5.0 L Mercruiser engine froze. HELP!!

vigil2448

Seaman Apprentice
Joined
May 8, 2010
Messages
30
Okay so I recently bought a 1994 Bayliner Cierra 2355 with a 5.0 mercruiser. I got a great deal on it, got it to start and found out that the block has a crack in it. The exhaust manifold are cracked. BUT there is NO water in the oil. I wasn't to sure if I should replace it with a remanufactured, repair it, or replace with a scrap yard from a vehicle. I'm not planning on keeping it, so performance doesn't matter. I just want to keep the cost low without losing a profit, while not having the next buyer ending up with a piece of crap.

1. Can the exhaust manifold be welded with a welder or repaired with "JB Weld"

2. Can I use a block either from a 350 or 305 from a scrapped vehicle rather then a expensive one from the marine shop?

2.5 What will I need if I just replace the block with one from a scrap yard?

And does anyone in colorado happen to have a GOOD block that they are willing to sell?
 

Howard Sterndrive

Rear Admiral
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Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

And does anyone in colorado happen to have a GOOD block that they are willing to sell?

you want a block?
you will first need to find out the size of pistons you have in the current one. std/.030 over...etc..before shopping
you have the tools, skill and time to swap all internals over to a new block?

budget $350 for lifters, gaskets, misc parts. + $200 or so for the block assuming you know how to inspect said block for reuseability

and then your conscience is going to request a new oil pump, timing chain, cam and bearings and rings.... another $350


might as well look for a reman at that point.
 

180shabah

Rear Admiral
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Messages
4,995
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

I smell a future craigs list story.....

Manifolds and elbows are NOT repairable, The inner walls are not accessible.
 

vigil2448

Seaman Apprentice
Joined
May 8, 2010
Messages
30
Re: 5.0 L Mercruiser engine froze. HELP!!

haha ya 180shabah. yup bought it on craiglist, but for only $1,000. I'm not to sure what to do at this point. Got any suggestions??
 

300sflyer

Chief Petty Officer
Joined
Jan 1, 2009
Messages
627
Re: 5.0 L Mercruiser engine froze. HELP!!

Part everything out... "The sum of the parts is greater than the whole".;)
 

z1nonlyone

Seaman
Joined
Apr 20, 2010
Messages
58
Re: 5.0 L Mercruiser engine froze. HELP!!

You can get a remanufactured engine for around $1400.00 or so.
 

cedarjunki

Chief Petty Officer
Joined
Aug 23, 2007
Messages
472
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

Manifolds and elbows are NOT repairable, The inner walls are not accessible.

they are if they are not cracked internally.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: 5.0 L Mercruiser engine froze. HELP!!

I agree - reman is the way to go. Even if you plan to sell, new engine and we just got one from a junk yard sound completely different.
 

bomar76

Lieutenant Commander
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Jun 27, 2002
Messages
1,963
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

they are if they are not cracked internally.

No competent marine mechanic (professional or shade tree) would ever repair a cracked exhaust manifold - or riser- as long as there is a replacement available.
 

cedarjunki

Chief Petty Officer
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Messages
472
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

No competent marine mechanic (professional or shade tree) would ever repair a cracked exhaust manifold - or riser- as long as there is a replacement available.

i agree on the risers....less than 200.00 for most..
but exhaust manifolds.....400.00-900.00 range. i know there are more welded ones being used than there are new ones!

even a local marina here will see if its repairable before replacing it.
 

bomar76

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Messages
1,963
Re: 5.0 L Mercruiser engine froze. HELP!!

I have never owned a boat with repaired manifolds.
Not one of my freinds has ever had a manifold repaired.
Of the marine mechanics I know in this area, not one would ever repair a cracked exhaust mainifold.
The only repaired manifolds I have ever seen were on boats that were otherwise quite dodgey.
 

paul ames

Recruit
Joined
May 6, 2010
Messages
4
Re: 5.0 L Mercruiser engine froze. HELP!!

The manifolds are cast and damnd near impossible to weld with any success,
I have a 302 sitting in my garage with one cyl low ,needs head on one side valve done, think it is no. 5 all other cyls are at 100 plus low one is at 75 eng only has 700 hrs, has manifold and all still attached. If you are in dire need of total set up we can talk
 
Last edited:

Howard Sterndrive

Rear Admiral
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Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

No competent marine mechanic (professional or shade tree) would ever repair a cracked exhaust manifold - or riser- as long as there is a replacement available.

I agree. manifolds for a sbc are not worth fixing. not even worth evaluating. any suspicions- toss em.

repairs are sometimes possible on antique stuff where it's worth the time and effort and replacements don't exist
 

bomar76

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Messages
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Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

even a local marina here will see if its repairable before replacing it.

I not only would never take anything there or ever reccomend them, I would speed up when I drove past their "business".

Hacks, that's the only fitting term for them.
 

craze1cars

Lieutenant Commander
Joined
Dec 26, 2004
Messages
1,822
Re: 5.0 L Mercruiser engine froze. HELP!!

With respect to your JB Weld question...since you report there is no water in the oil:

I personlly know of 4 different Mercruisers and one Volvo that have had external engine cracks patched up with a big glob of JB Weld. 2 of them had cracked exhaust risers which were also patched where they could be reached.

4 have been on the water for at least the past 2 years or longer. One was patched like this 8 years ago.

All run perfect and have balanced and high compression.

So if it were MY boat? And I was running inland lakes with a bit of traffic? And the safety of a dead engine happening in my boating location would not create a huge emergency?

I'd personally do 2 things:

1. Compression test. If pass then

2. I'd risk the $6 JB Weld and give 'er a go...

Waddaya got to lose? $6 and an afternoon of rowing or flagging down another boat for a one-time tow.

