Here’s how to keep that 5VZ-FE running smooth and leak free.
With over 130,000 miles on my 2003 Toyota Tacoma, it was time to undertake a bit of maintenance that often gets overlooked: a valve adjustment.
The 3.4-liter V6 engine that Toyota dubbed the “5VZ-FE” was stuffed into nearly every US-market Tacoma and 4Runner they produced between 1995 and 2004. It’s a stout, reliable, and resilient powerplant (if not a little thirsty). Still, the engine calls for a valve clearance check and adjustment to be performed every 60,000 miles. While I don’t have any statistics on the matter, I think it’s safe to say that most of these engines don’t get it – ever.
The reasoning for this lack of prescribed maintenance is two-fold. Firstly, these engines continue to run perfectly without ever getting a valve adjustment. And secondly, the adjustment is simply a pain in the butt to do.
It’s Difficult, Here’s Why
The reason valve adjustments on the 5VZ-FE are difficult is it utilizes a shim-over-bucket valvetrain design. This design is more efficient and quieter than a rocker arm system found in many other engines, but it comes at the consequence of requiring you to replace shims when the valve clearance goes out of specification. Add on top of that the difficulty of replacing the shims, and further still, the difficulty of accessing the valve covers, and you start to see why many owners turn this procedure a blind eye.
I’m not one to leave something like valve clearances up to chance, even if anecdotally, the engine should be fine if left alone. Also, the valve cover gaskets were leaking on my Tacoma, providing even more reason to give the engine’s valve lash a once-over.
Leaking valve cover.
Below is a gallery of the procedure from start to finish with some helpful information sprinkled throughout. At the very end are some relevant factory service manual files that can guide you through the procedure (quite literally by the book!). Also be sure to check out the video I made of the procedure here: https://youtu.be/08ia1PIgFz8
The Tear Down
Airbox & related plumbing removed.Throttle body coolant hoses, vacuum lines, and connectors disconnected.2-piece intake plenum removed.A better look at the valve cover gasket leak. When oil reaches the exhaust manifold, you get the burning oil smell.Coil packs, spark plug wires, and spark plugs removed.Fuel injector connectors & wiring harness disconnected. Engine lift bracket removed.Valve covers removed. Be sure to clean up dirt and debris before pulling them off so it doesn’t get inside the engine.A close look at the right bank’s valvetrain.Left bank valvetrain.
Adjusting the Valves
Before adjusting valves, you must first take the clearance measurements. Refer to the service manual file at the bottom of this post for that procedure. If you find valves needing re-shimmed, then you will have to get the following tool: Schley Products 88250. This “tool” consists of a pair of eccentric pliers and a spacer wedge.
I won’t lie – changing the shims is not easy. To do it, first hook the pliers around the camshaft and rotate them so that the eccentric depresses the valve bucket. Next, with the bucket depressed, install the wedge tool on the lip of the bucket so that it remains depressed. Do not let the wedge tool overlap onto the shim because you won’t be able to remove the shim.Use a small flat tip screwdriver to pry up the shim from the bucket through the cutoutUse a magnet to extract the shim.Use a micrometer to measure the shim from its center (this is the area that experiences the most wear, and is what gave you the valve clearance measurement to begin with).
Refer to the valve adjustment service manual file below to determine the correct replacement shim size. Your local Toyota dealer will more than likely have to order the shim in, meaning you’ll be down for a few days until it arrives. Repeat this procedure for all valves where the lash clearance is out of spec. Remember! Reinstall any shim you remove before pulling out the wedge tool that depresses the shim bucket. If you don’t, you may score the camshaft and be unable to re-insert the shim.
Valve Cover Gasket Replacement
To do a thorough job of replacing the valve cover gaskets, there are a number of parts you will need to buy. Below I’ve listed all requisite parts and the OEM Toyota part numbers for each. I recommend buying only OEM Toyota parts for this job:
Valve Cover Gaskets (Qty: 2): 11213-62020
Form In Place Gasket Sealant (FIPG, Qty: 1): 00295-00103
Cam End Plug Seals (Qty: 2): 11188-62010
Valve Cover bolt washers (Qty: 16): 90210-05007
Spark Plug Tube seals (Qty: 6): 11193-70010
Oil Filler Cap seal (Qty: 1): 90430-37140
Intake Plenum Gaskets (Qty: 2): 17176-62040
Note: Be sure to check places like eBay, as sometimes you can find these items sold in a kit offered at a significant discount.
Bend upward the small metal retaining tabs for the spark plug tube seals on the underside of the valve cover. Use a large socket and a hammer to tap out the old spark plug tube seals. You may need to use a seal puller tool to remove the seal from the backside of the valve cover if the seal breaks in half due to age and brittleness.I used a piece of PVC to tap in the new spark plug seals from the underside of the valve cover.With the new seals installed, push the metal retaining tabs back down.Clean out the valve cover gasket groove with a rag and brake parts cleaner. Then, install the new valve cover gasket into the groove.Replace the oil filler cap gasket by prying the old one out with a small flat blade screw driver.Before you put the valve covers back on, you might as well reseal the bearing end caps (2 of them, one per cylinder head located nearest the firewall), replace the end cap plug seals, and reseal the aluminum half moon plugs. All have the potential to leak oil.Clean up the sealing surfaces as best you can with a green Scotch-Brite pad, a can of brake parts cleaner, and some shop towels. Remove the old sealant residue from the the bearing end cap and half moon plug.Apply a thin layer of FIPG sealant to the bearing end cap, half moon plug, and the perimeter of the end cap plug. See the service manual file below for exact sealant placement. Install the end cap plug first, then the bearing end cap, then the half moon into the cylinder head. Expect a small amount of sealant to squish out when everything is installed.Before reinstalling the valve covers, place some FIPG sealant at the edges of the half moons and the corners of the of the bearing end caps. This ensures a leak-free seal on the valve cover gasket surface. Pictured here is the rear of the engine.Front side of engine.Left cover installed.Right cover installed with new valve cover bolt sealing washers. All bolts have been tightened to specification (See service manual file below for torque specs).
Putting it Together
Reconnect the fuel injector electrical connectors and put a new intake plenum gasket into place.Bolt the fuel injection wiring harness back into place.Install the spark plugs, plug wires, and coil packs. Route the necessary vacuum lines. Install the lower intake plenum and torque it down to specification.Install the upper intake plenum with a new gasket and bolt it down to specification. Route the throttle cable and vacuum hoses. Reconnect the throttle body electrical connectors and coolant hoses.Install the intake plumbing and you’re done!
