Mercruiser 470 question.

[Crawfish Dundee]

I just inherited an 1984 Starcraft, 20 foot glasser, my first inboard. This has been winterized before it was stored indoors, a dozen plus years ago. I know very little about this closed cooling system. I removed the coolant cap and a puff of pressure leaked out when I cracked it open, some pressure was there, however the reservoir was empty. My questions is, since there was some pressure in the system, I assume the block is ok? And do I just fill it up with antifreeze to the brim?

 

[stonyloam]

Yeah just fill her up with 50/50 auto antifreeze. The closed cooling works exactly the same as you car, except ti has a water cooled heat exchanger rather than an air cooled heat exchanger (radiator). When the coolant heats up and expands the overflow goes into the reservoir just like your car, so make sure the hose to the overflow is in good shape so that it gets pulled back in when it cools. Cooling is very critical with the 470, so replace the outdrive waterpump (impeller AND housing) with OEM parts before you put it in the water. If you do try to start it on muffs, keep the rpm low and watch the temperature. When you get it running and up to temperature look for antifreeze leaking from the front lower starboard side of the engine waterpump. If it is leaking you need new waterpump cam seals. Good luck!

 

[Crawfish Dundee]

Thank you! I will replace the impeller , I assume it still has the original one. This is a one owner boat, he may know if it was replaced when winterized last.

 

[stonyloam]

Winterizing (freeze protection) is not like other boats. The block is (should be) filled with auto antifreeze, so the block will (should) never crack from freezing. The only thing needed is to drain the raw water out of the heat exchanger. Feel around on the underside of the back of the exchanger. There are two brass plugs. The forward one drains the antifreeze the aft one drains the raw water. The aft plug may or may not be installed. If it is not there you will need to find it before you start the engine. Once you get it running you will want to do a compression check because 470s tend to have head gasket problems. Chances are the ignition points are shot, so you might want to just go ahead and change them, or at least hang a new set on hand when you go to start it.

 

[Crawfish Dundee]

Hummm, tell me more! Im listening.

 

[Scott Danforth]

Do a search on the forums for 470.....plenty of info.

DIY stickies at top of page has links for point ignition and specific 470 info in the mercruiser section

 

[stonyloam]

You will want to change the oil and filter, here are some filters https://forums.iboats.com/forum/eng...rcruiser-470-oil-filter-part-numbers?t=314199 l run a PH13 with anti drainback. For oil I run Rotella 15w 45, same oil I run In my diesel engines.

 

[Crawfish Dundee]

You will want to change the oil and filter, here are some filters https://forums.iboats.com/forum/eng...rcruiser-470-oil-filter-part-numbers?t=314199 l run a PH13 with anti drainback. For oil I run Rotella 15w 45, same oil I run In my diesel engines.

Thank you. The oil must have been changed at last winterization, it is clean new oil, not a hint of use.

 

[Crawfish Dundee]

It's in fair shape for an 84.