1996 26 Scarab 454mag issues and experiences.
 

Hey guys, I figured I'd start a thread about my boat and motor issues that I've had and continue to have. My hope (or dream) is that eventually everything gets sorted and I can enjoy my boat again. I welcome constructive advice and opinions as I am kinda nooby with all of this. This thread should also serve as a reminder for my self of things done and things that still need addressed.

So I have a 1996 26ft wellcraft scarab 454mag efi that I bought for what I thought was a great deal last year in March. It is my first boat and I bought it without a sea test as it was too cold and I was too hasty. A compression test was performed and passed and the motor was started briefly and sounded good at idle. The surveyor said the boat itself was in remarkable condition with very little moisture to be found anywhere on the boat. Then it was topped off with the seller saying it was "perfect turn key" so I eagerly pulled out a stack of greenbacks and bought it. On its maiden voyage last year I got an engine alarm and had to get it towed back to the launch. I got in touch with a friend of mine who is a boater and also a licensed auto tech to go though it and once it warmed up it started knocking, it sounded deep in the crank case so we pulled it. Long story short- once we dropped the pan we found that the motor was nuked so I purchased a newly rebuilt longblock and had my friend dress and install it. Once it was installed and after finally getting it running last year it was discovered to have a massive oil leak (1-2 qts or so per hour). My tech friend lives far away and had already spent many hours getting frustrated with it, so I took it to the shop where I purchased the longblock for them to diagnose and fix. Three weeks and $1500 later and it had shiny new oil lines and still a massive oil leak. At that point there was only a couple weekends left of the Michigan summer so I just kept oil filled before during and after every run, disconnected the bilge pump so I didn't pollute, and drained the bilge oil/water into a bucket after every run. Then when the year was over it was shrink-wrapped and winterized. I did still somehow have a decent summer on Lake St Claire with it even though I only have about 20 hours on it.

This year last week I took it to the launch and had a reputable boat mechanic check it out. The motor is leaking from the valve covers and the dipstick tube when under load. Excessive blowby was suggested as a possibility and I'm waiting for a leak down test to be performed Friday. I'm really hoping the motor doesn't have to be pulled again but at this point it's getting hard to think positive. Aside from the oil leak it hisses like crazy from the IAC which I've heard mixed opinions about, and it leaves soot all over my transom after about 1/2 hour run time which I've also got mixed opinions about. The idle is a little choppy but not bad, and performance seems on par with what a 454 mag should provide. It planes easy and tops out mid 60s @5200rpm (non-gps) or at least it did last year.

Other non-related issues that need addressed are the Bennett trim tab pumps leak and the Bennett hatch cylinders are painfully slow. My fuel and speedo gauges stopped working and the transducer for the gps/fish/depth finder got ripped off. (Sigh)

Did you use a marine long block or automotive ? that makes a difference.

It is a rebuilt Gen VI Mercury marine 454 Magnum 385HP longblock. The previous was a GenV 454 magnum.

Forgot to mention there is also oil splatter on the top of my hatch directly above the flame arrester.

What kind of ventilation do you have for the crank case ? do the valve covers have breathers in them, thats a lot oil the push out of an engine, sounds like posibly the rings didnt seat on the newly rebuilt longblock

Unfortunately, there will be 10-20 threads just like yours this years as there is every year. Bought boats with a piece of schit motor. Too many people that are scum out there.
Arcticfriends (Paul Smith), give him a shout. he's in MI...I know, big state. The injectors should be gone thru when everything taken apart again and he services those too.He know these MPI engines more than most. May be too late to get it done for this summer too, but who knows until you call.

https://cimg0.ibsrv.net/gimg/www.off...e5aa8da265.jpg

There are breathers on the valve covers, but I am honestly not sure what I have for crankcase ventilation. I am afraid that it is the rings also.

I'm sure you are right that I am one of many sob stories. I figured I could get some feedback from people on here and maybe get some ideas that I wouldnt have thought about otherwise. Thanks for the reference and I do want to get my injectors cleaned and serviced if or when they end up coming out again.

Does the 454 use a PCV valve in the right valve cover like the 502MAG?

Sorry to hear about all the issues you are having. It is very frustrating and makes most get out of boating altogether. It is to bad there are so many dishonest people. Hang in there.

I think it's just a breather that's in there.

Thanks, and yes it is frustrating but I'm not ready to throw the towel yet!

You are on Lake St Clair. Take it to NorthBay Marine. Thay will fix it and it will be right,

Compression test, and leak down test. That will probably tell the story and manufacture will probably want it for warranty claim.

Yes it was warrantied for one year, but I'm pretty close to that expiring. Thing is I already took it back to them once and they failed to fix it. If you want to know the place I used shoot me a PM so that you can avoid them.

Thank you for the reference.

Yes that's going to happen Friday. I'll update this thread with the results.

Update- Mechanic no-showed Friday :bong:

There is supposed to be a PCV valve in the odd bank's valve cover. The vacuum line from the PCV valve goes to a fitting on the intake (connects underneath). If you only have breathers installed, then that's surely a contributor.

Can you get us some pictures of what you have?

Thank you I'll take a look and take some pics.

On the odd bank (right side) where does the hose go to? Are the two sides connected together by chance??

Look under the plenum top. There should be a 90 degree brass fitting for the PCV hose. Is that capped off? If not, where does that hose go to?

I'll take a look later when I get home from work. So right now I have a Gen VI longblock/rotating assy/heads with Gen V intake, throttle body valve covers, vst, accessories etc... Doing a little research on Bam it appears that the Gen V has a breather elbow #97850T (which is what I have installed), and the Gen VI has a PCV valve #21-806603. It looks like the PCV valve would fit so do you think I should try it?

The Gen V uses a baffle assembly to use pull in vapors versus a PCV valve though the baffled set up should work ok.

My bad for not catching the differences between the two.

It would not be hard to duplicate the Gen VI set up if you wanted to do so. The PCV system will work a lot better.

Thanks for the insight. I'm going to have my friend that dressed the engine do a leakdown and compression test for me but he said it would be at least a week or two before he would have time.

I never knew when I bought the boat how many of life's virtues would be tested and worked on at once... Patience, perseverance, humility and self-control come to mind. All I was looking for was a little adrenaline, socialization, beer consumption and a tan. :faint2: