5.7 chevy replacement engine for Mastercraft

[Tamalewagon]

So it turns out the kids newer to him boat may need to get a replacement engine. Any thoughts on where to get a reliable yet inexpensive remanufactured 5.7 Chevy? Would it be wiser/cheaper to have his engine rebuilt? I don't know all of the particulars but apparently two cylinders are going south (compression 55 and 85 in #5 and 6.

Need some RDP input here...

 

[HALLETT BOY]

Jasper Reman has boat engines, and they come with a nationwide warranty

 

[4Waters]

Jasper Reman has boat engines, and they come with a nationwide warranty

I think I remember @Shlbyntro saying he has been having issues with them lately.

 

[mash on it]

@Tamalewagon
Approximately what year boat? Or any other relevant info?
There's a ton of small blocks out there.
LO5 to the ZZ6 and beyond.

Dan'l

 

[HST4ME]

have the heads fixed and keep running it.

 

[n2otoofast4u]

So it turns out the kids newer to him boat may need to get a replacement engine. Any thoughts on where to get a reliable yet inexpensive remanufactured 5.7 Chevy? Would it be wiser/cheaper to have his engine rebuilt? I don't know all of the particulars but apparently two cylinders are going south (compression 55 and 85 in #5 and 6.

Need some RDP input here...

Vortec variant, or what model is it? Nobody will like this, but I have used probably a half dozen crate and take out Vortec motors and put them in IO and direct drive boats over the years. I have lost track of a couple, but I can call 4 guys right now who still have them and all are running just fine 100s of hours later.

 

[Mandelon]

Marine Power $15,000 for a new Sport Pack

Marine Engine Depot

The Official Marine Engine Depot Online Store. Offering Brand New Factory Direct Marine Power and GM Engines, Engine Parts, Accessories, and General Marine Equipment.

marineenginedepot.com

A rebuild ought to be much less

OSO classifieds has take out motors all the time too.

 

[lbhsbz]

What the hell happened to those $2000 GM longblocks that used to be at Jegs/Summit/Everywhere?

 

[poncho]

Marine Crate Engine

atkhp.com

 

[Tamalewagon]

@Tamalewagon
Approximately what year boat? Or any other relevant info?
There's a ton of small blocks out there.
LO5 to the ZZ6 and beyond.

Dan'l

1997 Mastercraft Prostar 205 5.7 chevy

 

[Tamalewagon]

Is there a machine shop that would rebuild the cylinders?

 

[Tamalewagon]

Vortec variant, or what model is it? Nobody will like this, but I have used probably a half dozen crate and take out Vortec motors and put them in IO and direct drive boats over the years. I have lost track of a couple, but I can call 4 guys right now who still have them and all are running just fine 100s of hours later.

Its a 5.7. The boat is a 1997 Mastercraft Prostar 205

 

[n2otoofast4u]

1997 Mastercraft Prostar 205 5.7 chevy

picture of the motor will go a LONG ways. This is somewhat of the crossover era/year. More than likely it is a Vortec, but there were still some that I have seen that are TBI on a traditional roller 350 platform. Standard deal, as 2 question, you'll get 10 different answers, but a pic will tell the tale.

 

[mesquito_creek]

I recently took my 5.7 to a machine shop and re assembled it myself for about the same I could have bought a crate short block…

 

[77charger]

What the hell happened to those $2000 GM longblocks that used to be at Jegs/Summit/Everywhere?

They got out into 100k square Body’s. .

I use to have an extra 88 engine out of a worktruck never did do anything with it gave it to a metal guy before I moved. My plan was to build a 383 out of it for my boat over time then just swap it. Now I will have to pull mine out build it have boat down while doing so.

 

[Mandelon]

Arce Engines

arceengines.com

These guys are legit and local. Not sure if they do boats....

 

[Tamalewagon]

picture of the motor will go a LONG ways. This is somewhat of the crossover era/year. More than likely it is a Vortec, but there were still some that I have seen that are TBI on a traditional roller 350 platform. Standard deal, as 2 question, you'll get 10 different answers, but a pic will tell the tale.

