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Pressure test 717 on sportster 1800

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kgray61340

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Hello started my pressure test today :thumbsup:

Started with engine cooling system and pressure held good there :thumbsup:

Next was Bottom End and Top End It would leak down and I checked everything and everywhere with soap and water mixed and couldnt find a leak . Directions say then to block off inlet oil nipple to rotary valve and the return line for the rotary valve and see if it quit leaking down . And thats what it did ! :cheers:

Next was the Rotary valve shaft testing This is where it was leaking down at a good rate :( I checked the Plug for the Rotary shaft in the crank case no leaks .

Tried these two below : and the gauge show no noticable difference when the spark plug was loosened . same amount of pressure drop :(

Remove PTO side spark plug. If pressure drops, it
indicates a defective PTO side crankshaft inner
seal.
Remove MAG side spark plug. If pressure drops,
it indicates a defective MAG side crankshaft inner
seal.


sooooo I removed rotary valve cover and checked the rotary valve shaft seal and couldnt find a leak there either

sooooo I believe that meens that the crank case halfs is where my leaks are and the reason i get black oily plugs

Gonna start by removing magneto flywheel tommorrow and PTO flywheel and then check manual for next move :cool:


one more thing i took a video of the rotary valve splines and i could turn it back and forth three splines at a time with out the crank even moving dont know how to get video on her yet so any comments would be apprieciated :cheers:

http://www.youtube.com/watch?v=Vt2aCks6i08&feature=youtu.be

2013-09-03 16.41.24.jpg2013-09-07 18.22.52.jpg2013-09-07 18.23.17.jpg2013-09-07 18.23.37.jpg
 
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kgray61340 said:
Hello started my pressure test today :thumbsup:

Bottom End and Top End It would leak down and I checked everything and everywhere with soap and water mixed and couldnt find a leak . Directions say then to block off inlet oil nipple to rotary valve and the return line for the rotary valve and see if it quit leaking down . And thats what it did ! :cheers:

View attachment 21982View attachment 21983View attachment 21984View attachment 21985
Click to expand...

So, this leads me to believe you have a leaking crankshaft seal.
 
I think its the crank case leaking because the pressure didnt change when i loosend the spark plug ? im not sure first time ever working on one of these motors . so this is all new to me :)
 
kgray61340 said:
do you think it is one of the inner crankshaft seals or the outer seals near the flywheels ?
Click to expand...

Yes, some of the wording is confusing (for example: "I checked the Plug for the Rotary shaft in the crank case no leaks.") but if the crankcase leak stops when you block off the RV inlet and outlet oil nipples, then it means air is leaking from the crankcase into the RV gear oil bath cavity, no?

I can't tell if you pressurized the RV cavity itself to test the other way but it probably has oil in it, so any leak may be slow due to viscosity.
 
kgray61340 said:
do you think it is one of the inner crankshaft seals or the outer seals near the flywheels ?
Click to expand...

You didn't mention (as far as I read) if you pressurized PTO and MAG separately or both together, so not knowing this all I can say is it sounds like the inner crank seal that keeps oil from the RV gear bath from flooding into the crankcase, but cant' tell from the description too which half (PTO or MAG) the leak is occurring.

I can't understand the conclusion for why the leak is at the case halves mating flange if the air leak stops when you plug the RV oil nipples.

But, perhaps there's something in the shop procedure that explains how that would be in this or that case...... (intentional play on the word "case" as in the "engine case" vs in the "case" of a leak somewhere).
 
I did drain the oil from Rv cavity .

when i say plug for rotary shaft i meen the round circle plate under exaust manifold and near Rv oil return nipple (it looks like a freeze plug ) hope that helps lol

i pressurized the RV cavity threw the oil inlet side and blocked off the oil return side of RV
 
"Directions say then to block off inlet oil nipple to rotary valve and the return line for the rotary valve and see if it quit leaking down . And that's what it did"

Yes it did, but is it supposed to leak from crankcase to RV gear oil bath cavity? I wouldn't expect the answer to be yes. Maybe I misunderstand how that's good and/or normal.
 
kgray61340 said:
i pressurized the RV cavity threw the oil inlet side and blocked off the oil return side of RV
Click to expand...

And the result was there was no leak.....? That would be good.

But if there was an inward air leak in one side of the crankcase (PTO or MAG) then that cylinder would be running lean and burning the piston, not fouling on oil, correct?
 
this is where it kept leaking air but i couldnt find a leak and the manual said to losen spark plug to see if pressure drops then you would have an inner seal leaking depending on wich sparkplug you take out .

it was leaking down and when i took out a spark plug the pressure didnt suddenly drop it just kept leaking at the same rate that is why i assumed it would be the RV seal leaking but when i took cover off i couldnt find it leaking there either

so the manual says after that test you need to check the crank case halfs for defects and i figured it was just leaking from the sealant inbetween the case halfs hmmmmmm wish i knew lol
 
i did notice on one of my spark plugs rite on the end of it looked a little burnt i thought it was from me trying to adjust new carb and not knowing what i was doing
 
you could be on to something there because when i installed the new carb i didnt adjust the oil pump the rite way by lineing up marks it was putting to much oil in engine and the plugs were wet and oily but before i ever put the new carb on it was wet and oily too

the guy we bought the boat from said it ran great until we got to the water and found out different so i have learned alot in the last 3 months about this boat and how it works and havnt even had it on the water for some fun yet :( lol
 
kgray61340 said:
this is where it kept leaking air but i couldnt find a leak and the manual said to losen spark plug to see if pressure drops then you would have an inner seal leaking depending on wich sparkplug you take out .

