oil pressure high when starting

[willy3486]

I have a odd issue on a 70 c10 with a 307. This truck was stored for a while and I am trying to get it running.This was my father in laws so I am almost certian it has never been hot rodded so to speak. I changed oil, new plugs,etc. Before I even started I sprayed a little wd 40 down each cylinder to loosen it and hand turned over the engine with a wrench to make sure it was loose.It would turn over fine so I don't think it was stuck in any way.

Anyway there was a issue with the fuel so what I have wound up doing is to clean all steel lines and put new hoses on. I also have the tank unbolted so I can clean it out. .I also have a new gas pump to put on. While trying to get it to start as I was working on it to see if the gas would flow I noticed that the oil pressure needle would go over to high and peg it out if you would turn it over and over. I checked the back of the gauge and it has a small steel line coming out, no wires. I am new to these trucks but I think it is a pressure type reading and not the electrical type I am use to.

So what I am needing to know is this some type of issue with the engine that needs to be addressed? It is something normal with the pressure gauge pegging out when it is first started? I am getting ready to clean out the tank and put the gas pump on today. I might be able to get the engine started but I wanted to check to see if it might have another issue with it on the oil pressure.

[Sammy]

Signs of great oil pressure is good news. Nothing I would be concerned about. Normal for the gauge to do that. Most likely will drop after warming up.

[willy3486]

Thanks Sammy that is what I was hoping. I was thinking that was what was going on but I wanted to ask someone who would know. The truck was in perfect condition when my father in law got to old to drive. I will carry on and fix the gas tank today.

[Ol Blue K20]

Sammy, I think you forgot the pics, gotta see it. need pics......

[geezer#99]

When you do start it, if it stays pegged shut it down. The pressure releif valve in the oil pump might be stuck.
Not normal to peg the gauge just cranking it. Should only go to 60 lbs where the releif valve opens.

[1968k10blue]

I don't want to steal a thread, but I have a similar situation that I want to ask about. On my 68, it has a 350from a 73 truck with a few upgrades. What happens is when I get to about 4k RPMs the oil pressure will also peg out. Is this a broken or is it normal? The main reason I ask is because I seen to be loosing oil at an alarming rate

[68gmsee]

In both cases with high pressure above, I agree that if it pegs while cranking something's not right. Either the gauge or blockage somewhere. Same thing with running and pegging at 4k rpm. First thing to do is to start by adding a quart of diesel or similar additive (maybe transmission fluid) and crank or run it for a short period for the oil and additive to mix, drain it, replace the filter and refill it with 20W30. Check it again and if it still extremely high, then check (or replace) the oil pump for blockage.

Re. the tubing going to the gauge, that's oil line going to it. I'ts either copper or plastic if it's been replaced. To insure accuracy of gauge, go buy a gauge at local auto parts and hook it up to see if it reads the same. They're not very expensive and can always be used on something else, kept for testing or resold.l

[Sammy]

Agreed about the pressure not dropping after a few minutes of use. Pump relief valve can cause that also have heard of Fram oil filters internally failing causing the oil pressure to peg. So keep an eye on it see how it acts. If it doesn't drop after the oil gets warm then it maybe time to drop the pan and oil filter for a closer look at things.

[70blackfish]

if its cold where you guys are use thinner oil....

[willy3486]

I haven't got it started yet. When I drained the oil it looked ok, just like the oil when you normally drain it. So I am hoping it will drop down when it is started. It has sat for a few years so hopefully that is it. If it doesn't drop it I may add some transmission fluid to loosen the gunk. I accidentally added some transmission to my old mazda truck once and when I cleaned it out it got a bunch of gunk to come out as well. I had to replace the valve cover gasket a while after that and the valves when I took it off looked like they had just been rebuilt because they were so clean. I haven't had it started as of yet as I think now the float in the cab may be stuck . I have a good carb guy that is going to rebuild it so hopefully after that I will know if it goes down after getting it to run and get warm. Thanks for all the advice I think I am making prograss.

[geezer#99]

I wouldn't add anything to the oil. If you do loosen up some sludge you could plug an oil passage and have no motor to work on.
Get a new oil pressure gauge and line and see if that changes it. If it still shows pegged pressure while cranking save your time and put a new oil pump in it. You'll be money and time ahead.

[luvbowties]

Number 2 on Geezer's analysis and solution...totally agreeing with him on this--follow ALL his replies to your thread!
Sam