Help me choose - 72 65hp or 74 70hp

[sheboyganjohn]

I ruled out my last project boat (bad motor) and have found two other ones in the yard, identical boat models but different motors. One boat needs a new transom now, but the rest of the boat is in very good shape, only problem is after market seats that take up too much room. The other boat has a floor that will need to be done soon and a damaged windshield, but oriinal seat in good condition.

So here is where I am stuck. One boat has a 1972 65hp on it. Tested out the shift solinoids and both tested at 6 ohms. LU oil was good. They could not get it to start at the key when they tested it but jumped it to get it to run, and could not shift. Compression is 130 135 130. The other motor is a 1974 70hp. Compression 110 110 120. Both motors need water pumps, they did not circulate and ran hot.

The 72 is on the boat that only needs a transom, so it would be less work then the other boat, but more work on the motor. I also want the motor that is going to be easier to find parts for. I know the lower unit on the 1972 is hard to find parts for, but how about water pumps, power head parts, etc.

And before someone suggests it, no I will not buy both boats and switch motors, even though each one is only $400. I am having a hard enough time convicing the wife we need boat #3, to become the new #2, the old #2 is being parted out this year. #1 is a dedicated duck boat so I don't count it, but she does.

 

[KurtG]

Re: Help me choose - 72 65hp or 74 70hp

What make/brand boat and motors?

It's a huge difference juggling boat and motor costs if your looking at AL vs fiberglass and wood where a lot more may be rotted than you think now.

 

[sheboyganjohn]

Re: Help me choose - 72 65hp or 74 70hp

Sorry, fogot some of the details. The motors are both Einrudes, the boats are 15' Steury bowriders. They actually have an 18' Steury bowrider that I really like, but will most likely be out of my price range better condition, better trailer and has a newer Merc. on it. It has not been inspected for sale, so no price info yet. After doing a lot of seaching, I have decided I like the Steury's, now it is just a matter of which one. The two I am looking at are a 74 and 75

 

[jay_merrill]

Re: Help me choose - 72 65hp or 74 70hp

I have a '72 Johnson 65hp motor and am very pleased with it. That said, I also did a lot of refurbishment right after buying it, and during the first year of ownership. In all fairness though, any other motor of the same vintage and level of care previous to your ownership, will have similar issues.

The compression values that you obtained are about right for a reasonably well maintained '72 OMC 65hp. The fact that the impeller was allowed to get so bad that the motor now overheats would concern me a bit. There are also some other things that could be causing the problem, such as a bad thermostat or plugged cooling passages. Regardless, I would look for discolored paint on the powerhead, or other signs of overheating.

Failure of the motor to engage the starter via the key switch could be a number of things, but is usually a problem with the neutral safety circuit. In the Johnson version, the problem is usually in the shift switch in the control unit. The ERude version is somehwat different & hopefully someone else will have some thoughts on that - I'm not sufficiently familiar with it to give you good advice.

According to my OEM manual, the way to test the shift solenoids includes both an amps reading and a ohms reading. First disconnect the shift leads at the port side of the power head and test each circuit, one at a time. Set your ammeter on DC low and connect between the green leads - you should see 1.5 to 2.0 amps for 10 minutes. If the reading is high or low, you have solenoid problems. Repeat for the blue circuit. On the ohms side of things, you are looking for 5 - 6 ohms, so it sound like you are good on that test.

If you can resolve the starting and shifting issues, the '72 could be a good motor. I had no problems with parts such as the rectifier, coils, powerpack, timer base, water pump, etc., but the shift system parts can be a bear. Also, if you buy it and replace the water pump, be very careful not to put stress on the shift wires as you lower the gear box. The wiring section in the midsection sometimes gets brittle in these motors, so it can be easy to break the wires. If you do, you have problems, because its an NLA part.

Hopefully these thoughts will help you in the decision making process. BTW, tell your wife that you actually don't have enough boats! Afterall, a few of us have 14 or 15 motors, a couple of boats, and a pile of spare parts!

 

[F_R]

Re: Help me choose - 72 65hp or 74 70hp

I would be afraid of any motor that has been overheated, but especially the 3 cylinder 65hp loopers (Not sure about the 70, but probably that one also). The exhaust plate in those motors warps at the first hint of overheating, resulting in water squirting into the cylinders through the exhaust ports, resulting in total destruction.

