Spark Plug Tube Seal Oil Leaks and (1 Viewer)

[Craig Haworth]

As I am proceeding to replace the spark plugs and coils on our 2008 series 200 for the first time, with 350,000 miles on the clock, I am realizing I have another issue that needs to be fixed, but I'm hoping I can buy some time before doing the work. That issue is the leaking spark plug tube seals. When I removed the spark plugs, I discovered motor oil in every tube, but not being familiar with these 5.7L engines design, did not know the seals that were leaking, could only be replaced by removing the cam covers. Not how I would have designed it, but I guess Toyota thought it was a great idea....

Question : As I really do not want to expand this project right now, to include the removal and reinstallation of both cam covers, to replace the 8 lipped spark plug tube seals inside of the cam covers, what is the chance I can install the new rubber flat seals I bought from Toyota, that go between the top of the cam cover and the back side of each of the 8 coils, with a small film of Permatex Aviation non hardening gasket sealer under the seals, of course after thoroughly cleaning the top of the cam cover/tube area where seals sit. Am I missing something, or shouldn't this keep oil from coming up through the small gaps between the spark plug tubes and cam cover openings, and entering the spark plug tube, at least until I have the time to take on the removal and reinstallation of both cam covers?

Had Toyota designed similar seal recesses on the top of the cam covers around each spark plug tube, instead of inside of the cam covers, one could easily remove and replace lipped oil seals without the removal of the cam covers......and I would be a happier guy right about now.......

Thoughts?

 

[xeuxaz]

No offense, but that seems ridiculous. Replace the Valve Cover Gaskets and Tube Seals. You don't want pieces falling in on the next plug change or curing issues.

 

[doru]

Probably they do not leak since yesterday, and you'll be able to drive a few thousand miles like that until you gather the parts and make up the time.
I'll rather let it be for now and finish the job. And put it in my calendar now when I want to do the job (this way it doesn't get forgotten or forever postponed).
Doing a patchwork that is doomed to fail anyway it might make the things worse and harder when actually doing the proper fix. Plus, the added work no to put it on and then to take it off.
BTW there is nothing wrong with the design. All engines I worked on have it that way. Unfortunately, on our engines it is not as easy to remove the cover like it is on a 4cyl Toyota engine.
One thing you should think about is that ALL rubber under your hood is starting to gradually fail. I replaced all (outside and inside the engine) on my Camry after 20+ years in PNW and also on my Outback after spending 10 years in Texas high desert with the previous owner.

 

[bloc]

You won’t find this good news but according to a Guru around here (Taco2Cruiser) oil in the plug tubes isn’t necessarily the gasket at the top, but sometimes where the tube is pressed into the head. Meaning the tube has to be pulled to properly address the leak, in that case.

 

[Craig Haworth]

You won’t find this good news but according to a Guru around here (Taco2Cruiser) oil in the plug tubes isn’t necessarily the gasket at the top, but sometimes where the tube is pressed into the head. Meaning the tube has to be pulled to properly address the leak, in that case.

Finding that a bit hard to believe knowing these seals are known to leak with miles, and at 350k, I feel mine are definitely a huge part of the reason for some oil in every spark plug tube. Not saying there can’t be an issue with the pressed tube to head joint, but I find it hard To believe Toyota would have done such a poor job designing that joint.
Without looking at how these tubes are actually installed in the head, I can’t say it can’t be a part of the problem, but my gut tells me it’s the tube seals and the flat rubber seals under the coils.

Are these tubes simply pressed into the head with an interference fit, or are there O rings at the joint that can fail.

I may be the lucky one with a 1 in a million case of failed/poor Tube connections, but seeing how the seals under the coils were all leaking, I’m just hoping replacing both seals will stop the leakage.

Anyone else experience failed tube connections, or is it rare?

Thxs

 

[TimCFJ40]

How much oil? There's really no where for the oil to go in the spark plug tube, so even an exceedingly small leak will show evidence.
A few of mine showed some residue when I changed them, but spending the time to replace the seals based on the tiny little bit of oil collected over time didn't seem like a good use of time.

Also, on this forum it seems like a lot of folks want to dive in to fix tiny little oil leaks on high mileage trucks. There are a few moist spots on my 2008 (rear main seal, maybe a cam tower or valve cover) that I've been monitoring for years and they still don't even show down on oil level by the time I change the oil at 5000 miles. Tiny oil leaks are not going to cause any issues as long as you monitor oil level.

 

[bloc]

Finding that a bit hard to believe knowing these seals are known to leak with miles, and at 350k, I feel mine are definitely a huge part of the reason for some oil in every spark plug tube. Not saying there can’t be an issue with the pressed tube to head joint, but I find it hard To believe Toyota would have done such a poor job designing that joint.
Without looking at how these tubes are actually installed in the head, I can’t say it can’t be a part of the problem, but my gut tells me it’s the tube seals and the flat rubber seals under the coils.

Are these tubes simply pressed into the head with an interference fit, or are there O rings at the joint that can fail.

I may be the lucky one with a 1 in a million case of failed/poor Tube connections, but seeing how the seals under the coils were all leaking, I’m just hoping replacing both seals will stop the leakage.

Anyone else experience failed tube connections, or is it rare?

Thxs

By all means, do the upper seals, yes at your mileage they are probably the primary cause. I was just saying don’t be surprised if some still leak because this is an issue known by mechanics that have a lot of attention to detail. Taco2cruiser is one of those.

It’s not an o-ring down there, the tube is pressed in with Toyota’s version of RTV (called FIPG.) For context failing FIPG is the cause of the cam tower and valley plate leaks in our engines, neither of which are exactly rare to the overall engine family.

