7.4 Mercruiser engine shot!

Hello everyone,

It's me again!

I got some bad news from the boat mechanics today.

They say I got a broken rod, spun bearings, and pieces are broken off down in the oil pan; therefore, he is saying it would be cheaper to buy a small block and use all the exisiting parts.

Although, I am not following what he is telling me. I thought the 7.4 (454 motor) was a big block or long block? Would all of my parts from the 7.4 liter fit on a 5.7 block???

Any suggestions, donations (laughing...jk...), people with drills willing to go out and sink her with me or we could set her on fire and go down in a blaze of glory!!

thanks

Re: 7.4 Mercruiser engine shot!

therefore, he is saying it would be cheaper to buy a small block and use all the exisiting parts.

Click to expand...

I think he meant to say SHORT block, and not small block. The short block containes the crank, rods, and pistons. No heads, tin or manifolds. You would use those items from your old engine

Re: 7.4 Mercruiser engine shot!

Yep! your right sorry about that he did say a short block, I screwed up by saying small block. I did some research and if I have to buy a short block 7.4 liter it is going to cost me some serious money. I hate to say it but is there a less expensive way to go other than:

[years] 73-90
454 7.4
Marine
Chevrolet, Carb, Flat Tappet, 2 Pc. Rear Seal, 2 bolt main, 1 5/8" oval port heads, 330-340 HP, Standard Rotation
[core] $650
[price] $3,149

Does anyone know of a better method? Maybe replace with a new 5.7 liter or volvo, yamaha....?

thanks for your fast reply Don S...

Re: 7.4 Mercruiser engine shot!

http://www.rapidomarine.com/default.aspx?p=/engines/default.aspx

Awww, looks like yours is sold out for now.....maybe give them a call?

Re: 7.4 Mercruiser engine shot!

SWEET!!!

What ???

SON of a.......

Ok, I will call them to find out availablity on this block as the pricing is not too terribly high. Here is the deal I purchased the boat 3 weeks ago $4,000 + new trailer $3,000= $7,000 + invested already..Do you think it is wise to invest more money into a 1989 Cobalt 21' bowrider.

She is in really nice shape (hull, interior, etc..) but she will need the engine work done so 2,000 for the block 1,000 worth of labor = $3,000 + 7,000 = $10,000....i see a trend and it is called a MONEY PIT....

NOW I KNOW WHY THEY SAY B.O.A.T stands for:
BUST OUT ANOTHER THOUSAND

Re: 7.4 Mercruiser engine shot!

I called rapido marine and they are not dealing with the 7.4 short blocks anymore as they are hard to aquire and not in demand anymore...bummer!!

Re: 7.4 Mercruiser engine shot!

f-fighter47 said:

Here is the deal I purchased the boat 3 weeks ago $4,000 + new trailer $3,000= $7,000 + invested already..Do you think it is wise to invest more money into a 1989 Cobalt 21' bowrider.

She is in really nice shape (hull, interior, etc..) but she will need the engine work done so 2,000 for the block 1,000 worth of labor = $3,000 + 7,000 = $10,000....i see a trend and it is called a MONEY PIT....

Click to expand...

Did the engine run 3 weeks ago?

Re: 7.4 Mercruiser engine shot!

A Colbalt is a well built boat. You could sell out now for a little less than half of what you paid for it or spend the $3k and have a boat.

Re: 7.4 Mercruiser engine shot!

I guess it's up to you. Colbalts are nice boats. Definatly make sure your drive is ok, or you will be sinking more bucks into it. If you spend the money you should get a guarantee and atlesat you know you have a new motor instead of buying another used boat and run into more problems.

I had to put a new upper and lower drive on my bayliner and this forum recomended me to SEI.....really saved me a ton of money.

Do a cost analysis and go from there...it's only money..can't take it with you!!! haha

Re: 7.4 Mercruiser engine shot!

Howdy,


Yeah, A Cobalt is probably one of the best made boats out there......


If it were mine, I would buy a long block.

Up here in the NW, we have a company called USENGINE. http://www.usengine.us/mercruiser.html

I have only done one engine with them but it has been in the boat 2 years and has had no problems so far.

When I replace my 454 I'll probably get it from them. A replacement long block (that includes heads) for your boat would be about $2300 + core + shipping + installation.

I did some research and if I have to buy a short block 7.4 liter it is going to cost me some serious money.

Click to expand...

Um, ANYTHING for a boat that includes the words "engine", "drive", "rebuild", etc......will cost "serious money"



Sorry about that....


Rick

Re: 7.4 Mercruiser engine shot!

reply to airdvr1227: Did the engine run 3 weeks ago? yes & no

I purchased the boat from a boat mechanic that said the boat only has 480 hours on her and she was repowered with a 7.4 liter 454 that has only 150 hours on it and he said he just replaced the fuel filter and changed the oil filter and all the nonsense that comes with maintenence on a boat.

Therefore, I thought I was in good hands (kinda like allstate) but I was wrong!

The first time I set her in the water was just to go pick up the new trailer as the old one was all rusted out and shot, not road worthy at all. So she was spitting a sputtering for 10 seconds then would die. So my friend and I knew exactly what the problem was (old/bad gas) We filled it up with new fuel and dry gas (per specs of container) and boom she fired right up and ran fine.

Saturday - Bumper bash on the Magothy River, Annapolis MD. The boat was running along fine with no problems at all Oil psi was at 40 when running 3,500rpm and then all of a sudden no more oil pressure! We thought to ourselves maybe the guage stopped working as we did hit some pretty good wakes from other boats, but then 5 minutes later clank, clank, clank, bang bang bang......Died out on her own!

....and thats where we are today....

Although, he said he has a 5.7 liter mercruiser engine complete but it needs new pistons, rings, seals and valves but we could put that in to just make due for now and at that point I knew that it was half ***'ed to begin with. So I took that man out of the scenario all together as this is why I am having the problems I am due to lack of common sense and proper replacement of critical parts necessary for this huge 454 block to run properly.

YES - Cobalt boats are awesome, tough @ss boats that are well built and this is the reason I purchased her. I guess we will wait and see what happens today when I get the dreaded call from the boat yard...

If all else fails I will start ripping her apart and selling her parts like a underground black market in China!! Anyone need parts for a 89 Cobalt 21' BR...lol...

thanks for all the replies and links everyone!!

Re: 7.4 Mercruiser engine shot!

I'd keep looking for a block or short block. Cobalt is a good boat to have as they keep their resale better than many.

The 454 is a tough SOB as evidenced by running 5 mins. w/o oil, although something broke/let go that caused the loss of PSI.

I had to search a few weeks for a block earlier this year due to my poor winterization. They are out there, you just have to search... craigs list or ebay
I initially looked at a local re-man engine exchange company but ditched that idea because I was unsatisfied with the quality of parts that they used. You may also want to google a website called racingjunk.com I think is the name. That's a site for used racing parts. I'm currently running a 454 from my brothers old drag motor. It had 4 years of races on it totaling a whopping 3-4 hrs guestimate of run time. I've upgraded higher comp pistons that are factory balanced and mated to a balanced crankshaft. All that kind of stuff can be found on that website.

Re: 7.4 Mercruiser engine shot!

I just checked that website and they have some blocks available as well as a Gen V shortblock at a steal of a price.