Crank case and crank inner seal leaking oil into intake

[Mech]

1995 GTX - Rotax 657
Original symptom - running fine towing skier at the end of last summer, stopped for 1 min, then would only idle - Plugs were fouled with oil
Potential issues: oil pump, rotary valve seal, inner crank seals, cranks case joints
Crank leak test at 10 psi shows 1 psi drop over 10 min -> Pulled engine
Tested oil pump and all is fine (1500 RPM for 60 s ~ 2ml, etc.) no leaks at gear, no dripping with gravity oil feed
With oil pump removed, filled the rotary valve section with oil, put the engine on its side and applied 10 psi to the rotary valve volume, placed paper towel under engine and in each intake port - wanting to see where it is leaking
Oil is coming out of the PTO intake side and dripping from the crank seam between the upper and lower crank case in the rotary valve area (see attached image for case seam leak). So in the end there is an inner crank seal issue and crank case leak.

Question(s): If I replace the crank with a refurbished one (new inner seals) and apply Loctite 515 to the case when reassembling will that solve my issue? Or does a leaking case mean other issues. I would replace the rotary valve seal, block gasket, Mag gasket, and crank end seals as well. Are there other items/seals that I should replace if I am at this level? for example the Mag key? The compression is ~145 psi for each cylinder so top end seems OK. I replaced the top end gaskets last year, but not the rings. I am assuming that I cannot replace an inner crank seal - only option is to get a refurbished.

Thank you,

 

[LouDoo]

Yes, I think replacing the crank with a refurbished one and replacing the rotary valve seal will fix your oil problem, but if you're going to do that it would probably be a good idea to do the top end also. Honestly I'm not an expert on the internals of these engines I just replace the engine with a rebuild. Lets get the opinion of an expert [MENTION=57920]racerxxx[/MENTION] .

Lou

 

[racerxxx]

So, you pressurized the RV cavity and you got the leak on the RV surface at the case halves????? What I also don't get is if you put 10 psi in and it dropped to 9 psi over 10 minutes time that is a pass for the crank seals. If you continually get that oil on the RV surface, I would split the case, clean the cases uber good and reseal the case halves with threebond 1211. You really should only put 3-5 psi into the engine, not 10. Now a true test to would be to block off all the ports (intake and exhaust and pulse line, leave the PTO in) then pressurize again and wait, remove the PTO spark plug and see if you get a pressure drop, if no the the PTO inner crank seal is fine, repeat for the MAG spark plug, if you get an air leak while removing the spark plug then you have a bad inner crank seal. If no air out of either hole then your crank seals are good. But seeing that "drip" on the RV surface leads me to believe the case halves need to looked at. Re-pressurize and spray WD-40 on it and see if it bubbles. If you do tear it down to re-seal don't use any abrasive pads (3m cookie cutter pads) to clean the mating surfaces of the cases. Just use acetone and at worst a straight blade on edge and just "flick" the one Loctite off the case halves.

I also really don't think that amount of oil would cause your initial problem.

You will see in this thread what the crank looks like and also the threebond 1211 sealant too.
http://www.seadooforum.com/showthre...ct-Clapped-out&p=288612&viewfull=1#post288612

 

[LouDoo]

Thanks Dan, that's the information we needed.

Lou

 

[Mech]

Thank you for the feedback. I will use threebond 1211 when I fix the case. FYI, I have added a few more images.
Two are looking into the intake manifold where you can see oil. There was a lot of oil in the crank bottoms when I took it apart.
Another is of the oil marks on the paper from the PTO side - also a little on the MAG side. Oil was coming out of the pulse line and the PTO intake.
The waveform image is of the pressure at the pulse line when cranking the engine over. It shows 3.5 psi peak. I am not sure where I got 10 psi test pressure from, but figured that it reaches 3.5 psi so should test at more than 2 times that or I read it somewhere.

I did not mention that the pressure would sometimes drop by 2 psi if I rotated the crank and sometimes not. Not sure if that is just moving oil around in the RV volume.

I will try the pressure test with the other ports blocked. If the crank seal leak is small it will take time to fill up the PTO or MAG Cylinder/Case sides from the RV chamber and make a difference if the plugs are removed. Perhaps another way to do this is to measure the pressure on the MAG and PTO plugs - if they increase a little then there is a leak. It would seem that there will be a small leak between the PTO and MAG intakes across the RV itself as it is not a perfect seal. I will remove the oil that is in the RV shaft volume before I do the test. One thought is that the oil leak could get much worse when the engine is hotter and cause the fouled plugs. Do you have any other ideas as to why it would only idle? I have replaced all hoses a couple years ago and all filters/carb gaskets last year. Pop off pressure is 25 psi so I will need to lower that with a different spring. The plugs seems quite oily.

