Service and Maintenance on '77 Johnson 85hp

I just bought my first outboard- '77 - 85hp Johnson to go with the boat I will be restoring. It was $250 on Craigslist. When I picked it up it was lying on the grass under a covered carport. Outside of a bit of moss/mildew on the outside (typical for anything kept outdoors in the PNW) the engine is very clean. I've started stripping the paint to get it ready for a new paint job.

I bought it with the understanding that there was currently no spark. Obviously this could be from many sources so I won't be able to get it running right away.

Here's my question: I intend to bring it to a marine repair shop locally to basically give it a thorough servicing that one would typically do in between seasons. What should I expect them to do? As in, what does a full service usually cover? Is there anything additional I should ask them to do since it hasn't been running for two seasons?

Finally, since I am not an "engine guy" but have some experience working on car engines and do a fair amount of my own car repairs, do you think it would be a good idea to have the marine repair shop try to diagnose the electrical problem since it will be in the shop anway? I'm not a cheapskate but since it is a hobby, I would like to do as much of the work myself as can be reasonably expected.

Since this photo was taken I've moved it to my workbench and it is sitting upright (I've also cleaned up my garage quite a bit!).

Thanks all and I'm looking forward to being a member of this site. Great information here!

Re: Service and Maintenance on '77 Johnson 85hp

Full service means different things to different shops.
Your best bet would be to make a list of what you want done. Impeller, gear lube, lube prop shaft, tuneup, compression check, sync & link, carb adjust would be on my list.
Talk to the shop you want to use.
You can probably do all your own work, but you will need an OEM manual. With the manual and the help from this forum, you should be able to do all the work yourself.

You really need to get the spark problem checked out and the engine running first, and a compression check before you spend a lot of time cleaning and painting. Sellers tend to make probems sound minor in order to get the money out of your pocket and into theirs. These forums are full of examples.

Re: Service and Maintenance on '77 Johnson 85hp

Agree with Don S. Hook up the battery cables to the starter and see if the engine turns over. If it does, take a compression test on all 4 cyls. No sense in taking it to a repair shop if it has no/low compression on one (or more) cyls.

Re: Service and Maintenance on '77 Johnson 85hp

Thankfully, I do have a service manual for this exact motor that came with the purchase.

Well I seem to have averted disaster on the first check. I hooked it up to my car battery and the starter engaged and slowly turned the flywheel several rotations. There was the sound of the cylinders "popping" air. Each sounded just like the next as the fly wheel slowed and then released . There were no grinding or other stomach churning unexpected noises. I didn't go any longer than this because I don't want to risk killing the starter.

Assuming that checks out I'm going to assume the problem with the motor really is a spark problem.

According to the manual, no spark on four cylinders could be caused by any of the following:
1 Sensor Coils
2. Charge Coils
3. Power Pack
4. Key switch
5. 10 way connector

Any advice on a good place to start on this list? I don't know if one is more likely to fail than another or if one is an easy check to cross off.

I've got it sitting on a heavy duty bench now and will bolt it in tomorrow. I'll probably jack the bench up and attach it to the wall studs this week sometime.

Re: Service and Maintenance on '77 Johnson 85hp

I'm going to borrow my father-in-laws compression tool to see where it really is. It will have to be a cold test. The manual doesn't give me the ranges but I've heard around 100psi is normal. I'm still hopeful based on what I heard earlier.

Before I paint the remote I'm going to try to bench test the ignition switch with new wires - about 3 feet long and a marine battery. I'm going to replace all the wiring from the remote to the engine anyway since they are in pretty tough shape. I'm going to mount the remote to the front of the bench as though it were on the boat. Who knows, might even spark?

Re: Service and Maintenance on '77 Johnson 85hp

That engine should have had around 125 lbs compression on each cyl when originally shipped from the factory. When you do your test, you want all 4 cyls to be within 10% of each other. Test with all 4 plugs removed. You can test the ign switch yourself. Disconnect the plug wires and the control box harness-the large red plug inside the cowling. Put jumper cables direct to the starter to turn the engine over. If you have spark, then you know the problem is in the control box/key switch. It would be unusual for all 4 spark plug coils to fail at the same time, so you will be looking at these ignition components: timer base, stator and power pack. Statistically, the power pack fails at a higher rate than the other two ignition components put together-but with an engine this old, any of these three may be part of the non-firing problem. FYI, your 85 hp model is a small bore V4 that year. 92.6 cubic inches. The pistons/rings/heads are smaller than the 115/140's from 1977-at 99 cubic inches. All other parts are the same.

