Top end rebuild, what to look for??

[El Jefe 79]

Looking for some insight, looking to purchase a boat. The top end is being rebuilt, new cylinder heads, valve springs, retainers and keepers. New seat guides, stainless steel valves, new bottom rings. Minimum hone on cylinder walls, flushing cooling system on engine to remove residual sand.
It’s is a 2001, my understanding no major issues. Less than 400 hours.
Any concerns or red flags??
Thanks in advance.

 

[Shlbyntro]

IMO if the bottom is bad enough that they need to take it apart and change the rings, they should do it right and rebore it.... or leave it alone if it isn't. a rehoning only is really a corner cutting thing or an uneccesary upsale depending on the situation (my 2cents). top end stuff all sounds fine. Are there leakdown numbers prior to the engine being torn apart that justifies the tear down?

 

[El Jefe 79]

IMO if the bottom is bad enough that they need to take it apart and change the rings, they should do it right and rebore it.... or leave it alone if it isn't. a rehoning only is really a corner cutting thing or an uneccesary upsale depending on the situation (my 2cents). top end stuff all sounds fine. Are there leakdown numbers prior to the engine being torn apart that justifies the tear down?

He said, it was running fine in his opinion. Took a potential buyer and his “mechanic” for a ride. The guys mechanic said the motor was blown, to me, you know if the motor is blown. Maybe not so much if it’s just got some low compression. But hey I’m not a mechanic. The seller said he wanted to do right by whoever purchases the boat so he took it to his mechanic and this is what his mechanic is doing.
At the end of the day, if I go and we run it and it feels and sounds good and the mechanic has a warranty on his work, should I consider or stay away? Is it safe to say a boat over 20 years old could use a top end overhaul and get that compression back up, or does it sound like there may be under lying issues??

 

[Shlbyntro]

He said, it was running fine in his opinion. Took a potential buyer and his “mechanic” for a ride. The guys mechanic said the motor was blown, to me, you know if the motor is blown. Maybe not so much if it’s just got some low compression. But hey I’m not a mechanic. The seller said he wanted to do right by whoever purchases the boat so he took it to his mechanic and this is what his mechanic is doing.
At the end of the day, if I go and we run it and it feels and sounds good and the mechanic has a warranty on his work, should I consider or stay away? Is it safe to say a boat over 20 years old could use a top end overhaul and get that compression back up, or does it sound like there may be under lying issues??

that's why I asked if there's leak down numbers to justify the claim that it doesn't need a full rebuild. I professionally wrench on boats and I can tell you when an engine is running like shit just by listening to it. But there's no way to tell if it just needs service vs rebuilding the engine without at least taking a compression gauge to the engine, short of a knock anyway. If I as a mechanic am going to sell a customer on a partial rebuild vs a complete one, I am going to have leakdown numbers to back it up. a leakdown test not only tells you what cylinders are underperforming but also where the compression is getting away (rings vs valves vs head gasket)

in my experience, an engine that only gets a hone is being taken apart again in a not so far off time frame for excessive blow by.

 

[El Jefe 79]

His reply to me asking about leak down testing and what prompted the top end to get worked on…..

“It was just due for the valve job so we put new heads on it. He checked compression and did leak down. We had low compression in two cylinders. It was still running great no black soot in the exhaust or metal in the pan. I had it up to 68 just last week on a test ride but it was feeling like there was some power loss so we just decided to go through the top end and make it perfect rather than selling it needing the service soon.”

 

[Shlbyntro]

His reply to me asking about leak down testing and what prompted the top end to get worked on…..

“It was just due for the valve job so we put new heads on it. He checked compression and did leak down. We had low compression in two cylinders. It was still running great no black soot in the exhaust or metal in the pan. I had it up to 68 just last week on a test ride but it was feeling like there was some power loss so we just decided to go through the top end and make it perfect rather than selling it needing the service soon.”

That's 2 conflicting statements

If they did a leakdown, they should have individual percentages of leakage for each cylinder and should have noted where its leaking to.

If I were in your shoes, I would approach your valuation as a used engine that's received a valve job. It's not getting a complete rebuild and they haven't provided you with the proper due diligence on the mechanics part that shows the bottom end to be in a healthy state to where it wouldn't have required a full rebuild. If it were me, I would honestly prefer for them to leave the bottom end alone if they don't plan on machining it.

Let us all know how things work out

 

[El Jefe 79]

That's 2 conflicting statements

If they did a leakdown, they should have individual percentages of leakage for each cylinder and should have noted where its leaking to.

If I were in your shoes, I would approach your valuation as a used engine that's received a valve job. It's not getting a complete rebuild and they haven't provided you with the proper due diligence on the mechanics part that shows the bottom end to be in a healthy state to where it wouldn't have required a full rebuild. If it were me, I would honestly prefer for them to leave the bottom end alone if they don't plan on machining it.

Let us all know how things work out

Greatly appreciate your input and education. Thanks a lot!! Will let you all know how it turns out.