Mercruiser 5.7 Engine Block Drain Location

[Volksvolgen]

I recently winterized my Mercruiser 5.7 engine. I removed the hose from the bottom of the water pump and let it drain. I also removed the drain plugs from the exhaust manifolds. I searched for water drain plugs on the engine block, but could not locate any. Finally, I gave up and filled the block with anti-freeze, through the thermostat housing. It took about 3/4 of a gallon. Have I sucessfully winterized my block, or are there drain plugs that I missed?

I am considering placing a 100-watt light bulb in the engine compartment for the winter. Will this keep the engine above freezing? I live in Tennessee, wlhere winter temperatures occasionally reach zero.

[Eyehooker]

Better get out there-- there are drain plugs for the block in the middle usually take 9/16" wrench--- should hold more than 3/4 gallons of anti freeze futher always change oil and filter and put stabilizer in fuel and run for 5 minutes-- grease all fitting including gimble bearing-- store O/D in the down postion

[pikefisher]

they are almost directly under the the manifold drains, about 6 inches down further, right where there oil pan meets the motor, basically in the middle of the motor from front to back.

[Sleeper]

Why don't you reconsider your methodology and instead of draining, fill the SW side with anti freeze? I have always felt that the draining method never gets ALL the water out, it is probably true that not enough gets left behind to cause a big problem but to me the anti-freeze method is better.

1. Put all your drain plugs back in.
2. Suck up a mix of your choice with the engine running until you get the mix coming out the exhaust.
3. Now you know you are protected, you have added a corrossion inhibitor and spring start up is a simple turn of the key.

If you choose to use the environmentally safe polypropelene glycol (commonly called RV anti freeze). Do not mix it with water, use it straight. Some brands slush at 0 degrees and freeze at -50, some reformulated (full strenth) marine brands don't freeze until -100 F. If your engine is raw water cooled, do not be alarmed at the label warning on RV anti freeze that states "not for engine coolant". That warning is to tell you not to run this type of anti freeze in a FWC engine as your coolant. It does NOT mean it can't be used for winterization, just don't use it as your coolant mix to run with. From research of various brands MSDS sheets I find that they all have a 3% anti corrossive additive, even the cheap stuff. The expensive, marine version is 97% polypropelene glycol and 3% inhibitor. The cheap stuff is usually a lower %polypropelene glycol, with deionized water and 3% inhibitor such that the protection from a solid freeze is ONLY -50 with a slush forming at 0 degrees.

[Bucktail]

Ahh... Mercruiser 5.7 Liter. Nice motor, I had one for 8 years in my last boat, and winterized it myself every year. First off, there is NO reason to remove the thermostat or any of the hoses for any reason at all to winterize. You said that you found the drains on the exhaust manifolds, but you still have two more on the block itself. As Eyehooker said, they are 9/16" and are located (1) on each side of the block. Look under there and you will find them. The one on the Starboard side might be attched to the Knock Sensor. You will recognize this one because it has a set of wires attched to it. The wires have quick disconnect, and you will see a bolt below wire attchment. That bolt is the actual drain for the block, because the knock sensor is installed in the original drain.

Here is how I use to do it.

Loosen all drains so they are hand tight.
Start motor (Mine was running on earmuffs attached to outdrive) and let it run a few minutes.
While motor is running, unscrew the manifold drains one at a time and allow water to rush out of them. (This will help flush dirt out)
Put drain back in and proceed to the next one, all while engine is running.
When you are ready to do the block drains, unscrew drain and take a piece of 10-12 gauge wire and push it through the hole to assure
all dirt is being removed. You will be suprised as to how much stuff can be in there sometimes. Let motor run a miute or so with the drain out. (It will not hurt the motor!)
Finally, repeat the above process for the final engine block drain.

Now shut the motor off, and remove all the drains.
Let motor sit for about 5-10 minutes.
At this point you have drained the block. By removing the drains one at a time in the previous step, you are assured that all the water will drain, and that dirt won't clog the holes.


Now to winterize the block....

Put back in all the drains and tighten to spec.
Fill up a 5 gallon bucket of Freezeban with a shutoff valve. Attached to the shutoff is a hose attched to the earmuffs going to the outdrive.
Once 5 gallon bucket was full of the Freezeban, I would have a friend open the valve on the bucket, and I would start the motor.
The bucket would take 2-3 minutes (approximate) to empty.
While my partner was monitoring the fluid remaining in the 5 gallon bucket, I would be spraying a whole can of fogging fluid down the carb while motor was running.
When he signaled that it was almost empty, I would stop fogging, and shutdown the motor.

Thats it. The motor is winterized.

Like I said, I did it this way for 8 years up here in Maryland, and it can get below freezing 24 hours a day for weeks on end, and I never had a problem.
I learned the process from a Mercruiser dealer that I worked for while finishing up college.

[TN FREEBIRD]

Volksvolgen - 6/24/2007 12:50 AM

I launched my 23' Chaparral today, after having the long block replaced with a Jasper engine. The mechanic did all of the work in the shop and did not test drive it before releasing it to me. I observed the following problems and am turning to the experts on this forum for advice.

1) The boat runs fine and idles smoothly, but there is a vibration between 2,000 and 3,000 RPM.

2) The engine has a new thermostat. It now runs at about 170 degrees. The old engine ran at 120 degrees.

3) The top end RPMs are down, compared to the original engine. I used to get 4,400 RPM at WOT. It now tops out at 3,800 RPM.

The engine is a 5.7 Mercruiser, 2bbl.

Any suggestions or advice are greatly appreciated.

I was looking at your profile to see where you might be in TN and found this. You may not have block drains in that Jasper engine (probably not), so you better circulate some anti-freeze through that engine.