Looking for advice before giving up on Evinrude 85HP

[adogramacian]

I apologize in advance for the long-winded story, but I want to include all the details...

I've posted on here before about my father-in-law's 1970 85HP Evinrude dying after running for 25 minutes. Fast forward 2 years...I found a boat on craigslist with the same motor I've had experience with (Model 85093), and the guy offered a water test. Seeing the boat run, I figured I was all set.

Launch the boat, and realize she does not idle well. Ever. Additionally, she would die after 30-35minutes. Just lose power, RPM's would slow down, and then I could not get her started again. Time to row back to shore. I replaced the plugs and put a filter in the fuel line. Took her out a few more times...After rowing back 3-4 times, you start to think it might be time to have a pro look at things. Problem is, no one looks at 38 year old motors around here (Northshore MA). So we found a guy that worked out of his house, and he said he would take a look.

He did a compression test and told me we had 125lbs on each of the 4 cylinders. Based on that, he and I agreed it would be worth fixing this motor up. He cleaned and rebuilt the carbs, replaced a cracked fuel line, replaced the rotor (under the flywheel, had small cracks), checked and set the points properly. Powerpack was replaced, coil was not (was told coil was relatively new and should be ok). He supposedly checked the stator and other electrical components. He called me up and told me she was running great.

Took her out, and as usualy was stranded. She idles fine now (we don't have the be the a-holes that are going too fast in a no-wake zone to avoid stalling), but after 30-35 minutes, the engine just shuts down just as before. Mechanic tells me he ran the motor for over an hour on muffs, yet I can't get it to run in the water over 40 minutes.

My question is this: do I continue to tinker and attempt replacing parts, or do old engines sometimes just not work anymore? My mechanic mentioned before he did any work that sometimes over the years blocks change shape just enough that perhaps once the engine warms up, there is too much friction. Just seems strange that both 1970 85HP Evinrude's I have worked on stall after 25-35 minutes. Thanks.

 

[dimock44]

Re: Looking for advice before giving up on Evinrude 85HP

Are you running the second motor on your father in laws boat?

 

[Nandy]

Re: Looking for advice before giving up on Evinrude 85HP

Hmm, your mechanic shoudl know that runing a motor on muffs is not the same as the lake. I wonder what will the presure test will show when it fails to start. Something is getting overheate, that is obvious. good luck.

 

[F_R]

Re: Looking for advice before giving up on Evinrude 85HP

That line about changing shape with age is a crock. Somebody needs to be there when it quits to see why it quits. They don't just quit for no reason.

 

[1730V]

Re: Looking for advice before giving up on Evinrude 85HP

You need to determine what you are losing when it stalls. Most likely spark.

 

[iwombat]

Re: Looking for advice before giving up on Evinrude 85HP

Yes, it is weird that both motors stalled after 30 minutes. Have you checked your tank vent and anti-siphon valve?

I'd be checking out common elements on the boat before trying to fix the motor.

 

[jimmbo]

Re: Looking for advice before giving up on Evinrude 85HP

Sounds heat related. Try to keep the coil cooler, add insulation perhaps and see if it helps to run longer.

 

[allenx1966]

Re: Looking for advice before giving up on Evinrude 85HP

this doesnt make sense, but, my boat was doing the same exact thing. its a 1978 evinrude 85hp. model 85895c. believe it or not, it was the fuel line. did he replace all the fuel lines? i think the heat may actually do something to the fuel lines. mine was doing the same thing one day,then as i was pumping the fuel line ball from the tank, i saw a fine mist of fuel coming from where the tank line connects to the bottom of motor case. i took cover off, and sure enough, a pinhole was in the fuel line there. i had 4 fuel lines, 1 to the pump, 1 from the pump into a T,and then 2 going to carb, i replaced them all and she runs all day long with no troubles other than needing a very small shot of starting fluid when motor is cold.
im no expert, and the other posters are right, it sounds heat related, but heat can cause a multitude of strange issues, so don't discount your basic trouble shooting tests.

 

[adogramacian]

Re: Looking for advice before giving up on Evinrude 85HP

Let me start off by saying thank you to all for your advice. I though iboats automatically emails me when people respond, but since I did not get any emails, I checked the site myself. I truly appreciate people taking their time to help me out!

dimock44: I actually purchased a boat with a motor that had the same model year and horesepower as my father-in-law's boat motor. We have stopped working on his for the time being.