My son has the boat at a repair shop in Phx. The engine is either a Vortec 5.7 or Corvette LT1 350.

 

[stokerwhore]

632. Do it!

 

[rrrr]

Its a 5.7. The boat is a 1997 Mastercraft Prostar 205

That's a good boat. Had a lot of fun behind mine in the 90s.

 

[Tamalewagon]

My son has the boat at a repair shop in Phx. The engine is either a Vortec 5.7 or Corvette LT1 350.

Confirmed it is the Corvette LT1 350

 

[Tamalewagon]

What about doing the cylinder work and not rebuilding?

 

[rrrr]

What about doing the cylinder work and not rebuilding?

What exactly are you referring to with "rebuilding" the cylinders? What's going on?

 

[Tamalewagon]

What exactly are you referring to with "rebuilding" the cylinders? What's going on?

Compression is very low in the 5 and 6 cylinders. The spark plugs keep blowing out and Mechanic said exhaust manifolds are on their way out etc etc. I haven't spoken with him personally but it seems as though he is pushing hard for a rebuild. Hopefully I get the chance to get into the nitty gritty with him about the boat today.

 

[lbhsbz]

Compression is very low in the 5 and 6 cylinders. The spark plugs keep blowing out and Mechanic said exhaust manifolds are on their way out etc etc. I haven't spoken with him personally but it seems as though he is pushing hard for a rebuild. Hopefully I get the chance to get into the nitty gritty with him about the boat today.

OK, if the plugs are blowing out...one can assume there are not sufficient threads for a compression tester to seal....which makes a compression test void (unless he's got one of those old school deals with the rubber boot on the tip).

I would time-sert the spark plug holes on those 2 cylinders and try again....unless there is more to the story that invalidates this.

 

[4Waters]

Compression is very low in the 5 and 6 cylinders. The spark plugs keep blowing out and Mechanic said exhaust manifolds are on their way out etc etc. I haven't spoken with him personally but it seems as though he is pushing hard for a rebuild. Hopefully I get the chance to get into the nitty gritty with him about the boat today.

Spark plugs blow out like a 2 valve 5.4

 

[mash on it]

@Tamalewagon
How many hours on it?
Even if you went with new heads, they're $850 a side at summit and jegs. If that's the whole problem.

Dan'l

 

[Orange Juice]

Compression is very low in the 5 and 6 cylinders. The spark plugs keep blowing out and Mechanic said exhaust manifolds are on their way out etc etc. I haven't spoken with him personally but it seems as though he is pushing hard for a rebuild. Hopefully I get the chance to get into the nitty gritty with him about the boat today.

I’m still running a 1985 Mercruiser 350/260 in my eliminator.

Is there water in the oil?

 

[Tamalewagon]

I’m still running a 1985 Mercruiser 350/260 in my eliminator.

Is there water in the oil?

OK, if the plugs are blowing out...one can assume there are not sufficient threads for a compression tester to seal....which makes a compression test void (unless he's got one of those old school deals with the rubber boot on the tip).

I would time-sert the spark plug holes on those 2 cylinders and try again....unless there is more to the story that invalidates this.

Spark plugs blow out like a 2 valve 5.4

Here are the comments from the mechanic. The engine is a 97 Indmar 5.7 not the corvette.

A. Diagnosed the engine running rough and dying.
B. Ran boat and could hear/tell the engine was running rough and sounds like it's dropping a cylinder? Removed and inspected the spark plugs. Found that on cylinders 5&6 fouled and the electrode part of the plugs were blown off.
C. Completed a compression test to find that cylinders 5&6 have very low compression(55 psi) the engine is dying and will need to be replaced.
D. Additionally.... When run testing the boat/engine also diagnosed the raw water pump to leaking(failing) and the exhaust Manifolds and Risers are leaking(which will cause an engine to fail)

 

[Orange Juice]

Here are the comments from the mechanic. The engine is a 97 Indmar 5.7 not the corvette.