 

[Mech]

Leak testing @ 5 psi showed no leaks.
Racerxxx - you where right, oil in the crank is not my issue.
I have access to some sophisticated leak test equipment and can measure pressure changes down to <0.001s of a psi. There was no leak with 5 psi applied to the RV oil volume, PTO side nor coolant volume. The MAG had small leak of 1 psi drop over 44 mins, no other volume increased in pressure. I dunked the engine in a water bath to see if I could find the leak with no luck. It is likely out of the MAG crank seal. However as you mentioned this leak is not going to cause my issue with oil.

The oil must have been accumulated from sitting over the winter. So what could it be. As noted at the beginning it was working fine, stopped, then would only idle. With throttle it would bog. If I pulled the choke and gave it throttle I could make it work for a short bit. After taking the carb appart I noticed that there was a bit of matter on one of the valves of the fuel pump (image). Could it be that this was flowing through the pump and caused it to keep the valve open and make the pump no work?

 

[racerxxx]

I don't think that could do it since no oil is going thru the carbs. Over the winter one of the guys here (68ragtop) had found the little injector nipples were not working, they would not hold pressure so oil could potentially leak out of them. With oil tank mounted above (height-wise) the injection nipples, perhaps those are leaking. In your last pic you have the oil injection off the rotary valve cover, those little nipples that go into the mani are what you would check. Let's see if Ragtop chimes in on what he did. Also, I know it's a long shot but did you notice the tank level drop?

Oh and that vac tester is the cat's pajamas!!!!!!!!!!!!
[MENTION=57696]68ragtop[/MENTION]---Hey RT, how did you check the fittings (I'm lazy and don't want to read, LOL)

http://www.seadooforum.com/showthread.php?68441-injection-oil-check-valve-replacement

 

[68ragtop]

What I found is the check valves will hold +/- 3lbs of pressure before releasing towards the crankcase when they are brand new. weak ones maybe 1 lb. bad ones won't hold much of anything. They should hold that pressure almost indefinitely. A leak of any kind, will result in an oil leak. Slow & painful, & often unnoticed, but still a leak Of coarse they should also hold pressure the other direction (towards the pump) under any amount of pressure.

I believe the check valves on the 650 are located directly on the pump & what we see in the photo's are just open ports, correct?

The pumps themselves don't have any internal check valve & they will slowly gravity bleed if the check valves are shot. In this case, if you pressurize the oil inlet side of the pump. it should hold at least 1lb. If it leaks out, put some soap bubbles on each outlet on the check valve & see what ones are leaking.

if you don't have the tools to test it this way, just hook the pump up under the oil tank in the ski, gravity & oil from the tank will test them. Set some clean toweling under the pump ports & check it after a day or two of just sitting.

 

[racerxxx]

Hey thanks RT, I totally meant to ask you this today when I called you. Thanks for chiming in.

Sent from my SGH-T889 using Tapatalk

 

[68ragtop]

No problem! :thumbsup:

Once I started to understand these things better, I couldn't help but wonder after months of off season storage, how many crank seals are taking the blame for dripping check valves.

 

[racerxxx]

No problem! :thumbsup:

Once I started to understand these things better, I couldn't help but wonder after months of off season storage, how many crank seals are taking the blame for dripping check valves.

Been wondering that for a looooooong time. I have a liquid cooled 340 Skidoo engine that has been sitting for about 20 years with the RV oil reservoir attached and it's still at the same level. Only difference---it's a pre-mix engine not injection, the crank is the exact same construction.

 

[Mech]

No real leak in the check valves.
I tested forward pressure to the oil pump at 1, 2, 3, 4, 5, and 7 psi. The calculated leak over 10 mins was 0.05, 0.075, 0.1, 0.1, 0.14 and 0.25 psi drop. So the check valves seem to be holding quite well. I did not try and rotate the pump to see if that made a change. I will try that tonight. At the higher pressures you could see a bit of oil coming out as expected.

I happen to leak tested the RV oil section again at 5 psi and found a 0.2 psi over 10 min leak rate. So not substantial but something. I left the test running all night and the pressure was down to 2 psi by the morning. You can see the oil leaking out of the case even at 5 psi. There should be no oil in the RV cavity as I emptied it out. So this must have been left between the case halves. I used WD-40 as you mentioned to try and saw the bubbles coming out there. When i did the initial testing at 5 psi and found no leak I had the oil cover on and some rubber blocking the intake ports so that might have stopped the leak. Again the leak is not substantial the SeaDoo spec says watch for a leak in 3 mins so that would be 0.07 psi drop. Not much.

When I when further into the carb I saw some gunk on the low speed jet as shown in the image attached. Could this have cause the Sea Doo to only idle?

 

[Mech]

Picture with bubbles

Here is a picture with bubbles using WD40 - there where more bubbles flowing - this image only shows a couple.

Can i just run as is this season and fix it next?

