Questions regarding a weeping valve cover gasket

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I have a Toyota V6, a 3MZ-FE. An observed oil leak seems to be coming from the front cylinder bank valve cover. The forum here suggests that the gasket there could get hard with age and weep. And that it's not uncommon.

Engine is 18 years old, 100K miles, yearly oil changes with M1 10-30 and or Castrol Edge of the same viscosity.

Questions:

1) I see oil at the front bank gasket area. But because of the transverse nature, I can't see what's going on at the rear bank. What are the chances that the oil is coming from ONLY the front bank? Or is it a case of both will be leaking? And if somehow it's only the front, will the rear be leaking soon after.

I ask because the gasket at the front bank looks easy to replace. The rear bank looks to be horrendous. I'm not looking forward to even attempting the rear as the intake manifold and throttle body and a pile of other things will have to come out first (am currently thinking that'll be a pro mechanic's job).

2) What is the best way to clean up the coating of oil on engine parts so that I can see if a new gasket is actually solving the leak problem? (That is no more oil to be seen after a new gasket.) Spray with solvent? Brake cleaner? Detergent?

3) I think the answer is "it's not serious", but what are the ramifications of leaving this leak not dealt with for about 1000 miles? I need to go away for a few weeks. The car will be driven by a family member maybe once or twice a week while I'm gone.
 
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I'd only be asking question 1 if the front and rear cover shared parts that blocked access to them. Otherwise replace the front one and re-evaluate. It's probably not as hard as it looks. Don't let "lots of stuff" intimidate you. Watch some YouTube videos.

I'd hit all the potential oil attracting areas with regular degreaser and a light spray of water.

The engine needs to be kept at the proper oil level regardless of how much comes out. A leak in itself isn't harmful, well unless it started a fire and if that hasn't happened yet...
 

BobandWeave

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Inspect to see if the rear is leaking too. I don’t know what to tell you about the rear. They’re really a PITA. If it’s just the front, change it and move on. Clean things up with brake clean.
It's so hard to even inspect. It's so stupid that Toyota had to do so much shoehorning. Would it have killed them to make the vehicle 6-inches longer, making maintenance much easier? This applies to other manufacturers too like Dodge ramming in a Pentastar V6 into my Caravan. The rear bank in the Caravan is similarly impossible to get at.

I guess I will have to use one of those mirrors on a telescoping stalk.
 

BobandWeave

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I'd only be asking question 1 if the front and rear cover shared parts that blocked access to them. Otherwise replace the front one and re-evaluate. It's probably not as hard as it looks. Don't let "lots of stuff" intimidate you. Watch some YouTube videos.

I'd hit all the potential oil attracting areas with regular degreaser and a light spray of water.

The engine needs to be kept at the proper oil level regardless of how much comes out. A leak in itself isn't harmful, well unless it started a fire and if that hasn't happened yet...

Thanks. I've seen some videos that are both encouraging and discouraging.

The encouraging part is that no special tools are needed (though I don't yet have ratcheting box end wrenches yet; maybe it's a good reason to buy some!).

The discouraging part is that there is so much stuff. I'm getting old and I'm going to forget to screw down a bolt or connect a hose and lots of work will need to be redone because the engine will start throwing codes or there's some kind of rattle. I don't know how pro mechanics do this (remember to re-attach everything).

Another reason to go digging around there is that it gives me the opportunity to replace the spark plugs and spark plug tube seals. I learned that from the videos too.

The leak is one or 2 drips every day. The oil level is halfway between min and max (and if I recall, started not much more than this as I don't usually fill the oil right to the max.) I suspect that keeping an eye on oil levels will suffice.
 
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Well you're not going in the engine so your only critical thing is to keep parts and debris out of the valvetrain when the cover is off. Use some bright painter's tape on the end of everything you unplug. Write a number on it and keep a cross reference list or picture. Be patient getting the gasket situated and make sure it doesn't fall out of the groove when placing the cover back on. Inspect all hoses and keep an eye out for cracked ones.

Or take it to a mechanic. No shame, just in my area they are very, very expensive and not very good.

Bring the oil to the max line, NOT above, before a trip of any length and keep a couple quarts in the car. Be ready if it happens to get worse on the road.

Frankly I'd crack the cover bolts loose then snug them back up a bit tighter than they were and see if that helps. Careful though, you don't want to break one off in the head.
 

BobandWeave

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Use some bright painter's tape on the end of everything you unplug. Write a number on it and keep a cross reference list or picture. Be patient getting the gasket situated and make sure it doesn't fall out of the groove when placing the cover back on. Inspect all hoses and keep an eye out for cracked ones.
Great advice! I hadn't thought of the painter's tape idea. I do take many pictures, but sometimes I find I didn't get the right angle. I could also enlist the help of a family member, but I heard the procedure could take 4-5 hours or more if it's the 1st time someone is doing this for the first time.

