Stuck Valve/Cracked Head/Cracked Block

[Blaiser87]

I have a 1987 Four Winns Horizon 196 Sport with the Mercruiser 3.0 4 Cyl. She was flying across the water and started bogging down and just died. From all my research I thought I had a blown head gasket. Tore it apart, meticulously cleaned everything, inspected the block and cylinders and pistons and the head, replaced the head gasket and put her back together. She runs amazing in my driveway on the muffs, but in the water under load She won't get above 3000 rpm. I pulled the plugs and did a compression test and cylinder 4 has nothing. I'm going to pull the valve cover tomorrow and see if it's just a stuck valve, if I can't see anything obvious my question is will I damage anything using the boat for the rest of the season as is and put off the full tear down until October. I'd rather not pull the head and everything that goes into it when realistically I'm only going to get to use the boat another 4 or 5 times this summer anyways.

 

[Scott Danforth]

Your boating season is done. If there is a hole in the piston, wont take long before block fills with enough fuel vapor to blow up

 

[Blaiser87]

Copy that Scott. Thank you for your insight. I'll pull the head tomorrow and see what we're looking at.

 

[Scott Danforth]

I would do a leakdown test first, that will tell you what is wrong prior to pulling the head

 

[tank1949]

I have a 1987 Four Winns Horizon 196 Sport with the Mercruiser 3.0 4 Cyl. She was flying across the water and started bogging down and just died. From all my research I thought I had a blown head gasket. Tore it apart, meticulously cleaned everything, inspected the block and cylinders and pistons and the head, replaced the head gasket and put her back together. She runs amazing in my driveway on the muffs, but in the water under load She won't get above 3000 rpm. I pulled the plugs and did a compression test and cylinder 4 has nothing. I'm going to pull the valve cover tomorrow and see if it's just a stuck valve, if I can't see anything obvious my question is will I damage anything using the boat for the rest of the season as is and put off the full tear down until October. I'd rather not pull the head and everything that goes into it when realistically I'm only going to get to use the boat another 4 or 5 times this summer anyways.

I would not use it with only 3 cylinders firing. I am not totally familiar with a 3.0 but #4 seems to be the problem. If you tore it apart, you should have seen top of piston for holes. Perhaps you didn't adjust #4's valves correctly? Pull valve cover and watch to see if valves close. I assume that you inspected head and valves or had shop do the work on them???

 

[Scott06]

I would not use it with only 3 cylinders firing. I am not totally familiar with a 3.0 but #4 seems to be the problem. If you tore it apart, you should have seen top of piston for holes. Perhaps you didn't adjust #4's valves correctly? Pull valve cover and watch to see if valves close. I assume that you inspected head and valves or had shop do the work on them???

I try losening the valves on cylinder 4 see if you get compression

 

[Blaiser87]

I would not use it with only 3 cylinders firing. I am not totally familiar with a 3.0 but #4 seems to be the problem. If you tore it apart, you should have seen top of piston for holes. Perhaps you didn't adjust #4's valves correctly? Pull valve cover and watch to see if valves close. I assume that you inspected head and valves or had shop do the work on them???

When the head was off I closely inspected the block, cylinders, and pistons. I was actually surprised at how good everything looked for a 35 year old motor. I did take the valves out of the head for a thorough cleaning. I didn't do a valve job because honestly they looked that good. I didn't think it was even worth the time. I even made sure all the lifter rods went back in their respective homes they came out of. I did have a hell of a time getting the rocker arms back over the rods though, so much so that I now suspect that's where my issue is coming from.

 

[tank1949]

When the head was off I closely inspected the block, cylinders, and pistons. I was actually surprised at how good everything looked for a 35 year old motor. I did take the valves out of the head for a thorough cleaning. I didn't do a valve job because honestly they looked that good. I didn't think it was even worth the time. I even made sure all the lifter rods went back in their respective homes they came out of. I did have a hell of a time getting the rocker arms back over the rods though, so much so that I now suspect that's where my issue is coming from.

Pray that you didn't adjust valves too tightly and warp one by forcing it into it's piston top. Been there too many, many years ago. Good luck

 

[Blaiser87]

Found the problem with #4

 

[tpenfield]

I am thinking that should have made quite the noise . . .

 

[flashback]

If your engine is like an old 350 I had, rocker studs are press fit so be sure the stud didn't slip.

 

[76SeaRay]

If you bent the pushrod because it was too tight then you probably need to replace the lifter as well as it would have bottomed out.

 

[Bondo]

Pray that you didn't adjust valves too tightly and warp one by forcing it into it's piston top. Been there too many, many years ago. Good luck

Ayuh,..... Welcome Aboard,..... My guess is, the valves weren't adjusted,....
At All,......

I did have a hell of a time getting the rocker arms back over the rods though, so much so that I now suspect that's where my issue is coming from.

That's what happens, from attempting work, without the required knowledge,....

 

[Blaiser87]

Ayuh,..... Welcome Aboard,..... My guess is, the valves weren't adjusted,....
At All,......

That's what happens, from attempting work, without the required knowledge,....

Orrrrrrrrr you had the knowledge, just didn't quite get the steps right. Oh well, I'm learning as I go. Now I know what not to do next time !