guitarman376

Hi fellas, so my 351w has maybe 2000 ish miles on it since getting rebuilt. It was bored thirty over and is all stock. Obviously it got a new oil pump. For awhile everything was good. Now I am unsure what to do.

Maybe 2 months ago I noticed that at operating temperature the oil pressure was a little bit lower than what I remembered. The oil pressure continued to do this ( get lower gradually over time) very very slowly. The motor has been running great, other than severe hot starting issues. I suspect it is running rich, but I don't think that has to do with this.

I am using the stock gauge so I don't know if that or the sensor is failing me or if my oil pump/motor is. BTW even when my motor was new, if the traffic/weather was bad enough for the engine to get a little hot the oil pressure would get pretty low.

As instructed from the person that machined and built my motor, I have been running at least 20w50 oil the whole time. I already did an oil change and it did not affect this problem at all. I have been noticing that my motor is dripping a little oil from what looks to be the filter. However, I am sure the filter seal was dripping wet w/oil when I did the oil change and tightened it very adequately (I rechecked as well). It did this before and after the oil change.

Now, once it reaches operating temperature it reads very low on the gauge. While driving yesterday it dipped into the warning zone for the first time ever.

So my questions are:
1) How can I test the real oil pressure? Where on the motor/how do I retrofit a mechanical gauge?

2) Has anyone had this happen to them after rebuilding their motor?

3) More likely to be oil pump/shaft or something worse?
THANKS!

guitarman376

Oh one more thing. Before this, if I brought the rpms up the oil pressure gauge would go up just like it should. Now it doesn't do that.

palerider

That is pretty thick oil for a rebuild. I'm surprised they told you to run that high. Pressure at that thickness should be pretty high. Car guages are really inaccurate (mine barely register). Get your self a good mechnical oil guage rule of thumb is adequate pressure is 10 psi per 1000 rpm. Mine is a complete 347 rebuild done by quality shop with high end parts and barely registering that. took it to another builder to get his opinion and he said that was fine - lot of depends on tolerances builder uses. High oil pressure is over rated.

Randynj

The mechanical gauge will thread into the same spot as the current oil pressure sender

ajzride

You can buy a T fitting at Ace or Lowes which will allow you to keep the current in dash gauge, and add a mechanical one under the hood for verification / piece of mind. A mechanical gauge is less than $20 at any parts store.

rmodel65

if you add a mechanical gauge run a copper line and not the plastic one..it will chafe and make a mess

guitarman376

I'll be buying a mechanical gauge and I will update later. Thanks guys.

69dude

I second this, definately a copper line, seen what happens when those plastic lines go, be cleaning your carpet for days.

fastbackford351

Just shooting from the hip, if your pressure is steadily going down then it sounds like maybe your screen on the pickup may be getting clogged. I've seen them get clogged with rtv and cloth fibers from crappy, thready rags used to wipe down unassembled blocks.

That's why I poke holes in my screen with an icepick, so it won't get clogged.

+1 on the copper line for a mechanical oil gauge. Install it and forget it. 20+ years and never leaked a drop.

Stangatic

If it helps, I pretty much destroyed one of my first rebuilds because I used 20w-50. It ended up not allowing the hydraulic flat tappets to operate properly which resulted in a lot valve contact with the pistons!

I have had a plastic tube for my oil gauge for about 8 years now. No leaks and never had any issues. Used a grommet when running it through the firewall and secured it with zip ties.

Let us know what you are running when you get the gauge hooked up.