Compression test Merc 165 I/o in freezing temps

[all yeah boy]

Ok, well my lack of knowledge and just plain stupidity lead to a cracked block on my project boat this winter. It has a 165 merc I/O. Sad as it may be, there is some hope. I found a boat for $200 on craigslist with the same motor, and it comes with the entire out drive.

I plan on compression testing the motor before finalizing the purchase, same deal here as an outboard? Pull the spark plugs and set the gage in the plug then give it a few cranks?

Anyone know the ideal compression ranges for this motor?
And one more thing, it is sub zero out today, will this effect the compression?

As for water still being the block/ proper winterization of the boat, it will be hard to tell because it is so cold out. Any suggestions?

 

[Alpheus]

Re: Compression test Merc 165 I/o in freezing temps

Damn, winter hasn't even started yet. Compression check is the same as an outboard. I don't know the exact psi is but just make sure that they all are within 10% from each other...

 

[ErieRon]

Re: Compression test Merc 165 I/o in freezing temps

Ok, well my lack of knowledge and just plain stupidity lead to a cracked block on my project boat this winter. It has a 165 merc I/O. Sad as it may be, there is some hope. I found a boat for $200 on craigslist with the same motor, and it comes with the entire out drive.

I plan on compression testing the motor before finalizing the purchase, same deal here as an outboard? Pull the spark plugs and set the gage in the plug then give it a few cranks?

Anyone know the ideal compression ranges for this motor?
And one more thing, it is sub zero out today, will this effect the compression?

As for water still being the block/ proper winterization of the boat, it will be hard to tell because it is so cold out. Any suggestions?

Compression test is pretty much the same. The procedure is available in the manual here at iboats if you know the year and details; link; http://forums.iboats.com/showthread.php?t=288430

Compression is 150 psi, but I wouldn't expect that. As long as it is above 120-ish and each cylinder is within 10% of one another that's good.

I don't know about the sub-zero temps, but I think just getting it to turn over will be the issue. Ideally, compression tests are done at operating temp, but I'm not sure that's a big deal in your case.

Good luck.

 

[all yeah boy]

Re: Compression test Merc 165 I/o in freezing temps

thanks for the info guys.. I have a fresh battery in the garage so that is what I will use to turn it over. The guy has the boat stored outside, I may try to talk him into conducting the deal this weekend when it is supposed to be warmer.

Here is a though, Could I pull the drain plugs and put a propane tourch on the block to heat it up a bit to see if there is water in the motor?

I do own the manual for this motor.

 

[Bronc Rider]

Re: Compression test Merc 165 I/o in freezing temps

I would drain a little oil before I stuck a torch in it. If it hasn't been ran in a while all the water will be at the bottom of the pan.

 

[ErieRon]

Re: Compression test Merc 165 I/o in freezing temps

thanks for the info guys.. I have a fresh battery in the garage so that is what I will use to turn it over. The guy has the boat stored outside, I may try to talk him into conducting the deal this weekend when it is supposed to be warmer.

Here is a though, Could I pull the drain plugs and put a propane tourch on the block to heat it up a bit to see if there is water in the motor?

I do own the manual for this motor.

Doesn't that have a closed cooling system?

The torch thing doesn't sound too practical to me...

 

[Silvertip]

Re: Compression test Merc 165 I/o in freezing temps

Also sounds like a good way to warp an otherwise perfectly good motor. Too much heat on too little area is a recipe for disaster. The only difference between compression testing a two stroke and four stroke is the throttle must be open on the four stroke. Not necessary on a two stroker.

 

[all yeah boy]

Re: Compression test Merc 165 I/o in freezing temps

I was thinking along the same lines, with the torch not a great idea.... I just want to be sure the thing has been drained. With it being so cold out any water in the motor is froze solid.

 

[EddiePetty]

Re: Compression test Merc 165 I/o in freezing temps

.....with the temperature THAT cold, cranking speed will probably be reduced affecting the degree of compression. I would look for uniformity across the cylinders rather than an actual figure.
Oh, and be sure that the throttle AND choke are all the way open.
FWIW...Ed in 'ol Virginny

 

[fishinpa]

Re: Compression test Merc 165 I/o in freezing temps

Like Eddie and ERon and the others said
if its real cold out make sure you have plenty of battery and look for even numbers (or very close).

I also would not use any type of flame too warm the engine !

If you wanna warm it up borrow a space heater and let it warm it all up while you hook up batteries and check other connections etc...



fish

 

[Bondo]

Re: Compression test Merc 165 I/o in freezing temps

Ayuh,... As noted, Temps will effect the #s, but if you see 100lbs or less, it's Beat...

As for the drains,... Just pull it out,+ try to stick a nail or wire in it,...
It should go well over an inch,... Ice will block it where the drain plug ends...
No need for torchin' anything...

 

[Don S]

Re: Compression test Merc 165 I/o in freezing temps

IS this a 165 6 cylinder, or a 165 4 cylinder ???????

 

[ErieRon]

Re: Compression test Merc 165 I/o in freezing temps

IS this a 165 6 cylinder, or a 165 4 cylinder ???????

'zactly...