1998 wellcraft 240 SE 5.7 issues Prop Or engine?

[jws123]

Are you reporting speed based on GPS, or the speedometer?

A ‘97 wellcraft with a 5.7 base engine (doesn’t matter if Mercruiser or VP) would be a vortec series 5.7 w/roller cam. You can rev them right up to their maximum 4800rpm without worrying that it will blow up. FWIW, if it does blow up, the engine was going to fail anyway.

i would run it again with the 15p prop. As I said last year, when wellcraft tested the boat, they used a 15p with an engine that made an extra 50hp. I didn’t see whether you used GPS to determine your speed, but if you’re not using it, you need to start. Boat speedometers tend to be less accurate than boat tachs. Lastly, on a boat that is underpowered proper trim is essential. If your trim is way off, you can lose a lot of performance. Also read the owner’s manual for Bennett trim tabs. Many people mistakenly think that the tab operation correlated to tab switch position. In other words, they think that pressing the port side switch up, means the port side tab comes up. In reality it pushes the starboard tab down.

Let us know now what happens.

yes i use a gps even tho my spedo is accurate i tested was suprised lol. i plan on putting my 15p prop back on when i go out tomorrow i have a brand new one from last year i have nothing to lose according to the wellcraft site thats what it came with also have a 19p i paid $10 for i am sure it wont do anything but trying it any ways. Ihave trimmed the boat every way possible lol have found 1 spot where it feels good and does 20mph

 

[nola mike]

i have it runs fine am 100% sure has nothing to do with spark and or carb related its all in good shape fires right up every time without any throttle runs smooth.

This isn't verifying spark to each cylinder. A v8 can run smooth on 6 cylinders. Or fewer.

 

[jws123]

This isn't verifying spark to each cylinder. A v8 can run smooth on 6 cylinders. Or fewer.

Just got back i checked for spark all cylinders have spark. going to try 2 props tomorrow play with trim a bit more and really push it for a bit to see if it picks up speed if it blows up **** it :lol: if all else fails il pull it and go to the weigh station if that turns out good im rebuilding the motor found guys number that i bought it from i contacted him motor to his knowledge never rebuilt.

 

[garbageguy]

I dont expect a race boat ofc lol but i do expect to see at least 35 mph or so i am pushing 4k rpm to almost get 20mph what are your speeds?no idea if it was ever rebuilt. I will see if there is somewhere near me i can have the boat weighed how much should it weigh with nothing in the boat all cleaned out on the trailer? btw also what prop are you running?

AS far as blow by i took cap off valve cover when running and had some air but nothing crazy i think. Buti do notice when i stop the boat there is a oil smell not oil leak but oil crank case kinda smell i had to clean my flame arrestor once it got all clogged up also sometimes you see like a steam/smoke coming out of the valve covers/tubes to the flame arrestor but my old boat did that to. I am going to get a vid of what i am talking about.

Not sure what speeds are, probably about 25 mph just up on plane at about 3200 rpm. We usually run on a river (actually it's a strait), that has it's own speed. Also not sure about weight with fluids and trailer. I will put up what the prop is, but I'll be away for a little while..

 

[jws123]

Not sure what speeds are, probably about 25 mph just up on plane at about 3200 rpm. We usually run on a river (actually it's a strait), that has it's own speed. Also not sure about weight with fluids and trailer. I will put up what the prop is, but I'll be away for a little while..

ok ty

 

[jws123]

Ok so took it out 15x15 pitch prop was a pos didnt do **** but cavitate rev to 4600rpms

17 pitc prop rev to 4500 rps doing bairly 25 does not hold it well.

Said **** it went and got a 14.5x19 for $100 and boy what a difference yes you can feel it took some power and only revs to about 4200 maybe 4300 rpms now BUT. I had it up to 32mph drastic change and once i got her up and goin and trimmed i was able to hold 25 no problem at 3800rpms. Now i do think my engine is a little soft will probably rebuild over the winter so this prop witha rebuilt engine i think i might be golden. But i am tempted to try 18 pitch if i can find one just to see if it can take the edge off just a little for now.

Also i did these tests with a full tank of gas .

 

[jws123]

anyone know a good place to get a good marine short block? just askin for when i rebuild in fall I was looking around but so many sketch places like the ones you see on ebay i no longer have machine shops near me so rip.

 

[jws123]

of course i am still getting boat weighed before i do motor.

 

[jimmbo]

Before you go ripping the engine out, verify that you don't have a clogged up exhaust. If your engine has the flapper valves to prevent water back flowing into the engine, and they have come apart, they can effectively plug up the system. A fibre optic camera fed down the pipes can reveal it

 

[Bondo]

anyone know a good place to get a good marine short block? just askin for when i rebuild in fall I was looking around but so many sketch places like the ones you see on ebay i no longer have machine shops near me so rip.

Ayuh,.... You can buy a brand new long block from yer local GM dealer for 'bout $2500.......

 

[jws123]

Before you go ripping the engine out, verify that you don't have a clogged up exhaust. If your engine has the flapper valves to prevent water back flowing into the engine, and they have come apart, they can effectively plug up the system. A fibre optic camera fed down the pipes can reveal it

i checked those this year when i pulled risers to inspect them flaps where in good shape mine where easy to get to