 

[68ragtop]

10 minutes is really not enough time with respect to the pump & check valves. you really need to pressurize it to 2 lbs & leave it for hours, if not over night. The oil pump itself is restrictive, but pressure will pass pressure thorough it overtime. the check valves should stop all flow at low pressure 100%. anything over 2 lbs and they will probably start to leak down. if you don't want to wait, put a soap bubble over the 3/16 nipples, & se if they start to inflate. brand new ones will leak after 3 lbs, your just seeing the resistance of the pump.

Not saying that the checks valves are your leak, just worth looking at them closely.

 

[racerxxx]

I'd say the bottom end is good so to speak--it passes Doo's spec on the leak down kinda, but I really don't like the case half leaking in the RV surface. That being said, I don't really see it contributing to the original issue of only being able to idle and fouled plugs. The jets were probably the main culprit, not enough gas but the oil is still pumping in cause the engine is running. You could probably run it this season, it's just double work if you know what I mean as it's already out. For me, I'd just bite the bullet.

 

[Mech]

Long term oil leak test shows leak

Thank you for the feedback. It was helpful.

I put 2 psi into the oil feed line and recorded the pressure and the oil level in the output tube for 5 days. The image of the pump and tubes shows the oil level change from after 1 day to after 3 days. There is quite a bit of oil leaking out. The pressure trend shows the humps for each day as the temperature rises and causes the pressure to rise. The pressure leaks from 2 psi to 1.1 psi in 1/2 day then settles down to 0.7 psi. So the check valves leak. There would be around 0.4 psi pressure head due to the 12 inch height of the oil, not as much as 2 psi, but easily would cause oil to collect in the bottom case over time. I will be replacing them now. Thanks for the help.

Now need to decide how much further to go. Would it be enough to crack open the case halves and replace the following: 1) crank shaft outer oil seals (MAG and PTO), 2) O-rings on outer bearings, 3) Block gasket, 4) Generator gasket, 5) Circlips, 6) case seals using threebond 1211 - Or is it only right to purchase a refurbished crank shaft with new inner seals. I do not think that they are leaking now.

 

[jammin777]

No problem! :thumbsup:

Once I started to understand these things better, I couldn't help but wonder after months of off season storage, how many crank seals are taking the blame for dripping check valves.

thanks to you i found mine were bad. thanks for saving me storage frustration.

 

[68ragtop]

Mech, When you tested it this last time, did you allow the pressure to drop off on its own, or did you continues to apply pressure as it drops? sounds like you just let it drop. when it dropped to .07 did the oil stop flowing? In reality all the check valves are supposed to do is prevent the oil from flowing into the engine under the gravity weight of the oil from the oil tank. I would think that pressure probably isn't much, maybe less than 1lb? The ones that I found leaking wouldn't hold much of anything long term. in fact, when I was messing with this delima last winter, I mocked up my oil tank from the ski, bled the line to the pump & let it sit. overnight I saw the oil was moving in the small injection lines. not much, maybe a a few drips over night, but thats all it takes to make a mess when they sit for weeks.

I guess I am mentioning this again because I just want to make sure your not forcing the oil through with too much pressure. There are no specs on what the check valves should hold, but I just tested two other DI engine projects I have in the shop & all of these hold 2 lbs with no issue, but release just over 2 lbs.

I think I have a pump from an old 580 that uses the same pump mounted valves, I'll have to test that & see what it holds too. Hopefully I didn't toss it.

If you have bad valves, you will probably find the pressure drops below 1lb, if not a loss of all the pressure.

Not sure what you are using for a gage. I have a vacuum gage, that also reads pressure. hard to read pressures that low accurately.

 

[Mech]

Oil check valves leak test 2 psi drops to 0.6 psi

68ragtop, as you guessed, I had applied 2 psi pressure and left it alone, with no new pressure added, now for 9 days.

The pressure dropped to 0.6 psi over 3 days then held there for the rest of the time (see picture of pressure trend). I have access to high end equipment to measure leak rates and pressure. The pressure sensor I have can measure accurately to 0.025 psi. The graph shown is a trend of the mean pressure over the 9 days. The humps are due to daily temperature cycles changing the pressure in the oil pump I am testing.

I made a line on the tube at the oil level three days ago, and the oil level has not moved. (See picture).

If you calculate the oil pressure due to 12" of height difference between the case and the oil container you get ~0.4 psi. (using density etc.) So my oil check valves just barely able to hold this pressure.

It would seem that my original issue where it would only idle was a clogged low speed jet, perhaps with some debris in the fuel pump check valves. Thereafter I rode it for a bit using the choke and throttle to get it move a little faster on occasion, if you had the right level of choke and throttle, mainly to put it away last season. That caused oil to be pumped into the case, but with no engine speed to move it out. Or over the winter the check valves leak ever so slowly and filled the case with oil.

Engine is out so time to get it fixed. Still debating if it is worth getting a refurbished crank. But if the inner seals are not done yet they will be soon so ...

Thanks for your help.

 

[68ragtop]

it would be interesting to know how much pressure is seen from gravity & the oil in the tank. I think they hold a gallon or so or oil & the drop from the tank to check valves is about 12" or more?