Oil on spark plugs/inside cylinder

[billygoat8]

Hey everyone,
2005 LX470, 240k miles
Looking for advice on how much I need to worry about the possible valve cover gasket issue. While changing my spark plugs out on my truck the spark plugs had a burnt oil up on the white ceramic portion (cylinders 1/2/3) and the threads were really gunked up on all of them. 1/2/3 had leaked where the coil boot seats at the top of the threads. After this discovery, I got an endoscope camera to check inside the cylinders and after checking the front two on the drivers side (I think 1/3) I saw some oil on the top of the cylinder dripping down. Both leaks were on the rear of the cylinder. I wanted to check here before removing everything again and checking the other cylinders.

Is this something I need to address right away? Is this common for these engines and just keep going about my life? The truck seems to be running great besides maybe a couple extra cranks before starting recently (not sure if that's related).

 

[Trunk Monkey]

Actually a couple of very recent threads on this oddly enough. Be glad you caught it, one of the threads involved the plug blowing out. Scroll through the first few pages, you'll find them.

 

[billygoat8]

Actually a couple of very recent threads on this oddly enough. Be glad you caught it, one of the threads involved the plug blowing out. Scroll through the first few pages, you'll find them.

Oh man. Narrowly avoided i guess. Thank you for the tip. Would you think the oil in the cylinder is related to the plugs? I retorqued the head bolts and most of the front ones were finger tight at best.

 

[Bisho]

The oil most likely dripped in there because you removed the plug. I wouldn’t worry about that, but I would plan a half day to redo the gaskets.

 

[Kamran Khan]

Oil dripping down the cylinder is typically caused by failing spark plug tube seals or overfilling the engine oil. It can also result from excessive blow-by.

 

[OEMGUY0720]

When was the last time valve cover and spark gaskets were replaced?

 

[2001LC]

Looking at you picture of spark plug corona and last picture of bottom of spark plug tube along with capture threads. I see signs of a spark plug, that was loose (walking out), and getting blow by past the threads. Very likely, coil boot and coil was less than pristine color.

There also is another seal, we never talk about in the 4.7L. But we're seeing fail in the 5.7L (200 series). It's the tube to head press fit. In these 5.7L, press fit leaks. Toyota calls them, a non event. Even though tube fills with oil submerging coil. Toyota fix is replace the heads. Which they will not warrantee. One guy in the world, fixes these in suti. I've asked him, if any change after leak stopped (coil dried), like MPG?. He said only change, is less oil loss. Which anyone with a 5.7L knows they use a lot of oil. We don't use any oil in 5K miles, in the 4.7L. Toyota considers 0.6 qt loss in 1K miles acceptable in 5.7L. Freaky right!

The only spark plug tube seal(s), I've seen fail. Are ones, previously replaced. When a tube seal leaks. We can see oil on the seal, between top of tube and head cover. Which to date, previously replaced, are the only head cover gaskets and tube seals I've had to replace.

I have retorqued many head cover bolts to 53INCH-lbf. Stopping all head cover leaks, to date. It works until it doesn't. In time, since they are rubber, they will one day need replacing. But I've not seen this yet. Not even on, 25 year old w/400K miles. The head cover and tube seals R&R. Are not on my PM list, retorquing their bolts is. The trick is to get all bolts to 53INCH-lbf evenly. Which takes to passes three passes. First to snug to about 30INCH-lbf. Second to 53INCH-lbf and a third pass to 53INCH-lbf. I use a 1/4 digital torque wrench.

If PCV system not working properly. Crankcase may build excessive pressure. Which result in seal leakage, and not just spark plugs tube seals. PCV valve must be working properly. So PCV service is part of my spark plug (AKA: turn up service).

The very first thing I do, during any spark plug removal. Is clean top of engine and blow out spark plug tubes with my air pistol, before removing the spark plug(s).

