New to Me 1985 Evinrude 70 HP

[aMeyers11]

Hi everyone. Just recently picked up a new motor to work on. The previous owner explained that it ran fine but one day it started smoking and shut off. He said it fired back up but died again and would no longer turn over. He replaced the starter and start solenoid with no luck. There are some burnt wires under the cowling. The motor came with a good set of controls and a working power trim board with all the wiring. I'm a bit confused as it seems the motor should have self contained power trim in the bracket, but maybe it doesnt? Or maybe it doesnt work. Either way what I paid for the whole package is worth the trim board itself. The motor has good compression and the owner also informed me the previous owner thankfully removed the oil injection. Obviously there is a wiring issue. Just wanted to know what would cause it it to smoke and burn up these wires? Not super familiar with these motors. Thanks for any input. Hoping to get this running again and back out on the water!

 

[mngopher22]

You are in luck I’m working on a 70hp 1987 evinrude. Attached is your wiring diagram. You want to asses if that damage was due to external heat or due to large current flowing in wires creating the heat.
second, you can remove bridge rectifier for now , battery won’t charge while running but will help diagnose. Check the bridge make sure it’s not short, also check charging coil make sure it’s not open and is about 1.2 Ohms

 

[flyingscott]

What trim board? The trim relays on that motor will be mounted above the carbs in a black box. Not all 1985 models came with TNT. Your pic is of the power distribution board and that motor has been seriously overheated and the rectifier melted.. Or has had one serious Electrical malfunction the switch box is melted for the ignition. Before anything do a compression test. powerheads for 85 and 87 motors are NOT the same.

 

[aMeyers11]

Thank you both for the input. I'm really hoping it was an electrical malfunction. Both arent great news but I would much rather replace electronics than tear apart the powerhead. The guy said it has good compression many times he seemed very honest and he doesnt have the time to mess with it. He has plenty of money to pay for a new one. Hes even driving an hour and a half to drop off a part he forgot at the marina. Anyways with that said I fear his lack of outboard knowledge might bite me in the end. He offered me to turn the flywheel by hand to get a feel for it but I didnt care to. Obviously that's not really accurat . I will get a feel for it when I get home today and post more pictures. I will try using jumpers on the starter to compression test it. He tried putting in a new starter and solenoid. Obviosuly neither worked. What I meant by trim board Is I think he gave me a crc or aftermarket trim unit. So you mount the trim board to the transom. It has like a plate that extends out a couple inches and you mount the motor to the plate for power trim. I will check to see if the motor itself is equipped. Also if this thing overheated that bad I would think there would be some serious powerhead discoloration but it's dark black all around? Anwyays thank you both for the help. I will post back later!

 

[havoc_squad]

Never ever take anyone's word for "The compression is good". If you don't see it with your eyes on your gauge or at least they show you with theirs, it's all empty talk that means nothing.

If they provide a very recently dated service shop inspection invoice (a week or two max before listing it) that explicitly states the condition of the compression test, that has significant weight in price consideration.

If I can't verify the condition of the motor, I'm only going to offer it's value in scrap/parts.

 

[aMeyers11]

Never ever take anyone's word for "The compression is good". If you don't see it with your eyes on your gauge or at least they show you with theirs, it's all empty talk that means nothing.

If they provide a very recently dated service shop inspection invoice (a week or two max before listing it) that explicitly states the condition of the compression test, that has significant weight in price consideration.

If I can't verify the condition of the motor, I'm only going to offer it's value in scrap/parts.

Totally agree with you. Not checking it at the purchase was quite foolish regaurdless of how nice or honest the seller seems to be. I got the motor, controls, and that power trim mount(has motor switch and everything) for 200 bucks. I was expecting a project, but not a blown powerhead project. On the bright side I can always put the power trim on with the 35 Merc in currently running. That would be a welcome upgrade. Anyhow we wont truly know until I get some jumpers and a gauge when I get back to the garage. Also interested to check for power trim relay on the motor. Thanks for your honest advice

 

[aMeyers11]

Alright so I just got home to inspect the motor. Upon inspection I have found that turning the flywheel by hand i can feel/hear compression on each of the 3 strokes. Obviously not super accurate but I'm yet to get it on the stand until my buddies can help. I also need to get a compression gauge. In order to test I can just use jumpers neg to a ground and pos it stud on starter right(and hope the starter atleast works)? Also I have found that it doesnt have built in power trim. Hence the cmc like power tilt plate that the motor will mount to. I know those can be pricey and if this motor doesnt turn out I will be able to use the tilt on my current motor. Also I noticed that the wires on the opposite side of the powerhead dont seem to burnt like the other side. I would think with an extreme overheat that both sides would be toast and there would be powerhead discoloration? Anyhow. Will never know for sure until I get the compression gauge. Thanks!

 

[havoc_squad]

Totally agree with you. Not checking it at the purchase was quite foolish regaurdless of how nice or honest the seller seems to be. I got the motor, controls, and that power trim mount(has motor switch and everything) for 200 bucks. I was expecting a project, but not a blown powerhead project. On the bright side I can always put the power trim on with the 35 Merc in currently running. That would be a welcome upgrade. Anyhow we wont truly know until I get some jumpers and a gauge when I get back to the garage. Also interested to check for power trim relay on the motor. Thanks for your honest advice

Yeah, I understand at 200 dollars that's not getting really bad screwed over if the lower unit is good, the powerhead is usable for rebuild, trim & tilt if present is functioning, and the midsection is serviceable.

At 200 dollars, that's about salvage/scrap price, so probably a decent buy for something newer than 1980 if you are planning to make it into a project motor (translation, spend serious money to fix up).

 

[aMeyers11]

Yeah, I understand at 200 dollars that's not getting really bad screwed over if the lower unit is good, the powerhead is usable for rebuild, trim & tilt if present is functioning, and the midsection is serviceable.

At 200 dollars, that's about salvage/scrap price, so probably a decent buy for something newer than 1980 if you are planning to make it into a project motor (translation, spend serious money to fix up).

Yeah, that's very true. I know those universal type trim mounts can be very pricey, the guy wasnt going to include it until I asked him about it and he asked the guy doing his new motor set up if it was needed and it wasnt. So he threw it in. At the very least I will have a trim unit on my boat and have plenty of parts to sell if I decide not to rebuild(if blown). I know the controls/harness/cables have sold in the 150-250ish range on Ebay. I have had previous success selling parts on Ebay. So I'm not all that worried about not making my money back. Just hoping the compression is as good as the dude claimed . But I have doubts. I will report back as soon as I get an actual proper compression test done. Thank you

 

[aMeyers11]

Update: so unfortunetly I still havent been able to do a compression test due to not having the motor on a stand yet. I'm still waiting on my buddies to get the chance to help me. But I have looked at the motor a bit more and I realized the rectifier was toast and all of the surrounding wires along with it. I did some research and found that reversing the battery cables or having loose connections can cause a rectifier to fault and cause electrical fire. I think this is what happened as the wiring on the opposite side of the motor doesnt look to have been overheated or melted nor do other components surrounding the powerhead. Just the wires connected to and surrounding the rectifier. I havent been able to find a wiring diagram online for my motor. I have found diagrams through 1984 but not the 1985 model? In order to do the compression test can I just use jumper cables, pos to the big stud on starter and neg to ground? Will this damage any electronics? Thanks