What would a brand new 600 test for leak down/ compression? What is considered good for 600s with ~275 hrs?

Also should add, I had to do them with engines cold. I know the tests are supposed to be done on warm engines but was unable to do to pulled headers with lots of leaks. Not sure how anyone is able to do it warm on side by sides.

I can't answer your question. But, how did you know the headers were leaking? Externally or internal? Are there warning signs to watch for?

Internally. I Pressure tested them with a garden hose. doesnt look good.... here is a full album of pictures

https://www.facebook.com/media/set/?...1&l=edae8709ed

Were they all(cylinders) relatively close on compression? were both engines close?


John jr

I know the engines are in quite a bit of trouble, just trying to get an idea of how much. Im just about ready to pull the engines in the next couple days. Check out that link with all pictures. Im just curious what a good new engine specs are. Cant seem to find them anywhere online.

15% spread on the port side:

Cylinder # 1: 127 psi
Cylinder # 2: 133 psi
Cylinder # 3: 125 psi
Cylinder # 4: 134 psi
Cylinder # 5: 130 psi
Cylinder # 6: 132 psi
Cylinder # 7: 122 psi
Cylinder # 8: 114 psi


16% spread on starboard side (excluding the 0psi cylinder):

Cylinder # 1: 114 psi
Cylinder # 2: 123 psi
Cylinder # 3: 130 psi
Cylinder # 4: 131 psi
Cylinder # 5: 110 psi
Cylinder # 6: 122 psi
Cylinder # 7: 0 psi
Cylinder # 8: 118 psi


Leak down on port:

Cylinder # 1: 24%
Cylinder # 2: 36%
Cylinder # 3: 37%
Cylinder # 4: 38%
Cylinder # 5: 76%
Cylinder # 6: 28%
Cylinder # 7: 24%
Cylinder # 8: 66%


Leak down on Starboard:

Cylinder # 1: 59%
Cylinder # 2: 18%
Cylinder # 3: 19%
Cylinder # 4: 26%
Cylinder # 5: 37%
Cylinder # 6: 22%
Cylinder # 7: 61%
Cylinder # 8: 18%


Like I said, these were all on cold engines. Compression was done with WOT for 5 cranks. Leak down was taken with harbor freight leak down tester (im second guessing it as its only done at 15psi even with the compressor set to 100psi). Leak down was taken at TDC and numbers were recorded after 3 minutes on each cylinder

On the leak down it is important to listen to where the air is going. This helps determine how far your tearing them down.

With the high leak-down and low cylinder compression and evidence of water intrusion , you will at the very least have to pull the cylinder heads ...you can then inspect the cylinder walls for rust or damage ...I would guess the engines will have to be pulled and at the very least cylinders honed with new rings and a valve job .

This is a shame! I would say with those leak down numbers and pictures of a few of those exhaust ports that those two engine have to come out and a minimum of head work and hopefully not to bad in the cylinders, but I suspect thay will have to come down completely if the water spent any considerable time in those cylinders.

What year model were these engines ? as it seems as though this leaking Merc CMI sweeper headers had most failures and issues in the 2005-2007 models.
Hope for yours or the owners sake the repair is as reasonable as can be.

Best Regards,
Ray @ raylar

I'm going to pull oil and put new oil I today as well as soak the cylinders with wd40 just to help prevent further damage until I can pull engines. I just picked up some yardarm engine stands from yard arm yesterday and Jeff at yardarm is drawing me up an a Frame gantry so I can pull motors out, but will be a couple weeks now with my work schedule. Boat is a late 2005 model. Are the gen x headers any better? I'd hate to ever go through this again