Can someone explain this photo of my intake? | Ford Explorer - Ford Ranger Forums - Serious Explorations
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Can someone explain this photo of my intake?


New Member
April 21, 2012
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Year, Model & Trim Level
2002 Ford Explorer (V6)
My issue started when I began getting P0174 codes for System Too Lean, Bank 2.
I found the most common mentioned issue on forums was that there was likely a vacuum leak, or a bad intake manifold gasket. I didn't find any noticeably damaged vacuum hoses so I figured I'd replaced the intake manifold gaskets since that would be a cheap (although not incredibly easy) fix.

Once I got the SOHC Intake removed I noticed something ODD... One of the six intakes on the block looked different. 5 of them were black with a fair amount of buildup, but 1 of them was almost clean, just with an oily film. I've attached a photo.

My question is, would a bad gasket on that intake cause this...or do I have a more serious problem deeper in the engine?





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It's common for a leaking head gasket to clean a cylinder like this. The water leaking into the cylinder flashes to steam & cleans the cylinder.

Not saying this is your issue for sure but it kind of looks this way. Have you been using any coolant?

Could also just be a leaking intake gasket. The buildup is probably just from the EGR, but a leak on that one runner could result in less carbon buildup.

Try just putting in a new gasket and seeing if that fixes it.

you should be alright, make sure that the rubber for intake bolts are not to compressed to far other wise you will not get a good seal.

these bolts are bad as you can see the collar sticks out past the intake causing intake leak.



also autozone rents compression tester you can screw into the spark plug hole and crank over see if you have difference in psi on that cyclinder. also rent the coolant pressure tester see if you loose pressure.

post back let us know how you make out.

My cylinder 6 was the exact same way as yours. Maybe its just the way these things run. The PCV valve hook up is before the inlet to this cylinder, so maybe it doesn't attract a lot of oil into there.


EDIT: Another thing would be to yank the spark plug from cylinder 6 and another one and see what they look like and how they compare.

Did you spray carb cleaner around the gasket ensuring a leak?
My wifes Mazda had a manifold leak and when sprayed with carb cleaner it'd almost cut out thus identifying the issue.

Thanks for the helpful replies! This forum is awesome! I will try to get the compression and coolant pressure test tools from autozone if the rental isn't very much and check that.

I should add that there is some oil on that side of the engine, it appears like it's coming from the valve cover gasket. After replacing the intake manifold gaskets I'm still having an issue on that bank because the Long Term Fuel Trim for Bank 2 is still running at 16+. Bank 1 is running around 9. From my understanding my original P0174 system too lean code occurs once the Long Term Fuel Trim hits 18 or higher. I'm assuming it is not a vacuum leak because that should be affecting both banks.

On a separate note, I am having a problem were when accelerating and it hits like 2,000 or 2,500 RPM it revs up to like 4,000 for a second or two....would that mean my transmission is "slipping" or is it an engine problem? I also noticed that it's a lot worse after the computer is reset (from disconnecting the battery).

dobble check your spring valves sometimes broke inside. verify al of them, the one thats is clean looks like if some gasoline on compresion time is going back.

I agree with tmaher. 4.0L engines did not have many problems with leaking intakes or gaskets. I know they had issue's withe PCV hose on those. They would crack or on the rubber elbows would crack. It is a big hose plastic hose. It looks like a big L

I had 3 cylinders misfiring, so I decided to replace the engine after many other options were tried. My stuff looks the same except I had a nice swimming pool starting.