Blog
This blog page will serve as a place for instructional videos related to common repairs, improvements, and modifications on 1990-2005 Mazda Miata.
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Entry number 1 is about changing your valve cover gasket.
Oil leaks from the valve cover area are common on both 1.6L and 1.8L Miata engines from 1990-2005.
The valve cover gasket itself gets brittle over time and will begin to seep (leak) out oil. This will make a mess on the side of your engine and your driveway. It will also cause you to need to add oil to the engine in order to keep sufficient oil in the engine for operation.
This can often be remedied simply by replacement of the valve cover gasket.
Several options are available for new valve cover gasket.
The OEM Mazda gasket is always good, but an excellent aftermarket alternative is the Fel-Pro valve cover gasket.
At the time of this writing, there are several other acceptable valve cover gaskets on the market as well.
In order to replace your valve cover gasket, the first steps are to prepare to remove the valve cover(VC) and old VC gasket.
Before you can remove the VC, you will need to pull the spark plug boots off of the spark plugs and remove the coil pack from the back side of the engine (1990-2000). On the VVT engines, 2001-05, you will remove the coils and plug wires on top of the valve cover.
After the coils are out of the way, you're nearly ready to remove the valve cover.
Remove the 11 valve cover hold down bolts around the perimeter of the valve cover and through the center. (see photo). This applies to 1990-2000 engines.
Once these bolts are removed, the valve cover is ready to remove. You may need to apply additional upward pressure to remove the VC from the engine.
Once removed, you should remove the old VC gasket and clean the mating surface for the gasket on both the VC and the head thoroughly. Remove all oil and dirt.
Place your new VC gasket into the channel in the VC and make sure it is seated fully.
Before installed the VC back onto the engine, you must apply a small bead of RTV sealant to the 4 points on the front side of the head where the camshaft caps meet the head and also to the 2 points in the rear where the cam cap meets the head.
These are sharp corners where oil can possibly leak if not sealed with RTV.
After you've applied RTV to these areas, you are ready to install the VC with new gasket back onto the engine.
*note* This is a GREAT opportunity to replace your crusty, maybe rusty, old valve cover bolts with a nice, shiny, brand new set from MrMiataParts.
Go to the Product page and purchase a set here:
BUY Shiny New Miata Valve Cover Bolts HERE
A nice new set of bolts will be shipped to you and will clean up your engine bay and top off this job well done!
Ahem, now back to work.
With the VC back on the engine, you can installed the 11 valve cover bolts and tighten them all lightly by hand.
By hand. No power tools here. Unless you are highly experienced.
You don't want to break off a bolt because your power tool tightened it waaaay too much.
Follow Mazda's recommendation for tightening pattern and torque.
I like to go in a 3 step torque process.
The first pass is to tighten the bolts by hand to a "wrist snug" tightness in the suggested tightening pattern.
Next pass is a torque to the lower end of the torque spec (70 inch-lb) in the proper sequence.
The final pass is a tightening to the middle of the torque spec (about 85 inch-lb) in the proper sequence.
As a final check, I like to do the last step twice to make sure that all bolts are fully tightened to the desired torque spec.
With the bolts tight, you can replace your coil packs and spark plug wires.
Double check that you've replaced everthing that you removed when you began.
Now, you're ready to start the engine and check for oil leaks.
If you have no leaks after starting and running for a minute, you are good to go!
Great job!
Your Miata loves you and thanks you for this maintenance. <3 