Nandy: By pressure test, do you mean to try a compression test when the engine stops running?

F R: Thanks for the info. As someone with no mechanical training, its hard to know what is true and what isn't.

1730V: What's the best way to test for loss of spark? The nail in the spark plug boot test, or do I need the neon light referred to in the manual?

iwombat: My father-in-law swears that years ago when they used the metal tanks, they would leave the vent closed, and after a day of boating, they would release the vent and the tank would suck air in. My understanding is that the vent should be open when the engine is running. Is the anti-siphon valve located with the primer bulb? We did try 2 different gas tanks, but who knows....

jimmbo: Could a defective coil also cause an engine to die out? I guess that would go back to the "need to check for loss of spark issue"...

allenx1966: After the first time we got stranded after the mechanic repaired the boat, we did notice a fuel line leak inside the engine. He repaired it, and we launched again, but alas, she failed. I will take a closer look at the internal and external fuel lines...

 

[iwombat]

Re: Looking for advice before giving up on Evinrude 85HP

Your father-in-law probably had a metal tank with a leaky top or a very small motor. You can get about 1-2 gal or so out before it vapor-locks with the vent closed on a properly sealing can. Or, about 10-80 minutes depending on engine size and how hard you're running. I'll bet your father-in-law blew out the diaphragms on a lot of fuel pumps that way. The anti-siphon valve is on the output of most built-in tanks. I don't think the portables have them.

Two motors conking out after 30-minutes of running sure sounds like a fuel delivery problem prior to it ever getting to the motor.

 

[emdsapmgr]

Re: Looking for advice before giving up on Evinrude 85HP

The compression on the engine is solid, so it's worth putting some effort into the engine. You really need to know the reason the engine quits. For instance, if it quits and the plugs are still wet-you may have a spark issue. When the engine quits, pull the plugs and have a look. Also, when it quits, put a timing light on each plug wire while you crank the starter and see if you have good fire on each plug wire. If the plugs are absolutely dry when it quits, you should be looking for a fuel issue-pump, carbs, fuel line, etc. Pretty basic stuff, but you get the idea. It's likely going to be fuel or spark related. Give us some idea what you see with your investigation..

 

[JDSmith]

Re: Looking for advice before giving up on Evinrude 85HP

Does this engine have an overheat alarm? My 74 70hp Johnson does. I never knew it because it had never went off before. TO test it I removed the rubber sleeve covering one leg of the temperature sensor. I turned the key to the ON position, grounded it, and BUZZZZ, it worked. Now what I don't know is will that 33 year old temperature sensor really go off at the right temperature any more. Maybe your engine has an over-temp safety cutoff like that?

I made the mistake of not opening the vent on an old metal gas can once. It sucked in the side of it all at once while running - it scared the heck out of the wife and I with the noise it made all of a sudden!

I am pretty sure there is an anti-siphon device inside the pump bulb. If it you are getting 30 minutes of running off of the engine I dont see how that could be it.

Are you sure the water pump is pumping water up into the engine?

Does it just die all of a sudden and then what happens when you try to crank it? Can you carry some starter fluid and use a little of that in the carbs to see if it will try to fire up on recrank?

 

[adogramacian]

Re: Looking for advice before giving up on Evinrude 85HP

I purchased a timing light and spark tester. I have adjusted the spark tester to 7/16", and plan to test for spark before running the engine and when it quits. Once it quits on me, I'm going to check to see if spark is still present.


Also, I'm thinking of buying a new battery. I keep reading over and over that CD ignition requires a top-notch battery. So, I'm going to get a spankin' new battery to eliminate that possibility.

Going to the Cape this weekend to work on the boat. Wish me luck!

 

[CharlieB]

Re: Looking for advice before giving up on Evinrude 85HP

A unit that old I would automatically replace fuel lines, not an expensive and good maint/insurance. A pin hole BEFORE the bulb will cause small air bubbles to enter the line, on the hose it could run for a very long time but in the water in gear it would not be too long and simply run out of fuel and die.

We failed to ask youu, when it does die do you squeeze the primer bulb, is it firm? Trying to decide, if it runs out of fuel or aheat related electrical issue.

I had three of those mid-60's to early 70's in my shop this year. The spark amplifier was toast on two of them. New amps from CDI came with matching new coil.

