93 Mercruiser 3.0 swap to a 1984 Mercruiser 140, what do I need to know...

[saltybutwet]

1993 Chaparral 180 SL Mercruiser 3.0 with a cracked internal block, I want to swap a 1984 Mercruiser 140 engine. I purchased this boat only for the engine. It is pretty much all original, even the manifold, and risers are original. I checked the compression 148-150 on all 4

The owner, who has owned this boat for 20 years, said it started to run hot once recently, so he shut her down for a bit to let her cool off, then started her back up, then she was fine.

I decided to take a chance on the engine as a replacement for my 93 Mercruiser 3.0, of course only after I figure out what was the causes of that heating up issue, and if I figure out that, I would like to know what other parts can I transplant over to the 140, from my 93 Mercruiser 3.0. I also will want to sell some parts from this boat that I will not be using, and what should I keep

some background on what I checked out, and how the engine ran before I purchased it.

I did several visual inspections of the engine after the compression test, and didn't see any red flags, except for some loose wiring connectors, and i didn't see any oil leaks either

We then put the water to her and turned the ignition key, and she fired right up! sounded good, except for a slight miss, not that noticeable, and it maybe from the old ignition parts, or old gas, which smelled old. The boat has been setting for some time.

We let her run for about 40 minutes, I was watching the temp gauge, and she barely got above 140 the whole time. I checked the engine oil before we started her, and after we stopped running the engine, the oil looked the same, and the level didn't rise, and I didn't see any signs of water in the oil, nor did I see any steam coming out the exhaust, so i feel safe that the engine doesn't have water intrusion at this point.

I did hear a noise coming from the rear of the engine, sounded like maybe a bad gimbal bearing or bad coupler, the stern had a vibration all across it, and when pushed on the engine, the vibration got worse. the noise wasn't that noticeable at higher rpms, but the vibration was still there.

The out drive worked, but looks a little beat up, and the sea impeller seemed to be working. I did remove the drain screw from the foot, and black thick oil came out, no water
here are a few pics

 

[achris]

You are going to hit some compatibility issues. The 1984 block uses a 2 piece rear main seal, and the 1993 uses a single piece. The blocks are different, the crankshafts are different, the flywheels and couplers are different...

 

[saltybutwet]

You are going to hit some compatibility issues. The 1984 block uses a 2 piece rear main seal, and the 1993 uses a single piece. The blocks are different, the crankshafts are different, the flywheels and couplers are different...

Thanks for your input. I appreciate it
I was told that the blocks were the same, but i knew about the 1 piece vs 2 piece rear main seal, and crank
I knew I was going to have some compatibility issues, but I didn't know to what extent, so that is why I started this thread, hoping that the input, and advice from ones who really know, will point me, and guide me in the direction I need to go, to do the swap...

so, I do have my 3.0 crank, 1 piece rearmain seal, and coupler....basically i have a total engine with low hours, with ps also
I also have the140 engine drive components still connected together, maybe I need to do a total swap from the overdrive, to the engine
​i have no proble

 

[achris]

You can use the existing drive and transom housings, but you'll need to change the engine over as a complete 'drop-in'... I have heard there might be some flywheel and coupler adapters around somewhere, but you'll just be creating a FrankenMerc, and have to deal with a lot of problems to get it all to work together properly.

 

[saltybutwet]

update...

I have the 86 140 removed, and awaiting the transplant, but before I go any further... I would like to know, " If I just do a direct drop in of the 86 as is, would my alpha one gen 2 stern drive shaft go into the 86 coupler and work"?..Are the couplers different in length, ID, OD,ect.

.I have been told it would be a direct bolt in, change the flywheel maybe, coupler, maybe...idk

I'm just trying to figure this out. I know I'm not a Mercruiser professional, and may have to abandon this idea of a swap, I don;t want to create a FrankenMerc

thanks for your time and advice

 

[Bondo]

update...

I have the 86 140 removed, and awaiting the transplant, but before I go any further... I would like to know, " If I just do a direct drop in of the 86 as is, would my alpha one gen 2 stern drive shaft go into the 86 coupler and work"?..Are the couplers different in length, ID, OD,ect.

