Hello all.

So I'm chasing oil leaks now. Think I've got em narrowed down to one area. At first I thought my oil leak was coming from the oil pan gasket, but now that I've replaced it and it's still leaking, I'm not so sure. This has become a recent concern because I can no longer drive at highway speeds without a cloud of oil smoke blowing behind me. Putting a quart of oil in every two days isn't cheap in the long run, either.

The leak occurs on the front passenger side of the engine just below the fuel pump. The oil seems to leak directly from the bottom of the pump, onto the lip of the pan rail which makes it look like the oil pan is leaking there. The oil also drips along the bottom of the lower radiator hose and pools on the crossmember and leaks all over the center link and passenger side tie rod. My trans pan is also covered in oil droplets and much of the undercarriage. Nothing above the fuel pump has oil splash on it. The fuel pump gasket has been replaced and it does not leak from the top or sides. I cannot tell if it is leaking from the bottom because that area is covered in oil.

Have tested by cleaning engine block with degreaser and revving it to see if oil would seep out of anything, it does not. Either I am not revving it high enough or there is something about being in gear that increases oil pressure. Under sustained throttle the pump does not visibly leak. After every cleaning and episode of leaking, a small drop of oil does accumulate on the very bottom of the actual pump, and along the arm which connects to the block (basically the underside of the pump) Driving around at speeds under 35 does not aggravate it, but any higher and it causes the leak described above.

I am certain the oil is not coming from anywhere above the oil pump, and it cannot be coming from the pan seal because there is oil on the block several inches above the pan seal. My question is, is it possible for a fuel pump to leak this much oil, and how do I fix this? It only seems to occur under pressure (60 psi).

 

what year and model and engine?

 

My guess is that you have a front crankshaft oil seal leak. Simple repair that can be done with the engine in the car by pulling the harmonic balancer. You'll need a couple of specialty tools that you should be able to rent at the auto-parts store- a harmonic balancer puller and a seal puller and seal installer, though a big socket and a hammer can install the new seal.

Sometimes the crank snout will be grooved in the seal area. There are special sleeves made to fit over the snout and correct this.

What's happening is that there's enough oil getting blown back by the fan to reach the exhaust pipes.

You're a sharp guy, Andres. I have no doubt you'll figure this out as you have other issues. Worst to worst, clean the engine thoroughly with brake cleaner so it's absolutely dry, then spray some aerosol foot powder around the suspected leak area. The leak will reveal itself.

 

How high is your oil pressure?I had problems with my 350 leaking.It turned out to be crank case pressure.
railguy

 

It may be the fuel pump itself. There is a pin that the arm pivots on and if that has wallowed out, oil may leak from there. A fuel pump is not expensive and if its old, it won't hurt to change anyway. You can see if the pump leaks by removing it and filling the area where the arm is with oil. This will also eliminate the possibility of the fuel pump gasket leaking as you will be replacing it anyway.

 

Best way I know of, is putting some UV trace dye in the crankcase oil, drive the car around a bit, and scan around with a UV light. The lights aren't very expensive anymore, and could save you a lot of trouble.

 

It is a 1970 455. I will try that aerosol foot powder trick first to see if I can spot the main source of the leak.

My oil pressure is 40 at idle and 60 at highway speeds.

 

I would highly suspect that the diaphram in the fuel pump is broken, causing the oil to come from the weep hole on the side of the fuel pump. Fuel pumps are very generally priced very reasonable, and are typically pretty easy to change.

 

Solved. Fuel pump was the cause of the leaks. At high speed oil was shooting out of the weep holes on the sides of the pump, causing it to spray on the side of the block, then drip down onto the lip of the oil pan and down onto the cross member (giving the appearance of a pan gasket leak.)

While removing the fuel pump, and tipping it upside down to drain the gasoline, oil started leaking out of the weep holes. I have since replaced the pump and have not lost a drop of oil after 50+ miles of highway driving.

Thank you all!

 

Glad you found the problem.
And since the fuel pump was bad, there is a possiblility fuel got into the oil.
Pull the stick and check for thin oil, too much oil, or a strong smell of gas. Change it if needed.

 

Good work, glad it was something simple. Rob makes a good point on gas diluting the oil due to a leaking fuel pump diaphram. Go ahead and change oil anyway just to be sure- it's cheaper than an engine failure.