Risk it. Believe it or not, I can vouch for 5 separate cracked block and exhaust JB weld success stories.

FWIW, the Volvo is my own boat. A pawn shop find...1999 5.0L GL with an external crack on each side of the block. That one is the least tested...I have only about 20 hours on the motor since the repair. But I see no sign of failure and intend to keep the boat for 10 years or more. I'll report back honestly if the repair ever fails. After which I'll spend another $6 and glob it back up again and run it longer!! $6 is a bit cheaper than an engine...
 

cedarjunki

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Aug 23, 2007
Messages
472
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

ive ran across many 4 banger mainifolds that have been repaired. actually mine has been repaired in 3 areas i think. all done before i got my hands on it. ive owned it for roughly 6 years now, with no sign of leaking from a near impossible weld job!
my other boat also has a repaired manifold. which was also done before i purchased it. none of these welds look even remotely shotty.

and i know of a 140 manifold that was repaired internally with jb weld which lasted roughly 5 years before dishing out the 800.00 for a new one.

so maybe v-8's are different, i dont know, never had one yet. just going by what ive personally seen with the 4 cylinders. didnt mean to start any arguement or give misleading advice.

but the statement damn near impossibe is misleading. because welding cast manifolds is common and possible, (with marine and automotive) atleast in my neck of the woods.
 

craze1cars

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Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

but the statement damn near impossibe is misleading. because welding cast manifolds is common and possible, (with marine and automotive) atleast in my neck of the woods.

I agree completely. And no. V8 makes no difference. Years ago I paid to repair a cracked 1988 350 engine block from a Chevy Silverado that had been severely overheated. Had several broken water jackets welded up internally (FWIW the method the shop used was called "furnace welding" Most shops around here these days do NOT furnace weld anymore, but use a "pinning" method...or there's a brand name called lock-n-stitch that is very similar...these are generally considered easier and better repairs than welding on cast parts...if damage is totally external and accessible, the motor doesn't even need to be disassembled or removed from the car or boat),
Back to my story: Then the shop magnafluxed the block to make sure the welds were solid and nothing was missed. The shop then redecked everything nice and flat, then bored it 30 over. I took it home, reassembled with some high torque performance parts, dropped it back into the truck, and used it to tow my boats and snowmobiles for 10 years. It never missed a beat. Sold it in 1998, 75,000 miles later, running strong, to a buddy who owns a landscaping company. 12 years later, he's STILL using it to tow his trailer full of mowers every day of the summer. I have no idea how many miles are on that rebuilt motor now, but when he sees me, he raves that it runs like it does when he bought it.

Here in central Indiana where racing and performance shops are king...such repairs are STILL routinely done. And done well. if my Volvo's $6 JB Weld patch doesn't hold consistently, I may have it done again to my two external cracks...probably $200 to $300 ish, and done in the boat, fully assembled.

It's just the nature of today's throwaway society. People think these repairs are not possible because there aren't many people who know how to do it anymore, and with forum responses like many here there are even less people out there willing to trust those few who DO know how to do it. It's kinda sad. Usually the same people who say it is not possible to get a carb'd engine to run as well as an EFI engine....to which I also say not true...if you know how to PROPERLY tune and jet and setup a carb...rather than just blindly set it to factory specs like 98% of "carb tuners" do...I could go on, but it all falls on deaf ears mostly. Several will tell me I'm wrong and I won't bother to waste my time justifying what I have seen, done, and experienced, and therefore know to be true...

There are lots of dying arts in the mechanical field. Remember radiator shops that FIXED and recored radiators? Remember rebuilding your own generator at home (or later...alternnator)? Remember TV/radio/toaster repair shops? Some of us do. Most mechanics these days are just a combination of computer look-up artist and parts replacer. But many such things CAN be fixed WITHOUT throwing them away...and fixed properly.
Even cast parts.

I encourage those who do not understand the process to google "engine block repair service" and read all about the methods used and the companies who have made careers out of guaranteeing such repairs.
 

craze1cars

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Messages
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Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

I not only would never take anything there or ever reccomend them, I would speed up when I drove past their "business".

Hacks, that's the only fitting term for them.

Such sweeping generalizations are sad. You openly admit to personally knowing of nobody who does this or recommends it. And therefore the conclusion is that those who do are considered "hacks?"

Counterpoint: I feel those mechanics who don't even consider the possibility are not fully educated, and are certainly not working in the best interest of their customer.

I'd consider such a person or marina who suggests and considers these repairs to be one of a dying breed...an accomplished mechanic. One who has more than just ONE trick up his sleeve to actually fix a problem, rather than throw it away...and he would earn my future business and referrals.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,581
Re: 5.0 L Mercruiser engine froze. HELP!!

I agree with Bomar, No competent marine mechanic will EVER make such a repair. If he does, he is a HACK.

There is no way I would take my boat 15 miles offshore with a repair on an engine like that. I would not tow my boat to my favorite vacation destination and have my boat fail me either.

Reminds me of the saying "Penny wise...pound foolish"
and also applies to the one in my signature.
 

cedarjunki

Chief Petty Officer
Joined
Aug 23, 2007
Messages
472
Re: 5.0 Block Cracked!! Replace or Repair??

Re: 5.0 Block Cracked!! Replace or Repair??

It's just the nature of today's throwaway society. People think these repairs are not possible because there aren't many people who know how to do it anymore, and with forum responses like many here there are even less people out there willing to trust those few who DO know how to do it. It's kinda sad.






Most mechanics these days are just a combination of computer look-up artist and parts replacer. But many such things CAN be fixed WITHOUT throwing them away...and fixed properly.
Even cast parts.

QUOTE]

this sums it up perfectly!
 
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