Intake Valves Dont Completely Close | Ford Explorer Forums - Serious Explorations

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Intake Valves Dont Completely Close

Joined
September 27, 2011
Messages
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City, State
Oregon
Year, Model & Trim Level
1997 XLT
I purchased this explorer from a co-worker. It had been sitting for about 18 months. When doing the timing chain and components I have noticed that although i am at TDC. My intake valve for cylinder number 1 is not closed completely. It is at its highest point when i manually crank the engine. Same goes with all the other valves, they do not close all the way.

Could this be from sitting for 18 months? getting a droopy valves? The fact that all the valves are not closing is reassuring, i figure not all 6 could go bad. When a build compression in the engine will it then close completely?

Thank you.
 



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What motor is this? 4.0 sohc?

I really do find it hard to believe that its normal for a valve not to close all the way during compression.
 






yes this is for a 4.0 sohc.

This picture is of my #1 Intake Valve at TDC.

2011-09-27_17-33-09_479.jpg
 






The only way I can see it happen is if the timing is out of wack with several degrees. Maybe at some point, the chain jumped? How are the tensioner guides?
 






Your crank may be at TDC, but the cams don't appear to be. I have NO experience with the OHC engine, but common sense tells me the cams are not in time.
 






As you crank the motor over do the intake valves close at any time? If they do, then your valve train timing has to be off. your valve train needs to be re-timed.
 






I guess the questions are.... was the engine running before the "sit".... IF it was, then it is likely your "rebuild of timing" was up to "spec."... :-) or IF it wasn't running, then there was perhaps more things wrong than first thought.
 












"The only way I can see it happen is if the timing is out of wack with several degrees. Maybe at some point, the chain jumped? How are the tensioner guides? "

I did the timing with OTC 6488 tool kit per 2000 Street Rods Forum, The tensioner guides are new.

"As you crank the motor over do the intake valves close at any time? If they do, then your valve train timing has to be off. your valve train needs to be re-timed. "

The valves do not close at any point. This picture is of the highest point that #1 intake goes.

"I guess the questions are.... was the engine running before the "sit".... IF it was, then it is likely your "rebuild of timing" was up to "spec."... :-) or IF it wasn't running, then there was perhaps more things wrong than first thought."
I was told my the previous owner that all was running good before it quit, he did mention that it had like 9 quarts of oil in it for a couple months and i drained the oil and it was overfilled quite a bit. The vehicle has just over 100 k miles.

"Turn the engine 1--only one revolution, line up the tdc marks again, and take another picture of the valve please. "

Will take a picture after I turn the crankshaft 360 degrees.
 






Ok, How can this be that the intake valves never close at all? Guys, this does not make sense to me.

Even if the timing were off, you would see the valves close at some point in the rotation of the motor.

Cam lobes? Whats going on here?
 






2011-09-30_09-35-46_785.jpg


2011-09-30_09-29-28_853.jpg


Both of these pictures are 360 degrees from TDC or 1 revolution of the crankshaft.
 






A little bit more information:

Intake Valve #1 starts movement at 45* past TDC, Fully Open Valve at 95-100*, "Closes" at 180*-720*.

Closes is in quotes as "closes" refers to picture above.

Possible Causes:

Surface Rust on Valves preventing complete closure?

Valve Springs need replacement?

Just Ideas and thoughts.

Oh and as mentioned all the intake valves are not completely closing, not just intake valve #1.
 






really not closed?

Frankly, I can't tell from the photos if the valve is seated or not. When the crankshaft is at TDC for #1 on the compression stroke the timing slot on the front of the right (passenger side) camshaft should be parallel to the surface of the head that mates with the valve cover. Also, the camshaft lobes should be pointing away from the camshaft follower (rocker arm). If the crankshaft and the camshaft are in the correct positions then the intake valve should be closed unless the valve stem is bent or rusted to the valve guide or the valve spring is broken. To confirm that the valve is not seated you can blow air into the spark plug opening and see if it escapes past the valve. Be careful if using an air compressor because the air pressure could force the piston downward. Or you could squirt engine oil on the port side of the valve and see if it drains into the cylinder.

Did you or the previous owner remove the camshafts? Although unlikely, the hydraulic lash adjuster could be rusted in the extended position. Also, the camshaft follower could be installed incorrectly.
 






When you refer to the timing slot on the front of the right (passenger side) camshaft, you are refering to the front of the engine block where the OTC 6488 tools 6481 & 6480 attach to.

I will attach a picture of the camshaft at TDC.

I have not removed the camshaft and doubt that the previous owner did as well.

When looking through the fuel injector rails on all other valves, not intake 1, it appears to always have a gap.

I will try the compressed air and oil, too.
 






What are the odds of you seeing if the valve was closed with the cam removed?
 


















"What are the odds of you seeing if the valve was closed with the cam removed?"

I could try that i have to go to work. I also should mention that I can wiggle the rocker arm for intake valve #1 when at TDC.
 






Valve stems bended? Carbon buid-ups on all valves?
 



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Bent valve stems?

According to the photo:
The timing slot for the right camshaft is not positioned correctly unless the camshaft position sensor nub on the left camshaft is pointed down instead of up. The timing slot is above the axis of the camshaft instead of below the axis. See the photo below by CDW6212R for the correct orientation.
CamSlot.jpg

Below is another photo by Jefe the Gorilla:
LCamSlot.jpg

However, the camshaft being 180 degrees off will not prevent the valves from closing.
The cam followers are correctly installed;
The valve train looks free of rust.

A little play in the cam followers when the valves are closed is probably normal since there is no oil pressure in the hydraulic lash adjusters. Since your valves move vertically as you rotate the crankshaft they are not rusted in place. I suspect the timing slipped while the engine was running and the pistons collided with the valves bending the stems. Often when the left or right chain slips only the exhaust valves are damaged. If a chain breaks all of the valves can be damaged. Since none of your intake valves close either both upper chains slipped or broke or the primary chain (crankshaft to jackshaft) slipped or broke. What was the condition of the timing chains, guides and tensioners when you disassembled the engine?
 






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