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1977 Evinrude 85HP Coil Question

T

Trapset

Member
Howdy, I am replacing the coils on my 85hp V4, Model # 85793S. The original coils, no longer available, have 3 holes for mounting. One on each side and one in rear. All the replacement coils show two holes, one on each side, but no rear hole. Will this be a problem?

The motor runs ok but coils are very rusty, cracked and a couple look like they have been hot before. Figured I may as well replace them before they leave me paddling.

Thanks!
 
Great, thanks racerone!

Any preference on brand? The OEM seem right in the same range as Sierra and CDI. Just wondering if the older motors get along better with one over the other?
 
The ignition on your motor works the same way as the 1998 model.------Making your motor more reliable ?-----Water pump impeller replaced ?----Thermostat ( vernatherm ) looked at ?----Overheat horn tested ?----Gear oil checked / changed ?----Seal kit ?----Compression test done , post your numbers here.----Fuel pump diaphragm replaced ?
 
Thanks much!

Impeller is 3 years old and pumping good. I change lower unit oil every year and it looks good, seals are also 3 years old. I have not looked at thermostat or tested temp horn, I didnt know this motor had a temp horn. How do you test it?

I have a screen for the fuel pump coming, I might as well get the diaphragm coming as well, thanks.

Motor runs good so I haven't done a compression test. I suppose I could when I do the coils and plugs.

Any difference in coil brands as far as your concerned?
 
Thanks, I see the vernatherm 105 degree there but I don't see an actual thermostat. I thought the vernatherm controlled low temps while at low speed/rpms and there was a thermostat for higher temp control. Is that not the case?
 
You could check operating temperature of motor.----Install temperature gauge.-----Water pressure gauge.----Above all test the overheat horn.-----I have shown many owners the concept of testing the horn.----And yes most did not know there was an overheat horn.----Simply because most folks are only interested in turning the key and roaring down the lake.----Note-----I was working on these motors well before yours was built !
 
So easy.----Find the tan colored wire on cylinder head.-----Slide the rubber sleeve back to expose metal.-----Turn key to " on " .-----Touch the exposed metal on the tan wire to ground.-----Horn should sound.
 
Temp horn works. Glad to know that.
I did a compression test and got 95psi on each cylinder. I know my gauge runs low but it is unusual for all cylinders to be exactly the same. I’m going to charge the battery and check the cables because it doesn’t seem to be cranking as fast as normal. Might look into a new gauge also. I’ll report back here with what I find.

Thanks much for the help!
 
racerone said:
----Note-----I was working on these motors well before yours was built !
Click to expand...

I appreciate the experience!

I have a lot of older Johnson/Evinrude small motors. Seven 3hp JW's from 1950s to 1970s. Four 25hp, newest is 1984 and a couple 20hp, 1966 and a 69. One 35hp early 80's. One 1954 5.5hp. I've done a lot of wrenching on these motors on and off the water over the last 35 years.lol

However, the V4 is the first big boy I've had so I really appreciate the help! Coils came in so I'll be getting them on in the next couple days. I've got a new compression gauge coming so I'll warm her up and check #s again.
 
Got the new coils on and new plugs. Took her out and she ran great, except at WOT, about 5200 RPMs it would starve for a second or two and die. But ran ok at 4500. Ended up being the liner in the hose collapsing. Going to try new hose this week.

Prop question, it has a 13 3/4 x 15 and it runs 5200-5400 wot trimmed a bit. I want to get a new prop, the prop selector on this site, for this motor calls for 13 1/2 rather than 13 3/4. Shouldn't be a big deal to keep new prop 13 3/4 is it?
 
Got new compression gauge. #1 127
#2 125
#3 126
#4 126
I feel better about those numbers than the old gauge and the 95 pound readings. What is normal compression range for this motor?
 
New problem. The new spark plug boots are arcing to the porcelain causing black carbon on plug and miss at idle.

Just put new coils on with new boots and wires. Any idea how this is possible and or how to correct?
 
Well----I have never seen such a problem with new parts from OMC.-----My dealer would gladly take them back and replace them for me.
 
I want to make sure it’s the coils/wires/boots before I send them back and find out the new stuff does the same thing. Anyone else have experience with this problem?
 
I put old boots back on and it solved the problem. I think I think I may have messed up by spraying some WD40 in the new boots to get wires to slide in easier? Or they were just bad boots from factory. Used alcohol to slide in old boots and have no arcing now.
 
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