3.7 488r merc

[roffey]

Hi all, new to this from. I just recently purchased a Thundercraft 17.5 with a 3.7 488r merc. Has any one had any experience with these motors. For a 4 banger it seems to put out a large amount of hp, 188 hp to be exact. I can run mid 50 at 4800 rpm, this seems a little high, fun but maybe to many RPMs. Any advice or pit falls will be appreciated.

 

[Bondo]

Re: 3.7 488r merc

Ayuh,.... Welcome Aboard,.... Do a search for Mercruiser 470,.... You'll be readin' for Weeks,.....

 

[stonyloam]

Re: 3.7 488r merc

My advice, change the impeller in the outdrive as soon as you can get a chance. Replace the pump housing along with the impeller and use OEM Mercruiser parts. Overheating is the main killer of these engines. Yeah your PM is a little high. Gheck your tach to make sure it is reading correctly and your WOT should be about 4500 for that engine. Locate the little weep hole on the lower stsrboard side of the timing chain cover, make sure it is open and keep an eye out for leaks. Getting close to the end of the season, so to winterize it: Buy a cheap little antifreeze tester and check the engine antifreeze, should be about 50/0 automotive antifreeze. When you pull it out for the last trip of the season, simply remove the transom drain plug and remove the AFT drain plug on the heat exchanger and let it drain (only water will come out). I do it right on the ramp. That's it freeze protection is done, and if you get some warm weather later on, just put in the plugs and go, drain it again when you take it out. You didn't say what year but here is the manual for the 84 and newer engines: Boatinfo - Mercruiser Service Manual nr. 8 - 1985-1989 - Mercury Marine 4 Cylinder Engines good luck.

 

[matt167]

Re: 3.7 488r merc

My dad had a 488/ 3.7LX in a 1984 Imperial VC230. Good power, ran good but once the cam seal leaked and the engine overheated, the head gasket had blown and a short time later developed a knock.. So don't let it get hot and it will treat you well

 

[roffey]

Re: 3.7 488r merc

it's a 1985. The motor does not run hot, about 160 right now so I think the impeller is ok but I plan on changing it before next summer. Thnanks for the links.