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180 PISTONS MAKE A BIG DIFFERANCE?

J

JD

Well-known member
Have'nt posted in a while but been reading. I still haven't done anything different to the 180. Still does most everything I want it to do but it won't run dry. Went on a bad ass bowffishing trip a couple of weeks ago and shot 5 big buffalo and 7 huge flounder. My only chance to get this thing to run dry seems to be to pull a cylinder and check the pistons, to see if by some small chance they are the low compression ones. If they are, it's a $500 for parts fix. Don't know what the labor would be. And that's used parts. If I read it right, the low comp 180's are 168 HP. Would that last 12 HP make this thing move on the dry????? And the bolts from the cylinders to the case, where do you get a wrench to fit them? They look like a big allen head with not much room around them. Seems like I could check the piston on one cylinder myself if I had the right wrench. IS IT THAT COMPLICATED or is it a matter of torquing it back down right. I'd hate to get into it and put it out of commission right in hunting season.
 
JD,

I kinda doubt that changing the pistons is going to make the difference. I have had boats with 150 gpu (pe90) that would run dry with two people for miles. I would look at the hull and setup before doing engine work.

Grant
 
Just my opinion:
14% increase in Hp isnt much. If it wont run dry now it MIGHT run dry with the increase but if you stop I doubt it would get going again.
Tim
 
Hey JD,
I bought a pair from Aircraft Spruce and had to replace one. Here is a link for another place that sells them. You will need the 1/2" and 3/8"
internal hex wrenches. You should have these wrenches for proper torque.
http://www.skygeek.com/cylinder-wrenches.html
Buy yourself a manual and follow the guide-lines for torque. If you pull a cylinder to check a piston I'm not sure how you will identify it unless you have another to compare it with. Also those internal style nuts can be a real b!+ch. Be prepared to have to replace one or two maybe they might just strip out on you. Also have a cyl base seal on hand so you can put it back together. A good piston ring comp your gonna need too.
The other thing is if you decide to replace the pistons your gonna have to have the cylinder ID'd for the right replacement ring sets. Is your cylinder barrel steel, nitrided or chromed? I learned this the hard way.
75089 piston is the 8.5:1 piston. This is the standard piston for 180hp.
15357 is 9.1:1 h2ad "helicopter" piston. And there is another aftermarket piston that will push the compression to 10:1.
 
Consider a leak down test to make sure your compression is good in all four cylinders. If your engine is 180hp you might consider using the money in another direction. What are the numbers on your prop? Maybe consider that. Sensenich wood props are maybe another $250 over what you are considering spending. Or maybe replacing the hull. Now thats quite a bit more but if these two things were right that 180 should push you along pretty good.
 
what size hull and type of metal work do you have. What kind of prop. The ideal set-up for a 180 is a hull under 12ft.(Light Weight) w/ slick bottom, a light but strong set of metal-work, and the correct prop, whether it be a stick prop (wood) or a good composite. On a set up like this it would scream on the hill!
 
hey JD, i just replaced a cylinder on my 0540 SV. i got mine from Gibson aviation in Oklahoma. came with a all the seals and gaskets needed for like 290 bucks. really good people to work with. also, when you use those internal nut wrenches, just make sure to soak your cylinder nuts with penetrating oil for a few days and most importantly HOLD THE WRENCH LEVEL!!!! i thought it was gonna be impossible but those nuts are only tourqued to 40 and 50 lbs. the nut end of the wrench may not go inside there but 1/8 of an inch, but if you hold it level and push in hard you'll be alright. it was a lot simpler to get the nuts off than i thought it was gonna be. you may also want to get a new piston pin and some feeler gauges to set the clearance on your valves 28-80/1000ths. i didn't know jacks@#% about it until my airboat mechanic taught me through this one. but, i still don't know jack...lol
 
What do the plugs look like, clean, alittle brown?.....mkae sure the carb is working not pluged up...check your timing with a timing light, it should be 25 deg. on the flywheel.......a composit prop will make a diff too...
 
good point davie, my carb intake screen was clogged making me run too rich. i fixed that problem and changed the plugs.....i swear i gained 40 hp
 
Let me see if I can address all the respnses. The engine had a compression check and all cylinders were around 130 with one being 118(the oddball). Timing checked out at 25 degrees, carb butterfly wide open at WOT, The boat was 10' 9" and I added 2' to it and added poly. It's got a 3/16's bottom 5' wide and the sides are 1/8". The boat is now 12' 9" with poly and not a dent in the bottom. No cupped areas, I'm telling you it's brand new FLAT. The cage has 2 pipe hoops around the prop and the rest of it is EMT. The boat is 72" wide at the widest and a 68" prop is unsafe with only 3/4" clearance so I went with the 66" Whirlwind. On dry cut lawn I set the prop to turn @ 3000,3100.2900 etc and the boat never even tried to move until I turned the prop to 22 on the scale and the motor maxed out at 2500, THEN IT WOULD ACTUALLY INCH FORWARD. Some months back someone on this forum knew someones boat that had a 66 WW set @ 22 and their 180 turned 2900....That's a huge differance. At the 22 degree setting if mine would turn 2900 and the boat would start to move at 2500 then I know it would run dry. THIS BOATS NOT THAT HEAVY, AND I ONLY ADDED THE 2 FEET BECAUSE I WAS NOT PLANNING ON USING IDT EXCLUSIVELY IN THE SWAMP ANYMORE........oops, didn't mean to yell.....Anyway....the damn thing oughta run dry...Thanks for all the responces......but it ain't over with yet.....worn cam???? low low compression pistons/???? I dunno!!!!
 
it's your hull bottom...5' just isn't wide enough to displace any weight.
gotta be wider... replace the hull.
 
dblj might be right. i have a 200 angle valve with a 68" inch air prop that will scream. however, the hull i have it on is an old old hull that is only 5' wide with a slight V in the very front (i told you it was old) and it won't run dry. i know for a fact if i put it on a modern ultra light hull this baby would climb trees
 
Does your hull have a jack plate in it?
My hull is 11'8" and Five and a half wide at the bottom
and does just fine on the ground.
What style hull is it, some hulls don't have enough crown on
the bottom and need a jack plate.
 
Midnight, the boat has jackplates (2) and I jacked them all the way down when I played with it in the yard and all it would do is rock from side to side on the bulge it created in the bottom. I wish I could put a picture on here to show everyone the boat, it's like new with no hooks in the bottom and other than high sides it's just bare boat, no extras to add weight. There are guys I hunt with that have shorter and narrower boats than mine with smaller motors (150 HP lycomings that run dry with no problems and they are narrower to the point that their cages stick out 6" on each side of the boat. I would rather have mine though because if you run in trees allot you know what a problem that is everytime your cage hits a tree and hangs you up in the back. Anyway, thanks for all the input. JD
 
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