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How to Change Valve Cover Gaskets
1990-1994 Lexus LS400

By LexLS.com

Before doing anything read my disclaimer & safety info.



If you see oil leaking from the valve covers you probably need to replace the valve cover gaskets. It's a job that is very straightforward and seems simple but is more work than you might realize. In order to get the valve covers off there are many parts that need to be removed. Some of these parts are tough to reach, and if you've had oil leaking for a while like me these parts are going to be very dirty and oily. I must stress this: plan for enough time to complete this job. I heard that inspecting and adjusting the valve clearances is an 8 hour job for an official Lexus mechanic so that means it's going to take you much longer. Without even inspecting the valve clearances, removing and replacing all these gaskets took me about 2 full days; I took a ton of pics along the way and that always slows me down. Luckily for you I can share some insights for this job.

This procedure is really many wrapped up into one. It will get you to the point where you can inspect and adjust the valve clearances but I do not cover that here. Yes, I probably should have checked the clearances while I had everything taken apart but I didn't have the tools (or time) to change shims if any were out of spec. If you want to check yours by all means do so, the procedure and all the specs needed are in the EM section of the repair manual.

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Tools Needed:

Parts/Supplies Needed:

Optional Parts to Replace:

1) Disconnect battery, remove air intake and engine covers . Follow steps 3-15.

2) Disconnect the spark plug wires. I only disconnected them from the spark plugs since I was not replacing the wires or plugs. If you're replacing the wires fully remove them.

3) Remove the 2 10mm bolts and the two spark plug wire clamps. Each bolt holds one piece. Repeat for LH side.

4) Remove the throttle body. Follow steps 3-9. I've found that you don't need to drain the coolant. If a little coolant drips out of the upper by-pass hose plug it with a pen, you see this in the pics later on.

5) Remove the 2 10mm bolts highlighted in red on the left from the engine wire brackets. Remove the 2 10mm bolts that hold the engine wires to the fuel rail. Removing the bolts on the fuel rail gives you a little more room to get the valve cover off.

6) Unclip the wire clip from the wire bracket.

7) Remove the 2 10mm bolts and the upper engine wire bracket, the removed piece is pictured in the lower right. The bolts are a little hard to get to under the engine wires so use your angled sockets and extensions. The wires can be moved a little to access the bolts.

Optional: Attach a piece of string to your socket and box wrenches. There are several bolts that are very hard to see and reach coming up. You'll thank me when your wrench slips out of your hands when you're trying to undo a bolt and you can simply pull it right out!

8) Remove the 2 12mm bolts and the lower engine wire bracket. Yes, they're a pain to get to! I used my box wrench on a string to get these off. This bracket absolutely needs to come off to remove the RH valve cover.

9) Remove the 12mm bolt that holds the front bracket. This is optional but I removed it because it was so dirty and it also gave me a little extra room to get the valve cover off.

10) Remove the oil and transmission dipsticks. Remove the 12mm bolt that holds the oil dipstick tube to the engine. This was extremely hard for me to remove since it's behind the bracket. Again, I used a box wrench on a string. The repair manual says to also remove the oil dipstick tube but I just pushed the tube to the side and there was enough room to get the valve cover off.

11) Remove the 2 10mm bolts that hold the wires to the fuel rail. I also removed the metal bracket on the right from the plastic wire holder. This gave me just enough extra room to remove the valve cover later.

12) Remove the PCV hose and PCV valve.

13) Remove the 8 10mm bolts that hold the RH valve cover on. Repeat for the LH side, the bolts are in the same locations.

14) Remove the RH valve cover. It has to come straight back first to clear the spark plug tubes, then it can be slid forward and off. This is where it helps to have the bolts on the fuel rail removed so you can have a bit more wiggle room. This picture is after I cleaned all the oil and dirt that had built up from the leak.

15) Remove the LH valve cover. Similar to the other side but you'll have to bend the coolant hose a bit. Again, the pic shows after it had been cleaned up.

16) On each side, clean the area where the cover gasket sits so it's perfectly dry. Try to avoid getting dirt in the gears and on the valves. As you can see in this pic there will be some remaining FIPG material that needs to be fully scraped off. I scraped the remainder off with my fingernail. While you're at it, clean up as much dirt and oil from the leaking as you can.

Here's the back of the RH valve cover. You can see oil was leaking from the wet spots. The front and rear corners were the worst. The LH side was similar. Now to clean the covers and replace gaskets....

17) Remove the PCV grommet from the LH cover. I used a needle nose pliers and it came out in several pieces. Some fell into the cover but it wasn't a big deal to remove it. Yes, my covers were VERY dirty!

18) Remove the 4 spark plug gaskets for each cover. You can tap them out with a hammer and piece of wood or metal round bar if it fits directly over the gasket. I wasn't sure how they were held in place when I removed them so I cut them out. First I sawed as close to the edge as possible with a keyhole saw, but not all the way through since I didn't want to cut into the cover. Then I used a pliers to pull the gaskets out. When I look back it would have been much easier to hammer them out, just like they get hammered in.

19) Next remove the valve cover gasket on the bottom and finally clean the covers up. I did the bulk with paper towels and then used some throttle body cleaner and a rag to get the remainder. There will probably be some oil in the groove for the valve cover gasket and make sure that gets fully cleaned out. I didn't clean the under side of the covers much since they were fine.

20) Set each spark plug gasket in place and slowly hammer it in using a piece of wood/metal that fits over the entire diameter. I just screwed together a couple of pieces of scrap wood and that worked fine. You want the gasket to be flush with the top and even. Just tap it in slowly and check to see how far in it is. The gasket does have a top and bottom side so make sure to make a note of how they go in. After the gaskets are in apply a light coat of multi-purpose grease to the inside lip of the gaskets so they slide over the spark plug tubes without moving the gaskets.

21) Flip the cover over and install the new gasket. Start with the semi-circular areas and the rest will fall right in.

22) Apply some FIPG to the 8 highlighted areas. This is basically taking care of areas the rubber gasket cannot reach well. The corners around the curved areas and where the semi-circular plugs line up. The FIPG has a 15 minute work time.

23) Install the valve cover and 8 bolts with a new seal washer on each bolt. Torque each bolt to
52 in-lb (60 kg-cm or 5.9 Nm).

24) Repeat steps 22 & 23 for the LH side. The FIPG needs at least an hour to set up before the engine can be started.

25) Install is reverse of removal. Cross your fingers that you have fixed your leak!



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Last revised: Sunday, 29-Oct-2023 15:46:23 EDT