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Draining a enclosed system 1985 470

All you do for the 470 is pull

All you do for the 470 is pull the end caps off the heat exchanger. Tilt the bow up and own using the trailer jack and that's it for draining the system.
 
"Puget Sounder. I know that th

"Puget Sounder. I know that that will drain the "fresh water" from the system if you only want to winterize, but John seemed to want to drain all of the antifreeze and refill the system. There are 4 drain plugs on the 470, 3 on the port side, and 1 in the front of the engine behind the driveshaft damper. All 4 of these have to be removed to drain all of the existing coolant. Without a diagram showing where these things are, it's hard to explain, but there are 4 in total.

Bob."
 
OK makes sense. It was late wh

OK makes sense. It was late when I read the post and I'd had a couple if you know what I mean.

I have a 470 specific owner's manual. If I remember tomorrow I will bring it in to work and scan it to PDF. Since it was not part of the Mercruiser manual downloads it will be very helpful for those that don't have it.
 
"John, there is a plug as Bob

"John, there is a plug as Bob Hawes suggested if you are looking at the rectifier it is at the 7:00 position and this plug can be carefully removed. I installed a new camshaft and the three new seals on timing cover(two cam seals and one oil seal over crank). If this plug has not been removed in quite some time sediment builds up and blocks the drain plug hole which you can again carefully use a piece of mechanics wire or in my case I had to use a drill bit because it was packed so tight with horrible, rusty, sediment.(be careful not to strip aluminum threads on cover!) Hopefully, for your sake someone regularly removed and drained the system. I asked a similar question around a year ago on breezeworks 470 talk and found out from the guys on there that it is best to open this plug after every season so as to try and get heavy sediment out of bottom of water pump impellar housing. It tends to sit there by design and can cause water pump seals and cam surface to fail! Many of the guys on the site swear by the engine and have never had to replace seals because they keep the coolant spotless. After I rebuilt my engine last winter I removed this plug shortly after break-in and believe it or not I found quite alot more fine sediment. I used a paper filter and strained it out and reused most of coolant again because it was almost new. If you have the 4 inch heat exchanger there are two plugs on the very bottom rear of exchanger.(the one at the very rear is the raw water which should be removed for winterization, you should try and jack up boat if it is on a trailer as high as possible to try and get water out. The next plug towards the front of exchanger should be the coolant plug. Remove this one also and see if you get any fines or rusty sediment to come out. Remove cap on exaust riser before you remove plug at front of engine. It is a slow process but it is the lowest drain point on motor ensuring removal of any silt or solids. Not to sound smart but there is no book on this earth that will educate you about this. It is one of the more difficult weaknesses of the 470.(but only if you are not aware of the situation) I can't stess this enough so I will say it again "drain out entire system every season with fresh,clean antifreeze!" The guys on breezeworks also stated that if there were alot of heavy rusty fines and sediment and that particular plug was completely blocked up, then it would most likely be to late and damage to the camshaft would have probably already taken place which could eventually cause engine failure. I would also be careful about adding any type of radiator flush products to the system. (make sure it is recommended by Mercruiser first.) It could shorten life of cam seals which are a pain in the neck to replace. I guess I ate your ear off and maybe you already know about this but figured I would spread the word. best wishes, Tom"
 
Re: Draining a enclosed system

hi guys- im a new member and im from nova scotia canada. I just bought my firts boat this summer, and got a 470 merc. not knowing what i was buying, but im slowly falling in a love hate relationship with it as I go. i just today found out that I should change my 3inch exchanger and but a 4inch, that should help keep her a bit cooler? I just read from pegentsounder that I can take the end caps off my 3inch exchanger and that will drain my system? am I reading that right? or is there more to it?? cal
 
Re: Draining a enclosed system

papabear said:
hi guys- im a new member and im from nova scotia canada. I just bought my firts boat this summer, and got a 470 merc. not knowing what i was buying, but im slowly falling in a love hate relationship with it as I go. i just today found out that I should change my 3inch exchanger and but a 4inch, that should help keep her a bit cooler? I just read from pegentsounder that I can take the end caps off my 3inch exchanger and that will drain my system? am I reading that right? or is there more to it?? cal
Click to expand...

the end caps hold the sea water that flows thru the heat exchanger ..remove these to clean out any debris..

to drain coolant I have 3 plugs front cover below water pump.plug on bottom of the heat exchanger just inboard of the other seawater drain plug, and the larger drain plug on the exhaust manifold in the miiddle lower area port side..

do not mix coolant use green if green was used ..I use distilled water with the coolant 60% coolant ..

I have the 3 inch exchanger if the drive water pump and heatexchanger are good it should not overheat..

you must use the coorect mercrusier thermostat, if you remove the thermostat it will overheat..this is a 2 part controlling thermostat
 
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