Re: Service and Maintenance on '77 Johnson 85hp

Thanks so much, EMD!

You probably saved me 3 evenings of fussing around doing things that are irrelevant. You've answered a hotwire to the starter question I had too. I didn't know if I was supposed to get spark doing this or not, but apparently so.

Excellent information and all of it is relevant to this project. I checked my service manual and couldn't find anywhere what the original compression was.

Re: Service and Maintenance on '77 Johnson 85hp

The factory OMC service manuals do not list compression readings.

Re: Service and Maintenance on '77 Johnson 85hp

I just checked the compression - as best I could. I couldn't get the flywheel moving fast enough with the starter connected to my car battery to get each cylinder past 25 psi (each one went that high and stopped the flywheel) but when I hooked a socket to the flywheel bolt torquing it manually and took a measurement I was able to get each cylinder to peak at 52 psi, then 70 psi when I remembered to put it into neutral almost to the exact mark (yes, I reset the gauge each time). The even readings are a good sign in my book - even if it was at a lower threshold. There will certainly be some variance if I can get the flywheel up to optimum speed. The engine is also cold and the compression gauge is the type I have to push over the hold vs. the kind that screws in and I have to hold it tight while turning the flywheel. Still, I'm very encouraged by the results.

I came up with another question while doing this. When the cables were hot wired to the starter they got very hot. The positive was hooked to the starter where the red jumper attaches from the solenoid and I used the bolt on the starter attached to the block as the ground. Is there a chance that the starter is not grounded? I'm not sure if a car battery would have the sufficient amperage to turn this motor over. The service manual indicates that bold is the ground. My jumper cables are medium/light duty.

Re: Service and Maintenance on '77 Johnson 85hp

The fact that all the compression readings are close to each other may be a good sign. The starter is grounded to the block by virtue of it being bolted to the block. When jump starting, the red goes on the starter post (bolt) marked red, the black cable should be connected to the engine block. Jumper cables that get hot are probably too light a gauge wire. They won't transfer enough current, so they get hot. Try another set of cables. Typically, a starter should only be run for 10-15 seconds at a time due to internal heat buildup in the starter. You can probably rent a good compression gauge from any local automotive parts store.

Re: Service and Maintenance on '77 Johnson 85hp

I got back to work on my motor today. I pulled the starter and took it to Pep Boys to have it tested. Fortunately the guy testing it was also a boat guy. It checked out A-ok so I put it back on the motor. I did another bench test using better cables this time and the flywheel moved freely with the plugs out. This time I noticed a slight rubbing sound and there was still no spark. I pulled the flywheel and and look what I found!

I sanded and cleaned the points on the stator. Not completely thoroughly but enough to bench test it in the dark to see if there is spark. I also sanded and cleaned the flywheel.

This is probably not all that is wrong with the electrical but it sure won't start without fixing this.



I used the claw end of the hammer as a wedge between the flywheel and engine hang mount and lightly tapped the flat end. It took about 10 minutes rotating it 30 degrees and giving only a couple of taps each time.

Re: Service and Maintenance on '77 Johnson 85hp

Still no spark.

It looks like it's the timer base ($237), the stator ($234) or the power pack ($97).

I think my next purchase will be a multimeter. I have the service manual but this is going to be a monumental task checking all the voltages.

Re: Service and Maintenance on '77 Johnson 85hp

Double check your battery andf cranking rpm's. That engine's ignition system won't fire the plugs until the engine achieves a cranking speed of 250 rpm's. I've had good luck checking the voltage outputs of the timer base and stator. Those votages will tell you if the component is good or not. You can find some excellent ignition troubleshooting information at this website: http://www.cdielectronics.com. When you take the voltage readings, you will need a special "peak reading" voltmeter-a typical household voltmeter won't work. It's worth your time to do some testing, considering the expense of the components you mentioned. From a purely statistical standpoint, the power pack is the component most likely to fail compared to the other components, but I still wouldn't just replace it till you have done other dianosis/testing.

