2008 Outback wagon, auto, 2.4L base model. 178K miles. Rebuilt heads at 173k after previous owner had the misfortune of a TB belt break. Used subie gaskets for intake on rebuild and turbo gaskets for the heads. Running great for 5000 miles then flagged a CEL P0171, running lean. Found a crack in the airbox where it clamps to the throttle body. Put in a new subie airbox. Didn't fix the code. Finally took it to subaru dealer. They smoke tested it, found a cracked hose from the DS valve cover to the airbox (my bad, missed that). Also found a leak at the DS intake manifold gasket. Price to fix it was too steep for me so I just pulled the intake off. 

Both intake gaskets look rough. The DS intake manifold gasket is cracked fully through on cylinder 4 and has hairline cracks in other places. The PS gasket is also failing with hairline cracks. Will try to post some pics. Worried about using new gaskets and this thing failing in another 5k miles. Maybe the gaskets were damaged before the install, like handled rough? They look like some kind of metal sandwich. Also I have been advised about installing them with the marking up by the dealer. (Edit, gaskets actually have no markings and cannot be installed 'upside down').  

Edited July 29, 20223 yr by 89Ru

Parts dealer is replacing the gaskets (parts only) w/o charge. I had local dealer do the diagnostic as my parts supplier is across the state. This is how the head looked after pulling the intake. 

So possible scenario since both gaskets look bad. Airbox and hose leaks induce a lean condition, runs a bit hotter all around, further damages intake gaskets to the point of a full breach, flags code. All this in 5000 miles. Never overheated. Should I go with a different brand of gasket? 

Don't know what brand you used, but I've never had a problem with Fel Pro intake gaskets.

O.

 

i dont think it is the brand - i think it was installation error and possibly an issue with the mating surface of the intake...

the break looks a bit odd to me... spaced out, and offset... and if you look in the lower left corner of that picture, there is a spot that also looks like it was sucking in air.. as in there was nothing clamping it down/sealing it

as in, the gasket was torn during installation, and the one side shifted out of place

 

 

Edited July 19, 20223 yr by heartless

Heartless you nailed it. No clamping force on that portion of the gasket leading to its eventual complete failure. Here's why. The metal covers for the fuel injectors are reversible! It appears I reinstalled them swapped left to right. (Edit: covers CAN be swapped but CANNOT install in this configuration). As a result there is a 1/16" portion of metal interference of the cover vs. the head leaving a huge gap between the intake and the head, as you can infer on the straight edge at the 2.5" mark. 

Hard to believe it ran like this at all. The vacuum must have been able to keep up with the leak for a while! 

Definitely pilot error on this. Not the fault of the gasket. Thankfully the intake flats do not appear to be warped!

Edited July 29, 20223 yr by 89Ru

ayyup... that will do it.

so, mystery solved, get it put back together the right way, and you should be good

fingers crossed for ya!

Is the gasket also squashed on an angle like you suggest with the ruler? 

I reckon the installation played a part in the gasket breaking, or possibly the handling of the gasket prior to installing (possibly before you got them). 

Hopefully the new gaskets will sort out the issue and it’ll be happy days again! The dealership looked after you on the gaskets too! 

Cheers 

Bennie

2 hours ago, el_freddo said:

Is the gasket also squashed on an angle like you suggest with the ruler? 

 

In essence, yes. In the first pic, the southwest corner is the "high side" of the gasket as it was not squashed at all. You can see flow patterns imprinted on the gasket leading toward the chamber.

Update. Verified that the fuel injector covers are swappable left to right on the intake, however due to interference with the oil filler tube, the intake will NOT install with the injector covers reversed as previously thought. So the defect on the drivers side cover was preexistent. Used a cut off wheel to remove enough material (a sliver) for the intake to install flat to the block. Bolted it up. No codes. Will edit previous posts.