2007 Volvo Penta 5.0gxi - no compression in # 4 cylinder

[kkennedy34]

Looking for some help. I just launched for the season and on 1st run had port engine running rough. After about 20 minutes I pulled into the marina and asked the shop to have a look. The next day they did a compression test and #4 had nothing. The mechanic used a bore scope and told me that it looked like the valve dropped and made contact with the piston and did some damage. They just sent me an estimate for $17K to replace the block and put everything back together.
A few questions - 1) it doesn't appear they pulled the block open to fully inspect. Would a scope reveal that the block needs to be replaced? 2) If the piston is shot and the cylinder damaged are there options other than to replace the block? Can the piston be replaced and cylinder machined?

Appreciate for any advice on how to proceed.

 

[kenny nunez]

If you are handy with the tools just pull the head in question. Most likely the piston is not damaged enough to cause any problems. The head can be brought to any engine machine shop who can check if the head is still usable or not. You may have a manifold with an internal leak so plan on a new set.
If you are really lucky the valve was just stuck in the open position and the push rod jumped off. Sometimes a stuck valve survives a piston strike and the rocker arm stud gets pulled up. I have in the past freed up stuck valves, reset the stud and the customer lucked out. Keep your fingers crossed.
Since your boat is trailerable maybe you have a friend who can help.

 

[kkennedy34]

Thanks for the advice Kenny. Unfortunately, the boat is not trailerable - 32". Also I can do some basic wrench turning but this seems like might be beyond my skill set and free time. I am going to the marina tomorrow to talk to them. I guess I'll ask them to pull the head to get a better idea of what is going on. I thought it was extreme to send a quote for new motor before pulling it apart.

 

[Scott Danforth]

I would do the work yourself. Brand new long block is about $5k and it will take you a weekend or less to swap

 

[dubs283]

Looking for some help. I just launched for the season and on 1st run had port engine running rough. After about 20 minutes I pulled into the marina and asked the shop to have a look. The next day they did a compression test and #4 had nothing. The mechanic used a bore scope and told me that it looked like the valve dropped and made contact with the piston and did some damage. They just sent me an estimate for $17K to replace the block and put everything back together.
A few questions - 1) it doesn't appear they pulled the block open to fully inspect. Would a scope reveal that the block needs to be replaced? 2) If the piston is shot and the cylinder damaged are there options other than to replace the block? Can the piston be replaced and cylinder machined?

Appreciate for any advice on how to proceed.

1. Yes, I've seen the very same

2. Depends on how much damage is in the cylinder and how much/if it needs to be bored. If it's more than bigger rings can compensate then the other five cylinders will need bored as well

At the very least you need a valve job. As far as piston/cylinder damage it'll be apparent when the head is removed.

 

[Bondo]

Thanks for the advice Kenny. Unfortunately, the boat is not trailerable - 32". Also I can do some basic wrench turning but this seems like might be beyond my skill set and free time. I am going to the marina tomorrow to talk to them. I guess I'll ask them to pull the head to get a better idea of what is going on. I thought it was extreme to send a quote for new motor before pulling it apart.

Ayuh,..... Welcome Aboard,...... Figuring out exactly what's wrong, 'n why it happened, is the number 1 priority, as if ya don't, chances are you'll burn down a new / repaired motor

 

[kkennedy34]

Thanks for the all the advice.

Bondo - good point on figuring out what's wrong and why it happened. Maybe I'll dive in and pull the heads and go from there. If I can source a long block and swap it out over a few weekends it might be a fun project. Or a deep rabbit hole I'll spend the summer in

 

[Lou C]

Agreed as much as possible you want to know what happened to cause the failure. Have you looked under the valve cover to see if there was an obvious valve train failure?
Removing the head is not difficult and if the cyl wall isn’t scored you may be able to run it with a reman head if the piston damage isn’t bad.

 

[kkennedy34]

Haven't been able to get to the boat for more inspection this week. The mechanic who did compression test ran a scope of the bad cyl. He told me the valve dropped and made contact with the piston. Not even sure he pulled the valve cover to have a look. Going over today to have a look and talk to the mechanic.

 

[BRICH1260]

After a complete diagnosis, if an engine overhaul or replacement is due I would just consider a remanufactured/rebuilt engine for around 5k and do it myself or pay someone to do it. $17K seems a little steep, at least where I live.

 

[kkennedy34]

Quick update. Wasn't able to get to the boat today but spoke to the mechanic. He said he wanted to replace the block because the piston rod likely damaged the crankshaft - flattening the crankshaft. He said if he did did the heads it would likely blow the motor down the line. I am going to get the pics he took with the scope to see what I can find. Any thoughts?

 

[Bondo]

Quick update. Wasn't able to get to the boat today but spoke to the mechanic. He said he wanted to replace the block because the piston rod likely damaged the crankshaft - flattening the crankshaft. He said if he did did the heads it would likely blow the motor down the line. I am going to get the pics he took with the scope to see what I can find. Any thoughts?

Ayuh,.... You've still gotta figure out, Why,....

If detonation burnt the valve, there's probably a fuel delivery issue that caused it,......
If the valve stem rusted causin' the piston contact, the manifold/ riser is suspect,.....
Ship don't "Just happen",..... there's a reason, 'n ya gotta find it, so the repair don't repeat the problem,....

 

[Donald0039]

Well I think the mechanic is playing it safe. At your expense. Certainly the head needs to be pulled and inspected. The piston is aluminum and the valve is steel. The crankshaft is heavy & steel and is not going to be flattened easily. The crankshaft can be ground also.

I think there is a good chance you can just get a remanufactured head and you are fine.

 

[kkennedy34]

Thanks for the feedback. Going to insist he pull the heads and have a look at what we have. Need to figure out what caused the damage and build a plan from there. I think spending 17K with out openning up the motor doesn't make any sense.

 

[Donald0039]

Thanks for the feedback. Going to insist he pull the heads and have a look at what we have. Need to figure out what caused the damage and build a plan from there. I think spending 17K with out openning up the motor doesn't make any sense.

If I was the mechanic I might suggest the customer go for what I was positive would solve the problem. If he said too much $$ then we could talk about option that might involve labor to take things apart to investigate further.

He could be too busy and a new long block would take the least time to get the customer back in the water.

I had my VP outdrive at a large boat place in Delaware and they found metal in the outdrive gear oil. Took it apart further and found a large gear with a few missing teeth. They gave me a quote to rebuild the upper drive that was higher than new from VP. I concluded they did not really want to do the work. Even though they were VP authorized dealer. In the end I had them strap the outdrive to a pallet, sent by truck to a place whose business is rebuilding outdrives and they rebuild the upper and lower sections with VP parts for less than new and less than local dealer quoted for just the upper drive. The local dealer seemed happy to do the local work of reinstalling the outdrive.