Help me find the source of this oil leak

In our last episode, we resealed the oil pan and replaced the front crank seal. But that plucky oil leak would not be deterred (see: Lets play "Fix it or Scrap it")

With the front end off, my mechanic told me he found some kind of leak on the PS pressure hose under the sleeve. His initial thought was a PS fluid leak, but now I’m not so sure. The PS fluid levels are still steady and the leak I am chasing is definitely the brown color of engine oil.

After a bit more diagnosis, I’m certain it’s coming from that general location. Here are some photos to get your bearings:

and this is the view from the bottom (the area in front of the water pump):

Could I be seeing PS fluid that brown? Or is there another likely culprit that is leaking oil onto the pressure hose sleeve and from there traveling down below?

Send me your best guesses.

There is a lot of power steering fluid. So a small mist would take a while to show up level wise but it would leave that brown color. While the PS fluid doesn’t start out that color after years of use and dirt it will end up that color.

Clean the area reall really well. Then Zip tie paper towel around the line where you think the leak is coming from then start the car turn the wheel from one side to another. See if there is any sign after that. If there is fluid coming from the PS line you’ll see it on the paper towel.

A shout out to countcohn for that idea. I have used it several times on many occasions with good results.

After a drive and a cool down, I took a few more pics to try to isolate the source of the leak.

From the photos, this is what I think I can rule out, right?

  • PS pressure hose appears clean from above, and was clean to the touch below
  • the engine valley below the IM, and the the drain spout on the engine block which usually indicates a leak from the oil filter flange
  • even the water pump came out clean this time. I believe the other pipe with the markup is the bottom of the PS pressure hose. It was also clean.

(NOTE: These pics were taken looking up with the front of the car to the right, passenger side on the top, driver side on the bottom.)

What I can see is oil dripping onto the coolant pipe, and the black pipe beside it. This happens in front of the water pump. But I can’t see exactly where it is coming from.

With the borescope, I took some photos at the water pump and above––I see signs of oil, but I’m not sure exactly where that is.

For a frame of reference, here’s another pic of the front of the engine before it was cleaned. The area of interest was covered by my blue mark-up in the photo above:

I’m still stumped, but at least I can rule out the PS pressure hose? I’m gonna have to take the front end off again to replace the radiator, but I need to have parts on hand if I want to stop this leak. So I need to pin it down before I proceed.

The hunt continues. I put the car on a lift again and had a better look. This is what found

I tied some rags onto the coolant pipe right next to the water pump. That seems to stop the leak from traveling, it now drips in only that one location:

Here’s the cutaway view for reference:

I saw the oil collecting at the oil pan seal just above the coolant pipe near the water pump. This is where I tied the rags to stop the leak from travelling.

The oil pan was resealed a few weeks ago, so it couldn’t have been there. But I had it opened up again to have a closer look. The only thing I can find is oil collecting on the bolts that connect the oil pump housing to the crank case. The locations are marked on the front view of the motor above. (1) and (2) are right above the spot of the leak, and a peek at (3) also shows a bit of oil sludge on the passenger side, but no leak below.
I’m assuming it’s an engine out procedure to get access to the oil pump housing.


I took additional photos of the seam at the crankshaft level, and also the top of the oil pan housing by the lower flywheel. It all looks clean. The only thing I can see are oil drops collecting on the underside of the bolts.

Give me some ideas on what I can do next, such as:

  1. it’s a slow leak, just put a pan under the car and top-off the oil monthly
  2. “caulk” the seam with some RTV––would that work?
  3. Is there somewhere else to look in that general location?

If I knew the oil leak was taken care of, I’d go ahead and have the radiator and a few hoses replaced. They are showing signs on brittleness and bulging. OTOH, I don’t want to throw good money after bad if this is a lost cause.

Thanks in advance for your great ideas.

If it is where mine was, it is the oil filter housing gasket. The housing is at the rear of the valley, but there are holes in the vertical metal castings that allow it to migrate from the rear to the front:


Based on the location of your oil drip, this may be your source as well. Try and get a view of the under right of the manifold and see if there is evidence of oil there. Unlike cam girdle gaskets, these can be done with the engine still in the car (there are 2 gaskets for the housing).


No, I already had that problem and replaced the gaskets once before. There is a little bit of sludge there, but I checked the drain hole in the front and it’s still clean.

OK, then the next likely suspect is the oil cooler O rings.

Can you get a look back behind the oil cooler?


It’s the oil cooler on the other (pass) side. I’m certain the primary oil leak is to the right of the flywheel. It’s coming from somewhere above the water pump.

