HOW TO: Intake Valve check and adjustment

[360jeepboy]

This is a How To on checking and adjusting the intake valves on the Mitsubishi 6G75 3.8L engine. Hopefully this will save some people some money and help keep there Mistubishi in top running condition.

First thing you need to do is disconnect the battery. Next thing that will need to be done is to disconnect the air tube from the throttle body. (aftermarket or stock they should both come off pretty easy) You should be able to take off the intake with the stock air box still in place, but it would be easier to just remove it for convenience.


There are four bolts holding the throttle body onto the intake manifold. They should be easy to remove and make sure you put them in a safe place. You will also have to disconnect the throttle sensor form the throttle body. It is the only sensor on the actual throttle body so it should be easy to find. Press the release on the sensor and it should easily come off.

Remove all sensors on the intake manifold. There is one above where the throttle body bolts up.



Remove all wire mounts marked with a red arrow. remove the sensor on the top left side of the intake manifold marked with a white arrow.


Disconnect the brake booster line from the intake manifold.(circled in blue) The clamp is shown with a red arrow.


There is also a sensor connection that I didn't get a picture of that is right under the brake booster line... you can't miss it.

Take off the rear bolts that hold the intake manifold on. There are three of them: Two on the back side and one under where the throttle body is located. They are marked with white arrows.


Disconnect the EGR tube from the intake manifold.


Now your ready to take off the bolts that hold the intake manifold. There located with red arrows.


After you take the bolts out pull up on the intake and it will pull right off. The gasket can be reused.


I removed the lower intake manifold for P&P but you will not need to remove it to adjust the intake valves.

Your engine bay should look like this.


Now remove the coil packs from on top of the valve covers. There is one bolt holding them on. (marked in red) and make sure you disconnect the connector from each coil pack.


Just pull up on the coil pack and it will come right up. Make sure to set them in a safe place where they won't get damaged.


Now loosen the six bolts on the valve cover. (marked in green) take note on how easy they are to take off... this lets you know that you should be very careful to not over tighten them when reinstalling the valve covers.


Take off both intake valve covers.




To adjust the intake valves you will need a feeler gauge set like this one. I used the set to the far right that has the bend in it.


The intake valves are towards the top of the head on each side. (or towards the middle, closest to the intake manifold) There will be six to check and adjust in each head.


The amount of clearance that the manual says should be between the lifter and the valve is .008 thousands.


The next picture isn't that great which is bad because it shows how to check the clearance. There is a space you can see that if you pick up on the lifter it will move up from the valve... this is where you need to put the feeler gauge.


But before you do that you need to put your engine at top dead center. There is a little window in the passanger fender that if you take it out you can see the crank pulley.


You need to find the timing mark on the pulley. It is located on the back side and is a notch that has a white mark on it. There are markings above the crank pulley that have writing on it. This is called the timing indicator. You need to put the white notch to line up with the "T" on that indicator. This means that your engine is on TDC... or Top Dead Center. You will need a 1/2" powerhandle to get the engine to turn over and there is a slot for it in the center of the crank pulley.

Now that you have the engine on TDC you have to check to see which piston is on TDC of the compression stroke. You need to check cylinders 1 and 4. 1 is on the back head on the far left. (as your looking at the engine from the front of the car) 4 is the one in the middle of the front head. Move the intake lifter on 1 up and down to see if it has any slack. If it does then it is on TDC and can be checked and adjusted.

The cylinder count goes as followed:

The front head: (going from left to right as your facing the car) 2. 4. 6.

The back head: (going from left to right as your facing the car) 1. 3. 5.

If the number 1 lifters are loose (in a up and down motion) then you can check and adjust cylinders.... 1. 5. 6.


If the number 4 lifters are loose (in a up and down motion) then you can check and adjust cylinders.... 2. 3. 4.

To check the lifters pick the feeler gauge that says .008 and try and put it between the lifter and the valve. It should go in with a slight drag on the gauge. If it goes in then try the next size up to see if that will also fit. If the size .009 doesn't fit then your valves have the right specs and you are good.

If the feeler gauge will not go between the lifter and valve then you out of specs and you will need to adjust.

To adjust you will see what looks like a cross where a flat head screwdriver would fit. There will be a lock nut to hold it from moving and this will need to be loosened.

Adjust the lifters till there is a slight drag with the .008 feeler gauge. Hold the cross section with a flat head screwdriver so that is does not turn and tighten the lock washer with a wrench. Do not tighten to much just enought so you can't turn the center with your hand.

Now you need to have an Inch Pound tq wrench and tighten the nuts to 80 +/- 9 inch pounds. Recheck the clearance with the feeler gauge to make sure your still in specs. If you are then you are good and you can move on to the next one.... if not then you will have to loosen it up again and redo it. (I had to do this a few times so don't worry if you do aswell)

After you check and adjust you valves then you need to reinstall the valve covers and tq them to 31 +/- 4 inlbs. Tighten in a cress cross pattern to get equal tq on all bolts. There is no need for a new gasket because it is built into the valve cover and can be reused many times. Recheck the bolts and reinstall everything back the way it was.

Hook the battery up and start the car.

[EclipseFL07]

if you don't mind answering a few questions;

how long did it take you to adjust the valves?

would you suggest to grab an engine coherent buddy or is this pretty doable alone?

[360jeepboy]

If all I was doing was adjusting my valves then I would say it would take a good 6hrs. It took me 8 hrs and I was taking my time and trying to take pics and remember everything for the write up.

If you have never even seen a car with the vavle covers off then I would suggest you find a friend that knows a little about an engine.... but it really is easy and anyone that had time would be able to do it.

The 3 things you need would be time, tools, and this write up and it should be easy.

[HotGunAndRun]

Did you do a lot of adjustment ? How many on 6 ?

[360jeepboy]

Pretty much all of them where aournd .006. I went through and adjust them to .008. I had 2 of them that where on .005.

[macwest]

Thank you for the excellent information you provided , how many miles were on your engine when you did this?

[360jeepboy]

Right at 40K


Your welcome and I hope this helps a lot of people.

[itsreu]

will this help stop the annoying lifter tick my car has when its cold?

[360jeepboy]

Actually this may make it a little louder... but it is ok because that is how a Mits sounds

[Kilzod]

[HotGunAndRun]

Did you see a performance gain ??

[Live4Redline]

Great Write up 360jeepboy!


P.S: That motor looks totally sexy with no valve covers... I'm so gona rub one off to that picture.





eRep added!

[Asian Cracker]

BUMP... so I can find this thread again!

LOL


good write up!