Additionally, I replace coils top seal and boot (denso boot kit), as part of the spark plug service. The top coil seal, keeps dust/sand and water out of the tube. I torque coils to 66INCH-lbf. These seals, like those of head cover, washers of 10mm bolts and tube seals are rubber. Proper torque, insure we have proper & even pressure on rubber seals

 

[rexington14]

There also is another seal, we never talk about in the 4.7L. But we're seeing fail in the 5.7L (200 series).

Only one?

 

[2001LC]

Only one?

Nope! More than one leak on 5.7L

 

[billygoat8]

Oil dripping down the cylinder is typically caused by failing spark plug tube seals or overfilling the engine oil. It can also result from excessive blow-by.

No blow by. Oil was slightly over filled and I have removed some now to the correct level. Thanks for this info

 

[billygoat8]

When was the last time valve cover and spark gaskets were replaced?

no idea. I picked this up last year and dont see that on the records I got from the last owner. What are the spark gaskets?

 

[billygoat8]

Looking at you picture of spark plug corona and last picture of bottom of spark plug tube along with capture threads. I see signs of a spark plug, that was loose (walking out), and getting blow by past the threads. Very likely, coil boot and coil was less than pristine color.

There also is another seal, we never talk about in the 4.7L. But we're seeing fail in the 5.7L (200 series). It's the tube to head press fit. In these 5.7L, press fit leaks. Toyota calls them, a non event. Even though tube fills with oil submerging coil. Toyota fix is replace the heads. Which they will not warrantee. One guy in the world, fixes these in suti. I've asked him, if any change after leak stopped (coil dried), like MPG?. He said only change, is less oil loss. Which anyone with a 5.7L knows they use a lot of oil. We don't use any oil in 5K miles, in the 4.7L. Toyota considers 0.6 qt loss in 1K miles acceptable in 5.7L. Freaky right!

The only spark plug tube seal(s), I've seen fail. Are ones, previously replaced. When a tube seal leaks. We can see oil on the seal, between top of tube and head cover. Which to date, previously replaced, are the only head cover gaskets and tube seals I've had to replace.

I have retorqued many head cover bolts to 53INCH-lbf. Stopping all head cover leaks, to date. It works until it doesn't. In time, since they are rubber, they will one day need replacing. But I've not seen this yet. Not even on, 25 year old w/400K miles. The head cover and tube seals R&R. Are not on my PM list, retorquing their bolts is. The trick is to get all bolts to 53INCH-lbf evenly. Which takes to passes three passes. First to snug to about 30INCH-lbf. Second to 53INCH-lbf and a third pass to 53INCH-lbf. I use a 1/4 digital torque wrench.

If PCV system not working properly. Crankcase may build excessive pressure. Which result in seal leakage, and not just spark plugs tube seals. PCV valve must be working properly. So PCV service is part of my spark plug (AKA: turn up service).

The very first thing I do, during any spark plug removal. Is clean top of engine and blow out spark plug tubes with my air pistol, before removing the spark plug(s).

Additionally, I replace coils top seal and boot (denso boot kit), as part of the spark plug service. The top coil seal, keeps dust/sand and water out of the tube. I torque coils to 66INCH-lbf. These seals, like those of head cover, washers of 10mm bolts and tube seals are rubber. Proper torque, insure we have proper & even pressure on rubber seals

Great info and your thread on the spark plugs backing out was extremely helpful. seems like this was likely the issue. I have read through all the threads now on the spark plugs backing out. I currently have everything apart now and a denso boot kit on the way along with the new TT plugs so I can have a fresh crush washer. A few of the head bolts I checked I could unscrew with my fingers so that is likely where the oil leak is coming from I think. I am going through each tube now and blowing with the air gun and then using some rags with a bit of break clean to clean up the mating surface where the plug meets the threads. hopefully with everything clean and torqued to the correct specs it will fix the issue. You are right about the boots, the worst looking plugs had brown and brittle boots on the coils.

 

[2001LC]

Just to be clear. Air pistol, is used to blow out dust/sand, before removing spark plugs.