Clutchless

Have you checked for loose bolts on the timing cover? Or attempted to snug them a bit tighter? Others have found some could be tightened.

carguy75

No, but I will check for loose timing cover bolts during my next oil change. I will also check my rear valve cover gasket near the area above the weeping for leaks as well since it looked like my leak was coming from above the oil line banjo bolt along the seam where the oem RTV starts on the timing cover just under the valve cover. It may be a leak from the valve cover that drizzles down the timing cover.

To be honest, I really hope it only a leaky valve cover gasket instead of leaky timing cover RTV seal.

AlgoTrader

If its the RTV at the timing gear cover, here is a video that shows all the details of what's involved to reseal it with 3RX.
TLDR version: drop the motor/trans out of the car, take the 2GR partway apart, reseal, reassemble.

In the video below, he actually pulled this 2GR-FE out of a 3RX. Restart video at beginning to see that process.

RX in NC

^^ Extremely well-done video explaining, showing, and repairing the infamous timing cover leak that is unfortunately prevalent on these engines. Sure hope I get lucky and never have to deal with this issue on my wife's 2015 RX350 FWD now approaching 90,000 miles. I will take yet another look at the general leak area when I do the 90,000-mile service coming up in the next week or so.

carguy75

I watch the Car Nut videos and received a very good understanding about Toyota engines and repairs from them. I watched the video about common 3.5 problems and the video in the post a while back about the 3.5 timing cover leak repair. Hence, why I know it is very hard repair to perform for a DIYer; and that the repair can be put off for a long time because the leak is usually very slow and can be plugged(or reduced) with extra RTV or spray sealant placed on top of the oem RTV seal.

Abrar

i would double and triple check, the 2GR engine are known to leak from the front and back timing cover , where the block meets the cylinder head , where they both meet the timing cover.

carguy75

I can see why the timing cover may leak. Toyota has very complicated front cover install instructions for applying RTV in the service manual as well as bolt tighten specifications. The instructions probably confuses novice workers on the assembly line that build these engines which allows some front covers not to be properly sealed. Unfortunately, the poor RTV sealant application and/or loose bolts does not cause a leak until after many heat cycles with the engine head and front cover expanding and contracting which causes a leak in the weak sections many miles(or years) later.

mnalep

Can you explain, or show picture, of where these timing cover 4 bolts are?

AlgoTrader

I'm not sure what Toyota does specifically, however, in most high volume manufacturing assembly lines, silicones are dispensed using a robot. The robot is programmed to trace out a path and lay down the correct amount of adhesive. At my prior job, I worked for an adhesives distribution company that also manufactured and sold dispensing robots.
The TIS is for mechanics (technicians) in the field, as they won't typically have a dispensing robot.
Part of my job involved silicone molding and we had to mold them at roughly 200-250°F, and I learned that silicones tend to soften at temperature. This is part of the issue with the oil leak of the sealant in the 2GR. This combined with metal movement (expansion/contraction), hot oil being thrown against the silicone, etc. Silicones can degrade when exposed to chemicals, especially at higher temperatures.

Also, different formulations of silicones have varying mechanical strength and adhesion. To see examples of this, Project Farm on Youtube did a video where he tests various RTV's, including Toyota FIPG (the recommended "seal packing" from the TIS). Unfortunately, he only tests 1 flavor of Toyota FIPG black (there are 2 flavors). He tests it against Hondabond, and other RTVs. Surprisingly, the Mopar RTV is superior to Toyota FIPG. Also, he did not test them at engine operating temperature. Its still instructive to see how the different RTV's perform. You may find a new respect for the OEM RTV vs the auto parts store generic RTV.

carguy75

I have watch many of Project Farm test videos; including the RTV showdown. Not a perfect real world test for the RTV sealants, but informative for sure. I use Permatax Ultra black for sealing oily parts. Very good stuff to use that is very oil resistant. He did not test that one.

I have seen videos of robots(or dispensers) putting a specific amount of RTV on a part, however I have seen in a Toyota 3.5 V6 plant where a worker actually carries an RTV applied valve cover to place it on an engine by hand. So worker error can still be the reason many of the these timing covers are leaking or it could just be a case of not adding enough RTV in key areas since majority of the leaks occur after many years or miles later.

This Toyota worker carries a fresh RTV applied( I assume on the corners) V6 valve cover by hand to the engine block at about 2:16 in the video, which means that a finger could have smeared the RTV bead during installation and transport. So worker error could be a major factor in why some timing covers leak and some does not. In the second video a worker hand carried and assembled a RTV applied upper oil pan at the 4:20 mark in the video and another worker placed a front timing cover by hand later in the video.

RX in NC

Interesting video. I have always assumed that factory robots squirt the RTV beads on these components. That would indeed result in more consistent RTV application on the assembly line although no process is 100% perfect. If the RTV containers are allowed to run very low on product before they are replaced or refilled on the factory floor, that could cause the robots to get sloppy or skimpy with the RTV application process.

I just hope that my wife's engine received enough RTV in all the right places on the day it was built so I never have to deal with this issue. Time will tell.

AlgoTrader

I was just speculating that they may use robots to dispense silicone, as that's what most high volume manufacturers (in many industries - not just automotive). Regarding your comment about how the robots work - that's not exactly how they work. Either the operator is trained to monitor the amount remaining in the reservoir and knows that they need to refill it/swap reservoirs when it gets too low, or the machine itself monitors the level and either stops operating and flags a human, or it is setup to autofeed from another container. Typical tote size are 275 gallon totes.

So by way of example, I know first-hand that Tesla buys Part A and Part B silicone, both in 275 gallon totes. They buy multiple trucks of the stuff. Their dispensing equipment mixes part A and Part B, and applies heat to cause the silicone to harden (crosslink) from a liquid to a solid. So the machine uses 550 gallons before it needs to have the totes changed out. I know this first hand because at my prior job I assisted Tesla at their Fremont factory with setting up these systems. In this example, the dispensing machine is semi-automatic and the operator must monitor the remaining stock and swap out the totes when it runs out.

I don't know if Toyota does this, but it seems reasonable that they would, but anything's possible. Maybe they still do it by hand. I would disappointed to find out that this were true. At the same time, it might explain why the 2GR has this issue with such frequency. My own 2GR (2013 MY, built in 12/2012) is showing signs of weepage at the timing cover. Robotic application of adhesives is going to be far more accurate and consistent. Accuracy and consistency are critical for Six Sigma manufacturing.

carguy75

My best guess is that some workers may get confused when it comes to the dashed application of RTV as per the service manual and the one section in the leak prone area(under the banjo bolt) that needs a large solid bead of RTV. I believe that many timing covers are not getting the proper RTV application in the area under the VVT banjo bolt for what ever reason.

carguy75

Well the Permatex spray sealant seems to work to slow the timing cover weeping since the area is dry to the touch. However, I do have a leak in the lower oil pan seal just above the oil drain bolt. The area is wet with oil like before, but the top of the oil pan is dry. So it seems that I have a weeping timing cover and a slow leak in lower oil pan RTV sealant that is very light since it does not drip on the floor, but it does coat the oil pan just around the drain bolt.

So I will just buy a new lower oil pan and RTV it on the upper oil pan; since I do not want to clean off the off factory RTV and scrape away the black protective paint on the bare steel in the process.

Abrar

hi , but you do have to scrape away the rtv from the aluminum interface on the engine side correct ?