Decades ago, I remember adjusting valve lash on my 1st car so it won't be the 1st time tinkering in this way, but that was a 4-banger in an econobox and there was so much space in the engine compartment back then.

PS: A very nice video was this one that dealt with changing spark plugs but which also gets me into the same area:


He had a nice tip about tying fishing line around the bolts when putting them back in blind so they won't drop in and get lost somewhere.

Frankly I'd crack the cover bolts loose then snug them back up a bit tighter than they were and see if that helps. Careful though, you don't want to break one off in the head.

I don't mind replacing various seals and gaskets and, as you mentioned above, cracked hoses. I might also replace the PCV valve.

This vehicle, while old, has been very serviceable and reliable over the years and we see this as staying in the family for years. I don't mind refreshing things such that it stays in good shape for a long time to come.

We just got the timing belt (and water pump and pulleys and seals in the area) done at the dealer because that was similarly complicated and furthermore, I didn't have the specialty tool to keep the cams locked in the right place. My boy and I flushed out the brake fluid recently. It's satisfying to do this and saves money too. It Helps keep my old brain nimble as well (maybe).
 
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It's so hard to even inspect. It's so stupid that Toyota had to do so much shoehorning. Would it have killed them to make the vehicle 6-inches longer, making maintenance much easier? This applies to other manufacturers too like Dodge ramming in a Pentastar V6 into my Caravan. The rear bank in the Caravan is similarly impossible to get at.

I guess I will have to use one of those mirrors on a telescoping stalk.
Indeed.
We had a Lexus RX with a 3.0L V6-1MZFE motor and the rear bank, intake plugs, CoP and anything else you can imagine that was in the rear(firewall area) was very difficult to access.
 
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I also have a similar vintage 3MZ FE with minor oil leaks
You've either got a Sienna, RX330/400h, ES330, Highlander, or Camry SE V6
That 300cc extra really make the difference 🚄
The front valve cover gasket and tube seals will be easy practice for the rear, which is much harder to reach
If your pulling the manifold, consider coils and plugs all around, as they're on borrowed time at this age/mileage
Other than some burning oil smell, and periodic degreasing, there's no real danger or emergency to replacing them
As long as you don't have to add oil too frequently due to leakage, most people just live with it
I plan on gaskets and tube seals all around in the near future, it's somewhat of a job
Speedkar99 covers this engine and platform quite well
I suggest OEM parts, apparently the fel pro gaskets don't fit quite like the originals
Put the tube seals in the freezer the day before, they'll shrink a little and be easier to install
 
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Your Toyota is in the year range of the famous Toyota sludging problems. The sludge under the valve covers would bake and harden like volcanic rock, needing a cold chisel to remove. Lexus had the same issue. Hopefully your problem is not this bad, I would never use these EP oils in this or any other vehicle. As others have said wrap up the parts in colored tape and label every part. Sealing the Valve Covers may be problematic, lots of oil lives up there to lubricate the camshafts, clean, clean and clean the surfaces again. Try to find diagram of top of engine, there is a good chance that some kind of RTV was used at the factory. Felpro gaskets don't fit, odd but i believe it maybe.
 
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I haven't seen this mentioned yet, so just a heads up..... There is a coolant hose under the intake, it's a goofy place for Toyota to have put a rubber hose, but if it hasn't been changed yet, and you're already taking the upper intake off, you're almost there. Just a thought.

I have done the timing belt, plugs, valve cover gaskets etc on our 2007 Highlander with the same engine, it's not nearly as bad as it looks, just follow the good advice above and mark everything, take pictures, and (this is personal preference), use OEM parts as @michaelluscher mentioned earlier. Good luck!
 
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Your Toyota is in the year range of the famous Toyota sludging problems. The sludge under the valve covers would bake and harden like volcanic rock, needing a cold chisel to remove. Lexus had the same issue.
I will start off by saying that I admit I could be wrong, but I believe the 3.3 never had this problem, that was the 3.0 (predecessor to the 3.3) that had the sludge issues.
 

BobandWeave

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I also have a similar vintage 3MZ FE with minor oil leaks
You've either got a Sienna, RX330/400h, ES330, Highlander, or Camry SE V6
Correct!
If your pulling the manifold, consider coils and plugs all around, as they're on borrowed time at this age/mileage
Yes, it's about the right time for the spark plugs. I was going to replace the coils in the back bank. And then keep the 3 working ones pulled out to be spare for the 3 in the easy to replace bank. If any one of them go, I've got 3 spares. I didn't think coils frequently go bad though and so I thought I'd save a few dollars and not replace all of them.

