I have a 98 gs 400 with 187k on it. I replaced the spark plugs a while back. a few of them had oil on them and around the boot. Not inside combustion area. I'm thinking its a leaking valve cover gasket. Same way on both sides. Is this a very hard fix. Also are there any diy threads on this and what would be expected cost to have this done.

 

It's probably the valve cover gasket that's leaking. The gaskets aren't expensive and shouldn't be hard to replace. I have a 300, so I'm not familiar with the 400. But no need to panic.

 

Hi pitman, I am not an expert, but it is not that hard to replace the spark plug boot. if you can change brake yourself, you can do this. Just buy the valve cover caskets for both sides, spark plug boots, and the valve cover bolt washers, so that you have those parts on hand and ready to replace if need it while you are doing it. You can always return what you do not use later for a refund. There are nine bolts on each side with 10mm on the valve covers. I replaced mine all eight of them eventhough there were one or two bad on each side so you do nor have to deal with it later since you already have it out. If you do it yourself, it will cost around $150 on the high estimate on parts from the dealer. Bring it to a shop, I am not sure how much. I don't know how many hours they will charge labor. I know dealer charge $99 an hour, and may be independent shop will charge something like $50-75 an hour. It is easy than replace the brakes. You need to remember not to nick the edge of the spark plug boots when you pry or take out either with screw driver or the proper tool call Shaft Type Seal Puller made by Lisle part#58430. That was the tool I used when I replaced mine. It costs like $20 plus tax. Use this tool if you do not want any damage on your spark plug boot edges or lips where the spark plug sit in so that the oil does not get through it. I did not look at the DIY link when I did mine. You can try the link. I am sure there is one. Like I said it is easy than changing brakes. Torque the valve cover bolts to 11-12ft-
lbs, and the spark plug bolts to 35in-lbs when I asked Lexus dealer mechanic. Good luck. Let me know if you need help.

 

Thx. Just looks like some stuff would have to be taken off just to get valve covers off. I may be wrong. Didn't look real hard. Also im confused on this boot tool. My plug wires came off very easy from the spark plug. Will I have to take plugs out also before I can get valve covers off

 

Yes, you have to remove the nine bolts using 10mm on the valve cover in order to replace the spark plug tube seals or boots. Before you can remove the valve cover, you have to remove spark plug coils on both side, PVC hose and other hose as well on the driver side, including other stuffs that obstruct the pathway of taking out the cave cover itself. For the passenger side, you will remove part of the intake system and some hoses as well. The spark plug tube seals are setting inside the valve cover. GS400 do not use spark plug wire, it uses coil.

 

seems like alot more work than doing brakes. lol. and i know they are coil over plugs. just thought maybe you were saying the boot that goes on the actual spark plug.

 

Sorry for the terminology confusion, it sometime call the boot but the correct term is spark plug tube seal. No, it is not that difficult to do. I like said if you can do brake, you can do this. Just be careful not the damage the lips around where the seal sits when you pry it off with the very flat tip screw driver, or using the tool I mention earlier. If you don't feel up to the task, you can leave it for the mechanic, but I feel you can tackle this yourself. Take you time during the process and don't over torque the bolts. After you replace those tube seals, it is a good time to remove the spark plugs with oil contamination and clean the plug and the tube good. Good luck.