A. Diagnosed the engine running rough and dying.
B. Ran boat and could hear/tell the engine was running rough and sounds like it's dropping a cylinder? Removed and inspected the spark plugs. Found that on cylinders 5&6 fouled and the electrode part of the plugs were blown off.
C. Completed a compression test to find that cylinders 5&6 have very low compression(55 psi) the engine is dying and will need to be replaced.
D. Additionally.... When run testing the boat/engine also diagnosed the raw water pump to leaking(failing) and the exhaust Manifolds and Risers are leaking(which will cause an engine to fail)

It’s not a new motor. Fouling plugs is why it ran rough. No water in oil, I’d change the plugs and run it with a bottle of gas treatment, and take it easy.

Valve guides are probably leaking (Aka sbc)

My exhaust risers leak as well. Been that way for the last 15 years

They may leak 1/2 a pint in 4 hour of running. Nothing the bilge put can’t handle.

 

[rrrr]

Compression is very low in the 5 and 6 cylinders. The spark plugs keep blowing out and Mechanic said exhaust manifolds are on their way out etc etc. I haven't spoken with him personally but it seems as though he is pushing hard for a rebuild. Hopefully I get the chance to get into the nitty gritty with him about the boat today.

Are you sure it's not cylinders 5 and 7? There is a known issue with SBC blown head gaskets between adjacent cylinders. It's typically caused and exacerbated by repeated high operating temperature cycles.

I'm suspicious of a mechanic "pushing hard for a rebuild."

 

[lbhsbz]

It’s not a new motor. Fouling plugs is why it ran rough. No water in oil, I’d change the plugs and run it with a bottle of gas treatment, and take it easy.

Valve guides are probably leaking (Aka sbc)

My exhaust risers leak as well. Been that way for the last 15 years

They may get leak 1/2 a pint in 4 hour of running. Nothing the bilge put can’t handle.

That won't solve the 55psi of compression problem.

 

[lbhsbz]

Here are the comments from the mechanic. The engine is a 97 Indmar 5.7 not the corvette.

A. Diagnosed the engine running rough and dying.
B. Ran boat and could hear/tell the engine was running rough and sounds like it's dropping a cylinder? Removed and inspected the spark plugs. Found that on cylinders 5&6 fouled and the electrode part of the plugs were blown off.
C. Completed a compression test to find that cylinders 5&6 have very low compression(55 psi) the engine is dying and will need to be replaced.
D. Additionally.... When run testing the boat/engine also diagnosed the raw water pump to leaking(failing) and the exhaust Manifolds and Risers are leaking(which will cause an engine to fail)

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

 

[wzuber]

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

^^^^This is the only correct way to properly diagnose the real issue...
IMO if this guy was ligit this is what would have at least been offered as a diagnosis solution.
" the electrode part of the plugs were blown off"....... this phrasing....unless it's semantics, is concerning to me. Typically they burn.....(which is it's own issue) not "get blown off".

 

[Tamalewagon]

^^^^This is the only correct way to properly diagnose the real issue...
IMO if this guy was ligit this is what would have at least been offered as a diagnosis solution.
" the electrode part of the plugs were blown off"....... this phrasing....unless it's semantics, is concerning to me. Typically they burn.....(which is it's own issue) not "get blown off".

The plugs were actually getting blown out of their seating when the boat was running twice. Thought it was a bad plug but it happened twice in the same trip.

 

[Tamalewagon]

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

I will suggest this to my son.

 

[Tamalewagon]

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

Can the cylinders be tooled, boared or replaced?

 

[lbhsbz]

Can the cylinders be tooled, boared or replaced?

That's rebuilding the engine.

Entire engine gets disassembled, cleaned, then the block is fixtured on a boring machine and the cylinders are bored to the next standard oversize (usually +.030" to +0.060), then finish honed to achieve the final dimension and appropriate cylinder wall finish for the rings. New oversized pistons and rings are installed, along with all new bearings, gaskets, typically a new cam, lifters, and rebuilt heads. Rebuilding the heads consists of replacing the valve guides (in the case of an iron SB head....drilling them oversized and pressing in bronze sleeves, then reaming or honing to size), recutting or grinding the valve seats, ideally new SS valves and in a boat, new valve springs would be a good idea.

