Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

[ntheyer]

I bought a 1974 runabout and discovered, to my surprise, that the Mercruiser 3.0 per Alpha 1 drive has a cracked block. I checked the intake manifold as well as the riser, and they are both in good shape, so it's the block. I change the oil and within 2 minutes, the new oil is milky again... I have found a 1995 Mercruiser 3.0 engine with distributor, carb etc. but am wondering whether it will work with the 1974 Pre Alpha 1 leg/outdrive? I really don't want to throw good money after bad, but need to know, if I buy this motor, will it 'drop in'? Can I use the riser from the new motor, or do I use my old one? Any help that I can get would really be appreciated. I have asked two people and have gotten two different responses. Thanks again to all. Nicholas

 

[Bondo]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

The motor Will bolt in............<br /><br />But,................... <br /><br />In order to connect everything, You'll need to use Your Original Manifolds, Riser/Elbow, downpipe,.... And the engine Bellhousing(Rear motor mount)...................<br /><br />There might be some minor issues with the cannon plug wiring.....<br /><br />Ayuh,........ It'll Work..........

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

What is cannon plug wiring??? Thanks for the information. I've noticed your replies elsewhere in the lists, you are really helping a lot of people.

 

[Bondo]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Your Welcome..........<br />Welcome to the forums here at iboats as well........ <br /><br />The Cannon Plug is the big black rubber plug that connects the Engine package to the Boat package.......<br />There have been some changes over the years,... You Might Possibly find that the Pins don't line up, or are in the wrong places on the plugs.......<br /><br />That's where Duct-Tape,+ Creative Engineering come into Play..................... <br /><br />If You're Willing,+ Able to undertake this endeavor,... I'm Sure you'll find the "Work Around" for these things..........<br />If Not,.. Come on back,+ Ask Away..........

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Perfect, thanks.

 

[Mahoney]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Did you change the oil filter when you replaced the oil? Depending on how water got in there, maybe it had seeped in through the intake manifold if left in the rain and it leaked past the cylinder walls(not cracked block).<br /><br />It wont take too much water left in the oil filter ot bottom of pan to give that appearance of contaminated oil again after unning for a bit. I had to do about 4 oil changes and filter changes before mine cleared up, and now does not contain anymore water after running at all.

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Yes, I did change the oil filter, it was definitely getting new water, in large amounts from somewhere. In any case, I have the 1995 3.0L in my garage now and yes, the cannon wiring plugs are different. Does an adapter plug exist that will adapt the boat wiring package from a 1974 boat to a 1995 engine? I would really like to keep electronic igniton etc. from the new engine. Another question is that it looks like the carb on the newer engine is slightly larger in bore diameter from the old engine. Since I have to use the old intake manifold, is there any reason I can't use the new carb on the old manifold? I just don't want the boat to run too rich or have fuel problems from the mismatch of carb and intake manifold. I really appreciate anyone's help in advance. Nicholas

 

[Bondo]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Does an adapter plug exist that will adapt the boat wiring package from a 1974 boat to a 1995 engine?

What You Need is a plug from/for a 95 Boat.....<br />Just wire it into the end of the boat whip....<br />No,... I Don't Believe there's a "Plug & Play" Adapter............<br />

is there any reason I can't use the new carb on the old manifold? I just don't want the boat to run too rich or have fuel problems

If it bolts On,+ the linkages,+ All Fit,...<br />You'll have to Atleast "Tune" it..... Maybe a jet change,.... doubt it thou....<br />

it was definitely getting new water, in large amounts from somewhere.

Yank It Out,.... Flip It Over,+ Pull the Base,.... There'll be a Big Crack runing along the inside of the block,... just Oppsite where the Drainplug is on the outside..........

 

[rodbolt]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

the flywheels are different as well. but the cannon plug issue can be delt with by ordering a gauge panal extension harness. the pins will be correct but you will have to cut and splce some wires. but check the number of pins and the location. be aware that inside the harness some of the wire colors wont be what the manual says, especially if it has a tan/bnlue wire. they are usually pink between the engine and the gauge. not to be confused with the standard pink color used for fuel sending.<br /> in 74 your motor was most likly a 153 CID moptor, the 153 and the later (about 90) and up 3.0 motors use a different manifold. the spacer for the old flat riser is NLA and is now converted to the later riser. the shaft couplers on the two may not interchange. I belive by 95 the 3.0 had gone to a one piece rear seal. the bell housings will interchange but some of the post 92 models used metric threads on the starter and some had to use the small hi-torque starter.were a lot of changes in the mid ninties to the 181 CID (3.0) 4 banger. some are inconsequential and some look alike but wont work. they may in fact physically fit but wont work.

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

The '95 comes with starter, alternator, distributor and carb and all engine related wiring. I got the manifold unbolted from the '74 and the manifold studs pulled out of the old block since the long lag bolts from the '95 manifold won't work. The idea to get the plug from the newer boat package wiring is a great idea, and I will do that. In terms of the carb issue, at worst, I will use the carb off the '74 engine as well, it just needs some choke work. So as far as I can tell, this will work, albeit with a lot of slow, tedious work to do, the worst being the wiring I think, we'll see. I will keep all informed on my progress and let you all know if this works. I really hope so. I have enough money sunk into it now that it would hurt if it doesn't.