Simple test for spark, disconnect the white wire that runs from the amp to the point plate under the flywheel. Key on, listen carefully, the box emits a very high frequency 'squeel' many people can hear, ground the white wire, the coil should spark, ignition amp is good. The points MUST BE set to .020

I'm beginning to suspect the amp works when cool/warm but once placed under load it is heating up to operating temp and fails. It's a spendy part, prove it wrong before you buy a new one, get the CDI and NOT the OEM

 

[adogramacian]

Re: Looking for advice before giving up on Evinrude 85HP

Armed with a new battery, fuel hose, bulb, and connectors, as well as a voltmeter and timing light, I decided to perform some testing on my own.

A buddy of mine and I put together the new fuel assembly, squeezing the bulb and letting fuel come out the end of the hose before putting the connector on (just to make sure there was no air in the fuel line).

We installed the brand new battery (new, but I took time to make sure it was fully charged), cleaned the connectors from the motor, and connected to motor and tighened with a pair of pliers. Squeezed the bulb until firm and started the motor (on muffs, air temp roughly 50deg F).

We connected the timing light to the old battery for power, and clipping the sensor to each spark plug cable, we tested each of the four plugs for consistent power. For every plug, the timing light flashed (I'm assuming) every time power was delivered to a spark plug.

After running the motor for 20-25 minutes, it started to sound a little strange. So, I had my buddy move the sensor from one plug to another while I looked at the light. At first, only cyl#2 would miss. We shut the motor off for 5 minutes, Then started her back up again. She ran for another 10-15 minutes, during which time we just used the timing light to check for spark.

End results: Cyl #4 never seems to miss, Cyl #2 is the worst, but after 30-35 minutes, Cyl #1 and #3 also seem to miss fire. The fuel bulb remained firm the entire time, and when the engine started missing, sqeezing the bulb did not make a difference. To me it seems something is heating up causing the misfires. The only questions I have is how to figure out where the problem is coming from. Defective new amplifier? Defective coil? Or perhaps the points are off when components heat up?

But let me throw an additional tidbit of information into the mix...despite running the engine for over 30 minutes, it never warmed up. I know the engine pretty much remained at idle, and cold water was running through the engine, and the air temp was only 50, but I could put my hand on the cylinder heads and sides and it was only lukewarm. Like maybe 70-80 degrees. If the vernatherm (thermostat) was stuck open, what problems would it cause the engine?

 

[adogramacian]

Re: Looking for advice before giving up on Evinrude 85HP

One last thing: we did not test to see how long the motor would run. it stalled once after running for 10 minutes, but then started right back up. She probably ran for a good 35-40 minutes total, but once she started misfiring alot, we shut her off.

 

[iwombat]

Re: Looking for advice before giving up on Evinrude 85HP

I had a bike that did something like this once. Turned out to be a condenser that was working, but not in spec. As the ignition system heated up and the properties changed, the condenser could no longer function properly. A new condenser should cost you only a few dollars. Something very cheap to try anyway.

 

[Don S.]

Re: Looking for advice before giving up on Evinrude 85HP

Seems like your making headway, the battery I was going to suggest also, I was told it is uaslly a good Idea to change out the coil when you change the Amplifier. Could be BS.

I too am in the same boat when it comes to finding someone to help with my 1971 100HP. Most mechanics don't want to deal with these motors cause parts can be damn near impossible to get.

I currently have the power head off mine, and am sending it down to a machine shop to have some broken exhaust cover bolts machined out.

 

[emdsapmgr]

Re: Looking for advice before giving up on Evinrude 85HP

So you've got an electical problem. It is not unusual for them to show up after the components heat up.. typical. There are two significant electrical parts to test, the stator and the amplifier. (perhaps the clipper also.) I'd get an original service manual for the engine and test the electrical components according to the factory test procedures. Usually, there are a set of ohms or peak volt tests which will qualify all electical components. Ken Cook Co, in Milwaukee, Wi will get you a copy of the original service manual. The engine needs to heat up properly to keep the pistons/cylinder walls from coking up with carbon. The vernatherm should keep the engine somewhere between 140 and 150 degrees. If the vernatherm is stuck open, it will run cold. Replace it. While you are in the thermostat housing, look at the check valve and make sure it is functioning. If it is deformed, it could allow cool water to bypass into the head.

 

[adogramacian]

Re: Looking for advice before giving up on Evinrude 85HP

Does a motor with a CD ignition have a condensor? I don't remember ever seeing one...