Transmission cooler line leak?

I have a reddish brown leak when looked at on a white paper towel that doesn’t really smell to me that appears on the passenger side bell housing after driving (pic1). It doesn’t drip to the driveway yet so far as I can tell. I took the inspection cover off and it runs down to the lowest point of the bell housing on the passenger side (pic2), but not really on the driver side (pic3). There was no fluid on the flywheel or on what I could see of the torque converter. I wondered if it is a transmission cooler line leak because it’s on the passenger side and it seems moist (pic1) around the cooler line inserting closest to the edge of the bell housing but after taking the clamp off for the portion of the line closest to the bell housing, I didn’t see a larger wet area under the clamp. I didn’t do powder or UV yet to try to trace it further. Any ideas on where it is coming from based on the pics (ie still transmission cooler lines most likely or something else I’m not thinking of)? 3.4L V6 has 330K and original transmission replaced at 170K by previous owner (friend who passed & willed truck to me) per Toyota records (? New/? Rebuilt Aisin A340e) if it matters. Neither of us tow(ed). I don’t know if transmission cooler lines are original. Thanks

 

Could it just be a rear main seal leak? Looks like engine oil to me. You would have to pull the trans to replace that seal. I'm not super familiar with the v6 though.

 

I forgot to post the paper towel. I was hoping against a seal leak since it was dry on the inner side of the inspection cover, flywheel/flexplate, and torque converter. Fluid was in a line along from the upper to the outer lower passenger portion of the inner side of the inspection cover where it bolts to the bell housing (pics).

 

Looks like engine oil to me.

 

Check the valve cover gasket on that side.

 

Looks like engine oil. I suspect valve cover gasket also. At 330k, if you've not changed the valve cover gaskets yet, you're probably overdue. Mine were toast after 73k miles and 16 years. Of course if that's not it, AT-205 may help to rejuvenated whichever gasket is toast.

 

Well I changed the valve cover gaskets and in doing so, created a new problem for myself. I managed on the reinstall to cross hoses. I’m a bonehead I know.

On the side of the throttle body closest to the firewall and down low there is a coolant hose that has a compression clamp (Haynes labels it as “water hose” see pic, and below that there is a vacuum? hose (Haynes labels it as “air assist hose” see pic); I crossed those two hoses on the rehook up.

When I started the truck it ran fine for 15 seconds and then died and would not again turn over. I didn’t figure it out at first. I checked connections and fluids. When I opened the radiator cap I heard a sucking/gurgling sound and antifreeze streamed out of the higher of the two crossed hoses since it doesn’t have a clamp on it. I realized the problem and switched the two hoses with each other to the correct position.

I tried to start it and it almost wouldn’t turn over and then finally did. Then white smoke poured out of the tailpipe as my family watched in horror from the windows above and a daughter ran out of the house to tell me “mom wants you to move the truck out of the garage before the truck explodes.”

I drove it down the street and back (2-3 miles at 30-40mph), and it drove fine like before the valve gasket change. No check engine light. No white smoke from tailpipe when back in driveway. Oil on dipstick looks like oil I think (see pic).

What happened when I hooked up the hoses incorrectly? Did I skirt disaster, or am I in for it now and the end is near? Oh, and no oil leak so far as I can tell after the valve cover gasket change. Thanks

 

It would seem when you reversed the lines, water was getting pulled in where air would normally go - i.e. into the cylinder. White smoke coming out of the tail pipe being the result of combustion w/water in the cylinder. If so, you're lucky you didn't hydrolock your engine.

 

The only thing different that I have noticed so far is that there is now a clicking sound at about 10 times per second, but never when the engine is just started, and I have only noticed it when idling. It takes a couple of minutes to show up after the truck is started. It otherwise drives fine (town and hwy) so far as I can tell. Any ideas? Thanks again.

 

Maybe it was there all along. Lots of 1GT owners on here complain of ticking after engine warms up. Injectors, exhaust manifolds are usually the suspects.

 

I forgot to mention that once it shows up at idle, if you rev the engine, the clicking goes away during the revving and stays away during idle for 1-2 minutes after revving and then it returns. Does this help narrow what it may be? It wasn’t present before the gasket replacement based on old videos. Thanks once again.

 

I also replaced spark plugs (NGK laser platinum BKR5EKPB-11) with the valve cover gaskets if that makes a difference.

 

Does it increase with the revving?
Have you attempted to pull the power from each coil pack while the engine is running to see if the popping disappears?
Did you happen to check out your coil packs and whether anything was cracked? (try the previous test first to see if it's even related to spark)

Well, yeah, any maintenance changes make potentially a huge difference, so important to mention.

Where'd you buy them? Just curious. Hopefully not scAmazon, king of counterfeit spark plugs.

Toyota calls for the Denso K 16TR11 for this application, specifically a two-electrode plug, which the NGK you purchased definitely should be. Some members have found out the hard way running single electrode plugs.