.I have been told it would be a direct bolt in, change the flywheel maybe, coupler, maybe...idk

I'm just trying to figure this out. I know I'm not a Mercruiser professional, and may have to abandon this idea of a swap, I don;t want to create a FrankenMerc

thanks for your time and advice

Ayuh,..... When ya get 'em both, sittin' side by side on the floor,...

Start Measurin' to See,....

I suspect, it'll drop in, as a complete bobtail unit,...

 

[saltybutwet]

Ayuh,..... When ya get 'em both, sittin' side by side on the floor,...

Start Measurin' to See,....

I suspect, it'll drop in, as a complete bobtail unit,...

thanks Bondo

I thought about doing that, but my 93 is in pieces, so I will have to figure out another way to measure, but I think I can figure out something

 

[Bondo]

thanks Bondo

I thought about doing that, but my 93 is in pieces, so I will have to figure out another way to measure, but I think I can figure out something

Ayuh,.... Put it back together enough to measure it,... Mock it up,.....

 

[fishrdan]

Here are some things to check, or incompatibilities:

- The spacing of the 2- engine mount bolt holes of the rear motor mount (flywheel cover),,, between the 2 engines. Are they the same distance apart or is one wider?

- The crank bolt pattern is different between the 2 engines, so you're not going to be able to swap flywheels.

- Old coupler bolts to the crank, newer coupler bolts to flywheel, so you can't swap couplers.

- Check drive input shaft lengths (part that goes into coupler), is one longer?

- The shift cable anchor points, if they don't match up you'll probably need new (longer-shorter) shift cables.

- Carb cable anchor point? Can this be swapped?

The old engine has an automotive fuel pump, needs to be changed to a "marine" fuel pump.

 

[saltybutwet]

Here are some things to check, or incompatibilities:

- The spacing of the 2- engine mount bolt holes of the rear motor mount (flywheel cover),,, between the 2 engines. Are they the same distance apart or is one wider?
The spacing is the same, and i believe the flywheel housing for the 93 3.0 & 86 140 have the same replacement part numbers, would have to double check

- The crank bolt pattern is different between the 2 engines, so you're not going to be able to swap flywheels.
I read, and had comments on that one. I will keep the engine bobtail, as Bondo called it

- Old coupler bolts to the crank, newer coupler bolts to flywheel, so you can't swap couplers.
I think the 86 flywheel has the threaded holes in it, same as the 93 flywheel, but I will double check

- Check drive input shaft lengths (part that goes into coupler), is one longer?
I will check that tomorrow, and update

- The shift cable anchor points, if they don't match up you'll probably need new (longer-shorter) shift cables.
I have the 93 3.0 rocker cover, It has the cable anchor points on top, so I think I can use that

- Carb cable anchor point? Can this be swapped?
I may have to figure out something

The old engine has an automotive fuel pump, needs to be changed to a "marine" fuel pump.

I thought that the fuel pump looked odd. I do have the one that was on the 93 3.0, and will use it

I might add that I plan on swapping all the 93 electronic ignition components, to the 86 140. I know that I will have to time the engine per the service manual once I do this
thanks fishrdan

 

[Bondo]

- Check drive input shaft lengths (part that goes into coupler), is one longer?
I will check that tomorrow, and update

Ayuh,... The shorter drive shaft thing ended in, I believe '79, or '80,....

 

[saltybutwet]

Ayuh,... The shorter drive shaft thing ended in, I believe '79, or '80,....

I couldn't wait until tomorrow to measuer...maybe this is one I can cross off the list of being a potential issue,
I can't draw a straight line sometimes, but it is measured from tip end to yoke

 

[saltybutwet]

I think I will have to change the intake/exhaust manifold, and riser because the riser will not work with the newer style exhaust elbow
What are your opinions on this?
here are more pics

 

[fishrdan]

I thought that the fuel pump looked odd. I do have the one that was on the 93 3.0, and will use it

I might add that I plan on swapping all the 93 electronic ignition components, to the 86 140. I know that I will have to time the engine per the service manual once I do this
thanks fishrdan

You may run into problems doing that with the fuel pump. I put a newer style 3.0L fuel pump on my 73' 140HP and ran into all sorts of issues, starving, cold start issues. I swapped it over to the correct 140HP pump and those problems are gone. The 140HP pumps mount "above" the block's fuel pump hole and the 3.0L pumps mount below the block's hole. The fuel pump bolt holes may have a different spacing height on the block too, not sure, just know it didn't work for me.

