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In between studying for my insurance license, taking care of my son, and tinkering around with designing a fuel economy modification I decided to take the top off my intake manifold. I have been wanting to see what it looked like in there so that I could fabricate an airfoil to go in each individual intake runner to create some air spin for better in-cylinder mixing.
As a side note what I am doing is nothing new. I honestly thought of the idea on my own but after doing a patent search found that several other people thought of it as far back as 2000. Even so, there is nothing wrong with doing it on your own - where you get into trouble is when you market it as your own or try to make money off of it. But I digress.
I spent about an hour carefully taking the top half of the intake manifold off and took detailed notes so that I would have a shot at putting it all back together again. Upon taking the top half of the manifold off I immediately noticed oil in the intake manifold. I do not think there should be any oil in there. Some of the oil in the main plenum was fairly clean. There was oil that had pooled in the intake runners and it was pretty dirty. The down tubes to the heads are pretty filthy as well. I cannot imagine that this is good.

I am trying to figure out what would cause the oil to be there so I can fix it. Several possibilities come to mind but I really need the advice, thoughts, ideas, and experience of the members here. My short list of possibilities is:

  • malfunctioning PCV
  • blown head gaskets
  • worn rings
  • burnt valves
The coolant system has no oil in it nor does the oil have any coolant in it either. The truck burns no discernible oil. I have noticed a slight rough idle from time to time but nothing major. I have not pulled the plugs yet but probably will here shortly.

I put everything back together again with only one minor mishap. My son was "helping" me and during a moment of inattention I managed to drop a nut down on top of the motor and under the intake manifold. Fortunately I was able to see it with a flashlight. I took a five minute break to cool down and with a flashlight, coat hanger, and a whole lot of luck managed to fish it out on the first try. Amazingly the truck still runs.

I have attached some pictures of the discovery and would be most grateful for any thoughts, advice, or guidance the members here can offer.
 

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If your lucky it's just the pcv valve staying open. Did you see if the spring is working on the valve. Has it ever been over filled with oil that you know of? Good luck man I hope it is nothing serious.
 

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If your lucky it's just the pcv valve staying open. Did you see if the spring is working on the valve. Has it ever been over filled with oil that you know of? Good luck man I hope it is nothing serious.

Going to pull plugs and check the PCV valve now. Just noticed that part of the gasket is missing - possible culprit?
 

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Lizard, no worries here. Almost every car make intake manifold will have it. I had it on mine, when I took it apart, also when I've helped my friend with his Acura TL type-S, same thing, BMWs same thing. So in my opinion there is nothing to worry about.
 

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2015 Toyota Tundra DC SR5 5.7L
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Tobester,

Based on my experience, it can come from:

1. Excessive crankcase pressures (worn rings, cylinder walls, etc)
2. PCV valve failure (make sure to closely inspect the PCV valve seat gasket/bung as well)
3. EGR activity
4. Gasket failure

If your PCV valve and its bung is OK (pull it, see if it rattles freely; if not, blast with brake cleaner and reinstall), pull the EGR lines and see if there is heavy moisture/oil residue from that. If not, then it is probably a gasket issue. If your issue is crankcase pressures, you'll see other problem areas, i.e. blown oilpan gaskets, etc.

Do you have any oily moisture/residue on the top half of the intake plenum? How about the back of the throttle body?

I'm kinda with Crazy Ivan on it. It's generally considered "normal" in terms of typical PCV operation and ageing of the motor. Will it leave you on the side of the road in the next 1,000 miles. Probably not. Would I be concerned if it was my engine? Kinda. If I didn't see blue exhaust smoke, or poor idling, etc though, I probably wouldn't lose sleep over it as the accumulated oil volume isn't excessive.

I would definitely make sure to replace the intake gasket(s) and apply a sealer to the intake plenum install bolts.

Any idea whether you're going to have the dealer do a diagnostic on it?

D~
 

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Fairly common in most engines today. The last truck I owned I actually installed a "catch can" in the pcv system to accumulate the oil being sucked through the pcv system. You'd be surprised how much it would collect.
 

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Discussion Starter · #9 ·
Hey Guys,

First off thank you so very much for your responses.

Lizard, no worries here. Almost every car make intake manifold will have it. I had it on mine, when I took it apart, also when I've helped my friend with his Acura TL type-S, same thing, BMWs same thing. So in my opinion there is nothing to worry about.

Hey Ivan,

Thank you for your input and experience - I feel at ease now. Still shocked over the amount of oil there. Really do appreciate your response.


I noticed this in both my new motor and old motor. I didn't think twice about it though.
Hey Apimpdad,

Thank you as well for your response and sharing of experience.

Tobester,

Based on my experience, it can come from:

1. Excessive crankcase pressures (worn rings, cylinder walls, etc)
2. PCV valve failure (make sure to closely inspect the PCV valve seat gasket/bung as well)
3. EGR activity
4. Gasket failure

If your PCV valve and its bung is OK (pull it, see if it rattles freely; if not, blast with brake cleaner and reinstall), pull the EGR lines and see if there is heavy moisture/oil residue from that. If not, then it is probably a gasket issue. If your issue is crankcase pressures, you'll see other problem areas, i.e. blown oilpan gaskets, etc.
Hey Remmy,

Thank you for your timely response as well. I think I can rule out the PCV. I cleaned it not too long ago but went ahead and pulled it about an hour ago and checked it. Everything seems fine there.

I will check the EGR lines in a minute and let you know what I find there. Which leaves the worn rings or a head gasket failure. I am going to call my buddy (the other half of the "Real Men of Genius" dream team) and see if he can show me how to check my compression.

Do you have any oily moisture/residue on the top half of the intake plenum? How about the back of the throttle body?
Back of the Throttle Plate was clean but I just cleaned before my last oil change. Overall it looked good. There was oil on the upper manifold (as seen in the second picture) along the gasket surface. I noticed that part of the gasket is missing in the third picture.


I'm kinda with Crazy Ivan on it. It's generally considered "normal" in terms of typical PCV operation and ageing of the motor. Will it leave you on the side of the road in the next 1,000 miles. Probably not. Would I be concerned if it was my engine? Kinda. If I didn't see blue exhaust smoke, or poor idling, etc though, I probably wouldn't lose sleep over it.
No exhaust smoke ever on this truck. As far as I can tell she has never burned a drop of oil but then again the dipstick is not exactly a precision measuring instrument from Brown and Sharp (or Lufkin)

I would definitely make sure to replace the intake gasket(s) and apply a sealer to the intake plenum install bolts.
Absolutely, as soon as I put some metal that does not belong in there.

Any idea whether you're going to have the dealer do a diagnostic on it?

D~
Yeah, not really. No money on this end here until I get my license back and start smiling and selling. Maybe for Christmas I will treat the DC to some much needed (and deserved) maintenance and upkeep beyond the usual F&F (fluids and filters) change.



Fairly common in most engines today. The last truck I owned I actually installed a "catch can" in the pcv system to accumulate the oil being sucked through the pcv system. You'd be surprised how much it would collect.
Hey HyToyo,

Thanks for the response. The common consensus seems to be that it is alright. My first time in that area of the engine and was just caught offguard like a newbie trying to run with the bulls - not a pretty sight.
 
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