I got confused by the “Passenger Side” blue writing on one of the pics.

Well there aren’t too many places for oil to come from if it’s not the oil filter housing on that side, and they way oil leaks present, there should be a tell tale sign.

From top to bottom:

1, Valve cover gasket
2. Cam Girdle gasket
3. Head gasket.

I would find it hard to believe the head gasket is your issue. Can you see down the driver side of the engine to find the source?

Alternatively you can clean all oil off the engine and look again once it shows signs of leaking.


Speaking of oil cooler O-rings, I have a pair, but it’s not clear how/where to put them on. The oil cooler seems buried behind the alternator––can you change the O-rings from the bottom?

Not according to Bentley.

I did mine when I did the WP. I had noticed some aged oil stains across the bottom of the engine, and when I pulled the bumper and moved the lock carrier to a service position I saw it was migrating across the bottom of the engine from the passenger side. After some research I determined it must be the oil cooler O rings.

The only way to get to them was to remove the alternator, and it still was quite finicky. Right after the instruction to drain coolant was remove alternator. Your best bet would be to access some kind of repair manual.

If I can figure out a way to save an attachment I will do it.


My leak is coming from the right side of the crank girdle next to the thermostat. Full engine pull for me yay…

You would be the first to have that particular area leak. But I am sure you know what you are looking at. if there is no oil dropping down from the valley or the valve cover/cam girdle there’s not much else there it could be coming from.


I think I’m looking at something similar, but I want to confirm with a borescope. Do you have a photo? Or can you draw on one of the photos above so I know exactly where to look?

Also, I tried to measure the leak by weight, and it looks like ~1g for an aggressive 10mile drive.

Is it correct to say that this adds up to 1 liter for every 10K miles???

Am I rolling the dice to say that this is just a cosmetic problem that can be solved with monthly top-offs?

I tied rags to the coolant pipe in an effort to stop the leaks from traveling. Now it seems to drip in 2 spots

the oil pan from the area under the belt tensioner (pass Side), from the coolant pipe between the brackets (its clearly traveling here) and from somewhere that drips onto the water pump.

the black pipe behind the coolant pipe is pretty clean (green lines)

I took some more videos with the borescope, and I just see a lot of mess just above the oil pan, and also somewhere back around the oil cooler. Have a look.

You mention oil cooler, however, at least on my car, the oil cooler is on the opposite side of the Water Pump. Are you sure it is an oil cooler you are talking about?

Was the lower crankcase dr to passSide shot from above or below?

Was the *behind belt tensioner PassSide shot from above or below?

Some of the videos (at least for me) are difficult to get a frame of reference.

Is your vehicle a Right hand or Left Hand drive?

The one video seems to show the oil starting at the crank case girdle, but it is difficult to see. If it were me, I would be pulling the nose off the car to investigate. You can leave the AC condenser attached to the AC system, just rotate it down and to the side. You will have to drain the coolant though. That way you will absolutely be able to tell where the source of the oil is coming from.

The coolant pipe has the yellow rags tied to it in an attempt to keep the leak from traveling. But your right, I’m now seeing drips on both sides of the crankcase. Passenger side it travels to a low spot on the oil pan to the left of the oil Level sensor before it hits the ground. On the driver side, it collects at the bottom of the water pump. But the pump actually looks pretty clean, so the source is elsewhere.

“Lower crankcase, dr to pass side” was filmed from the bottom. I think I’m seeing the seam where the oil pump housing touches the lower crankcase.

Lower crankcase pass side was shot from above. I’m seeing a mess on the foot of the oil pump housing, the seam just above the oil pan. I also see the leak traveling down the bracket that holds the coolant pipe. But it seems odd that the lower crankcase is clean, I would have expected that oil would have dropped down to the footing. But it looks like oils is climbing up from the oil sump pan. I had the oil sump pan seam resealed twice, so it seems that it should be fine.

“behind belt tensioner PassSide” Was shot from above. The bore scope was raised from the bottom to the top of the motor. It starts off an oily mess somewhere near the level of the oil cooler, then it’s clean as I raise it past the crank case, and then I see another mess—maybe at the cylinder heads? But it seems to me than any active oil leak up there would leak down below.

Thanks for the pic––that’s clean! Mine look a bit messier. The first pic with the markup was 2 weeks ago, before I put the car on a lift. At that time, we wiped it as clean as we could.

These pics were taken yesterday with maybe 4-5 drives on the engine and a bit of leakage on the floor.

IMG_4253 IMG_4263 IMG_4264

I see signs of oil, but it doesn’t seem to be enough to match the leak I see on the floor.