I own a 1997 F150 4.2 Liter V-6. The oil pressure gauge flutters. When I come to a stop sign, the gauge falls to little or no oil pressure and the engine dies unless I put the truck in neutral. This started over two years ago. The check engine light stays on. When this started to occur, my mechanic told me it was the oil pump which he replaced. My family and I was on our way to Virginia Beach and got stuck in traffic and it started repeating the same thing again. I took it back to him and they are baffled. It continued to run, but I'm now having to put anti-freeze in it monthly and it won't hardly start and it has no power. It is going downhill fast. I hated to take it to the Ford Dealership due to already spending over $300.00 on this, but at this point, I don't even know if they could diagnose it. Anyone had similar problem or know what it might be? Camping season is coming up and I want to be able to pull my camper, but it won't even pull itself at this point.

 

First off, the stock guage is just a mechanical idiot light. Only a real guage will give you true oil pressure readings.

The 4.2 is subject to gasket failures that I've read about here. For more info, try a SEARCH on "hydrolock" or wait until someone chimes in with first-hand information.

Steve

 

Your lower intake gaskets have failed and are now allowing coolant into a cylinder or cylinders.You better get them replaced ASAP or the next time you try to start it all you will get is a "THUD" noise;that means a cylinder or cylinders is full of coolant and if you continue to try to start it,it will hydro-lock! Go to the "V6 FORUM" and do a search on "hydro-lock" and "lower intake gaskets"!

 

I'm not commenting on the water problem, but if your engine stalls out and the oil pressure guage jumps when you put on brakes, then you probably have a screwed up brake booster. They run off engine vaccume. I've heard of them going bad and choking the engine to death with air, but the brakes continue to work fine.

 

You've got other problems besides oil pressure. You're probably losing oil pressure from coolant getting into the crankcase and diluting the engine oil, from the lower intake gaskets and/or front timing cover gaskets. Depending on how many miles you've got on this thing and how long you've been losing coolant, you may want to start thinking long block.