 

No cracks in coil plugs. Plugs new from NapaAP. Removed plugs (sample pic below). Have not pulled power from coil packs but can do if you think it would help. Watched videos of the 5VZFE “TacomaTic” on TacomaWorld and it matches (“suddenly appears” one day, doesn’t appear until couple minutes after starting and only while idling, doesn’t increase with revving, goes away briefly after idling and then returns). I did have the Denzo OEM plugs before the NGT. Here is a video of the truck ticking. Let me know what you think. Thanks https://youtube.com/shorts/GI98MRUcJSY?feature=share

 

Plugs look great.

Just to remove ignition from the equation, I'd still unplug power to each coil pack, see if it goes away, re-plug, move to the next one. If you get through all 6 coil packs and the ticking is still there, clearly it's not related to ignition.

I'm leaning towards exhaust manifolds. When metal heats, it expands, so if things could change with engine temp. And it's a known issue, the exhaust manifolds cracking, I'm not sure if it impacted both V6 and V8 though.

 

Just listened to the video.

Does the sound still happen with the serpentine belt off? Does the speed of the tick increase with RPMs?

I have a very similar sound from mine, same thing I'm complaining about. It seems to be worse when warmed up. I'm not unconvinced it's the injectors (on mine at least).

 

Didn’t go away unplugging each coil pack. Speed of tick didn’t increase with rpms. Using a stethoscope on everything in the engine bay I couldn’t localize it. Then I held each hose and found that one hose vibrated in sync with the clicking. It localized it to the lower Vacuum switching valve (VSV) hose in the back of the engine bay. It was the problem. No more TacomaTick!

So that’s the good news. Bad news is the oil leak is back showing up at the same passenger side of bell housing and coolant lines but coming from above. Now I know it’s not the valve covers leaking. What else could it be, any ideas? Thanks

 

Glad you got it fixed. Got a pic of the leaky area? Is it not the valve cover?

 

It’s coming down from the passenger side.
Not seeing leakage from valve cover.

 

I'm having a hell of a time trying to figure out the orientation of the photos. I feel like you posted plenty, but my head is having a hell of a time trying to wrap around what we're looking at.

 

Sorry I’ll post some better pictures this morning. The pictures are looking up from underneath the truck on the passenger side. Pic 1 is the starter I think and the circled area is a groove on the bottom of the starter and in that groove there is oil that collects. Then it next (runs down?) and collects along the passenger side transmission cooler lines (pic 2 top right) and then it appears to run down further and collect on the bottom of the bell housing (pic 2 bottom two circles are left side of bell housing and lowest point of bell housing). I checked again on the back of the valve covers after the valve cover replacement and I don’t detect any oil there. It is coming from somewhere below the valve covers on the passenger side. I am hoping there is something I can tighten or replace to stop it. It doesn’t happen when idling even if I let it idle for a hour, but will happen only after being driven. It doesn’t make a puddle in the driveway (yet). The oil is always black and not golden in color, like what is on the oil dipstick. I have cleaned everywhere that I can reach on that side. Any ideas?

 

Pic 1 above shows back of passenger valve cover camshaft plug reflected in mirror. No oil detected after valve cover change.

Pic 2 shows semicircular plug reflected in mirror. Also no oil detected after valve cover change.

Pic 3. Shows top of starter from above on passenger side of engine bay for orientation.

Pic 4. Shows side of starter for orientation.

Pic 5. Shows fresh amber/golden oil below starter. Picture taken from under truck.Pic 6. Enlargement of Pic 5 to show the fresh oil. And from there I think it drips down onto the passenger side transmission cooler lines and then it runs down the bell housing and the oil maybe mixes with other crap and turns black by that point.
Any help on pinpointing the source of the leak and how to fix/plug it up would be much appreciated.

 

Is it coming down your dipstick tube/support? That's what was happening on mine. I notice a lot of scuzzy buildup on receiver tube.

But I'm dropping an arrow on this spot also, because at that curve, it looks like a stream of oil has been coming down a this spot, maybe you can trace upward?

Notice the support bracket for the dipstick is not far above the butt of the arrow. And directly down from the arrow point, see the gunk on the receiver tube.

​

 

Well I looked all around up there and couldn’t find a current leak. There may have been a leak in that location before the valve cover gasket repair. I was reading that oil on the starter can be from a rear main seal leak so I re-explored that and took off the flex plate cover again and revved the engine with it off but no oil flew out onto the pavement. It is dry on the flywheel/flexplate. Pic 1 is the back of the flexplate with the oil impression on the white towel (it is reversed), pic2 and 3 are close ups of the flexplate cover. Based on a dry flywheel/flexplate, no spewing of oil with revving, and oil only around the edges of the flexplate cover, I was thinking that this doesn’t fit for a rear main seal leak, do you agree?

 

I don't disagree.

Give everything a full wipe-down now you've done the gaskets. I did mine. Then I had to do it again two more times, even though the leak was fixed. I guess there was a lot of residual trapped that migrated from heat in the weeks after. I was almost convinced I did something wrong.