marcuscarr
Cadet
Thread starter- Joined
- Jul 19, 2005
- Messages
- 25
I am looking for verification that I am on the right track in troubleshooting an issue with a boat I just purchased.
Engine:
1989 Force, model 856A9F
Prop:
3 blade, 13.5 x 15
Boat:
17' Maxum Runabout
Problems:
When cold it has trouble idling without dying.
When warm, it idles well.
Boat is difficult to get up on plane.
WOT achieves 4200 RPM, 23mph
The engine pulses a little at WOT.
Plug examination:
Cylinder 1 - slightly oily
Cylinder 2 - clean, with milky white bubbles on it
Cylinder 3 - less clean, but still with some bubbles
What I have done so far:
Increase idle RPM from 700 to 1000, temporarily.
Check spark:
With inline tester...I get good spark from all three coils. I am also using brand new plugs of the proper type. (don't grab the spark tester when the engine is running, the insulation must be there for looks because it shocked the hell out of me)
Check compression:
Warmed up engine, removed all plugs, pushed disengaged throttle forward, disconnected the shut-off lanyard.
Cylinder 1 - 120
Cylinder 2 - 80
Cylinder 3 - 80
I believe this engine should be between 125 and 145, and all three cylinders should be within 10%
Everything so far has led me to believe that I have a cracked block or blown head gasket.
So...I pulled the head and examined the head gasket. It's trashed. The area around cylinder 1 looks the best. The area around cylinders 2 and 3 have breaks, areas of rust, and chips missing from them.
My plan is to clean up the block and head, then install a new gasket and rerun the compression tests.
My questions:
Should I do or examine anything else while I have the head off?
When I install the gasket, do I install it dry? Put a coat of oil on it? Use gasket sealer?
Do I need to run a break in period after having the head off?
Should I run the engine for awhile, then tighten the bolts on the head again?
What question did I not ask, that I should have?
Thank you for your time and advice.
Marcus
Engine:
1989 Force, model 856A9F
Prop:
3 blade, 13.5 x 15
Boat:
17' Maxum Runabout
Problems:
When cold it has trouble idling without dying.
When warm, it idles well.
Boat is difficult to get up on plane.
WOT achieves 4200 RPM, 23mph
The engine pulses a little at WOT.
Plug examination:
Cylinder 1 - slightly oily
Cylinder 2 - clean, with milky white bubbles on it
Cylinder 3 - less clean, but still with some bubbles
What I have done so far:
Increase idle RPM from 700 to 1000, temporarily.
Check spark:
With inline tester...I get good spark from all three coils. I am also using brand new plugs of the proper type. (don't grab the spark tester when the engine is running, the insulation must be there for looks because it shocked the hell out of me)
Check compression:
Warmed up engine, removed all plugs, pushed disengaged throttle forward, disconnected the shut-off lanyard.
Cylinder 1 - 120
Cylinder 2 - 80
Cylinder 3 - 80
I believe this engine should be between 125 and 145, and all three cylinders should be within 10%
Everything so far has led me to believe that I have a cracked block or blown head gasket.
So...I pulled the head and examined the head gasket. It's trashed. The area around cylinder 1 looks the best. The area around cylinders 2 and 3 have breaks, areas of rust, and chips missing from them.
My plan is to clean up the block and head, then install a new gasket and rerun the compression tests.
My questions:
Should I do or examine anything else while I have the head off?
When I install the gasket, do I install it dry? Put a coat of oil on it? Use gasket sealer?
Do I need to run a break in period after having the head off?
Should I run the engine for awhile, then tighten the bolts on the head again?
What question did I not ask, that I should have?
Thank you for your time and advice.
Marcus