Re: Service and Maintenance on '77 Johnson 85hp

Here's a very fundamental question- With all the plugs pulled should the flywheel be able to spin freely or is there supposed to be resistance?

I can turn the flywheel with a socket but there is a fair amount of resistance. It certainly wouldn't be able to spin on its own. I'm not hearing anything other than a slight pop as the cylinders move.

Re: Service and Maintenance on '77 Johnson 85hp

Have you put a small amount of oil in each cylinder to prelube the ringsets? That engine flywheel should turn easily by hand when the spark plugs are removed. The fact that the lower unit is still attached and the water pump impeller is providing some drag will slow the powerhead down somewhat. It is always possible that the engine sat for so long that the cast iron cylinder walls are covered with a light coat of rust. When the spark plugs are out, have a look inside with a pencil light and try to see if the walls are shiny or rusted. If you don't like what you see, you may have to pull the heads off for closer examination.

Re: Service and Maintenance on '77 Johnson 85hp

Thanks, EMD. I searched for countless hours on Youtube but coulddn't find anything that remotely answered my question. The guy I had test the starter also recommended that I spray some WD-40 in the cylinders. I did that and it loosened them somewhat. I've got some 3-1 I can put in there too.

If what I've found in the rest of the motor is any indication, there probably is a layer of something in the cylinders.

Re: Service and Maintenance on '77 Johnson 85hp

I decided to go ahead and take the heads off. The whole notion of there being rust was just not something I could live with, especially considering the other places I found rust. The cylinders are very smooth and there doesn't appear to be anything awry. One of the gaskets was in perfect condition while the others could use to be replaced (of course, I will replace all of them). I still have a feeling there is another gasket at the rear of the engine on the port side that might be blown since I can feel air come out right next to the solenoid/below the rectifier.

At the very least, giving the engine a good thorough inspection and new gaskets will give me peace of mind.

Anything look unusual here? I know the inside of the cylinders can't be seen clearly, but the heads are.

Re: Service and Maintenance on '77 Johnson 85hp

The rubber water deflectors appear to be installed incorrectly and may block cooling water flow through the block. Those are the 4 small hoses inserted into the block: Your center picture shows both deflectors. I'd replace all 4 to insure they are installed per the factory service manual before you reinstall the heads. I've attached a picture of a block similar to yours. One deflector (on the left) is correctly installed, the other has moved and is out of position. Everything else appears very normal-that's a good thing. Regarding the compression leak: It is possible that you may have two issues: 1. the gasket on one of the side intake (bypass) covers may have loosened up and should be replaced. That's an easy fix and needs to be corrected before you run the engine. 2. You may have a bad base gasket. That's the one between the powerhead and the midsection. This is a little more involved, as the powerhead must come off to replace that gasket. Some additional investigation here is needed.

Re: Service and Maintenance on '77 Johnson 85hp

One of these days this will start to look like a rebuild but I'm going the wrong way!

The gasket on the side intake was in tough shape. It was original so there were probably some holes I couldn't see. I ripped those all out tonight as well as the exhaust cover. Nothing too exciting to see under the exhaust cover or bypass covers, just signs of use that a little thinner cleans right up. There was a sloppy job sealing the starboard intake bypass gaskets and goop was all over. I'm soaking everything in laquer thinner to clean them up.

I've found the gaskets (and water deflectors) I need online and will order them next week. I hope this weekend to have everything that needs to be pulled off the engine pulled and stripped and prepped for painting.


To keep the parts straight, as there are starting to be quite a few of them now, I'm using all those plastic country crock tubs I've been saving for some reason. I'm putting the small pieces of each project part in them and separating them by side and labeling them with a sharpie. I can also soak the bolts in thinner overnight to loosen the paint this way. I used to put all my Legos away in just the same way LOL.

Re: Service and Maintenance on '77 Johnson 85hp

I picked up a 1975 115HP today from an engine scrap heap for $300. It has a cracked block but I verified the ignition system parts (timer, stater, power pack) I needed match mine and they are in great condition. There are many other parts I can change out if necessary too. I'll check the lower unit and probably put that up on Craigslist to recoup some of the cost.

I painted the parts and block with high temp engine paint and did a light reassembly. I have to order the gaskets tomorrow and will hopefully have the block reassembled in a week or two.

I hope working with a clean platform will make hooking up the ignition system easier. It's a very good thing I have a manual!