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25 HP Mercury 4 stroke. I've always changed my own engine oil and was wondering the difficulty of changing the lower end oil. Are there any web sites that tell you how to do it and what the oil capacity is? I like doing things myself, that way I know it's done right. Thanks in advance guys.
"Shep" aka Bluegill Bill
look in the owners manual, it should give the specs for your motor, or go online and should find it there if you don't have it. not familar with your motor, but most have 2 screws/plugs on the lower unit. Crack the upper one, then remove the lower one and the gear oil should drain into a pan. let it drain for a good bit to get all you can out.
To fill up, remove the top/upper plug, and insert the tip of gear oil tube/bottle into the lower hole, and squeeze the oil in until the new oil starts to come out the upper hole. stop and insert the plugs/screws back in, lower one first so the oil won't drain back out.
Search youtube, there should be some vids there.
Same here, except I use a pump on the bottle of oil. Hand pump the oil in the bottom hole, with the top plug out. When it runs out the top, replace top plug. Unhook pump hose from the bottom hole, replace bottom plug, Done. The top plug tight will prevent the bottom hole from losing much while you get the bottom plug in, no venting.
This is the best way to do it. Be sure to replace the gaskets on the plugs as this is a common place for water intrusion.Quote:
Originally Posted by talltimber
If old oil has milky look to it u got a water leak, stop & get it fixed ----don't know about u motor but mine has tiny washers on those 2 screws u remove & they must be replaced so don't loose them when removing screws
For questions try marine engine.com. I have used them a lot, very helpful, knowledgeable. Will need your year, make, model, serial number. Will make diagnoses easier for them. Just rebuilt my carb & lower unit. Had water in lower unit, and a bad primer diaphragm on the carb. Have also replaced the stator and rectifier. It would have taken a lot longer without their help. Will need to sign up like u did here. I'm not on their much, I'm loosenut on their. Good luck.
I have a two stroke merc 25hp. Is the 4stroke better? Worse? Thinking about a newer boat. Don't really want to give my motor up after what I just fixed on it!
the below is how I do mine--albeit its a 150 but should be the same procedure
http://www.nitroowners.com/projects/...nitproject.htm
Do it just like talltimber said and replace the gaskets on the drain and vent plugs, very easy job...
X2 on the$$Quote:
Originally Posted by talltimber
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