What the heck is it?

[arctictraveller]

Originally Posted by bet on black

i'm pretty sure the CHT and knock sensors both go in blind holes in the valley. the same hole in the head casting, since both heads are the same.

Further research seems to point out that the CHT sensor is indeed in a blind hole. More reading turned up one guy that said "Just change the crush washers on the banjo bolt behind the alternator" Further inspection found what may be another sensor or the suspect banjo bolt with a lot of oil around it. I found the photo below that shows the thing that may indeed be a banjo bolt. After looking at a bunch of photos of 5.4s it seems there is only a coolant pipe (prone to leaking coolant) the CHT sensor and this mystery bolt. Anyone know if it's tapped into an oil galley? It's the thing in the center of the valley at the front of the engine, under the alternator.

[arctictraveller]

[QUOTE=AT does your oil show up at the outside passenger edge of the block/head or is does it exit more towards the center? Do you have a photo of the leak as its collecting on the back of the engine?[/QUOTE]


The oil is running down the passenger side of the bell housing, and coming from under the intake manifold. Carefull inspection with my bore scope seems to show that there is no oil seeping between the head and the block, as the entire parting line is clean. Also no oil can be seen running down the head as you would expect with a lose valve cover. Since everything under the intake manifold seems to be wet, it's hard to really tell what may be leaking, but there seems to be more oil towards the front of the valley.

[bet on black]

That black donut looking sensor that has the bolt go through it like a banjo bolt is the knock sensor.

[arctictraveller]

Originally Posted by bet on black

That black donut looking sensor that has the bolt go through it like a banjo bolt is the knock sensor.

Well, thats a bummer then, since I doubt it leaks oil. Back to square one.

[JWA]

AT can you get your borescope under the intake from the back of the engine?

Since you're not seeing the leaking I describe I'm more and more curious where it's originating. (Hope I'm not clogging up your thread here. )

[bet on black]

you may have to clean the whole valley up and then run the motor again to identify the leak. Likely either seeping from the head gasket or the valve cover gasket.

[arctictraveller]

Originally Posted by JWA

AT can you get your borescope under the intake from the back of the engine?

Since you're not seeing the leaking I describe I'm more and more curious where it's originating. (Hope I'm not clogging up your thread here. )

I've run the scope in from the back and the front, driver and passengers sides. The valley seems to be wet with oil pretty much everywhere, and since it's mixed with dirt and dust, it's pretty hard to tell. It seems there is only the knock sensor, the CHT sensor, and a coolant pipe in the valley. The two sensors seem to be screwed into blind holes and I'm not leaking coolant, so that kinda leaves the headgasket or valve cover. Running the camera down the area where the heads meets the block under the manifold doesn't show anything obvous, and it looks like a valve cover leak would only allow oil to run down the outside of the block, rather than into the valley. I may try adding some UV dye to the oil, but my black light won't shine very far under the manifold as it's too big to fit. Fortunately, the leak isn't bad enough yet to keep me from driving, but I doubt it will get any better by it's self, and no doubt it will get worse eventually. So, it's time to button everything back up and head out on the next trip. Thanks for everyones ideas and suggestions...........