Other than some burning oil smell, and periodic degreasing, there's no real danger or emergency to replacing them
As long as you don't have to add oil too frequently due to leakage, most people just live with it
(y)
Speedkar99 covers this engine and platform quite well
And he's a fellow Canadian!
I suggest OEM parts, apparently the fel pro gaskets don't fit quite like the originals
Put the tube seals in the freezer the day before, they'll shrink a little and be easier to install

Thanks for the tip. I've learned my lesson with cheap brake parts and now will go OEM nearly always.

One thing I worry about is counterfeit stuff. I hate how counterfeits are so common. I'm not sure who to trust or where to buy. The dealer is so expensive. I've read complaints of even sparkplugs being counterfeit. :mad:
 

BobandWeave

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I haven't seen this mentioned yet, so just a heads up..... There is a coolant hose under the intake, it's a goofy place for Toyota to have put a rubber hose, but if it hasn't been changed yet, and you're already taking the upper intake off, you're almost there. Just a thought.
I'll inspect it. I saw either Speedkar99's or someone else's video talk about it but not mention replacing it. I think I will be proactive.
 

BobandWeave

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I will start off by saying that I admit I could be wrong, but I believe the 3.3 never had this problem, that was the 3.0 (predecessor to the 3.3) that had the sludge issues.
I didn't think the 3.3 had this either, but it's a possibility whenever an engine has not been maintained well.

I've been fairly punctual with it, never going too long before oil changes. It sounds bad that I've done it only once a year but that's lately when it hasn't been driven as much. Previously, I changed my oil every 4- to 5000 miles (I consider it cheap insurance).
 
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Even my 02 Taurus V-6 requires you to remove the intake manifold to get to the rear bank valve cover.. I know its leaking, it drips on the exhaust and stinks up the car sometimes. I ignore it and top off my oil as needed. Switching to M1 0w-40 for giggles, I've some leftovers laying around. I'm actually curious to see if the frequency of the leak changes.. Doubt it.
 
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Coolant plate re-seal while your in there, here's the thread too, you'll likely see dried chunks of coolant down the center and falling out around the thermostat. You shouldn't need the part, I've only linked that as example of what your re-sealing.

And get a new thermostat housing being it's plastic.

A tip for getting the intake plenum brackets off is to loosen them from underneath first. I think there is like 2 possibly 3 brackets, just get it up safe and high enough because it is at the lower part of the rear head where you'll find the brackets/fasteners. Thinking I found this in a YouTube video, I'll post reference when/if I find it.

And now that I think about it, seems the wiring harness is slightly difficult because it is over the rear valve cover, and if your without a helper take all the clips/mounts off and push/prop it over to the right as much as possible. This step is necessary because there isn't much room with the wiring harness being over the valve cover, it is fairly doable, just slow and patience to get the gasket in place.

Then when you have the valve cover back on go around it with a mirror and/or camera(on a phone/tablet) to see that the gasket is correctly in place.

I'd agree with practice/do the front bank first, and not planning to do them both in the same day will lower any stress, then watch many different tutorials repeatedly before taking off the intake and doing the rest. Sounds to me like you can/should handle the job yourself and would have a good time doing it if your confident of all the steps before digging into it.

And if ultimately you hire the job out, you'll have the insight to have hired hand tackle all the associated parts too (knock sensors and the short part of the wiring harness attached).

1. Coolant plate and that previously mentioned coolant hose (dealer item, is where I think I got mine)
2. thermostat housing
3. knock sensors and their part of the wiring harness (just thought of that)
4. previously mentioned spark plugs/coils though on this motor it is possible to change them out without removing the intake, as I understand it.

And as you've experienced, good reliability is what we should get from this motor, so hopefully many more years of service for a reward for your efforts.
 
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He had a nice tip about tying fishing line around the bolts when putting them back in blind so they won't drop in and get lost somewhere.
I wish I would have done that when I dropped a thermostat housing bolt down into the coolant passage. Ended up at the bottom of the engine in a narrow, dark passage blocked from view. Sheer luck and the grace of God are the only things that let me find it with a boroscope. I've got to be WAY more careful with stray parts when an engine is opened up.
 
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New valve cover gaskets, new spark plugs (iridium or ruthenium), and every other seal/gasket you need to remove on the way there.

You could use a UV dye to see where a leak is coming from :unsure:


It's so hard to even inspect. It's so stupid that Toyota had to do so much shoehorning. Would it have killed them to make the vehicle 6-inches longer, making maintenance much easier? This applies to other manufacturers too like Dodge ramming in a Pentastar V6 into my Caravan. The rear bank in the Caravan is similarly impossible to get at.

I guess I will have to use one of those mirrors on a telescoping stalk.

Even worse, Toyota tilted the engine backwards to make it even worse :sneaky:

The Sienna and SUV's (RX, Highlander, etc) are even worse than the sedans.

This is why I like the 4-cylinder Sienna and always opt for the I4 when both I4 and V6 are offered for the same car :D
 
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