Compression Testing

[Boilers2000]

Quick question...I've been overly paranoid with the first winter, and now that its finally warming up I'm eager to start working on the boat to get it ready for the season. I really want to compression test the cylinders to make sure the engine survived the winter, it was winterized at a service shop, but knowing I didn't do it myself is driving me crazy. Also noticed last fall as I was warming the engine up for an oil change unusual exhaust around the engine and found a loose spark plug. I hand tightened but cant remember if I gave it a 1/16th turn with a socket before taking it for winterization and them running it through antifreeze tank. I'm paranoid something got boogered up. I know...I am a mess. I dont want to fully unwinterize the engine since it's still getting cold at night, but since the engine has sat for 7 months would a compression test tell me anything? Is there any visual inspection I can do? Sorry for the long winded message, but really eager to start tinkering again!

 

[QBhoy]

Oh jeez, it’s always a worry on the first spring start up, but maybe over nothing.
Personally if I was you, id be maybe just changing the plugs anyway (or if you had it serviced before hand) and firing her up, after checking the plugs were tight enough.
The 4.3 is amongst the best engine ever put in a boat, in my opinion.
New br6’s, 5 litres of quicksilver synthetic blend, oil filter and fuel filter....and she will be grand. The alpha will of course need fresh quicksilver premium or performance gear oil. 1.5-1.8 litres from memory. Don’t worry yourself otherwise and unless you have real reason to suspect failure. The 4.3 is as hardy as they come. Just get on with it.

 

[Scott Danforth]

Quick question...I've been overly paranoid with the first winter, and now that its finally warming up I'm eager to start working on the boat to get it ready for the season. I really want to compression test the cylinders to make sure the engine survived the winter, it was winterized at a service shop, but knowing I didn't do it myself is driving me crazy. Also noticed last fall as I was warming the engine up for an oil change unusual exhaust around the engine and found a loose spark plug. I hand tightened but cant remember if I gave it a 1/16th turn with a socket before taking it for winterization and them running it through antifreeze tank. I'm paranoid something got boogered up. I know...I am a mess. I dont want to fully unwinterize the engine since it's still getting cold at night, but since the engine has sat for 7 months would a compression test tell me anything? Is there any visual inspection I can do? Sorry for the long winded message, but really eager to start tinkering again!

how did you winterize it?

if you fully drained it at all locations, and probed all the drains to make sure they were clear and changed all your lubes and filters, you were fully winterized.

if you attempted to suck up antifreeze thru the muffs, you most likely have a busted block.

if you paid somebody to winterize, and all they did was suck up antifreeze, make sure you have your receipt, because if you have problems, it will be on their dime.

 

[Boilers2000]

I changed engine oil and gear lube before taking to a shop to get winterized. I believe they have an antifreeze tank, and they drain the engine then run it through the tank. Still have that receipt.

Making my list for all the startup supplies, and trying to get some bigger jobs scheduled.

Thanks for the feedback. Just ready to get back on the water ASAP!

 

[Bondo]

I really want to compression test the cylinders to make sure the engine survived the winter,

Ayuh,...... A compression test won't find a frozen busted block,.......

Ya gotta pressure test the coolin' passages for that,......

 

[tpenfield]

Agreed^^^^^

a compression test won’t tell much about winterization.

you could do one after you have that boat prepped for the season, just to get a baseline.

 

[Boilers2000]

D'uh...that makes sense...that's why I come to this forum to bounce my ideas of guys and gals of have been doing this for a lot longer than me.

Thanks again!

 

[Mad Props]

I agree with Ted... Even though it most likely wouldn't identify a cracked block (4.3s almost always crack in the galley under the intake manifold) it would be good to get a baseline set of numbers since its a new to you boat.

 

[Boilers2000]

Compression tested when I bought it, engine was cold but around 150 psi and all cylinders within 5-7 psi. Want to do it again just to recheck my base line.

 

[Bt Doctur]

I really want to compression test the cylinders to make sure the engine survived the winter,


Compression test is meaningless at this point . Check the oil level to see if it is at the correct area on the stick.high on the stick is a sign of elevated oil levels usually from water in the pan. If level is good then just try to start it for a second or two. If it just goes "clunk" most likely you have a manifold failure and water in the cylinders

 

[Boilers2000]

So would that indicate that fluid in the block leaked into the pan from a crack?

 

[Bt Doctur]

thats how gravity works.2 types of cracks , internal and external. You can try removing the large hose from the T stat housing and filling with water. If the level holds for 20 minutes no large crack, if it drops, cracked someplace.
Then run the motor to operating temp and check the condition of the oil, white and milky means a crack

 

[Boilers2000]

Potentially dumb question...the -stat housing is towards the top above the pulleys and has an inlet and outlet tube, right?

 

[Scott Danforth]

The T-stat housing is on the front top of the intake manifold. you will have 1 large inlet hose from the circulating pump. one small house from the raw water inlet and at least two outlets to the exhaust (not to mention the internal passages)