Where are my drain plugs?

[tuanp]

I'm trying to drain and replace the coolant on my boat but I'm not sure where the exhaust manifold and engine block drain plugs are. The engine setup is a '85 Merc 170MR (GM inline 4, I believe, Alpha 1 Gen 1 sterndrive).<br /><br />My Clymers manual has crude hand-drawn pictures that don't match what I see on the engine. I see two bolts at the rear of the exhaust manifold but I'm not sure which is the drain plug. And I have no idea where the engine block's drain plug is; manual just has an arrow pointing to center of engine port side.<br /><br />I have pictures of the exhaust manifold and engine here if someone can take a look and point out which one is the exhaust manifold plug, and where I may find the engine block plug.<br /><br />Thanks in advance.<br /><br />tuan

 

[crazy charlie]

Re: Where are my drain plugs?

Sand the paint off of them and the drain should be brass.Charlie

 

[yoced]

Re: Where are my drain plugs?

Your drain for the manifold should be a 1/4" brass plug near the front of the manifold (1/4" brass plug will typically have a 9/16" hex head).<br /><br />Your elbow/resevoir should have a 1/8" brass plug on the inboard side near the front (typically with a 1/4" square head on it)

 

[flashback]

Re: Where are my drain plugs?

TuanPhan, please purchase a manual for your rig and then if you have questions please ask them..a lot of things you post are readily available in repair manuals. thanks for posting and please don't be offended/.//

 

[tuanp]

Re: Where are my drain plugs?

flashback,<br /><br />Please note in my original post that I do have a manual (I have two in fact). It's just that the manuals don't have enough details for me to find the drain plugs.<br /><br />Believe me, I scoured every part of the manual looking for answers first before asking here. And even before that, I search the threads on this forum looking for answers. One of the two manuals is in the bathroom that I read every time I'm in the can.<br /><br />Thanks,<br /><br />tuan

 

[fireship1]

Re: Where are my drain plugs?

And I thought I was the only one who read service manuals while on the throne!

 

[kcole683]

Re: Where are my drain plugs?

Your engine is a Mercury Marine Aluminum block with cast iron head modified from a 460 CI ford V8 engine.<br />It is also known as a 470. This is not a GM engine.<br />You should have a heat exchanger drain second from rear should be the closed cooling.<br /><br />There is a drain on the bottom of the circulating pump on the front of engine(make sure sediment is not built up by cleaning out with a wire or something if necessary).<br /><br />Should be a drain on the reservoir where the pressure cap is.<br />Should be an exhaust manifold drain too.<br /><br />Not sure where the block drain is ,but if it is threaded in and doesnt have a hose or wire or etc. on it then it is probably a drain.

 

[tuanp]

Re: Where are my drain plugs?

Thank you for the tips, especially about the Ford block; for some reason I assumed it was GM. I found all but the block drain. And yes, there was gunk plugging up the waterpump drain and I had to clear it using a small screwdriver.<br /><br />I found the owner's manual for this boat and it does describe the engine block drain, although they say it's hidden behind a hose. I haven't had a chance to look for it yet but I have an idea where to look from the picture in there. Thanks again for all the help.<br /><br />tuan