Valve job in my future?

[msballin]

I've just had a conversation w my mechanic regarding getting ahead of a potential issue with my engines he mentioned for me to be aware of. My 2000 340 Dancer has 7.4 Horizons. I've just shy of 600 hrs on each engine and regardless of the low hours, I've been cautioned about the potential for a valve job...irregardless that my engines had the updated 3" risers from the factory. My manifolds elbows and risers were replaced in Spring of 2015 and the risers are showing wear already with approx 150 hrs since the install. (I don't know that the latter is relevant at all)

My question is, how, if at all, does one get ahead of needing a valve job if there are no particular signs or any issues from a performance standpoint? I saw earlier in a thread a compression test can be performed. Thoughts? Thanks in advance.

Mike

 

[Thornton69]

Did your mechanic see something that made him caution you?
Oil consumption, condition of plugs and possible loss in WOT rpm's would be all that might concern me.
You're approaching 20 years on your engines and although only 600 hrs, I would be leaning more toward refreshing with long blocks rather than just cleaning up the tops.

 

[Strecker25]

Maybe he’s aware of the exhaust and reversion issues those motors faced. Does your boat have the “log” style exhaust, or is it fitted with water lift mufflers? A compression check will help give you an idea of valve health

Honestly, If they run well I wouldn’t worry about it, especially if the compression numbers come back in spec.

 

[hottoddie]

Did your mechanic see something that made him caution you?
Oil consumption, condition of plugs and possible loss in WOT rpm's would be all that might concern me.
You're approaching 20 years on your engines and although only 600 hrs, I would be leaning more toward refreshing with long blocks rather than just cleaning up the tops.

Never in a million years would I replace long blocks with only 600 hrs. If properly maintained these 7.4 blocks are good for 2-3000 hours. In the next post Strecker asks about the mufflers. The original log style mufflers were responsible for water reversion issues and valve issues. If not converted to water lift mufflers you should focus on getting that done.

 

[BillK2632]

"Honestly, If they run well I wouldn’t worry about it, especially if the compression numbers come back in spec."

This - If you are 600hrs in, you are not likely to have any exhaust related water "reversion" issues. Stay on top of the other maintenance items, especially risers - if there is a such think as "getting ahead of a valve job" I guess this wold be it. If I were going to spend $$ I would look into changing to a lift style muffler system if that is not already in place. I think a 2000 year boat was in the change over years, so yours could have either. Listen to your mechanic, but also realize he doesn't make money unless something is wrong.

A 2000 340DA with 7.4's, I see a lot of trouble free boating hours in your future, just stay on the maintenance.

 

[scoflaw]

Why does he think you need a valve job ?

 

[Thornton69]

Never in a million years would I replace long blocks with only 600 hrs. If properly maintained these 7.4 blocks are good for 2-3000 hours. In the next post Strecker asks about the mufflers. The original log style mufflers were responsible for water reversion issues and valve issues. If not converted to water lift mufflers you should focus on getting that done.

Maybe the point I was making wasn't very clear. It was that before I spent several thousand to replace the heads on 18 year old engines, I would double it and go all the way. New heads will more than likely increase overall efficiency of the 600 (run) hr'd engines but everything below them have still been sitting in a bilge for well over 150k hrs.
To each their own.

 

[msballin]

Did your mechanic see something that made him caution you?
Oil consumption, condition of plugs and possible loss in WOT rpm's would be all that might concern me.
You're approaching 20 years on your engines and although only 600 hrs, I would be leaning more toward refreshing with long blocks rather than just cleaning up the tops.

Nothing at all re: above. All running fine. He just mentioned that at 18 yrs just to be aware because these 454's are known for valve seats wearing mostly on the middle 2 cylinders.

 

[msballin]

Why does he think you need a valve job ?

Actually, doesn't think I need one. Just that at the age of the engines, regardless of the low hours, the valve seats are known to wear.