I do believe I got bit by my purchase...
 

1st thread here...hoping this site is helpful for my situation...Livin' in Coeur d'Alene, Idaho.

1992 Cobalt 243 originally with a 454/Bravo One...The boat had 244 hours on it total when I purchased it 2 months ago, but was advertised as only 20 hours on the Crate 502HO...Sweet. As I have discovered through paperwork inside the boat what appears to have happened was that there was a Crate 502 (Chevy not Merc) may have been installed in '09 2 owners ago, ran for 15 hours, sold to last owner when the motor started puking oil & had to take it in to Eastside Offshore Marine Service near Seattle...

The Eastside Offshore receipt (August 2011) showed that the motor would not turn over 4200 rpm & was way out of balance...Tore into it to find the wrong crank for a 502 + 2 recently replaced rods...They built the motor with a new crank, new cam & lifters, & showed a dyno break-in of 527HP/570TQ (not sure if these results were with the current Edelbrock RPM intake & Carb). So this was 5 years ago & 20 hours before I purchased it through a consignment that gave me a 30 day warranty for major defects.

So I've had the boat for 2+ months & put 11 hours on it when it started a major knock in the middle of the lake with some pretty good white cap weather...I limped in to the closest marina where I could secure it...then retrieve it with the truck & trailer later. I had tried to get a maintenance base line a few run-hours earlier with new spark plugs, oil change, oil filter, & fuel filter even though winterization was a week or two away. It ran great. On the last cruise I got it up to maybe 55 mph/4800 rpm for maybe 5 minutes...the rest of the time it was a pretty calm run. Oil pressure was great & running cool.

It's been at a pretty big shop but they are in that busy winterize/storage season so there has been a delay. The most experienced mechanic ran it in the tank & said it had a hard miss & thought the noise was in the valve-train...Next step is compression test to pin point the problem...How is that for luck? I'll update when I find out...

Welcome to boating!

:cool-smiley-026:

BOAT break out another thousand,lol.

Yep, 4th boat in 25 years...just never any catastrophic issues on the front end .

Just so you feel a little better... Took my compression last week, engines were all in like new condition, on my boat i owned for 2 years... Good news!
Last ride this w-end, wich was the first after the compression test... Broke a valve cruising at 3300 rpm and filled 3 gal of water...

Some here might say... Told you!!! End of my luck!!!

S..t happens, you just don t know when and why...

Where do you boat ? I'm right in the middle of the state.

Really? Your numbers looked good. Hours were high. Sorry I said go for it with all that luck you had. Sorry to hear that

"Where do you boat ? I'm right in the middle of the state."

Coeur d'Alene Lake, mostly...Idaho

Wete you the guy asking about your motors that had 700 hours or 1200 hours on them?

1233 hours! yes!
it is me!!!!

that lake in Idaho is really nice. I actually sold some boats in my past to that area from Texas. How bad and cold is your winters ?

Maybe and my good guess would be ---- your oil bypass valve was not set up properly for an oil cooler marine big block.

Welcome to the club! If we had perfect boats then we wouldn't have found ourselves here, so you're amongst fine company. Lol

I was going to mention that many $15k motors have been toasted because of a $15 bypass valve, but BUP beat me to it. Best of luck and hopefully it's simple!

6 month boat storage winters...and I'll search the rest 😩

Oh nothing new to me -- once to 3 times a year I see this, brand new big block crate engines lasting only 15 to 60 hours only.

That is correct 15 dollar - wrong by pass valve still installed that was never changed.

Thats where I bought my boat . Beautiful lake!
Im in central Washington on the Columbia.

Do you have a link to a good write up or video on how you set up a non-marine crate motor for a marine application?

Sorry to hear your misfortune, at least it was end of season though. Yours was definately the exception to the rule, one way you can look at it is the motors lasted so long without a rebuild that even if you have to buy a new engine you saved so much not going into the engines your still ahead, Smitty

Let me update...The local boat shop did not do a compression test after all...I picked up this morning, as the dealer is willing to work with me @ his mechanic's cost & parts cost. I think we/they may be pulling the motor in about a month & sending it to an engine builder they use...Since I've got 4 weeks to wait I drained the block this morning & I wanted to try and figure the history on the previous build...

What I don't know:
1) Can't for the life of me find the block casting number...but I did find the block casting date stamp of IJ6 (& I don't know what that tells me).
2) The 2011 rebuild by EastSide Offshore Marine states an upgraded Cam & lifters...I tried calling them & the number is disconnected (out of business?)...

What I do know:
1) SUPPOSEDLY the motor was dyno'd by Eastside Offshore @ 527 hp & 570 torque...but not sure if it is with the current top end.
2) Has EMI Thunder Exhaust
3) Has Edelbrock 7562 Performer RPM Air-Gap intake...
4) Has Edelbrock 1410 Performer 750cfm marine carb...
5) Has Bravo One 1.50r w\ a Mirage Plus 19p prop...(this appears to be the original for the 454).

Do you see any problems with that intake & carb vs. the dyno results (are those dyno numbers possible with that carb?), My goal is to get this up and running again while leaning towards more reliable not necessarily faster.