it was leaking down and when i took out a spark plug the pressure didnt suddenly drop it just kept leaking at the same rate that is why i assumed it would be the RV seal leaking but when i took cover off i couldnt find it leaking there either

so the manual says after that test you need to check the crank case halfs for defects and i figured it was just leaking from the sealant inbetween the case halfs hmmmmmm wish i knew lol
Click to expand...

Okay, so you pressurized the RV gear cavity and it didn't hold air, it was leaking. But, was the crankcase completely sealed at this point, did you remember to plug your crankcase air pressure test port? If it was plugged, then there should be nowhere for the air to go until you removed a spark plug(assuming no leak at case halves). If yes to all this, then I'd be forced to agree about a leak between case ahlves but my next question would be why wasn't your bilge full of oil?

You must've bought a pressure test kit or something, or you've made your own. Anyways, kudos on actually doing the pressure test, which is the correct way to do it, as opposed to just guessing.
 
i will take the head off tommorrow and check that piston to see if it is burnt . if it was burnt on piston would that meen the air would have to come threw the outer crank seal and the inner crank seal to get to the piston ?
 
kgray61340 said:
the guy we bought the boat from said it ran great until we got to the water and found out different so i have learned alot in the last 3 months about this boat and how it works and havnt even had it on the water for some fun yet :( lol
Click to expand...

I'm confident you'll get it going, you're taking the right approach and you're on the right track.
 
kgray61340 said:
i will take the head off tommorrow and check that piston to see if it is burnt . if it was burnt on piston would that meen the air would have to come threw the outer crank seal and the inner crank seal to get to the piston ?
Click to expand...

I think I would concentrate more on the pressure testing results as opposed to removing the head right away just to get a look at the top of the piston.

If there is an inward air leak at the crankcase halves or outer crankshaft seal, the engine would draw in air from there while it's running, and the fuel:air ratio would be lean. This can cause a miss in the cylinder if large enough which would first appear at low engine speeds but at higher engine speeds it would simply run leaner than normal by some small percentage and it could cause all kinds of issues, mostly heat related, like detonation from a lean mixture which would erode the piston crown, or it could simply cause the piston temperature to rise, to the point the piston to cylinder wall clearance would become too small as the piston heats and expands, to the point the oil film breaks down and the piston skirt begins scraping on the cylinder wall. In this case, you could see the partial seizure as scoring on the piston skirt by looking into the exhaust port.
 
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yes i made my own kit took me all day to figure everthing out but i got the test done lol you know thats gonna drive me crazy wondering if i plugged that port on top of exaust manifold but to tell the truth i think it was open :(
 
one last thing before i goto bed i took off the rv cover with the oil pump attached to it do i need to put that back on to retest the rotary valve cavity ?
 
kgray61340 said:
one last thing before i goto bed i took off the rv cover with the oil pump attached to it do i need to put that back on to retest the rotary valve cavity ?
Click to expand...

It depends on how/if you plan to do more pressure checking, the RV cavity is still able to pressure check with RV cover removed but the crankcase obviously isn't.

BTW, the two bottom bolts holding the RV cover on, go straight through into the crankcase I believe, so if one of those didn't have sealer on them, then the crankcase could leak through those threads.
 
i did notice that both of the two bottom bolts had red sealer on them i thought it looked like red thred locker

what would you do next if you were me ? thanks again !
 
Good morning sportster I was curious if you saw that video of rotary valve ? Is that a lot of play or normal ? The link is in the first thread on YouTube. If timing was off a little would that cause a little lean condition ?
 
To properly check the rotary valve cavity you must have the RV cover on and sealed. Block every orifice, pressurize the RV cavity from the carb side to 4-5 PSI. WAIT and watch the gauge, if it falls you have a leak let the gauge go to zero or damn near close to it. Now, remove the PTO spark plug, if that side of the crank seal leaks you will hear(listen closely) the 4-5 psi that leaked when you almost have the spark plug out. If it doesn't make any noise, re install the spark plug and do the same for the MAG spark plug. If you get air from the MAG plug you know the leak is on the mag side crank seal. If you've never had the bottom end apart, I would doubt the case halve seal is leaking. DO NOT take the engine apart until you have been satisfied with your results and have pin pointed the leak. It is possible that both sides are leaking.
 
Thanks alot RacerXXX !

I have been reading alot of Threads by you and as always very informative !

Thanks for your knowledge and skills and time ! And to all others that are here helping newbies like me out !

I hope my rotary valve cover seals back up ok the O ring around it looks pretty thin .

Thanks again and I will do like you have suggested :)
 
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