Thread: crankcase pressure problem
11-26-2007, 03:54 PM #1
crankcase pressure problem
Ok guys (and gals), hereís my dilemma. This may be a little drawn out. I have a 02 F12X I bought from a guy who was selling it for a girl friend and didnít have a clue. I think he actually ran it out of water thinking it was a 4 stroke and didnít need to be because when I bought it he didn't know where to attach the hose. Anyway, the problem Iím having is I get a lot of crankcase pressure and it will blow enough oil into the air box that I get an oil alert. I can put more oil and run it for a short while before it happens again and I get a bow full of oil. Itís always had what I thought was too much crank case pressure but now it blows.
Iíve done a compression test and Shawn told me to do a leak down test. Here are the results starting from #1 cylinder. Compression 150, 140, 100, 135 lbs. Leak down is 5, 6, 8, 5 %. Also note this is a cold engine, throttle wide open and sub air box on. I did notice during the leak down test that I get a bleed over between #2 and 3 cylinder. I can hear and also feel it in the next hole like a blown head gasket. I donít know why I get as high a compression on #2 since I am getting the bleed to 3.
I understand my lack of compression problem but since I havenít removed the head to check anything else, is it possible Iíve had at least a small leak until it finally blew from one of the cylinders into a oil drain valley running from the top of the head back into the block creating my crank pressure.
I would also like to do a valve job since Iíll have the head off. Iím also considering the heavier springs if it will do me any good. If I canít find anywhere here to get it done, Shawn do you and how much would it cost to have you do the valve job.
Thanks in advance for any input.
11-26-2007, 06:11 PM #2
Just a guess, but I would say it got hot and cracked, or warped the head.
11-27-2007, 10:15 PM #3
I have blown head gaskets before, but I'd think that water would pull in because of the block jackets. Best thing to do at this point is pull the head.
I got some Titanium spring kits here, so we could at least update the Head and valve spring problems would not be an issue. Kit is $495 (forum price) with all the required parts, Normal List is $635
11-28-2007, 02:27 AM #4
Shawn, whats the advantage to the titanium springs over the F12 springs. Keep in mind that I'm not racing this ski but I do like occasional wide open runs. Actually I like to accelerate, cut and play more than running WFO all the time.
11-28-2007, 08:01 PM #5
- Join Date
- Apr 2007
11-29-2007, 01:30 AM #6
1WR, do you know the price on the dual springs and are the 05's different than other years. Also, I'm thinking once I get the head off (I got the intake Assembly off before dark) I'm going to make a plate that will fit one cylinder at a time and do another leak down test to see how the rings are before I pull the whole engine. Whats the consensus here, does that sound like it will work? I'd rather not have to pull the block if I don't need to.
Last edited by spatera; 11-29-2007 at 01:38 AM.
11-29-2007, 07:29 AM #7
The titanium spring kit, has dual shot peened springs with titanium retainers and harden shims. They will not break like the stock ones. I broke a stock Honda spring 3 years ago and then got them out of all my motors due to that. The stock retainers can be a problem too.
Due to the lighter weight of titanium you get a performance advantage because the valve will follow the cam lobe more accurately.
Pull the head first and if you need to go further, just pull the motor. Takes me about 1 hr to do.
11-30-2007, 06:14 PM #8
Well I got the head off today. I know this sounds weird but I was disappointed because I was expecting to see a blown head gasket. I still donít understand how I could feel air from one plug hole when I was pressurizing another. I canít find any obvious problems. Iím going to stage all the caps and shims and turn the head completely over and check for warp but so far I donít see a thing. I guess since I have it this far down I may as well pull the rest of the motor and check the rings. Damn it.
11-30-2007, 07:09 PM #9
I use 2 - 1 inch PVC tubes 18 inches long.
Replace the cams with these, put the cam caps back on and turn the head over..
When you're racing you don't have any time to fool with buckets and shims getting mixed up so I came up with that 25 yrs ago and always done it.
11-30-2007, 08:26 PM #10
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