There were a few writeups about this issue but few pics so I thought I would post some up. Please ignore the Big Gay 2f colors.
Location on head. Above and slightly to the right of the 5 plug hole from right to left (or front of block to back)
It's a known potential problem on 2f motors that this plug can fail and fall out. It's an alumiunum plug that covers up where Toyota had to drill an oil passage so they could route the oil up to the top of the head through one of the head bolts.
If it fails it will allow oil to come out. Ususally all of it. As Mark W said "It's on the opposite side of the exhaust so usually there is no indication that it has failed since it doesn't hit the exhaust". When this happens your engine locks up and means an expensive rebuild.
The fix. Drill out the plug. I used a center punch and then drilled it with a 1/4 bit and then stepped up to a little larger size. About half way through the plug started rotating and I pulled it out with the bit. The plug is right at 7mm wide.
I have seen a few people who tap this out with an 8mm 1.25 tap. I chose a 5/16 tap just because I knew and allen set screw would be more availabe in this size. A 5/16 tap requires using a f drill bit. Where the 8mm tap doesn't require any more drilling.
Basically drill and tap. As a note. I have the head off. Some have done this with the head on. If you do it with the head on you want to try to keep any metal shavings out of the head. https://forum.ih8mud.com/showthread.php?t=113830
Make sure you use cutting or tapping oil. Go slow turn. Once the tap gets in a few turns and is good and centered it good to turn in a 1/4 turn and out a 1/4 turn then back in a 1/2 a turn. This will minimize a tap breaking. Then screw in the the set screw with some red thread thread locker or pipe sealant.
This is the other side of the plug. This is where a headbolt goes.
And the other side. This is where the oil galley to the head is. It goes into the rockers to provide oiling.
Location on head. Above and slightly to the right of the 5 plug hole from right to left (or front of block to back)
It's a known potential problem on 2f motors that this plug can fail and fall out. It's an alumiunum plug that covers up where Toyota had to drill an oil passage so they could route the oil up to the top of the head through one of the head bolts.
If it fails it will allow oil to come out. Ususally all of it. As Mark W said "It's on the opposite side of the exhaust so usually there is no indication that it has failed since it doesn't hit the exhaust". When this happens your engine locks up and means an expensive rebuild.
The fix. Drill out the plug. I used a center punch and then drilled it with a 1/4 bit and then stepped up to a little larger size. About half way through the plug started rotating and I pulled it out with the bit. The plug is right at 7mm wide.
I have seen a few people who tap this out with an 8mm 1.25 tap. I chose a 5/16 tap just because I knew and allen set screw would be more availabe in this size. A 5/16 tap requires using a f drill bit. Where the 8mm tap doesn't require any more drilling.
Basically drill and tap. As a note. I have the head off. Some have done this with the head on. If you do it with the head on you want to try to keep any metal shavings out of the head. https://forum.ih8mud.com/showthread.php?t=113830
Make sure you use cutting or tapping oil. Go slow turn. Once the tap gets in a few turns and is good and centered it good to turn in a 1/4 turn and out a 1/4 turn then back in a 1/2 a turn. This will minimize a tap breaking. Then screw in the the set screw with some red thread thread locker or pipe sealant.
This is the other side of the plug. This is where a headbolt goes.
And the other side. This is where the oil galley to the head is. It goes into the rockers to provide oiling.
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