"New" '84 Johnson 90HP V4 - questions

[Thirsty Endgrain]

Hi again, different engine this time. Just picked up an '84 90hp V4 that has been sitting for about 10 years, but looks to have not been used and abused. I couldn't properly do a compression test when I got it, didn't have muffs and I've read it's not good to even do a comp test without water running? Plus all of the wiring was disconnected, soooo. But was owned by a boat mechanic before it was stored, and it was an "it ran when it was stored" kind of thing. Time and detective work will tell. LU oil is oil colored, phew! Shift rod moves up and down, throttle moves nicely, plugs didn't look to be fouled up. Basically, as much as could be good without having it running in front of me was good, so I went for it.

It was $500.

Anyway, got it home and on the hastily thrown together stand. A few questions:

-It has tilt/trim thankfully, that looks to be in good condition. No bad corrosion around the cylinders. Unfortunately wires were cut willy nilly on this poor thing, and I'm not seeing an intuitive way to hook the tilt/trim switch back up. Hoping no major piece is missing. I'll include pics, maybe someone can point something out? I'd like to get this part working for ease of access to work on the thing on the stand.

-I want to start it obviously, but I want to make sure I do everything that should be done right beforehand. Bought a new impeller, and was going to install it before attempting to start it. Is that sound reasoning?

-Have new plugs, so I'll install those before attempting to start as well.

-Should I clean the carbs before starting? Assuming I should make sure the bowls are drained, though he said they were drained before storage.

-A friend said to run it with 50/50 mix/seafoam and let it sit for a couple of days. Is this sound practice?

-Was thinking to replace all of the fuel lines in the engine compartment before starting, to make sure there aren't cracked bits that end up in the carbs.

-I did just manage to get the ignition wires hooked back up to the point where i can push the key in to choke, and turn it to engage the starter. Finding the wiring color key was....key. Might have some questions on this once I dig deeper.

Pics to follow in next post, and fingers crossed.

 

[Thirsty Endgrain]

First pic shows the two 2-wire cables that come from the tikt/trim. Would appreciate any help as to where exactly they go and how to hook them up. Forgot to include, but the tilt/trim switch is three wires. Blue-green-red. Then from the pics the wires from the tilt trim are blue/White and green/White. The smaller cable with two wires is I'm guessing for the tile trim gauge?

I know there's also supposed to be a relay but I'm having trouble locating that...

 

[oldboat1]

Don't do SeaFoam. It will just make diagnosis more difficult, and if it runs well without it -- you didn't need it. Need a clean tank and clean carbs (separate operations). Starting a motor without water will burn up an impeller in nanoseconds. Cranking to check compression or measure spark is safe enough (no starting -- plugs out). Change out the impeller before firing it up -- not good to have rubber bits in the cooling system.

might help: https://maxrules.com/graphics/omc/wiring/84_V4_TNT.jpg

 

[flyingscott]

Compression and spark test before anything. Dont worry about the impeller because it needs to be changed anyways. Lube the cylinders with some WD-40 and let it sit overnite. Then do tje compression test.

 

[havoc_squad]

Compression and spark test before anything. Dont worry about the impeller because it needs to be changed anyways. Lube the cylinders with some WD-40 and let it sit overnite. Then do tje compression test.

+1 Don't waste a single minute or dollar before you compression test that motor. As mentioned, you need to lube the cylinders all around them and let that sit for a day or two before you attempt to start it.

Once the oil has had time to sit, I'd recommend taking the spark plugs out (ignition off) and try to turn the flywheel clockwise (towards starboard) by hand a full revolution before using the starter.

If you can turn a flywheel two full revolutions without something binding or stopping you with the spark plugs out, it should be safe to at least use the starter.

Cylinder wall pitting and bearing surfaces corrosion near the crankshaft are going to be your biggest concern with that motor left to sit for a decade.

 

[Thirsty Endgrain]

Flywheel turns clockwise, have had a little 2-stroke oil in there since yesterday, and just gave each cyl a wd-40 shot a little bit ago.

Tomorrow I'll get a lug crimped onto the positive batt lead so I can get proper juice to the starter.

