Mercruiser 5.0 replacement

[cjstimpson]

Hi, I'm looking at replacing a 2008 Mercruiser 5.0 TKS using a long block and transferring components. How can I know if the long block I order is a fit? There's also a 5.7L which might be a fit as well, but it isn't clear to me whether any extra tuning is needed for the larger displacement, such as on the carburetor.

Any tips are appreciated!

 

[Scott06]

Hi, I'm looking at replacing a 2008 Mercruiser 5.0 TKS using a long block and transferring components. How can I know if the long block I order is a fit? There's also a 5.7L which might be a fit as well, but it isn't clear to me whether any extra tuning is needed for the larger displacement, such as on the carburetor.

Any tips are appreciated!

If it is a vortec long block 96 and newer it is identical to what you have. Good time to drop in a 5.7 which is externally identical. May have to reject the carb or step up to a 4 bbl edelBrock 1409.

I installed a partial engine from these guys in 2016 has worked excellent for over ten years now. Below is a 5.7 package with carb and intake will drop in and might have to go up in prop pitch 2” or so

5.7L Vortec Marine SILVER Package - 315 hp - (1967-2015)

5.7L Vortec marine engine-SILVER Package (1967-2013 replacement)

michiganmotorz.com

 

[nola mike]

Might want to check out this thread:

1997 5.7L thunderbolt ignition. Slow crank

Hi guys Okay I've done a lot of research on the internet and iboat, and I'm stumped still. Hoping someone could steer me in the right direction with my individual problem. Took the boat out of storage from winter, everything fired up just fine, Strong crank and fired with minimal effort. went...

forums.iboats.com

 

[Bondo]

Hi, I'm looking at replacing a 2008 Mercruiser 5.0 TKS using a long block and transferring components. How can I know if the long block I order is a fit? There's also a 5.7L which might be a fit as well, but it isn't clear to me whether any extra tuning is needed for the larger displacement, such as on the carburetor.

Any tips are appreciated!

Ayuh,...... Welcome Aboard,....... How did you come to the conclusion that you need a new/ rebuilt long block,..??..??

 

[cjstimpson]

Ayuh,...... Welcome Aboard,....... How did you come to the conclusion that you need a new/ rebuilt long block,..??..??

A mechanic diagnosed this for me and said a couple cylinders have too little compression. It overheated and I'm guessing the new impeller had problems.

 

[cjstimpson]

If it is a vortec long block 96 and newer it is identical to what you have. Good time to drop in a 5.7 which is externally identical. May have to reject the carb or step up to a 4 bbl edelBrock 1409.

I installed a partial engine from these guys in 2016 has worked excellent for over ten years now. Below is a 5.7 package with carb and intake will drop in and might have to go up in prop pitch 2” or so

5.7L Vortec Marine SILVER Package - 315 hp - (1967-2015)

5.7L Vortec marine engine-SILVER Package (1967-2013 replacement)

michiganmotorz.com

Thanks for the link. And for the tips about the carb and prop. I was looking at perhaps getting this one.

Remanufactured 5.7L Vortec (1997-up) Marine Base Engine

Family owned and operated with over 40 years in the marine engine and parts industry. Our Florida location provides you with affordable marine engines and parts

marineengines4less.com

 

[alldodge]

With the overheat and a blown head gasket, most likely all you need is a new head gasket

 

[Scott06]

With the overheat and a blown head gasket, most likely all you need is a new head gasket

I missed that 100% if it’s just a head gasket due to overheat worst case you need the head resurfaced and valve job

 

[cjstimpson]

To not leave this story open ended, I learned both head gaskets are blown and an exhaust valve was stuck open. Next, I'd like to know if the head/block is warped. Does anyone have tips on knowing how to find that out? I've done plenty of engine work before, but not on heads.

 

[Chris1956]

You could put the blue dye on the head mating surface and a piece of sandpaper on a piece of plate glass and rub the head around to see where the dye comes off. Obviously, the old head gasket needs to be scraped off first.

It is important to find out why the valve is stuck open. Is it bent?

The block would need to be done with a steel straight edge, and your eyeball.

 

[cjstimpson]

You could put the blue dye on the head mating surface and a piece of sandpaper on a piece of plate glass and rub the head around to see where the dye comes off. Obviously, the old head gasket needs to be scraped off first.

It is important to find out why the valve is stuck open. Is it bent?

The block would need to be done with a steel straight edge, and your eyeball.

Yes, the valve is bent. There's also signs it has been hit by the piston.

 

[Chris1956]

So why did the valve stick open? Valve timing jump? Overheat?

That needs to be figured out and rectified.