overheating mercruiser 228

[hazelheckler]

1978 mercruiser 228 overheats.

new sea water pump, cleaned manifolds and exhaust elbows, what is the water flow rate incoming from the sea water pump at idle? , at higher speeds?

I checked it at the hose coming into the power steering cooler and it is about 1.5 quarts in 15 seconds at idle, is this enough? my books don't say what the flow should be,,, Thanks

 

[cr2k]

Re: overheating mercruiser 228

It should be coming faster then that. When you replaced the impeller was it all there? The first place to look for blockage is the Heat exchanger. usually port side low on block. The water from the outdrive goes thru this to cool the PS fluid.

 

[hivoltg]

Re: overheating mercruiser 228

That water volume sounds low to me.

 

[achris]

Re: overheating mercruiser 228

It is too low....

Here's the service bulletin from 1982 detailing how to check water pump output, and what the results should be.

OP.. You should have a 1.50:1 drive ratio (but check it)...

http://forums.iboats.com/attachment.php?attachmentid=209346&d=1377415737

 

[hazelheckler]

Re: overheating mercruiser 228

thanks for the service bulletin,,, I will let you know how i make out with it,,, Oh do you know how i would determine the Gear Ratio? thanks again

 

[achris]

Re: overheating mercruiser 228

.. Oh do you know how i would determine the Gear Ratio? thanks again

2 ways. A difficult way, and an even harder way... (not sure which is which, even now)...

Method one. Remove the top cap from the drive and count the teeth. Drive gear (in from the engine) will have 20, and the driven gear (the one 'laying' in the bottom of the top housing) will have 22 teeth...

Method two. Take the plugs out of the engine, have a friend at the back of the boat counting the turns of the prop. Put the drive in forward gear and start turning the engine by hand. When the prop has turned 10 times, divide the number of times you had to turn the engine by 10... That will be your drive ratio... (should be 15)

Chris.......

 

[hazelheckler]

Re: overheating mercruiser 228

Hi chris,,, the clog turned out to be impeller pieces in the crossover channel in the upper part of the outdrive, just as the service bulletin mentioned. After i got the cap off the crossover channel i had a hard time getting the large screw behind it out, so drilled it out enough to get an ez out in it and unscrewed it with that. When i looked thru the channel the other side was completely blocked by pieces of impleller , i pulled the pieces toward me till the channel appeared clear and flushed out from the water inlet hose in the boat and water and remaining impeller pieces came out,,, lots of them.

Without the service bulletin I probably would have spent another day or 2 trying to figure out where the clog was,, Thanks again

 

[achris]

Re: overheating mercruiser 228

Hi chris,,, the clog turned out to be impeller pieces in the crossover channel in the upper part of the outdrive, just as the service bulletin mentioned. After i got the cap off the crossover channel i had a hard time getting the large screw behind it out, so drilled it out enough to get an ez out in it and unscrewed it with that. When i looked thru the channel the other side was completely blocked by pieces of impleller , i pulled the pieces toward me till the channel appeared clear and flushed out from the water inlet hose in the boat and water and remaining impeller pieces came out,,, lots of them.

Without the service bulletin I probably would have spent another day or 2 trying to figure out where the clog was,, Thanks again

Another satisfied customer..

Please send money ....

Glad you got it sorted...

Chris.....

 

[hazelheckler]

Re: overheating mercruiser 228

Went down to the cottage today to put the lower unit on, put the boat in the water,temp came up about 1/3 through the green, no signs of overheating, thanks again,,,, mike