lower unit or power head swap can it be done

[kramerpage]

I looked at a boat today that had two different length motors on it. The original blew up from no oil. They replaced it with a shorter version. He said he would give me the original motor. So do you switch power heads and install old blown motor or switch lower units. I did not purchase boat because of this but I love it. Original counter rotation is on boat serial number below. I don't have serial for original standard rotation since it was on floor. Boat shows 117 hrs on motors. So I don't know to buy it or not. I would have marine mechanic do work. Any guess on money?

 

[Scott Danforth]

Unbolt the power heads and swap. Need 2 gaskets

 

[kramerpage]

Thank you Scott. Do you know how I check serial numbers so I know they are indeed compatible?

 

[Scott Danforth]

I would have to look up the info on a few web sites. However I'm currently on vacation up in Hayward Wi. Since I'm on my phone, I can't even tag a few of the forum members tthat deal with OB's every day

 

[Scott Danforth]

The serial numbers are close enough that I believe they are compatible

 

[GA_Boater]

The power heads should be a match, the serial number range includes both of your numbers;



Your numbers also fall in the range for 1994 - D284788 - G127860

The Mid-section diagram from Crowley because the Crowley OEM parts listings used by iboats don't have a diagram. - http://www.crowleymarine.com/mercury...cfm?mdl=NZ8FMV

Search for the gaskets on iboats, they cost less here than Crowley.

 

[kramerpage]

Hey guys I appreciate the quick turnaround. With this information I'm going to schedule a test drive on the water today. The seller states that there is no reason to do the work since there are no performance issues. I find that hard to believe. It's a cash as is sale off craigslist so I'm trying to be very cautious. The deal seems to good to be true. I've been looking since May for a uses boat to fish Erie.
They state they abandoned the oil injection systems and add oil directly to the fuel tank at a 50 to 1 ratio. They start up turn of the key. Power trim works. They smoke heavenly while running. Also there was a small 6 inch puddle of oil on ground under each prop after running for 7 to 8 minutes each. Oils comming from inside prop exhaust. Is that normal? He states they are indeed 1994 black max engines 135 hp.

I am going to have him open oil drains on lower units to look for oil. I mentioned a compression check. He said he has never done one. I have a gauge kit for that. What is the range I'm looking for.

Thanks for getting me through this stressful .

 

[Scott Danforth]

Could be over oiled and non burned oil conning out the exhaust

 

[kramerpage]

So we decided to do a compression test first before a water test. Here are the findings.

We ran each motor to operating temperature before the test. We pulled out all six plugs, placed in neutral and set throttle to wide open and the went plug 1 thru 6.
Gauge was an autozone rental

Original motor;
1...105
2...103
3...105
4...102
5...102
6...102

Replacement motor;
1...105
2...102
3...105
4...105
5...105
6...105

The original motor runs smoother than the replacement is the only difference I could tell by listening to them run.

Are these numbers within range? Thank you

 

[Scott Danforth]

The numbers are consistent. If the gauge is accurate, they are a little low.

 

[kramerpage]

Thanks Scott. I have been reading post for 3 hours and it seam they are low. Should be 115 to 120. My last effort is to de-carbon the motor. Let it sit for a day and then lake test it and then check compression again. Geee Whizzz the seller is very frustrated with me.

 

[Scott Danforth]

Tell him he should maintain his crap so you don't have to before you buy it

 

[kramerpage]

No Title

Well I told him that to de-carbon these motors using seafoam deep creep will foul all the plugs and I would not be responsible for the motors not running. He went out and bought 12 new ngk plugs tonight so he is motivated at least. I got him to greatly reduce the price or I would walk. Thanks for your help. I'll follow up on this sale.

 

[kramerpage]

After running 3 cans of deep creep seafoam soaking for one hour here are the new compression numbers. Not as even as before. Test drive is late this after noon.


Original motor;
1...105
2...100
3...103
4...100
5...105
6...103

Replacement motor;
1...105
2...106
3...110
4...105
5...106
6...107

 

[kramerpage]

No Title

Can you help me with the proper manual to change powered please? I going to try to do it myself. Maybe some basic pointers. Thanks oh and where I can get the two gaskets.

 

[ondarvr]

Decarbing does not foul the plugs, it cleans them up along with the rings and piston. Gauges can read very differently from each other, another gauges could easily read 10-15 lbs higher on each cylinder, being relatively even is a good sign.

Some quick adjustments could make the the rough running motor much smoother.

 

[kramerpage]

Decarbing does not foul the plugs, it cleans them up along with the rings and piston. Gauges can read very differently from each other, another gauges could easily read 10-15 lbs higher on each cylinder, being relatively even is a good sign.

Some quick adjustments could make the the rough running motor much smoother.

The issue is the replacement motor is too short. The prop slips horrifically. So I thought just put old original on and change Powe head. Thanks

 

[kramerpage]

Well as an update the short shaft motor is off boat. Original long shaft is installed. The powerhead has been removed from long shaft with no issues. The trim on this motor was frozen from sitting in a barn for 10 plus years. Finally got it free and is working correctly.

Now the short shaft power head does not want to come off. This was a saltwater motor. It has been soaking in PB. I will apply heat with a torch to see if it can be removed. If I damage it I will have to purchase powerhead and dress the head. I need some luck....

 

[kramerpage]

Well I have soaked heated hammered lifted and cannot get power head to come off. Now plan B.

 

[kramerpage]

I finally got both motors mounted and working properly. That was a lot of Time and work. My port motor seams to be idling too high. Gauge says 1000. I see the manual calls for 850. Shifting seams to be stressful on the lower unit as I hear / feel the clunk more than the star motor which gauge says 800 - 900. Im guessing there is no interrupter circuit like on a Mercruiser sterndrive unit.

How can I lower that port Idle down a hair?
Its a WMH-30 set up on a 1994 135HP V-6?
Do I have to adjust all three carb sets or is there a linkage type stop. The engines are running well so I don't want to adjust them just yet without the proper knowledge.

The idle circuit is independent of progression and main circuits. The idle circuit consists of
externally adjustable fuel mixture screws, idle air bleed jet, and factory set air trim screws
located beneath welch plugs.



Manual states this but I'm thinking this is not what needs to be done.

IDLE CIRCUIT ADJUSTMENTS
a. Fuel mixture screws (2 per carb.) - When adjusting fuel mixture screws all screws must be turned
the same amount and the same direction for engine to operate efficiently at idle speeds. DO NOT
remove mixture screw caps to further richen or lean fuel flow.
Clockwise direction - leans mixture
Counterclockwise direction - richens mixture
NOTE: If caps are removed from mixture screws and screws are removed for carburetor cleaning refer
to ?IMPORTANT? preceding.