I have a 2001 Navigator with the 5.4L 32 valve engine. After discovering that my PCV valve was bad, and replaced it along with the rubber elbows that are on the vacuum supply line to the PCV valve, I've now got a substantial oil leak coming from somewhere up on the passenger side of the engine. It is leaking approx 1 qt per 50 miles, so not a good thing!! I managed to strip away the ECU plugs and hoses that covered the passenger side valve cover, since a bad gasket was my first guess. When I wiped all around the cover, I didn't find any traces of oily mess??? So I put the engine back together enough to be able to fire the engine and look from underneath and trace the leak back to it's source. No luck there, because it seems that while sitting still the engine doesn't leak? But when driving it spews oil all over the underside of the truck?? So now I'm at a loss as to where the leak is coming from? I have been able to feel along the rear valley of the intake and found no oily mess. I also checked the oil cooler lines, but they are on the drivers side, along with the oil pressure sending unit.
Any help at this point will be appreciated!! I've not totally ruled out changing the valve cover gasket, but hate to fork out the 60$ if it's not the problem!!
I've had some success on tracing back mystery leaks by cleaning the block and then running it and then dusting the are with powder, not always easy, but it works. What if you increase engine rpm while sitting?
Thanks for the tip!! I had sat with the engine running for 30 minutes, and during that time had my son hold the engine rpm's at 2500-3000 for several minutes at a time? Still no oil dripping to the ground? I'm not 100% sure that it's not leaking while not driving, but that the oil is possibly puddling in some spot that isn't allowing it to reach the ground? Thinking that the wind as driving is drawing the oil out of it's hiding place!!??
That's quite a bad oil leak if it's using 1 qt per 50 miles .If it has only started since replacing the PCV and hoses I would double check that in case there is blockage some where causing crankcase pressure to build up and blow out oil .
I agree with Logan. Not sure why sitting still makes the difference as there's not place that I can think of that could collect that amount of oil. When sitting in a driveway, you're nearly freewheeling the engine, when moving, you have a load where pressure is more apt to increase. I would also pay close attention to the vacuum lines attached to the PCV valve.
I had verified that the PCV was functioning properly after installation, and again just recentally, since I'd seen the condition of the rubber elbows, I was worried about the same thing...clogged lines. But I do have excellent vacuum at the PCV.
A little more history......prior to the PCV going out I'd always had a small leak from the same general area, but it would only amount to a half quart, or so thru the course of a oil change (3-5K mi.) The leak only got really bad after PCV had been bad. So, in my pea brain, I'm guessing that I've blown some seal or gasket out somewhere on the passenger rear side of the engine??? Anyone else leaning towards the valve cover gasket?? That would be the same side of the engine that the PCV is located on, not that the crankcase pressure wouldn't be "equalized" throughout the engine???? Thanks for the help guys!!
CatSkinners advice would probably be the best bet and then you would know for definite that was where the oil was leaking from .Used this type before when there was doubt , uncertainty where exactly leak was .
Well over the Thanksgiving weekend, I changed the valve cover gasket on the passenger side. This didn't solve the problem!! I've been reading some service bulletins from Ford about external oil leaks from the head gasket, but this SB didn't include the 2001 Navigators, only up to 1999. The DOHC engine hasn't seemed to exhibited this problem?? Anyone else with Ford mechanic experience have a diffrent opinion? Engine again is the 5.4L 4valve DOHC. I'm really not looking forward to the thought of having to do a head gasket job on this truck, but may not have any choice! I'm still trying to figure out a way to view the rear side of the block to be certain that the leak is coming from the gasket! Here's a link to the SB I was reading: http://www.thedieselstop.com/faq/949...les/022207.pdf
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