Sea Trial question WOT question

Four of A Kind

New Member
Aug 17, 2019
8
Boat Info
400 EC
Engines
7.4 Mercruiser
I sea trialed 1998 400 EC - here is the issue.
The boat has Horizon mercruisers 7.4 new long blocks installed in 2015 with approximately 100 hrs on them.
On the sea trial the port engine WOT 4600, Starboard engine was at 4150. What can be the issue ? I was thinking bad cable, possible dirty air breather?? At 3200 RPM the boat ran 19 knots The starboard throttle was pined where the port engine had some more to go.. any thoughts????
 
There are so many possibilities,

dirty bottom (usually affects both motors)
prop damage
fuel issue
ignition issue

The good thing is that you hold the power, have the issue corrected before purchase.
 
There are so many possibilities,

dirty bottom (usually affects both motors)
prop damage
fuel issue
ignition issue

The good thing is that you hold the power, have the issue corrected before purchase.
Thanks for your response, I’m thinking the same thing
There are so many possibilities,

dirty bottom (usually affects both motors)
prop damage
fuel issue
ignition issue

The good thing is that you hold the power, have the issue corrected before purchase.
The bottom was clean, did the running gear inspection prior to the sea trial. Like you said it can be a number of things, I’m not going to make it my problem to find out what’s wrong. The boat is clean, but I need it running correct.. I think they should be running at 4500 only had 1/4 tank of fuel and very little water in tanks with 4 people onboard.. don’t want to take on someone else’s issue.. Thanks
 
That would be an acceptable explanation. I'd probably want it verified though. I haven't heard of many 400EC's that have suffered from inversion, especially if they made it to 2015?

Has this boat been in fresh or saltwater? If the latter, I'd have to wonder if a lack of maintenance resulted in ingestion due to failed exhaust.
 
That would be an acceptable explanation. I'd probably want it verified though. I haven't heard of many 400EC's that have suffered from inversion, especially if they made it to 2015?

Has this boat been in fresh or saltwater? If the latter, I'd have to wonder if a lack of maintenance resulted in ingestion due to failed exhaust.
Boat is in saltwater, according to owner never ran the engines to WOT, I am a little concerned about that, if I installed new long blocks I would have the tested at WOT, he says he never runs the boat past 3100-3200 that the boats sweet spot.. which is acceptable, but needs to be performing at the RPM specs....
 
So he's either claiming that the issue with starboard is so new that he hasn't experienced it, or you caught him in a lie: if he runs at 3,200, that currently IS WOT for the starboard engine.
 
Have them do a compression and leakdown test. That will at least rule in/out major mechanical issues.
 
IMG_4230.JPG
Boat is in saltwater, according to owner never ran the engines to WOT, ...
Not a credible assertion.
 
Gonna ask the captain obvious question here... are you sure it's not a gauge issue?

ie was the sync off or was it pulling toward starboard?
 
I'm having the same issue. Have a 1997. 330, Port engine run great WOT 4200 rpm. Other one, at best getting 3100.
 
So why don't you quit screwing around and get a professional Marine Surveyor to do a complete survey. I have been boating for more than 50 years, owned a few and even worked on them professionally and I will never....let me repeat that....NEVER buy a boat without a survey.

Let the surveyor determine what's wrong with it. Remember, the seller wants to sell the boat. you have to assume that most of what he tells you is crap. With a survey you can go back to the seller with proof of the issue(s). At that time you can demand the seller make the necessary repairs to make the boat right. If he refuses or is unwilling to adjust the price to cover the repairs....WALK AWAY! There are way too many boats for sale.

Good luck
Shawn
 
^ that is such simple, sound advice, but for some reason we (me included) tend to get emotional on purchases of things we really want (cars, boats etc) and just make the whole process way too complicated.
 
So why don't you quit screwing around and get a professional Marine Surveyor to do a complete survey. I have been boating for more than 50 years, owned a few and even worked on them professionally and I will never....let me repeat that....NEVER buy a boat without a survey.

Let the surveyor determine what's wrong with it. Remember, the seller wants to sell the boat. you have to assume that most of what he tells you is crap. With a survey you can go back to the seller with proof of the issue(s). At that time you can demand the seller make the necessary repairs to make the boat right. If he refuses or is unwilling to adjust the price to cover the repairs....WALK AWAY! There are way too many boats for sale.

Good luck
Shawn
Not sure a surveyor would diagnose. He'd just report. What he (actually the owner) needs is a mechanic to get in and diagnose. I'd start with compression, but that's me.
 

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