Intake manifold gasket

[Chumlee]

1984 90hp
Behind the spark advance lever it looks lihe the intake has a leak. it is wet with oil that kinda runs back towards the bleeder intake but hasnt made it there yet. There seems to be no wetness towards the front side of the gasket which is the intake. Motor is a little hard to start have to give good hard squeeze on primer bulb and a shot with primer selonoid. When the motor is at idle is fluctuating rpms between 1200 to around 950. When in gear at low speed motor surges just a bit. when open to just before 1/4 throttle it takes right off and seems good all the way to wot. Its just the low speed surge. I have rebuilt carbs, replaced all fuel lines, replaced exhaust cover gaskets because of water leak, decarbed, replaced spark plugs gapped to .030, and added water separator with extra inline filter, ran compression check- all cylinders were from 120 psi to 123psi, removed vro and put on new non-oil standard mallory pump. Change all bleeder hose and the little plastic tee. I think thats about it.
I have order intake gaskets, leaf plate gaskets, and carb to intake gaskets.
When I remove intake is there anything inside I should be checking while i have it opened up? Next is when putting it back on is there tightening sequence like a car? Or should I snug then start torque in the center bolts and work my way outside crossing back and forth like you would on a car ?
I have the torque poundage from the solec manual for size range of the bolts.
Just wanting to make sure I am going about this right to do it right the first time.
Thanks for your time and patience.

 

[tx1961whaler]

Re: Intake manifold gasket

Before I took the intake off, I'd spray around with some WD-40 to see if I could pinpoint the location of the leak. The engine will speed up when you hit the spot (if the leak is big enough...)

 

[Chumlee]

Re: Intake manifold gasket

I will do tomorrow with the wd40. Thanks

 

[emdsapmgr]

Re: Intake manifold gasket

Any air leak of this type is critial and you are correct to try to address it. An air leak of any type will cause the engine to run lean and that can cook the powerhead innards quickly. Fixing an intake manifold leak is not too difficult-other than a few hours of labor and a gasket. Not a big deal. Check to make sure it is not a leak between the two crankcase halves. That's a big deal.

 

[Chumlee]

Re: Intake manifold gasket

EMD, I think u hit the nail on the head.
Here is a pic.
First arrow on left puddle of oil
middle arrow- is gasket between crankcase (was oily, wipe metal off with finger)
third arrow on right- is where it seems to be running towards intake and down to timing lever.
How big of project is it to replace gasket?
will do some reading in manual tonight.

 

[emdsapmgr]

Re: Intake manifold gasket

It is unusual to see a crankcase leak in this area. Suggest you check something else first. Those drippings could be from the stator under the flywheel. I'd remove the flywheel and just double check the stator to be sure it is not deteriorating and dripping onto the block. If the stator appears ok, at least you will have a better view of where the leak may be coming from. You can get a good parts diagram that will show your engine component relationships off the web: epc.brp.com

 

[Chumlee]

Re: Intake manifold gasket

Not trying to argue here and i know this will sound like it.
But if it was something under flywheel wouldnt be all over the top of motor and not designated to one area?
I looked under the flywheel (attached to motor of course) and the bearing housing which i believe it is called, looks pretty clean. If it were the stator are the low throttle surges symptoms of bad stator? Or would a stator going bad effect a motor thru out the whole rpm range? I guess I should pull the dang plugs and see if they show a lean condition, but plugs are fairly new, dont know if it will show up on them yet.
Thanks again

 

[emdsapmgr]

Re: Intake manifold gasket

The center arrow indicates the point at which the two main crankcase halves are bolted together. The gasket between these two halves is actually a type of gelatin seal that is impervious to gas and oil. Usually this seal is long lasting and is a low failure seal. If it does not seal completely, it will cause a leak. The crankcase alternates between suction and compression every rpm. If there were a leak in this area, you should see evidence of this leakage/suction every rpm. Spraying carb cleaner by this type of leak will usually raise rpm's slightly due to the enrichement of one cyl.