I may pull the valve covers tomorrow (dont have all the tools I need with me now) to get a look at the springs, rockers, & pushrods. I expect some damage. I did get my inspection scope inside one of the covers & see the rocker arms are stamped. I'd also like to get the head casting numbers.

Any input/advice is appreciated. Thanks!

Yup, looks like last FB entry was 2012

https://www.facebook.com/EASTSIDEOFFSHORE-355734525987/

Looks like he had a clue...hopefully he knew about the 30# filter by-pass on this crate motor...encouraging.

A 750 Edelbrock ? I'm not so sure they did on this motor.

That's kinda what I was curious about...I think maybe he offed some parts (intake and carb) when he sold the boat. So "unknown" upgraded cam that's a part of 527/570 dyno event then is now part of a 750cfm carb creates what kind of limitation/danger?

Just a lament, but when I got into powerboats I asked around and found the most recommended mechanic and he knew nothing about the #30 bypass filter, and missed a ton of other specifics. He was a good parts changer though.

A 500+HP motor should be spinning a 23p prop at minimum so a 19p isn't encouraging. A 750cfm seems small for a warmed up BBC. My internet guess that whatever engine is in there is putting out 375-400hp at most.

Ok, the plot thickens...the PO also had some really expensive 4-blade stainless prop but wasn't included in the deal. I think he wanted more than $500, maybe $800 for it. Maybe the 19p mirage is the stock one for the OEM 454 mag? Would the boat maybe benefit from a prop change?

I saw a CL ad from 2010 that states the boat ran in the low 70's...I was only able to hit 58 mph in the brief time I have had it. Thanks for the continued help...

again in English please??

Sorry, I think the previous owner stripped some bolt on parts, different intake, carb,& 4-blade prop before he dumped the boat. Trying to cut his losses. He left the exhaust and upgraded cam (which I do not have any specs).

A couple things here...

What ratio is your drive?

If its a standard 1.5 and you were doing 58 with a 19 pitch prop, your tach was probably starting to smoke,,,

with a 1.5 gear in a smaller boat and a 23p prop 58 is around 4400 rpm

So what kind of speedo and how accurate?

given an avg prop slip of 12% or so 58 on a 19 pitch is about 5500 rpm.

So if your spinning 5500 rpm its probably not going any faster because your may be sitting on the limiter... if the engines built for it, if not your boat may not be the only thing floating.

You need to try a 23p because by the math is seems like you have been running the car floored in second gear wondering why it wont go faster.

The boat's tach has never been over 5k the couple times I've tested it...maybe it's not too accurate ��. I did check my speedo vs gps app on my phone and it was pretty close. Maybe that's the cause of banging. I'll get the VC's off tomorrow and see if anything broke.

plugging the numbers in, with 12% slip and a 19 p prop doing 4900 rpm would be right if you had a 1.36 ratio bravo..... Why it would have a 1.36 instead of a 1.5?? unless somebody toasted a drive and threw one on....

No, it's the original Bravo One drive (I have the tag) w/ 1.50 ratio.

Sorry bro... but your boat has more issues than my ex....

LoL, thanks for you help. I'll get it fingered out.

Now I'm getting somewhere...This morning I took the port side valve cover off first...easiest to remove...here is what I found:

Heads are casting # 12562934 which is a 2000+ rectangle port, open chamber, Gen. VI 502 Marine head...

FIrst visual shows 2 Comp Cams 1.72 roller rockers arms off of their pushrods (#5 Intake & exhaust), No broken springs, 1 severely bent pushrod (#5 Intake), & some cast chunkage in the mix. I won't even look at the starboard side.

http://i690.photobucket.com/albums/v...&1477242654886http://i690.photobucket.com/albums/v...&1477242654886
http://i690.photobucket.com/albums/v...s/IMG_2061.jpg

I'm pretty sure they work better when connected. ;)

Why would that happen in a fairly mild motor? Over revving with that tiny prop?

The last day we were on the lake...with a pretty full load, I eased it up to about 55mph (checked with GPS app) & it was turning 4800 by the boat's tach...When it self destructed it was a couple hours later with mostly <35mph...UNfortunately I had to "limp" to the closest marina for about 30 minutes...wind picked up and had some "guests" on board.
I'm assuming this calls for an autopsy & rebuild...

Here's what metal pieces I could fish out of the head with a magnet...#5 Exhaust CompCams Rocker arm ball...good grief.
http://i690.photobucket.com/albums/v...s/IMG_2086.jpg

U had a good run. I think the bird just came out the clock.

Man what a beat down . Ive seen a few guys fumble the 305 to 350 vortec crankshaft flip flop , but i dont think i have ever seen or even heard of anybody having the balls to just grab a crank out of the pile and just slapping it in a 502 . Kick that edelbrock carb to the curb and get a holley 800 or 850 double pumper.
Once the rest is uncobbled even kia driving drunk young women will be able to identify the difference in midrange punch between the holley and that edelbrock .
Cant go back and look now but make sure cooler lines arent reversed and what distributor ya got on there?

Yes, do not buy any of those same type rockers when you rebuild. Those rocker arms are known to do that. Oiling / wear / overheating problems between ball and rocker arm.

Thunderbolt iv...talk to me about the cooler lines?