Intake manifold oil leak

[ColonelPanic]

Finally got around to replacing the intake gasket. Cold idle was quite erratic, especially the colder it became. Not much in the way of drivability concerns otherwise and it never threw any lean codes (was running lean but not yet at the magic number that would throw codes.) I decided today was about as good as it is going to get weather-wise so I went out with my iPad and followed the DIY over on toyotanation.

For some time, I've had oily sludge building up underneath the intake and I figured I would look into it when replacing the gasket... When I took it apart, I was surprised at the amount of sludge that was everywhere. The inside of the intake manifold is coated with it and into the head seems quite a bit crusty. The bolts holding the intake on had fresh oil covering them. I've looked at many pics/videos of this operation and I see *some* oil on theirs but mine seemed a bit excessive.







The gasket was absolutely SHOT. It ripped in two as I was removing it.






(sorta) cleaned up and the proper new orange Toyota gasket installed. Also replaced the throttle body gasket for good measure.


I didn't go too deep with cleaning this thing up, wasn't really sure how to go about it. So I mostly cleaned the mating surfaces and stuck it back on.

I'm trying to figure out why there was such an oil leak with this thing -- was it simply a result of the failed gasket or do I have something else going on? Replaced the PCV valve for the first time earlier this year and noticed a split in the PCV hose. Replaced that with the OEM part from Toyota (since it was a different size on each end, seemed the simplest way to go.) I'll monitor for new buildup over the coming months.

At any rate, the old girl runs beautifully now. Fuel trims looked pretty good on cold start, I'll check them again in the morning. This is the most invasive surgery I've done on a car in quite some time, glad it actually worked.

[vibrologist]

Colonel: the most likely source for oil in the IM is a failing PCV valve. The most likely reason for a failing rubber gasket is oil. You should be good for now.

[ColonelPanic]

Thanks! That's what I was hoping.

[circuitsmith]

I bet the throttle body needs cleaning too.

[ColonelPanic]

The throttle body actually looked pretty clean on both sides so I decided to leave it alone for now. I do plan on cleaning it up anyway at some point, now having the knowledge of how all this comes apart should make it a quick process.