www.iFourWinns.com

So im dealing with 2 low hour engines. 7.4 Gi's

they have not been run for 4 years. both fired up. starboard engine runs good. port engine had a dead miss and low compression in several cylinders.. Does fogging oil (which its super thick and sticky) have a tendency to stick the rings?? We started these engines in 35ish degree weather so that could be exacerbated due to cold weather..

i know it sounds like im trying to confirm my theory, but i want to ask others who may have possibly had the same experience???

A boroscope inspection showed a decent amount of carbon buildup too...

Dry

1 - 170 2 - 115
3 - 142 4 - 110
5 - 170 6 - 170
7 - 150 8 - 180

Wet (with PB blaster)

1 - 170 2 - 160
3 - 160 4 - 150
5 - 170 6 - 170
7 - 150 8 - 180

Thanks, Duck

I am not a mechanic but I suspect your test was flawed.

180 is high and there is a rather significant variance in all readings.

I dont know your back ground. Have you completed much testing in the past?

Was this a salt water engine and how was it treated before put away for 4 years?

_________________
2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

No.
Contaminated fogging oil could, though...

_________________
2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

Normally fogging oil would not cause ring sticking, actually its used to prevent that. But if the engines were not run in 4 years, and it was stored in a damp climate, you could possibly have sticky valves or rings if it was not fogged enough. Was your compression test done with the engines warmed up and the throttles wide open? If not then some of your lower results may not be valid. I'd want to make sure the test was valid before I did repairs. If you go over to the Merc I/O form on iboats forums a user by the name of tpenfield did a great report on compression testing and the results of decarbonizing his engine. He has a pair of Merc 7.4s. I'd take a look at his results and see if you want to try that first, then re-test and see what you get. The miss suggests a sticking or stuck valve or one not seating. That could be a rusted valve stem, or un even carbon build up.

http://forums.iboats.com/forum/engine-r ... 7-4-lx-mpi

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Hey lou, engine was cold, throttle cracked open. i was just trying to isolate a dead miss/hole. i could hear several cylinders down on compression while cranking and wanted to see if it was a burnt valve or rings not sealing with a wet/dry test.. i'll get them warm and decarbon and see what i get then..

here is some of the other stuff i build in my spare time for friends and paying customers.

1000hp - 565BBC



mild 12:1 406 - 650hp

So I guess you are relatively confident that you possess the knowledge to compete a proper compression test.

_________________
2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

Yep, I'd guess he is relatively confident in compression testing.

Nice looking engines BTW.

_________________

Current Boat
- 2001 Four Winns 328 Vista "Hour Decision"
- 2010 310 Mercury Inflatable

Previous Boats
- 30' Doral Prestancia
- 25' Doral Citation

Why not do a leak down test to isolate where your issue lies.

_________________
2001 328 Vista "Nauta Dream 2"
AB Inflatable 10AL "Little Dreamer"
2000 248 Vista
1997 225 Sundowner


Mike

Maybe a dumb question...and off topic but it is winter. Do all Chevy blocks have the drain plug. I thought it was a marine feature but see the same plug on that bad boy motor.

As to your compression test results....over my head:).

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http://i1339.photobucket.com/albums/o71 ... wqm355.jpg


08' H210SS
VP 5.7Gi

Yes they do and most others do as well. Sometimes there is just a bolt there with sealer. The reason for it is to be able to drain all of the coolant when changing it. In practice they are often frozen in place so all you can do is remove the lower rad hose and jack up the rear of the vehicle.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

If it was me, I would use Marvel Mystery Oil in each cylinder. Let it sit for 5 min, start the engine and do this 2 or 3 times. In other words, let the oil work itself in. The rings may be a little rusted and need to work themselves loose.

After that, the engine may have to be pulled. You could take the heads off and look and turn it over by hand just to see. But just taking the heads off, you can't replace the rings.

Someone mentioned if the boat was used in salt water. Salt water has nothing to do with this, under normal conditions. The engine has been seating for 4 years, even if it was fogged well. It’s still a long time.

If a healthy engine was fogged well, 4 years is not a long time.

Key term is healthy. Knowing if this was a salt water engine or not it would be a good start in determining whether or not it was healthy, would it not?

We have an '86 Liberator with original raisers and manifolds. I would consider the engine to be healthy. Obviously, if this was a salt water boat I could not have made the same statement.


Any who...


I wonder how the OP made out?

_________________
2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

It all depends on maintenance... If the mainfolds and risers were done on schedule then yes it could be fine. My '88 is on its 3rdset since I've had it (2002), never had any water in the engine.
Always fogged as well. Salt water is not a death sentence you have to have a basic understanding of adjusting your maintenance to fit the environment you are in.
If you're a real good mechanic you can even keep your trailer brakes and lights working lol...

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Could not have said it better! "Salt water is not a death sentence you have to have a basic understanding of adjusting your maintenance to fit the environment you are in."

As Lou knows, there are many salt water boats that are over 30 to 40 plus years old were the 2 of us are.

Yep, nothing wrong with what Lue had to say at all.

So I guess you are also saying you now understand how salt water vs fresh water could play a role in premature valve or ring failure.

_________________
2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP