,..... Ya might get by with just a lower unit, but My guess is, the entire drive is trashed,.......

SEI is the cheapest way out,.....
Click to expand...
Meh lots of used around for cheap. At least here in the Chesapeake Bay area. There's like at least four boat wreckers (ahem, parts recyclers) in the DC/Baltimore region.
 
2X on the entire drive being scrap metal.....they don't survive long with a load and no oil, especially with the water being circulated....
 
This is all very good information, but my original question is, why would this cause it to get hot. Before making contact with the object in the water, I had driven for about an hour with no over heating.
So can the hole cause it to get hot so fast? If not whats the odds that my water pump could go out at the same time?
Could a hole in the lower unit have interrupted the flow of water?
 
??----The hole in the gearcase has nothing to do with water getting to the pump.----Perhaps read some manuals on boat motors and the operation of them.
 
Theory: Without lubrication the driveshaft bearing overheated and wrecked the impeller.

Question: Has anyone inspected that impeller (or did I miss that)?

Jeff
 
I would suggest that you stop spending any time worrying about it, and purchase a replacement drive with a new seawater pump and impeller.

Install it and operate the engine while on the garden hose and water muffs.

You should see right off the bat if the engine is having an over-heating issue or not.

If it has been a while since last looked into..... remove the exhaust elbows and clean out the seawater transfer ports.
Go back together with new gaskets and go boating!
 
re: "clean out ports".... trashed impeller parts tend to accumulate in these ports restricting flow and causing overheating.
 
..... and rusty bearings would place a load (hard to turn!) on the drive train and the engine and could contribute to overheating.... that and obstructions anywhere in the raw water circuit.
 
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