 

[rodbolt]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

carefully check the port matching between the 74 manifold and the 95 head. some were radically diffrent. there is about 7 diffrent intake/ex gaskets for the 153 and the 181.

 

[tommays]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

for about 300 dollars you can buy a brand new boat side of the wireing harness that will plug right into the motor <br /><br />its color coded you will be able to use a current diagram to hook it up and you will have a boat that will be done right <br /><br />your current wireing is 30 years old and sure to cause endless problems at this age<br /><br /><br />tommays

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Just an update... I just finished bolting on the '74 manifold... No problem, just stole the threaded studs from the old block with locking pliers and used the old nuts. I also removed the '74 backing plate and installed on the '95 engine. Fits perfectly other than the engine wiring plug is on a bracket on the '95 and on the '74 backing plate, the mount for the engine wiring is included in the plate... I will most likely cut the backing plate where the mount for the plug is, or figure something else out. The engine wiring is too short by an inch or so to reach the mount in the '74 backing plate. The female receiver where the shaft from the leg inserts into is slightly different from one engine to another, but they are mounted extremely tightly to the flywheel and I figure there is no consequential change between the two. I hope the '95 receiver works with the '74 shaft from the pre-Alpha leg. Tomorrow I will take a really close look at the difference in the carbs and see if I can't take the '95 carb and mount it on the '74 manifold. So far so good! I also ordered the 'Instrument Harness' which means I just have to rewire the boat side and plug straight into the engine. I do appreciate the suggestion and it really does make the most sense. I bought it from Stem to Stern for around 160$. My local dealer quoted $231 for the same part. Thanks again!

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

Here is the continuation. I just received my new boat wiring today and installed it. Everything on the dash seems to work, but when I go to start the motor, the slave solenoid clicks, but no attempt to crank. I also hear nothing from the starter solenoid. I replaced the starter solenoid with a solenoid that's known to be good, but no difference. While I was poking around a bit looking for an answer, I had the ignition left on and the wires on the boat wiring started smoking right by the valve cover under the electrical tape. So I've got a short somewhere? The issue is that the boat has no safety switches like neutral safety etc. so I don't know if this is what is keeping the starter from attempting to turn over. It also still does not answer the smoking wiring issue. The smoking wiring came from ignition on only. Whether I attempt to start or not, the wiring is heating up. I'm a little baffled as to what's going on.<br /><br />Thanks.

 

[tommays]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

the smokeing wire sounds fun<br /><br />if you cant tell from the tape which one it is it may be easyer to untape the harness than start unhooking things untll the smoke stops <br /><br />you may not have hooked up anything worng the harness on the motor could have taken a wack during all the moveing around<br /><br /><br />the correct craft decieded to start cranking it self last summer from a short under the tape on the motor harness lot of tape to find that<br /><br />can you get the starter to work by jumping it at the starter<br /><br />tommays

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

How should I jump it at the starter? The two poles don't really look like I can get a screwdriver across them? Is there a secret way to jump the starter directly?

 

[Bondo]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

You Jump it from the Battery Wire Lug, to the Small Exciter Lug.....<br />I Believe it's the Small 1 next to the engine Block.....

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

This is getting more convoluted as I go on. I tried jumping the starter... no luck, at all. This is the soleniod that I know works. I have been studying wiring diagrams closely. I notice on the engine there is a purple/yellow wire from the ignition coil to the side of the solenoid that is next to the block. I don't find this wire on the diagrams... next is that the Mercruiser boat wiring diagram talks about connecting the red/purple ingition wire to an orange wire and then running the orange wire through a fuse and then making it red/purple again to the switch. Right now, I am straight to the switch. The question is, where is this orange wire? There is no orange wire in the factory supplied wiring. Everything seems to be behaving properly. When I turn on the igniton, the lights and instruments respond correctly. When I rotate the switch to start, I get a click that is definitely at the starter slave solenoid. I try jumping the starter solenoid with a screwdriver, get a bit of sparks, but no click or anything from the solenoid. I friggin' hate electrical!!!! What is the most direct way for me to troubleshoot this stuff? The wiring diagram does not have wires like my purple and yellow one from the coil to the starter, and I don't know what it's function would be. The motor looked like it was in good shape when I dropped it in. I think it should have been fine the way it was wired. I am pretty discouraged right now. To have come so far, yet have these problems now.... Help, please?

 

[ntheyer]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

One other question... where should I ground both the battery and the black ground wire on the engine harness. I have the battery grounded at the back of the starter where the back bolt attaches the starter to the block and the engine harness is grounded to a bolt and nut on the engine.

 

[tommays]

Re: Swap from 1974 Mercruiser 3.0 to 1995 HELP!!! PLEASE!!!

on my boat which has a 1995 3.0 the battery ground is on a stud on the port rear side of the block below the manifold<br /><br /><br />if the starter cant be jumped directly it may just be bad or still have a bad connection the ground is just as inportant<br /><br />the short answere on the smokeing wire is that one of your positve wires which gets LIVE when you turn the key is somehow most likely reaching ground and not were it should go <br /><br />in a perfect world every wire would have a fuse like a car and you would have a better idea were to start<br /><br /><br />tommays<br /><br /><br />if you look at the wireing diagram that narrows it down to a few wires