4.3 cooling questions

[Riddler6.7]

My father in law passed away a few months ago and left us a boat. Not 100% sure on the year right now but believe it to be 88-91 Regency Dynasty boat with a 4.3 mercruiser. We have been out to the lake a few times this year and yesterday noticed something. When sitting and idling the temp would start rising to 210F and above. The qauge does not have any indication as to what temp is overheating, no red zone or anything. I turned the boat off b/c it was the upper end of the gauge. While moving the boat stays around 160F or so.

What is the top end safe range of this motor? Why does it start heating up quickly when idling, is that normal?

Also when we got back to the shop, i noticed a rather large hose (2"-3" in diameter) that runs from around the propeller area up towards the motor. It is cracked and cut. It seems to be pretty well protected inside some shields or something on the lower unit or sterndrive or whatever you would call it. IM guessing that has a lot to do with it.

I am very mechanically inclined when it comes to trucks and cars but boat sterndrives is a new deal to me, obviously you can tell.

Thank you

 

[danond]

Re: 4.3 cooling questions

If you haven't yet, you need to get a manual for that drive and engine. The Merc guys can help with that, I believe there's copies available online.

It sounds like you should consider putting a new impeller in the water pump. They should be inspected yearly and replaced every few years. It tends to explain your overheating problems. Anything over 200 is too hot to continue running.

Also, good maintenance includes replacing the bellows, u-joints and gimbal bearing every 5 yrs or so. Cheap insurance that provides for many more seasons of trouble-free boating.

I think the hose you're seeing is your shift cable jacket. If it looks like my OMC one, it's supposed to look like that. Pictures would help.

Tips if you're new to I/O drives: never run without a water source. Never! Don't listen to the guys who "clean it out" after they put it back on the trailer or "just test it on the trailer before I put it in the water to be sure it's going to run OK". Load of bull and a great way to fry your exhaust shutters and your impeller almost instantly. Also don't run the drive in the "full up" position. The huge angle on the u-joints wrecks the joints and will likely shred the bellows, too.

 

[Riddler6.7]

Re: 4.3 cooling questions

Thanks for the help. I wish i would have taken pictures of the hose but i didnt think about it. My boat is about 20 miles away right now at my shop. It is a really thick hose that just got cracked and now has a large cut it in, looks like dry rot all over it.

I would love to get some manuals for these units if some one could point me to the right place. How would i know what model sterndrive i have? Ive read about bravo and alpha units, but have no idea.

 

[Riddler6.7]

Re: 4.3 cooling questions

also what is it about a boat engine that makes the operating range so much lower. I know on my truck 200 is about the normal range. Also on my camaro the cooling fans dont even come on until 210+

 

[Riddler6.7]

Re: 4.3 cooling questions

are you talking about replacing the water impeller on the water pump located on the engine or is there another impeller in the sterndrive or lower unit that also needs to be replaced? where in the sterndrive is this piece located?

Any one have any manuals?

 

[Bondo]

Re: 4.3 cooling questions

Ayuh,....Welcome Aboard,...

The Manuals can be found Here,...

Btw,...
It's the rubber Impeller in the outdrive's Lower Unit that needs replacing....
And,.. By the sounds of it,...
All of the Rubber in the transom assembley is in need of Replacement too..

 

[Riddler6.7]

Re: 4.3 cooling questions

thanks, how vital are those rubber boots or hoses in the transam assembly if they just incase cables? ill have to take a better look at it tomorrow when i go to the shop. Im not 100% sure what sterndrive i have so i was going to get the numbers off of it and figure it out unless you guys could tell me that only a certain one came with that motor...

Im guessing its just an alpha. Do most places keep these water pump rebuild kits in stock?

 

[Bondo]

Re: 4.3 cooling questions

how vital are those rubber boots or hoses in the transam assembly if they just incase cables?

Ayuh,....

Vital,.?? If they Leak, the boat can Sink,+the drive will be very Expensive to repair...
Possibly the Motor as well.....

 

[Riddler6.7]

Re: 4.3 cooling questions

hmm, well maybe they are not the hoses/boots you guys are thinking of then. No unusual water has entered, especially not the engine bay. That i have been watching. I definitely will be replacing them, especially if they can result in what you describe. I am just trying to watch my budget, bc there is no point in fixing the boat right now if we cant even afford to take it out after the parts are payed for.

I will try to remember to get pictures of them tomorrow and post them up.


edit... after looking at a parts fiche, it looks like the tube im describing is described as the bellows exhaust... what is the significance of this part

 

[wca_tim]

Re: 4.3 cooling questions

exhaust ois wet anyway, that bellows wont't hurt you. The only thing is that if it is bad, what kind of shape is the other in... if the upper leaks, it'll ruin some significantly more expensive stuff (ujounts, gimbal bearing, etc...) and can sink the boat, etc... worth changing or having changed when you get round to it...