 

[sheboyganjohn]

Re: Help me choose - 72 65hp or 74 70hp

Thanks for the input. For the amp test, is this something you do with the engine running or can you do it with it off? The reason I ask is that I am buying the boat from a charity that has a whole yard full of them and I don't know if they have the time to keep pulling boats in to the shop so I can play with them. I have been doing all the testing out in the yard. Could I just run a wire from the hot side of the battery to test the solinoids? Has anyone seen a solinoid that tested good on ohms and bad on amps? I am leaning towards the 74 since it appears to have a longer range of interchangable parts and has the mechanical shift. But I keep looking at the work that boat needs in comparision to the boat with the 72 on it and like its condition better. Hopefully the bigger boat will come up at a good price and I can end this debate, but I doubt that will happen.

As for the number of boats, when I add in the two trucks and 30' camper in the back yard, not much room for more boats, at least until we get a house with a bigger yard. I have also taken over half the shed, one of these days I will work on the two extra outboards I have in there, especially the old lightfour.

 

[sheboyganjohn]

Re: Help me choose - 72 65hp or 74 70hp

F_R I was typing the last post when you responded. I don't know if they ever overheated or just ran hot (that was the test results at the shop for the charity). Both boats need transom work and one a floor, so that might be why they were donated. I also don't know how long they sat around before being donated, then tested, so the impellors might have dry rotted in storage. If/ when I get one of them I will open them up and check the exhaust plates, of course after I get the factory manual.

 

[jay_merrill]

Re: Help me choose - 72 65hp or 74 70hp

The motor does not need to be running for the amps test, but the battery should be fully charged and in good condition. Just turn the key switch on and do the test.

From my OEM Johnson 65hp manual:

STEP 2. SHIFT SOLENOIDS
a. Neutral solenoid - connect low reading DC ammeter between green leads.
b. Shift in Neutral psoition - key switch on.
c. Ammeter should read 1.5 - 2.0 amps for 10 minutes.
d. If reading too high or low - solenoid should be replaced.
e. Repeat test between blue leads. Use same test values and procedure.
f. Ohmmeter Test (Key switch "off"). Connect meter between green lead and ground and then blue lead and ground. Low ohm scale should read 5-6 ohms.

 

[F_R]

Re: Help me choose - 72 65hp or 74 70hp

It is ok to test the solenoids, but the truth of the matter is that the solenoids themselves give very little trouble. I don't know why they have such a bad reputation. When/if they do go bad it usually is the result of water in the gearcase, and if that is the case you have far more serious problems than the solenoids. The solenoids do not shift the motor--it is shifted by hydraulic pressure. The gearcase oil is the hydraulic fluid. The solenoids only operate a couple of valves which control the hydraulic circuit. Hydraulics require oil--not water. Water in the oil messes it up.

The wiring is far more toublesome than the solenoids also. With 40 years, the wires tend to get pretty crummy. And last but not least, the shift switch in the remote control is somewhat troublesome and outrageously expensive and hard to find.

 

[sheboyganjohn]

Re: Help me choose - 72 65hp or 74 70hp

Thanks again F_R. I checked the lower unit fluid and it was clean (no water) and based how fast it ran out, I would say it was the right stuff. I am not too worried about the switch. I have read a bunch of posts about these switches and see that there are ways to make your own, so I am not too worried about it. I am going to make a run out tomorrow and look over both powerheads to make sure it does not look like either overheated at all. I want to get the inspection right this time, 80+ miles each way is going to get old in a hurry.

 

[sheboyganjohn]

Re: Help me choose - 72 65hp or 74 70hp

Well I went back out today and looked at both of them. Both powerheads looked fine, no signs of overheating (but the 74 looked like the cover was left off for a bit due to the bird poop on it). Both need coils, the ones in them have visable signs of cracking. I crawled over both boats and think that even though it needs more work, the one with the 74 would be the best one. However I found out that they will be placing the bigger boat up for sale soon and it is just above what I wanted to spend. I am going to hold out for that one, and if I don't get it I will go back to the one with the 74 on it. The whole shift wiring thing has me a bit worried with the 72. I know myself well enough that I will find a way to break it. Thanks for everyones help.

 

[tashasdaddy]

Re: Help me choose - 72 65hp or 74 70hp

the solenoids and wiring harness to them are not available. i have a 71 50hp that has a great power head, and usless lower unit.

 

[jay_merrill]

Re: Help me choose - 72 65hp or 74 70hp

TD, that powerhead may bolt up to a '73. '74 or '75 OMC 50hp.

The exhaust tower gasket and adapter gasket part numbers are the same for the newer motors, so the powerhead base is probably the same as the older motor. The crankcase assembly part number is different, though. I think the critical issue wouild be whether the older motor has the mounting boss for the shift lever. The diagram at shop.evinrude. com shows it, but sometimes the drawings are wrong, so a quick look at the actual powerhead might be worth a minute of time.