Oil pressure increase after valve cover gasket change

[JunkyardDog]

My 2007 1500 5.7L has been leaking oil for a little while now. I have been diligent in keeping the level where it should be. The gauge has always hovered in the middle, or a little above, since I acquired the truck a year ago. When the engine has warmed up, the oil pressure gauge will ease down at stop lights. It does not hesitate to raise back up when increasing RPMs. My delay in taking care of the leak is due the nature of the leak. It hasn't been exactly easy for me to see exactly where it is leaking. In my presence, the oil level has never reached the danger level. It always sounds good and pickup is sound for 170K miles.

The leak was on the passenger side. But, it never dripped to the ground. I could smell it burning off of the exhaust manifold. So, my best guess, along with opinions from a few others, pointed me to change the valve cover gasket. My son and I did that today.

I tried to take much care in disassembly so that there was plenty of room to remove and replace the cover without interference from cables and such. We removed the air breather/MAF assemblies. We removed the EGR and EGR pipe. I even tied the cables out of the way. Before removing the cover, I blew away as much of the loose debris as I could. Removal and replacement was quite easy. I took a little time to clean out the cover. It had no sludge at all. The old gasket did have some small cracks that makes me think it did experience some overheating or it dried out and lost some pliability or sealing capability.

We got it back together easy enough. It started right up and sounded smooth. The only glaring symptom, for better or worse, is that the oil pressure shot up to the high end of the gauge mid range. Not railed to max. Shutting it off and restarting allowed the pressure to make a quick enough retreat and then charge ahead to its new plateau. We had some plans and had to cut troubleshooting short. I will do more in the AM.

My primary question is, will a leaky head cover gasket cause this much oil pressure loss? I can see vacuum loss, but, oil pressure loss? Also, will a new gasket recover this much oil pressure?

 

[LoneWolf3574]

Typically your truck will have one of two types of oil pressure indication, either a sending unit or pressure switch. Both give an indication on your cluster, but the switch is just a "feel good" device and the sending unit, thanks to FCA engineers, doesn't give a warning until the pressure drops below 4psi and hangs out at the middle/top once indication drops below 10psi. I suggest you pick up a cheap oil pressure gage at your local parts store, carefully remove your oil pressure sending unit/pressure switch (it's located above the oil filter toward the front of the engine, the other sensor facing toward the RH wheel is for the oil temperature, either should work though), install the oil pressure gage, start your engine and see what your pressure really is. At the moment, I can't remember what it normally is at normal operating temperatures, but it's not terribly high, somewhere between 15-20psi when at idle I believe. Mine is around 50psi when cold.

 

[JunkyardDog]

I am going to look into putting one in more permanently. I figure the status of that type is pretty important.

Do you happen to have any recommendations, tips or tricks on what is best to get for that plan?

 

[LoneWolf3574]

Most come with 1/8" plastic tubing, it works okay as long as you keep it away from heat sources that could melt it. I'd find some brass tubing and use that instead, it costs more but you definately don't have to worry about a major oil leak due to melted plastic tubing. Personally, I'd tee it in and use it in conjunction with your oil sending unit. Your oil pressure plays a part in your engine management system and I don't know if your PCM would be too happy if it doesn't see oil pressure for an extended period of time. As far as gauges go, I prefer Auto Meter or Bosch, though I've seen one by Holley out there as well.