How To Change Valve Cover Gaskets

[mts]

Originally posted by "mazda-fla"

 

I don't know what exactly you have to remove to get to the point to change the valve covers, but you could just start removing parts until you get to the point that you have removed the valve cover. And by the way, it is not called a valve cover on a Millenia, Mazda calls it a "Cylinder Head Cover". Sounds more sophisticated that way.

 

I do have the instructions on how to install the new gasket and reinstall the cylinder head cover, once you get to that point. The instructions are different for the 2.3 and the 2.5. Which engine do you have?

 

There is a certain step-by-step procedure you have to follow when installing the new gasket and reinstalling the cylinder head cover. To know where to apply the silicone sealant, sequence of torquing the bolts (you have to do it in the right order), foot pounds of torque for each bolt, etc. If you just drop the cylinder head cover on, and tighten the bolts any old way, then you will have a cylinder head cover oil leak. Or worse, you would wind up warping the cylinder head cover permanently.

 

The 2.5 does have a tightening sequence. And there is certain places you put the silicone sealant.

 

The 2.3 is a little more complicated than the 2.5. The silicone sealant on the 2.5 is more or less fairly obvious where you would apply it (around the edges). On the 2.3 it is applied to specific places. It also appears that there are 2 gaskets for the 2.3, instead of one like on the 2.5.

 

If you don't use the right tightening and torqueing sequence, you risk warping the cover.

 

Cylinder Head Cover Installation:

 

Caution: Silicone sealant hardens and causes oil leakage when it is left for an extended period. Therefore, install parts within five minutes of applying sealant.

 

1. Apply silicone sealant to the two bottom half circles of where the blind covers fit on the cylinder head. (Note: This is done on the cylinder head side).

 

2. Install the new blind covers into the cylinder head.

 

3. Apply silicone sealant to the cylinder head cover around the entire outer edge of the cyclinder head cover. Apply silicone sealant completely as a circle around the 11 bolt holes. Apply silicon sealant to the three round areas (about 3 inch diameter) next to bolts 5 and 6 (one to the left of bolt 6, one to the right of bolt 5, and one inbetween bolts 5 and 6). The thickness of the silicone sealant should be 1 to 2 milimeters (or 0.04 to 0.07 inches). (Note: This is done on the cylinder head cover side).

 

4. Install the new cylinder head cover gasket into the cylinder head cover.

 

5. Apply silicon sealant on the top half circle on top of the new blind covers. Apply about a quarter inch stripe of silicon sealant on each of the two corners where the camshafts are located. One quarter inch stripe right below the number 1 bolt, and the second stripe right above the number 8 bolt. (Note: This is done on the cylinder head side).

 

6. Install the cylinder head cover and tighten the bolts in five or six steps in this order:

 

Starting from top left to top right on the top row of bolts, then from middle right to middle left on the middle row of bolts, then from bottom left to bottom right on the bottom row of bolts.

 

The bolt tightening pattern looks like this:

 

1 2 3 4

7 6 5

8 9 10 11

 

The tightening torque of the 11 bolts should be:

 

(6.87 - 9.80 N:m) or (70 - 100 kgm:cm) or (60.8 - 86.8 in:lbf) depending on what scale you use.