Spark jumps a 7/16" gap on all four, tried to do a comp test but couldn't get enough cranking from the starter, again, need to get a lug crimped on, and I'll go through the main + - connection points to make sure I have good contact everywhere.

Cleaned the carbs. Hopefully get comp test numbers tomorrow.

Anyone have any insight on the tilt/trim situation? Is there anything major missing? I've read that there should be a relay somewhere that I've yet to find.

Thank you all so far!

 

[Tassie 1]

I've read that there should be a relay somewhere that I've yet to find !

Should be in a little metal or plastic box, probably up under the boats gunnels

 

[havoc_squad]

Should be in a little metal or plastic box, probably up under the boats gunnels

It is a plastic box and it should be mounted on the top of the exhaust cover, where two screw mounting holes stick out on the plate. That would contain the relays for the tilt and trim system and the wiring for it.

I checked the exhaust cover part number and it is the same as my V4 90 HP motor for your year. So if your exhaust cover has those mounting holes, it should be there.

If the motor does not have it, the PO was a bit destructive with their removal or never bothered to fix it. Which would concern me because if someone doesn't fix the tilt and trim, they likely expect the motor to not be of much value or use.

See if you can get your hands on that tilt and trim wiring/box assembly. If not, you may have to do a mix of used E-Bay part shopping and new parts buying to fill in the missing parts.

 

[racerone]

The spot for the relay box is shown in the third picture.

 

[Thirsty Endgrain]

Thank you, I thought those bosses might have been for the relay box, now confirmed. Ok so I'll have to hunt one down (if the motor checks out first of course).

Can you just feed the blue or green wires 12V to get the motor to pump? I tried straight from battery but the motor didn't engage, is there a transformer in that relay box that steps voltage? Realizing I need to confirm it has a good ground.

Been trying to do the comp test still, When all of the plugs are out and the gauge isn't connected the strater will turn the motor at a good speed. As soon as I connect the comp tester, it will only turn over 1-2 chugs per second. With all plugs in it's more like 1 chug per second.

Gonna just bypass the solenoid with jumper cables I think, to rule out solenoid and batt cables for now.

Doing the test in this way I'm getting 90PSI in all 4 cyls, but I'm wondering if the slow starter is suspect, also it's a harbor freight gauge and I don't necessarily trust its numbers.

Racerone you mentioned in my other post to pull off some kind of cover to get a look at the rings, but I'm still trying to figure out where that is. I'll look again because a visual inspection would be helpful.

 

[havoc_squad]

Doing the test in this way I'm getting 90PSI in all 4 cyls, but I'm wondering if the slow starter is suspect, also it's a harbor freight gauge and I don't necessarily trust its numbers.

Racerone you mentioned in my other post to pull off some kind of cover to get a look at the rings, but I'm still trying to figure out where that is. I'll look again because a visual inspection would be helpful.

Compression gauge from Harbor Freight, I would definitely say don't. They do have some good tools at quality prices that I own, but that "ain't" one of those good tools.

You might try an OTC or Bosch brand, those are usually found at local Auto Parts stores. You might even be able to do a loan-a-tool a higher end compression gauge.

Bypass covers look like a trapezoid shape. They are on the outer sides of the motor, directly adjacent of the engine heads. There is one per each cylinder.

If you look at the fourth picture, and remove the starter solenoid, you'll be staring right at a bypass cover.

 

[Thirsty Endgrain]

Usually I only buy things like sockets or a screw-style tranny jack at HF, this was one of the rare occasions that I tried for what should be a reasonably accurate tool. I was hoping it would be close enough, and at least show me that the cyls were within range of each other. It was on sale for $20 and I think I'll just take it back and go for a better one like you're suggesting. Thanks for the intel on the bypass covers!

 

[CatTwentyTwo]

There are 2 diagrams for tilt & trim in my manual. One with a fuse and one without, no idea which yours might have had so this is the one with a fuse.

 

[Thirsty Endgrain]

Quick update, so I guess I didn't realize that the tilt/trim motor simply runs on + - with polarity reversed for opposite direction. I thought for some reason that the motor was grounded and you apply voltage to one or the other. Tilt and trim works perfectly! Luckily my uncle came over and showed me around the outboard a bit, (been a commercial fisherman for over 40 years, so, knows a thing or two). Now just need to track down the relay, since I know it functions.

