5.7 G.M. Water Pump Pulley Size

[billscott9]

I have a 1987 Sea Ray with a 5.7 litre engine, many years ago the pulley for the water pump was changed. The mechanic that the previous owner took it to couldn't find the proper size pulley so he put a seven inch pulley on. Ever since then the engine over heats at idle. As soon as the rpm is raised the temperature drops back to normal. Does anybody know what the original pulley size for this engine would be?

 

[alldodge]

Re: 5.7 G.M. Water Pump Pulley Size

The original part size was 5.5 inch and was replaced by Mercury to a 7 inch http://www.mercruiserparts.com/bulletins/018/04//1997/EN_04.PDF

I don't think your overheating has to do with the size of the pulley. I am assuming you have an Alpha drive and therefore; have you replaced the impeller? If so have you checked to see if all hoses are clear and make sure the power steering oil cooler is clear. If the impeller has ever come apart in pieces, some of those pieces could be clogging thigs up.

There are two deisgns for the thermostat housing and they have different sleves used.
Design 1 Design 3
Item 7 design 1 and item 6 design 3

 

[billscott9]

Re: 5.7 G.M. Water Pump Pulley Size

That is the next thing I am going to check. I just found a service bulletin from Mercruiser about the change in pulley size.