More here:

Oil in spark plug wells

So I recently picked up a 2010 lc from out of town. I had a Toyota dealer do a pre purchase inspection and they recommend replacing the spark plugs. After driving it for a few days and noticing the MPG averaging 13ish I decided to try and tackle changing the spark plugs myself. Unfotunately I...

forum.ih8mud.com

 

[Craig Haworth]

So after reading a long list of posts about oil in spark plug tubes, it’s obvious it’s a common problem with multiple causes from sealant failure at bottom of tubes, tube seals inside of cam covers and boot seals under the coils!

So much for my thoughts these 5.7s are near perfect, but what engine is. What I’m reading is replacing the seals inside of the cam covers may not resolve the issue of oil accumulation in the tubes, or at least may not fully resolve it.

In our case, we have a 08 200 with 350k on the clock, has lived in Florida its entire life so it’s been subjected to lots of heat and humidity, so just about every plastic clip, part or hose/tube , has become brittle, where removing anything results in additional broken items. Knowing we plan on letting it go as soon as we can buy a replacement for it, I’m now wondering how much time, $ and effort I am willing Put into it. I’m not lazy, and have worked on vehicles and trucks for 54 years now, and it’s been an amazing vehicle for us, but even with a new transmission, it’s only worth so much, so putting another $2k to 3k into it to replace all 8 coils instead of the one that failed, alternator, AC compressor, Cam cover gaskets/seals, etc…. when it’s got this many miles where we need to replace it, just seems wasteful. R&Ring the cam covers just to replace tube seals , that may not stop oil from getting into the tubes, seems dumb at this point, especially when it may lead to more broken plastic clips and connectors that have become brittle from years of excessive heat!!

I think I’m going to replace the one bad coil, replace the plugs and see if I can clean and seal the boots under the coils, which should stop oil coming up and into the top of the tubes from the cam area Inside! If it stops 50% of the oil, it sounds like it is tolerable as so many of these engines are in use with some oil in the tubes, even after changing the seals inside of the covers!!!

Beyond frustrating, as this is obviously an issue of these 5.7s, and it appears Toyota knew of it long ago but never designed an upgrade or fix!

 

[Craig Haworth]

As for my concern of how much oil may have entered the cylinders, I think I am going to disconnect the fuel pump and ignition relay(s)/fuses, remove all plugs, vac out all oil I can in tubes, spin it for 10 seconds, vac and clean the tubes again, put it back together with one new coil and new plugs, and see if the P 0358 code disappears….

My guess is it will run great again, and will get us by until after the new year, when we can trade it in for a newer SUV..

 

[xeuxaz]

I'll admit, I had no idea FIPG was part of the installation of the tubes at the cylinder head. I would be frustrated, too....

 

[TimCFJ40]

As for my concern of how much oil may have entered the cylinders, I think I am going to disconnect the fuel pump and ignition relay(s)/fuses, remove all plugs, vac out all oil I can in tubes, spin it for 10 seconds, vac and clean the tubes again, put it back together with one new coil and new plugs, and see if the P 0358 code disappears….

My guess is it will run great again, and will get us by until after the new year, when we can trade it in for a newer SUV..

You never mentioned if it was leaking even enough oil to measure over the course of an oil change. Does it even leave a drip on the driveway? If not, I wouldn't wait a second longer worrying about it personally. Any motor that makes it over 350k miles and still runs well with just minor oil leaks is vastly exceeding the majority.

 

[doru]

I'll admit, I had no idea FIPG was part of the installation of the tubes at the cylinder head. I would be frustrated, too....

Nothing new here. Even on the 30 years old Toyota 4 cyl engines they used it. But the tubes were screwed in instead of pressed. I still wonder why the tubes are pressed in. It doesn't look like a better design. It might be cheaper not to have to thread the tubes and the head, but it also means the tubes have to be machined to tighter tolerances for a good press fit, and maintenance is much harder to do.

 

[Craig Haworth]

Nothing new here. Even on the 30 years old Toyota 4 cyl engines they used it. But the tubes were screwed in instead of pressed. I still wonder why the tubes are pressed in. It doesn't look like a better design. It might be cheaper not to have to thread the tubes and the head, but it also means the tubes have to be machined to tighter tolerances for a good press fit, and maintenance is much harder to do.

Well, I finished most of the repairs and ended up replacing 4 of the coils feeling they should all be replaced. I vacuumed out oil from every tube prior to removal of old plugs, sprayed brake cleaner to assist and vacuumed again. Sprayed compressed air to blow out any remaining and removed all plugs.

Zero oil remained, but had I not done that, a lot of oil would have entered the cylinders no doubt.

I did not remove the cam covers to change the tube seals, hearing it would probably leak anyway, so instead, I thoroughly cleaned the top of the tubes and cam cover where coil boot sits, and put a small bead of Permatex ultra black RTV sealant on the back side of new boots, and reinstalled. If seals inside of cam cover leak, which mine will, this small bead of sealant will not allow oil to get by and fill the tubes, and will still allow coil removal for the next plug change in 5 or 6 years. It will also stop the oil leaks I had at every coil before I tackled this job. Now, the only way oil will fill the tubes is from the fpig sealant failure at the base of the tubes, which may not be leaking, but if it is, is a major to address!

Car started, warmed up and zero codes came back . Idles and runs like new albeit a bit lower rpm than it should which may be fuel issue… next on list, but still need to replace the other 4 coils.

New fuel pump , 4 coils and injectors are next to replace. Once that’s all done, I might have to replace a few sensors, but I sense it will then be 1000% better than it was…..and may lead to 500k as we had planned, rather than selling it. Drives beautifully…. and will need an alternator , water pump and AC Compressor down the line too, but so what, it’s the only suv we will own, and everything will require maintenance and repairs….

 

[bloc]

Good work. You may find the idle returns to normal values as the engine adjusts it's fuel and timing trims to account for the improved efficiency.