485 mercruiser over heating

[randallal]

ok so i picked up a boat. ( my first ) it had been sitting 3 years. changed the impeller plugs wires plugs. fluids. ignition. starter. all relays. oil oil pump. so on and so on. it had a miss in it so rebuilt the carb. but one problem i have is it over heats. and when i say over heats i mean it dont take but 10 mins to be in the red in temp guage. there is a water pump looking thing on the front the has a weephole and it is leaking water out of. and by i say water pump looking thing. it does not have a pully on it nore does it have a belt. a hose goes in with fluid and it goes on tino my motor. the motor is a 485 and it is in a 83 cheetha 176. can someone please help me

 

[randallal]

Re: 485 mercruiser over heating

pic of motor

 

[salty3rd]

Re: 485 mercruiser over heating

Your engine is called a "470". People either love or hate these engines because they require alot of attention. For starters; be real careful about overheating these engines, when these engines overheat thier is potential for major problems. You are correct about the water pump on the front of the engine; that circulates anti freeze since this is a closed cooling system. The anti freeze that you see dripping out is a tell tale sign that the internal water pump seal is bad and will have to be replaced. As for your overheating; is it pumping water out of the back of the boat when its running? If you look around on this forum you will find all kinds of info on these engines. The charging system is also a common problem on these engines. Good Luck

 

[HT32BSX115]

Re: 485 mercruiser over heating

Yeah. the Infamous 470 (3.7L) Mercruiser.

If it's overheating, you probably have a raw water FLOW problem.

The raw water comes from the raw water pump (you replaced it?) to the heat exchanger via a hose.

If the raw water pump has failed (catastrophically) in the past (they do frequently), you may have impeller fragments or other debris clogging the heat exchanger. That will absolutely cause overheats.

Also, since the raw water exits through the riser before going overboard, you could have a partially clogged (with rust) riser.

Either way ANY restriction in raw water flow from the Sea water pump to the heat exchanger and riser will cause overheats.

If you have power steering, the raw water path is through the PS cooler, and could also be part of the problem.


Once you determine that your raw water path is unrestricted, you can look to the engine coolant path.

In either case, the heat exchanger is the common element in both.

A dripping circulating pump is a possible problem but it won't the immediate cause of an over heat unless you let it drip long enough to lose all the coolant.






Good luck.


Rick

 

[Eric 3.7LX Alpha 1]

Re: 485 mercruiser over heating

Here is an article on the weephole leak from the engine. This drip will not cause the overheat as mentioned above unless you allow enough coolant to be lost and cause high temps.

http://www.sterndrives.com/470_coolant_leak.html

 

[salty3rd]

Re: 485 mercruiser over heating

Here is an article on the weephole leak from the engine. This drip will not cause the overheat as mentioned above unless you allow enough coolant to be lost and cause high temps.

http://www.sterndrives.com/470_coolant_leak.html

I have read through this post and I didnt see anyone refering to the weep hole leaking as a direct cause of overheating.

 

[Eric 3.7LX Alpha 1]

Re: 485 mercruiser over heating

I have read through this post and I didnt see anyone refering to the weep hole leaking as a direct cause of overheating.

Unless you leak enough antifreeze coolant it will be fine. Mine dripped for a couple of months before I got around to fixing it. Just kept a couple of gallons of water in the boat, just in case the temp climbed. Which if continued to loose fluid without replacing, eventually it will loose enough antifreeze and run warmer.

 

[randallal]

Re: 485 mercruiser over heating

i have no ides i have been forcered to send it to the shop. the guy told me it was cause the hole and it was not getting pressure to send the coolant to the rest of the motor. ima have him do a whole flush. he got to talking figures and all i herd was money slowly crawling from my pockets and wallet