Starter motor is not working properly, makes crying banshee noises and won't turn engine fast enough, even directly jumped to contacts from a running vehicle - just to make sure. Sooooo new starter on the way. Few days out.

Just replaced impeller and will probably hang it up until the postman arrives with my present. Thank you all!

 

[Thirsty Endgrain]

Hey y'all, a couple of questions:

-I have a newer fuel pump from the '77 Johnson 70hp, and I'm wondering if I can retrofit it to this motor? I'm ditching VRO and mixing. Pic attached. There are mounting bosses for the thing that seems like I can just slap it on and it receives pulses from where the VRO pump takeoff was. Do I then just plug off the barb at the bottom, or does that need to connect somewhere else, like receiving pulses from the other side of the crankshaft? If the pump works right now with the oil line blocked off I'll just let it lie, but if the old VRO pump doesn't pump fuel I want to be able to swap the other pump in correctly.

-Attached is a pic of where the main engine ground was connected, and it doesn't look right to me. The cable lug is the wrong size for the stud, it's something like a 1/4" stud and a 5/16" or 3/8" lug size (don't have in front of me to measure but the pic shows). Should the main ground lug be connected to the starter attachment bolt, the one that goes directly to block? The sizes work so it seems like sound reasoning to me, but I can't find info to confirm.

LU back on, refilled with fresh oil, new impeller. Old oil looked in quite good condition. Timer base was sticky so pulled flywheel and cleaned everything up. Moves like a dream now. Starter here tomorrow. Almost time to cross fingers and crank...

(Pics on page 2)

 

[Thirsty Endgrain]

[No message]

 

[Thirsty Endgrain]

I'm hoping someone might have answers to my last questions, appreciated if so.

Starter was supposed to be here on Thursday but ups lost it. Of course. I'm still just hanging here and waiting for them to find it, if they don't tomorrow I'm going to order another one (maybe via FedEx this time). So I STILL don't know if I can get this thing to run. Thanks in advance!

 

[Thirsty Endgrain]

Well following up. After a lot of bungled ups'capades the starter arrived yesterday. Slapped it in and boom! Fired right up. Now I have next to zero experience with outboards, so I'm unsure of what this thing should sound and look like while running, and I have a couple of questions related to that. Hopefully the video will link here:

-there is water coming from places and I want to make sure it's from the correct places. When I reinstalled the LU after impeller replacement the washer/gasket/grommet that slips over the driveshaft wasn't in great shape, and didn't make any real kind of seal over the impeller housing. I'm wondering how important that is? Does it keep water from coming up and out of the water pump?

Related to that, in the video at the end I'm showing where the water is coming from at the front of the LU, and some seems to be coming from behind where the LU pivots, may be hard to see but those with sharper eyes and experience will know I'm sure.

-I can't tell if it's running rough at all, it jumps around a little, but I don't know how smooth it's supposed to be?

tried to get comp numbers one more time from the hf gauge I got but it just shows 95-95-100-95 and I don't trust it's numbers at all.

Thank you!

https://youtu.be/KhivY1ctgjk

 

[TrueNorthist]

If I could intrude for a quick rant... Take every can of wd40 you have and throw them away. Unless you actually need an explosive water displacer. It is NOT lubricant, it might clean a little and it will prove useless for virtually everything else claimed on the can. Use fogging spray, honey goo or fluid film. Heck, dilute some 2 cycle with kerosene and put it in a pump sprayer. Melts the rust in my woman's heart and works even better on stuck rings.

Oh, and seafoam (etc) is a scam. Mechanics do not live in little bottles of snake oil.

\rant

 

[Thirsty Endgrain]

I don't know, why don't you tell us how you really feel?



I won't be throwing away my wd-40 now or ever. I just use it for the things that it's good for, no more and no less. No decently self respecting person ought to believe that there is such a thing as a mechanic in a can, but personally my fingers are too big to pick the carbon piece by piece out of a powerhead, so I'll give a chemical the benefit of the doubt in this case. If it doesn't work you're free to say I told you so.

If anyone felt like perusing my questions well, I'd really appreciate it...