The electronic ignition will work, but if it's an EST ignition you'll have to change the shift interrupt switch to +12V instead of ground. (EST uses 12V for shift interrupt while points and DDIS use ground for shift interrupt.)

For the manifold swap, you'll need to look at the manifolds to see if it's possible. There were different port configurations used over the years and some are close enough to work, while others are way off....

 

[saltybutwet]

You may run into problems doing that with the fuel pump. I put a newer style 3.0L fuel pump on my 73' 140HP and ran into all sorts of issues, starving, cold start issues. I swapped it over to the correct 140HP pump and those problems are gone. The 140HP pumps mount "above" the block's fuel pump hole and the 3.0L pumps mount below the block's hole. The fuel pump bolt holes may have a different spacing height on the block too, not sure, just know it didn't work for me.
thanks for that info, and I appreciate it vary much, I will get the correct fuel pump, sounds like the way to go


The electronic ignition will work, but if it's an EST ignition you'll have to change the shift interrupt switch to +12V instead of ground. (EST uses 12V for shift interrupt while points and DDIS use ground for shift interrupt.)
I have the Delco EST ignition, and I will have to do what you said, any info on how to change that? I know I need to read up on how that switch is wired.

For the manifold swap, you'll need to look at the manifolds to see if it's possible. There were different port configurations used over the years and some are close enough to work, while others are way off....

I knew that mercruiser used different ports over the years, and it would just be my luck that the newer style manifold from the 93 has larger ports, but I will have to do more research on it..

thanks again, for providing great helpful info

 

[saltybutwet]

Update on my progress with the 140

I removed the old alternator, the old wiring harness, the old fuel pump tube, the rocker cover, cleaned up the engine, and painted it.

I pulled the old spark plugs out, and they fuel fouled, especially #1 & # 4. I probably will need a carb rebuild, I think the needle is bad, or the seat, or both. I do have the 93 carb, which I believe they are both Mercarbs, however the 93 carb was running rich before I disassembled the engine, so I think it too will need a rebuild

I am now in the process of setting up for the Delco EST system. I have to get the #1 cylinder on TDC compression stroke, then pull the old dizzy out ( I got to thinking on how I was going to turn the crankshaft so I could get all the timing marks lined up before I pull the dizzy, but I figured it out, see pics below) , and replace it with the Delco EST. I will also be using the entire wiring harness from the 93 3.0 on the 86 140

here are some pics from today

 

[saltybutwet]

I have a few question

#1. Does the 86 Mercruiser 140 head have the same size port openings, as the 93 Mercruiser 3.0LX?
I have done some research and are confused, looks like the 3.0XL has larger ports, but the 3.0 has the same size ports as the 86 140.


will the 93 intake/exhaust manifold work on the 86 140?
I will have to change out the riser on the 86 so it will hook up to the 93 newer style exhaust elbow that is still in place on the Chap

thanks for the help

I feel like this is going to be an interesting swap

 

[saltybutwet]

update...

Today I worked on my rider mower, had to order some new idler pulleys, oh well back to my update.

I was able to remove the the 2 piece riser and manifold. I wanted to see what shape they were in. I also wanted to see if the head ports were the same size as the ones on the 93 3.0LX, and they look the same.

I took the 86 140 manifold gasket, and compared it to the 93 3.0LX manifold gasket, and they are a perfect match. I also saw lots of water sitting in the bottom of the manifold, not surprised knowing the deterioration of the riser, and the manifold water chamber could have rusted through also.

Now I also saw 1 small casting plug in the head leaking, so I decided to call it a day, and go spend the afternoon with my wife

here are some pics

 

[saltybutwet]

more pics

 

[saltybutwet]

I would like to know if there is a way to check the condition of the flywheel coupler? Just one more item I need to ensure is in good condition before i put the engine back in the boat. Thanks!