Block draining idea for older Mercruiser v8

tango13

Seaman
Joined
Mar 10, 2015
Messages
71
Hi All,

Like most boats, mine is a major PITA to winterize. I have to remove my whole rear bench interior, just so I can crawl in to drain the block plugs on the old 350. I would really like to set it up so I can simple reach into the engine compartment to winterize (also planning to relocate oil filter).

I have been searching for a way to make my own ezy drain system for this old mercruiser setup (1977 "250hp" 350ci), and I found this drain assembly kit for a air compressor that I think might work:

https://www.amazon.ca/Hromee-Extend...ank+drain+assembly&qid=1600381346&s=hi&sr=1-2

I would install it without the 90 degree elbow (so I can reach in with a coat hanger incase I get a blockage), and have the ball valve at the end, hanging out so I can simply reach in and open the valve come winterization time.

All the pieces are brass and stainless, so corrosion shouldnt be too much of an issue.

Does anyone see any reason why this wouldn't work?

Thanks
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,557
it wont work the same reason the easy drain systems dont work. the debris in your block will plug the hoses. all the stuff you must poke and prod out of the NPT port to get it to drain will simply plug that little hose up.

seriously, every hose on a mercruiser 3-point drain and 1-point drain will plug with debris and you end up with a busted block

your motor lasted 44 years by doing it right, why break what is right by doing something wrong..
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,557
if you have a fresh water only boat, pull the heads, make sure the water jacket is clean, then install a heat exchanger. then you only need to drain the raw water supply line, the manifolds and the PS cooler
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,754
It would work til it clogged. Drain it, then use air pressure to blow back thru it. Blowing air into it and let drain a couple times will ensure it stays clear
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,855
Actually you would be better off, redesigning the seat, to make it less difficult to remove. That's what I did on my '88 FW H-200. I got rid of that heavy bench seat that was impossible to move and made a new rear bulkhead that is split down the middle vertically. There is a take apart hinge in the center. For seats I used a pair of pontoon bench seats each 36" length. The rear bulkhead and the dividers in the engine compartment are held together with machine screws and wing nuts for easy dis-assembly. So what I do is lift out the seat back for the port side bench. Then lift out the bottom; I made up handles out of rope so I don't have to bend over to do this. Now remove the wingnuts holding the port side rear bulkhead to the divider, then open it like a door. Then remove that divider and I can get in and change the oil and reach the drains; have to stretch a bit on the starboard side but do-able. I only have to remove one side for winterizing. For big jobs I remove both.
This way you winterize it the correct way and don't break your back moving that foolish big seat. In fact I am thinking of a future re-configuration to make this even easier....
 

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Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,855
Doing my winterize today. Here’s how my engine compartment door opens...
D3ECC29F-786D-45B7-AF67-49502F2ED80F.jpeg
 
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