What makes Oil Pressure run high

[71 BRNCO]

My new rebuilt motor is having some issues. Its a 302 bored .030 with all new internals. When driving on the highway the oil pressure is reading like 90. These seems entirely to high. So what could cause this and how can I try to problem solve. The motor is leaking oil like crazy but I can't figure out where it is coming from. Someone mentioned to me about the motor not breathing enough and might need more venting. I am so confused. I just want my new motor to be rigth and not dump oil everywhere. Any tips or suggestions about how to proceed would be great
kyle

 

[Broncobowsher]

Most of the time, high oil pressure is the result of a bad gauge.
If for some reaso you actually do confirm that the oil pressure is up around the 100 PSI mark, you should start noticing the oil filter will grow. When you do an oil change, the old filter will be talle then the new one (providing same brand etc.).

There is a limiter on the oil pressure. It is the relief valve built into the oil pump. Unless you have a real nice pump, then there isn't much you can do with it. I don't think you can even really get to it since the spring cover has a pressed on plug in it.

As for your engine breathing, that has nothing to do with the oil pressure. You need to have your PCV connected and working properly on one valve cover (passenger side) and some other way for fresh air to enter the engine. This is either a stand alone breather/oil fill cap or a oil fill cap that has a hose that breaths through the air cleaner. This fresh air entry is also a bad air exit during accelaration when there isn't enough vacuum to pull the vapors out the PCV. If it can't breath, then the pressure that builds up inside (that little bit of leakage past the rings) will find a way out, usually the weakest seal. PCV is the first line of pressure reliev, breather is second.

 

[broncnaz]

What kind of oil pump did you use on your engine? 90 is a bit high but with everything tight on a new engine you will get higher pressure also what weight of oil are you running? does the oil pressure drop after the engine is warmed up it should drop a little cold oil will read higher.
Cant help you with the oil leak until you find out where its leaking from. But you may want to check the valve covers with 90 psi most of the oil will be in the top end of the engine and it may not be draining back to the pan as fast so the valve cover gaskets could be leaking.

 

[71 BRNCO]

I purchased an Autometer ultralite oil pressure gauge that I am going to try to hook up later this week. I want to run its own wiring so that I know everything is correct. Maybe the factory guage is wrong. I know for a fact that the floor of the garage is covered- I just need to make sure it is oil. Tonight I am going to line the garage floor with cardboard and fire the truck up for about 10-15 minutes and then shut it off and see where the oil is dripping. This may be the best start. THis motor is perfectly painted and spotless so it should be alot easier to find the problem then it is. Thanks and keep the thoughts coming...i am learing alot already.

 

[jonsgolf]

Dont forget the fan is going to blow alot of oil around. Good luck I hate oil leaks.

 

[dpmerrill]

Just to rule it out, try changing the oil filter when you are doing your leak test. A clogged filter can also raise oil pressure.

Since you say it's a fresh rebuild, you never know what could be in there...

 

[Broncobowsher]

A clogged oil filter will not cause a high oil pressure reading on a small block ford. The oil leaves the pan, goes through the pump where the pressure regulator should dump excess pressure to prevent damage to the oil pump driveshaft/distributor/distributor gear/cam/timing chain. That oil is then fed to the filter, then from the filter to the rest of the block including the oil pressure port. If the filter is clogged, the pressure before it will be high, but after will be low.

I still say test the gauge first. Stock 30+ year old gauges can easily be wrong.

 

[airman]

I think what they're trying to say is pull out the oil sending unit and screw in a gauge that you can read and check it. Get a second opinion. Also if the connector is getting any kind of short to ground it will peg the stock gauge too.

I don't no how important it is at this point but just for the talley books, list the oil and weight of the oil you are running too.

Jeff in AZ

 

[Skuzzlebutt]

Oil filters also have a pressure bypass valve in them so oil will flow normally if the filter medium becomes clogged.

 

[76Broncofromhell]

Make sure the PCV and vents on the valve covers are working properly. If they are plugged the inherant blowby in the engine will pressurize the crankcase and blow oil out the places with the least resistance like front and rear main seals. I had this happen to my Bronco, and once I got the right valve covers and PCV for it, there is not a single leak.

As far as pressure, my guess is the actual is probably around 60 psi, since the stock gauge uses the shotgun method to read. Most oil pumps will start to bypass internally around 65-70 psi so that would be my guess

 

[CrazyHorse70]

If it is a fresh rebuild, then the oil pump was most likely changed. Was a high volume pump installed? You usually get higher pressure with a high volume pump. I have been running a high volume pump for years and have 90-100 lb. oil press. when rpm is above idle.

 

[71 BRNCO]

Thank you to everyone for your continual help. It is a fresh rebuilt with under 500 miles total. We did not replace the oil pump. and I do not believe it is a high pressure unit.

I am using 10w-30 valvoline oil and an amsoil filter just changed last week. I fired the truck up and let it run for like 10 minutes and shut it off. The only thing I could see leaking was the power steering pump-reddish fluid, but the pump is not reading low at all and its a lot of oil on the ground. I think that it may be the pump I wish there was a way I could check the fluid on the ground but I can't seem to tell the difference. I got my new oil pressure gauge mounted, now I need to wire it which looks like it may take awhile. the oil filter does not look enlarged at all.

I am going to check the rear main seal tonight, but it seems like most the leaks are at the front end. I will also check tranny and transfer case too. I know they both leak a little.

 

[SaddleUp]

Get a good mechanical guage to verify accuracy. Even if you run the electric you are talking about hooking up (I'm assuming you are refering to an electric based on comments about hooking it up) you can still use the mechanical one for verification. As for hooking up a mechanical one for testing all you need to do is pull the sending unit out and replace it with end of the line (adapter) for the mechanical one. It isn't necessary to mount it or run any wires.

 

[wildbill]

;D ;D ;D If you are not running a HV pump then your relief valve spring is sticking or they put one to memey shims in it. You should watch it as over 100 lbs it could blow the filter and you lose a motor. I did watch a 318 go to 150 lbs and then did it make a mess. Good luck. Bill %)