1998 75 force head gasket

[TwoFish]

Motor 1998 75 Force.

I?m planing on replacing the head gasket & inspecting the exhaust plates at the next service. I?m running the motor in salt water and as far as I know they haven?t been looked at before.

Can the lower cowling be unbolted and lowered or do I need to remove the powerhead to get to the bolts if I need to use heat?

The thrust washer for the prop seems to be seised on. Does it need to be loose enough to remove easily? Is there any trick to removing it?

I found out the previous owner had it service at the local lawnmower shop.

Any help would be appreciated.

Dean

 

[jerryjerry05]

Re: 1998 75 force head gasket

As far as removing the headgasket,you should be able to undo the bolts with a socket wrench.If they don't move easily then re-think taking them off.You can twist the head off and then your doing a lot more work.Start with PB Blaster.Start spraying the bolts.Do this for a couple of days.
The cowling you can loosen it and it will move back.taking it off I believe the PH needs to come off.
The exhaust plate.The bolts that hold it in place are weak and the heads will twist off REAL easy.If it's not leaking I'd leave it alone.Again PB Blaster at least a week before you try to loosen it.
Take the prop off and turn it over,place it on the ground or work bench.Use a long screwdriver or punch and try a hammer through the splines.It should pop off.
Now that you own it you should run it on land after every use.Change the impeller.Make sure the oil in the lower is clean and replaced at least every year.J

 

[TwoFish]

Re: 1998 75 force head gasket

Took the boat out today for a run (Like I stole it). It ran well. No missing. Plugs looked fairly even considering being fed by 1 carby. Top plug cleanest with the bottom plug the dirtiest.

Noticed a couple of things.

Chugged a bit at idle. Idle is set too low 650 rpm. Which could account for why it dies away and stalls sometimes. Probably needs a good tune.

There was a lot of salt build up along the bottom of the exhaust plate. I?ve noticed this before but this time there was more. Possibly from running the motor harder than normal. I take it that isn?t a good thing.

The thrust washer I mentioned earlier is stuck on the gearbox shaft. It has been like that since I?ve owned the boat. I thought of heating it slightly & giving it a very light tap. I'm concerned about it corroding into the shaft.

I?d like to get on top of the maintenance with this motor. Just not sure how far I need to go.

Thanks for the help!

 

[jerryjerry05]

Re: 1998 75 force head gasket

You use heat on the prop shaft your gonna end up resealing the lower unit. Try tapping the washer with a small hammer.It shouldn't be that stuck.
As far as salt on the exhaust housing.It's gonna get there.If you get lucky and remove the screws.Then change the gaskets.It gonna do it again.
Try to loosen/tighten the screws.GENTLY!!!! You might get lucky and they come loose.
Adjust the idle:in gear and warm about 750-800 RPM
Reset air screws same way warm:just bottom out and turn out 1 and 1/8th turn.turn in till it starts to cough/stumble, then out 1/2 turn.
As far as regular maint.Keep the plugs clean.Carry an extra set on board.Do a compression test every so often.
Use fuel stabilizers.They putting ethanol in your fuel in AU.??
Make sure the lowerunit oil is clean.
Outboards are designed to RUN, ideling or trolling is harder than running wide open.They carbon up faster.And letting them set isin't good for them either.J

 

[TwoFish]

Re: 1998 75 force head gasket

Thanks for your help again.

I?ll have a go at side plate this weekend. I?d like to see what condition the water galleries are in (Run in fresh water mostly before I bought it 2 yrs ago). I?ll take it really carefully. Can?t say I like the idea of going to all the trouble of replacing the gaskets and having the salt coming out the side plates again quickly.

I plan to do a full service on the motor once I have the gaskets sorted.

In Adelaide, South Australia, Ethanol blended fuels are available but are not the norm yet. Unleaded petrol (91 octane) is to be fazed in by 2012 and replaced with E10. This will leave us 95 octane or 98 octane petrol without Ethanol. Not looking forward to it.