It's rare that I've found an engine rebuilder that actually understands WHY they're doing the things they do during the rebuilding process and consequently don't really do the best job....and they've all "been doin this for 30 years" so aren't really open to suggestions or education. If staying stock, I try to simply purchase OEM new engines....far less headaches that way typically for not much more money in many cases.

 

[Dkahnjob]

Blue Print engines are very good and quite reasonable. If you purchase from Summit Racing the shipping is free.

 

[n2otoofast4u]

chevy Vortec 5.7 motor1996-2002-high torque - auto parts - by owner - vehicle automotive sale - craigslist

This engine is hand fitted and assembled, All new high quality parts : Clevite bearings, Hasting rings, Johnson lifters, new oil pump, Felpro gaskets, reground crank, new timing gears and chain,...

inlandempire.craigslist.org

 

[rrrr]

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

Based on the comments from the OP, it's apparent the mechanic hasn't performed the most basic diagnostic procedures.

He's recommending a costly solution to what may be an issue that could be resolved with much less expense.

 

[Willie B]

chevy Vortec 5.7 motor1996-2002-high torque - auto parts - by owner - vehicle automotive sale - craigslist

This engine is hand fitted and assembled, All new high quality parts : Clevite bearings, Hasting rings, Johnson lifters, new oil pump, Felpro gaskets, reground crank, new timing gears and chain,...

inlandempire.craigslist.org

… late 80s… I was getting reman… 350 long blocks-for under $1000… there was always ads for rebuilt short blocks and long blocks in the recycler… but not the internal components listed above… never had a problem with one…

 

[Tamalewagon]

If we needed a replacement engine, I would just want a good used cheap engine to drop in to use for a few more years.

 

[Mandelon]

GM built marine crate engines:

https://poweredsolutions.gm.com/products/?filter=engine

 

[Rotten deal]

We just pulled a good motor out of a boat today that stringers rotted. I’ll ask owner what he wants and we could do a compression test for you.

 

[Rotten deal]

 

[Orange Juice]

View attachment 1349741 View attachment 1349742 View attachment 1349743 View attachment 1349744

There you go drop in friendly.

 

[shunter2005]

OK.

He's at the mercy of the mechanic since it doesn't sound like he's capable of doing this in the driveway...

We have low compression. Low compression due to wear can't very well destroy the plugs as is being described, they'd just be dirty and fouled depending on WHY the compression is low.

If this were me, I'd perform a leakdown test on those 2 bad holes....open up the oil cap and pull the airbox to access the throttle body. With the valves closed, pressurize the cylinder and hold a piece of tissue paper over the oil fill hole...see if air is blowing out and moving your tissue paper. If not, open the throttle and hold it in front of the throttle body. If not, hold it over the exhaust dump. Air is leaking somewhere if he has 55psi of compression. If it's coming out of the oil fill, then the rings or cylinder walls are the issue. If it's coming out of the throttle body, we have a leaky intake valve. If it's coming out of the exhaust, we have a leaky exhaust valve.

If you can isolate the problem to the valves, then I'd pull the heads...if the cylinders look good, do a valve job and put it back together. If the cylinders have damage, it needs an engine (or a rebuild).

This is almost exactly what I was going to suggest. lbhsbz just said it better than I could have.

 

[Tamalewagon]

View attachment 1349741 View attachment 1349742 View attachment 1349743 View attachment 1349744

YES PLEASE!

 

[Tamalewagon]

We just pulled a good motor out of a boat today that stringers rotted. I’ll ask owner what he wants and we could do a compression test for you.

This is exactly what we need. Please keep me posted. My cell is 619-517-7192 Thank you. Scott

 

[Bigbore500r]

What the hell happened to those $2000 GM longblocks that used to be at Jegs/Summit/Everywhere?

Well you see.......somebody in China did something involving a bat......and then Joe Biden was elected 46th president of the United States