when does one consider doing a top end job

[SanJuanDreamer]

I have a 1998 Carver Mariner 350 with two Crusader TBI fuel injected 454’s.
The motors have a little over 1400hrs on them.
I’m mechanically inclined, not a professional but in my experienced opinion they run fine to me.
Over the course of my 14 day San Juan trip I placed 40hrs on the motors. The 40hrs were a combination of doing 9mph to 26mph.
the starboard motor used a quart of oil while the port used about 4oz.
They don’t smoke

Question is, when does one consider doing a top end job or is it needed or should I wait until something really stands out to fix?

[bud37]

In my opinion leave em alone...you have 1400 hrs already,( which to many is the cliff ) and that much oil usage is nothing really.......if you start with the heads it will turn into rings and bearings shortly after ........take care of them and start your happy fund for ??????....lots of people get 2000 + hrs on their BBC.

[tomschauer]

I'm with Bud. With 1400 hrs that isn't bad. Also if you have no smoke, maybe the oil is leaking into the bilge or into the raw water through the oil cooler and not being burnt by the engine?

[waybomb]

If it were smoking at idle I'd be doing valve stem seals.


Sounds to me like the one engine is telling you to start saving money for reman.

I think you are good for quite a while yet.

[waybomb]

Know anybody with a vacuum gage?

Hook it up to the oiler engine.

At idle, describe very exactly what the needle is doing, how often. How much vacuum is indicated, etc.

When at cruise, are the throttle settings about the same?

[mjk1040]

Dreamer;
Curious, what weight oil you using? My 1998 TBI Crusaders call for 40W. IMO I would hold out till it got real serious on the oil usage. And if your not smoking at all, I too would be looking else where. Are engines closed cooling or open? If closed check the antifreeze for oil. You could have a pin hole in a cooler or an external hose even. Really check for any and all external leaks first. Hate to say it, but I too would go with complete repowers with that amount of hours. In any case good luck! Mike

[Viper]

Without some obvious signs of poor conditions and no readings from some key diagnostics, it'd be difficult for me to commit to doing anything if I were in your position. High hours tend to scare a lot of people but there are too many variables involved to have that be the only deciding factor on whether an engine needs a rebuild. High hours are okay if they've been properly maintained over the years, the problem is you don't know for sure unless you have documentation from previous owners. How the engines/boat was run also factors in. I'd feel more comfortable high hours that have been properly maintained than low hours that were not. I'm also not crazy about older vintages with low hours as that means they've sat idle for most of their life which is not good either, they need to be run.

I'm with Fred in that testing would go a long way to help make the determination on whether they need a teardown or not. The typical tests would be compression, leak down, and the best IMO at telling you several things while they're actually running is the vacuum test as mentioned. It's a great tool not used as often as it should IMO. In trained hands, it'll tell you a lot about the engine's condition.

Having said all that, you have to weigh the pros and cons of tackling an engine rebuild sooner than later. In my case for example, I know what I have and would prefer to simply rebuild the same blocks when the time comes rather than end up with long blocks that I have no history on. For this reason, I'd be proactive at the first sign of major work needed before there's a catastrophic failure resulting in a scrap engine. One of them is also a counter rotator and while the hardware specific to it is still out there, it's not as easily available as the standard rotator hardware.

At this point, it doesn't sound like you have enough real/measured data to make an educated decision.

[waybomb]

With what viper says, if you do not grenade your engines, those you have would be ideal to rebuild.

Me. I would have them done by an offshore power boat rebuilder, NOT an automotive rebuilder. Clearances and tolerances are not the same.

But I would not worry about this now.

Let's get some vacuum gage indications.
Before you do this, change the plugs and make sure timing is right on.

Fwiw, I drive German cars and they allow for using a quart every 600 miles! They say that's acceptable limit before rebuild.

So for now keep oil on hand, check often, get some history under your belt, and watch the oil pressure gage.