"New" '84 Johnson 90HP V4 - questions

[oldboat1]

Time to put it in a barrel and see how it runs. Sounds good on the muffs -- and you got a look at the venting. Predict it will be nice and quiet/smooth in the water (about half way up the leg btw, well above the pump).

 

[Thirsty Endgrain]

Ran it for about 3 mins the other day after finally getting it hooked to the boat with controls et al., and noticed that the port side head was almost too hot to touch. Starb side was nice and cool. So naturally did a little bit of investigating and found a bunch of corrosion in the heads' cooling passages. Tested the thermostats after a somewhat painful extraction process (why did they make access so difficult? At least this is not the bubble back motor).

Strangely the port side seemed to function with the hot water/cold water baths, and not the starb side. Either way I'm replacing both along with poppets, grommets, diverters etc. I did the best I could to remove the corrosion, dipped heads and covers in salt-away (or whatever it's called) for like 20-30 mins, which really didn't seem to help that much. Got in there with brushes that I could find, but still there are deposits.

Are there some better methods to remove the corrosion, or is it just painstaking no matter what?

There were salt deposits filling all the little grooves in the head covers, which seems like they're supposed to be dry, but I guess over time the gaskets degrade and don't hold the water back anymore?

Lastly, I've read up on this but want to make sure. I have the sierra gaskets for the head covers, do they need any kind of gasket compound, like the Johnson gasket sealing compound that remains semi-liquid?

Lastly lastly, the cylinder walls look great. Almost not a single score anywhere. Nothing perceptible by feel. Some of the (I'm assuming, but is not necessarily) original cross-hatching is still visible.

 

[emoney]

Motor sounded ok in the video. However, you had water coming out everywhere EXCEPT the "telltale". That little black rubber hose that exits the cowling on the starboard (right) side in the read should show a steady stream of water. Thats how you know the boat is cooling. Usually a water pump needs replaced if you haven't already.

As to compression guages; as long as the numbers are even you'll be ok. You can normally borrow those from the Auto Parts store, btw, if you're concerned about the HF ones you have.

Tilt/Trim; "Blue" = sky, "Green" = grass. Easiest way to remember which wire is for up and which is for down.

 

[Thirsty Endgrain]

Have done a lot since that video, the telltale hose was a bit plugged, as well as it has a WP gauge teed into that hose was just spraying freely elsewhere too. Stream is nice and strong now, thanks for the feedback! The comp numbers were even, within 5-7 PSI I think?

WP is new. Though I do have a question about that, which is that the Sierra impeller kit had an o-ring in it, said to use it at the base of the impeller, which I did. Then I realized that there's supposed to be an o-ring at the top of the crankshaft, and was wondering if that o-ring was actually for the top of the crankshaft (@ crankcase). I put one in that I had around that seemed to fit, but I am about to pull the LU again to replace the intake screen, as I found bits of it chipping off. So will re-inspect that crankshaft o-ring, but is there really supposed to be an oring at the base of that Sierra impeller?

 

[emoney]

Did you get the WP kit? If so, it should've come with the O-rings that were needed. I've never owned a 90hp, so I can't answer that question for you. I do recommend you try to find a Factory Service Manual. They're still out there and it's the only source I trust for those type questions.

 

[iggyw1]

Thirsty Endgrain, I disagree with getting rid of the Seafoam as well as the W-D40. Seafoam is not a scam in my opinion. I use Seafoam religiously, and it keeps my 70 H.P. motor running nice and clean with no problems so far, and it is a 1992 model. I had a motor before that was soooo carbined up, I gave it a good, heavy dose of Seafoam in the gas and the junk came right out of the exhaust. Cleaned that motor up real nice and it ran great afterwards.

 

[racerone]

I would sand blast those heads and covers.----Good way ( quick too ) to clean them up.

 

[Thirsty Endgrain]

I would sand blast those heads and covers.----Good way ( quick too ) to clean them up.

Was gonna try to pressure wash, but I have a friend with a bead blaster. Would bead blasting also work? Or needs to be more aggressive like sand?

 

[racerone]

I am sometimes frugal / cheap.------I go to the beach and select the right sand for the job.-----Bead blasting works too.

 

[Thirsty Endgrain]

I might be able to soda blast, seems like the best option.

Can anyone speak to the necessity of any kind of gasket sealing compound for the head covers?

 

[Thirsty Endgrain]

Still wondering if anyone has insight into the head cover gasket questions above.

Also, I have a new valve body for the thermostats, and one that came with a used cover I got off of eBay. The new valve body has one little hole at the bottom, and the older one has two little holes. I'm assuming these are some kind of bypass, should I use the new one with one hole or the old one with two?

 

[flyingscott]

Leave the Vro pump and just disconnect the oil line from the motor and plug it. Then unplug the pump electrical plug. Then disconnect the tank wires.

 

[rebuilt]

On page 4-19 of my '89 OE 60 hp service manual, under power head it states, "Install cylinder head using a new gasket. Use no sealer." It's gotta be the same for your 90. I'm following this thread cuz I have the exact same engine in addition to my 60. Best of luck.

 

[rebuilt]

I was gonna edit but it was too late. I have the same engine, yes, but no OE service manual for it. Yet. That's why the refernce to an '89 60 hp. Still looking for the OE manual. Not gonna hijack here. I've got a thread open for the manual search. Best of luck.

 

[Thirsty Endgrain]

Thanks Rebuilt. I'm wondering about those head cover plates more than the heads themselves. I have a pdf copy of the manual, which is great, but I'd really like a print copy. Who the heck wants to look at a computer while working on an engine? Like said in the Hitchhikers Guide to the Galaxy, "they invented books first AND THEN computers, totally backwards!"

In my manual, for head installation it says,

"Place a NEW head gasket on the cylinder block. Head gaskets for late model powerheads are clearly identified as to which side faces the block and the head. Take an extra minute to be sure the gasket is properly positioned. If the gasket does not have any identification, it may be installed with either side facing the head. Check to be sure all bolt holes are properly aligned, indicating the gasket is positioned properly end-for-end. NEVER use automotive type gasket sealer. The chemicals in the sealer will cause electrolytic action and eat the aluminum faster than you can get to the bank for money to buy a new cylinder block."

One, I hope this person is still writing manuals.

Two, interestingly it does not say whether to use sealant or not, just which kind NOT to use. Ambiguously written IMO.

 

[flyingscott]

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

Disappointing, how does that help the OP ? Of course WD 40 is a Lube.

 

[Thirsty Endgrain]

Disappointing, how does that help the OP ? Of course WD 40 is a Lube.

Actually made me look even more fondly at my WD-40. It's so............controversial.......