To fix or replace?

[nightshark14]

I am new to I boats and this is my first thread so bare with me.

I have a 1980 Sea Ox sporting the same year Merc 470. It overheats frequently, and despite a few mechanics going through it, nothings changed. Ive heard a lot of bad things about this motor and need some direction. Is it worth it to keep chasing the problem? Or should I look into a new motor/outdrive package for it? I know you may think that's an expensive fix for an older boat, but it was my first and frankly, its hard to let her go . Any help or advice on this is greatly appreciated.

 

[cr2k]

Re: To fix or replace?

If you like the boat and are able, put what you think is reasonable in it.

 

[90stingray]

Re: To fix or replace?

Welcome to iboats! I have heard that even a well running and well maintained 470 is a handful and problematic. But i have NO first hand experience with them. If you decide to repower, you should not need to change the drive, depending on what the ratio currently is and what your future plans are. But keeping the boat and doing that much work and spending that amount of money, would depend on the current condition of the boat... even if it's your first.

 

[Eric 3.7LX Alpha 1]

Re: To fix or replace?

I am new to I boats and this is my first thread so bare with me.

I have a 1980 Sea Ox sporting the same year Merc 470. It overheats frequently, and despite a few mechanics going through it, nothings changed. Ive heard a lot of bad things about this motor and need some direction. Is it worth it to keep chasing the problem? Or should I look into a new motor/outdrive package for it? I know you may think that's an expensive fix for an older boat, but it was my first and frankly, its hard to let her go . Any help or advice on this is greatly appreciated.

What has been done to date to attempt to resolve the overheat?

 

[stonyloam]

Re: To fix or replace?

Forget the repower, a lot of time money and trouble. Lots of help tracking down your problem here. Answering Eric's question will give a good start. To give an idea of where to look, the first thing will be a new impeller, including a new pump housing. Consider going to a 4" heat exchanger, at least removing the end caps and cleaning the one you have. Check the thermostat. You also need to evaluate the motor's overall health, so a compression check and cooling system pressure check are in order (borrow the tools from Autozone). Should be able to get you running right.

 

[stonyloam]

Re: To fix or replace?

I have heard that even a well running and well maintained 470 is a handful and problematic

On the contrary, most of the 470 problems result from neglect. If you don't maintain the cooling system on a 470, it will overheat, just like if you don't drain a 4.3 it will crack! Either can be quite problematic.

 

[fmalott]

Re: To fix or replace?

i'm in the middle of rebuilding my 1983 470 and yes there is some common problems with this motor but it is still a very good motor, the most common problems with them is the number 4 cylinder it's always the first to go the remedie is a new head gasket because the head is cast iron and the bottom end is aluminun the other common problem is the water pump seals there is two of them that the camshaft goes through they wear a groove on the camshaft and they start leaking so keep that in mind and the old saying preventative maintenence goes a long way
P.S. there is GREAT advise on this forum listen to them and you will not have a problem keeping you motor running great i learnt a hell of alot from this forum good luck !!

 

[nightshark14]

Re: To fix or replace?

I started with the basic resolutions. New impeller and pump housing. Took the caps off the 3" heat exchanger, everything's clean inside. New thermostat and reservoir tank. One end cap on the exchanger was pissing water before I got a new one, so I'm assuming its not the raw water end of the deal. The last time out on the water it ran fine for about 2 hours (full throttle and trolling speeds). Then once I got back in the river it started to heat up. I shut it down and let it cool off, but after I couldn't drive more than 100 yards without the temp skyrocketing. Almost as if the coolant wasn't even circulating...

 

[fmalott]

Re: To fix or replace?

have you had it out of the water and on muffs. starting with new impeller and housing is a good start also did you inspect the water hose from impeller to heat exchanger( the hose that goes through the gimble housing) i'm not very experienced on heat exchangers but i know how they function you might want to get the exchanger inspected to make sure it's working properly but as mentioned above you want to convert to a 4" exchanger, make sure you got no blockage in the exhaust manifold and riser, change thermastat, if i'm not mistaking there is alot of info on the cooling system in the sticky's
View attachment A1 Impeller replace.pdf

 

[nightshark14]

Re: To fix or replace?

Ive had it out of water on muffs a couple times this past year. Never overheated once. Ill look into the hose between the outdrive and exchanger. Ill see if I can get my hands on a 4" exchanger too. Thanks for the help guys.

 

[fmalott]

Re: To fix or replace?

sometimes you can find 4" used ones on Ebay, they are expensive brand new 600-700 dollars so shop around you will find one

 

[stonyloam]

Re: To fix or replace?

When you start to overheat, does the heat exchanger get really hot. If so it would indicate insufficient flow through exchanger. If it stays relatively cool it would indicate a engine circulation problem, thermostat?

 

[nightshark14]

Re: To fix or replace?

Thermostat has been changed. And i don't believe the heat exchanger gets hot. I'm leaning toward the engine circulation problem. I cant find any leaks so i doubt its the pump or pump seals. Anyone know where else I could look?