Johnson 90HP head gasket replacement

[sixdeep]

J90TLETS - 1993 Johnson 90HP v4
Ive gotten a complete powerhead gasket set just in case there are extra things to replace. What i wanted to know was what the head bolt torque settings are and if there are any other bolts that need a specific torque setting?
Any other tricks/tips would be great. It looks pretty simple to do from the outside anyway.

Appreciate any help

 

[emdsapmgr]

Re: Johnson 90HP head gasket replacement

18-20 ft lbs. Work in a circular direction from the middle of the head outward. Best to retorque them after the engine has gone through a couple of heat/cool cycles.

 

[Charlie in TX]

Re: Johnson 90HP head gasket replacement

Use anti-seize. Run a tap into the block and a die over the bolt to clean threads.

 

[boobie]

Re: Johnson 90HP head gasket replacement

If you use anti-seize make sure you get the right one. I always use OMC gasket sealing compond or Permatex # 3.

 

[durban]

Re: Johnson 90HP head gasket replacement

most important if you gonna use the deflectors make sure you put the slot for the water in the correct way , otherwise gona over heat , plan B . works ,

 

[V153]

Re: Johnson 90HP head gasket replacement

Coincidentaly I'm in the midst of a cylinder head job on my 140. Same block, mine just has bigger carbs'n less restrictive exhaust. I'd leave the "water pass divertors" in place. Better yet replace with new. Mine are where they're sposed to be'n "look" good. But hell they're 30 yrs old. Heard horror stories about them detiriorating & plugging up the water jacket. I'm gonna replace em.

 

[Bob_VT]

Re: Johnson 90HP head gasket replacement

most important if you gonna use the deflectors make sure you put the slot for the water in the correct way , otherwise gona over heat , plan B . works ,

Great idea since you are in the motor. I do mine with every head gasket change.

 

[durban]

Re: Johnson 90HP head gasket replacement

,........................thks

 

[V153]

Re: Johnson 90HP head gasket replacement

I do mine with every head gasket change.

Considering the minimal cost, I think you'd have to be a fool not to go ahead'n change 'em out.

Are those deflectors not included in the 'complete' gasket set? Boy you'd think they oughta be. Hmm. I got mine from a buddy today, $10 for all four. Fyi Sierra part #18 0892 (OMC #322411)

I suggest you check your heads with a straight edge to see if there's any warpage. If you suspect any, it might behoove you to bring em down to your friendly local machine shop'n have em decked. The boys bead blasted & knocked a couple thousandths off the face of mine, for $20. Your price may vary but it shouldn't cost a helluva lot more than that?

Good luck.

 

[powrguy]

Re: Johnson 90HP head gasket replacement

most important if you gonna use the deflectors make sure you put the slot for the water in the correct way , otherwise gona over heat , plan B . works ,

What "slot" are you talking about? Slot in the head gaskets? Aren't they all marked with "this side out", or some other info?

 

[powrguy]

Re: Johnson 90HP head gasket replacement

J90TLETS - 1993 Johnson 90HP v4
Ive gotten a complete powerhead gasket set just in case there are extra things to replace. What i wanted to know was what the head bolt torque settings are and if there are any other bolts that need a specific torque setting?
Any other tricks/tips would be great. It looks pretty simple to do from the outside anyway.

Appreciate any help

Make sure the gasket surfaces are CLEAN and DRY. Chase the threads in the block with a tap. Change the water deflector tubes and make sure they are flush with the head surface when you install the head, and not protruding above the cylinders to interfere with torquing and seating of the head on the cylinder. As someone else mentioned, CLEAN the bolt threads with a die, and use the OMC sealant on the threads, NOT Loctite, as you'll be re-torquing them after a few heat/cool cyles, to assure proper sealing and bolt tension.

 

[sixdeep]

Re: Johnson 90HP head gasket replacement

Thanks for all the info, very much appreciated.
Got all the head bolts out with none snapping which made me very happy. The powerhead set doesnt come with deflector tubes but now ive read about them i'll order some before i reassemble and get that OMC sealant. I'm in New Zealand so bit of delay getting parts from the states but its way cheaper than local. Will price the tubes locally first.

Is it recommened to also remove the cover on top of the head and replace that gasket and clean the heads? I snapped 1 bolt undoing them all on one head but it should be able to either drill and retap or maybe even ezyout it.

Also the water galleries in the block look like the have a bit of gunge in them. I assume that's normal? Do people clean them somehow?

 

[danoutbard]

Re: Johnson 90HP head gasket replacement

Dont forget to never use liquid scealent on the headgasket....its in every repair books
Good luck

 

[sixdeep]

Re: Johnson 90HP head gasket replacement

Dont forget to never use liquid scealent on the headgasket....its in every repair books
Good luck

When you say dont use liquid sealant on the headgasket i would have thought you dont need to put anything on the headgasket? just clean the faces then put the headgasket in and sealant on the bolts ?

 

[powrguy]

Re: Johnson 90HP head gasket replacement

most important if you gonna use the deflectors make sure you put the slot for the water in the correct way , otherwise gona over heat , plan B . works ,

You're talking about the "slot for the water", meaning the slot in the head gasket, right? Aren't they all marked "this side toward xxxxx", or something, so you don't put them in with the wrong face out, and have the water passage slot in the wrong place? The deflector tubes are simply a rubber-hose-like gadget, that is pushed in place and routes the water around the perimeter of the cylinders?

 

[danoutbard]

Re: Johnson 90HP head gasket replacement

When you say dont use liquid sealant on the headgasket i would have thought you dont need to put anything on the headgasket? just clean the faces then put the headgasket in and sealant on the bolts ?

Nothing, no sealant on headgasket, at leats for my 90 V4 crossflow 1985.

Double check for your motor.

If you want to lock the bolts its up to you.

 

[sixdeep]

Re: Johnson 90HP head gasket replacement

OMC gasket sealing compound was $50 in a bug tub which i dont need so i grabbed some permatex #3. Removed the head covers, cleaned up all the water galleries, stripped the old gasket, cleaned all the bolts up and refitted with some permatex on the threads.

Have removed the exhaust housing cover too and done the same, not sure if you're meant to be did it while i was there.

Cleaned up all the head bolts and replace the water deflectors. The old ones came out really easy, just a pull with some long needle nose pliers was all it took. Cleaned up the build up where they sat, lubed up the new ones and they slotted 95% of the way pushing with thumb. Pushing with the pliers was all it needed to get them flush. Ready to reattach the heads once i borrow a torque wrench. Is there a torque setting for the head cover bolts? I just snugged them up tight. Havent torqued the exhaust cover ones either if any one knows what they should be?

 

[durban]

Re: Johnson 90HP head gasket replacement

1\4 inch threads , torque 60-80 In\Lbs , Ft\Lbs 5-7, newton meters 7-9 . for head cover