Kind of "Mystery" Coolant leak back of engine (heat exchanger valley leak)

[bloc]

The air injection system pulls air from behind the front bumper around the pumps located there, through the plastic/rubber piping in front of the water pump, under the intake manifold, into the valves in the above pictures. It then runs outward into metal piping that goes behind the head, then around the side above the exhaust manifold where a small port above each exhaust port lets the fresh air mix with the exhaust gases within the exhaust port. It then flows to the cats with the rest of the exhaust.

As for exhaust leak smells.. Either at the junction between the metal pipe along the top of the manifold where it connects to the pipes coming out of the SAIS valves.. there is a flange and gasket there.. or at the SAIS valves themselves. Likely there, considering the trouble accessing those bolts as described above.

I'm attaching a picture of the bare right exhaust manifold. The small 2-bolt flange at the upper left corner is the location of the junction I mentioned. The pipe out to each port is the formed stainless steel plate/pipe that moves to the right and down from that spot.

 

[virtualfriday]

Thanks for the picture and explanation, very helpful. I found a Tundra forum and it looks like some Tundra 5.7 owners have had issues right where the air injection tube connects to port on the exhaust manifold resulting in noise and exhaust leaks in the engine bay. As soon as I get the truck back I will looking there.

 

[Ratchey]

Thanks for the picture and explanation, very helpful. I found a Tundra forum and it looks like some Tundra 5.7 owners have had issues right where the air injection tube connects to port on the exhaust manifold resulting in noise and exhaust leaks in the engine bay. As soon as I get the truck back I will looking there.

The gaskets between the SAIS valves and the tubes that run to the exhaust are extremely easy to drop and not even notice. It is possible they left one or both off when reinstalling the valves.

 

[virtualfriday]

Found the exhaust leak, it was at the location where the air injection enters the exhaust manifold. From searching the web I found some Tundra 5.7 owners have experienced a failure of the flange on the exhaust manifold, instead of replacing the entire manifold they had some luck simply adding a strap or hose clamp to hold it tight. I used a hose clamp but here is another picture I found to give you an idea.

 

[bloc]

Found the exhaust leak, it was at the location where the air injection enters the exhaust manifold. From searching the web I found some Tundra 5.7 owners have experienced a failure of the flange on the exhaust manifold, instead of replacing the entire manifold they had some luck simply adding a strap or hose clamp to hold it tight. I used a hose clamp but here is another picture I found to give you an idea.

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So how did yours fail? Flange broke?

 

[virtualfriday]

My best guess is that it was already weak and was “disturbed” by the tech during the process of fixing the heat exchanger leak with all the things removed to gain access. I am thinking specifically the process of removing the air injection pumps and their tubes. I honestly couldn’t see exactly where the issue was, I could feel the exhaust escaping so I threw the clamp on as a Hail Mary and was pleasantly surprised.

 

[Hoosier Daddy]

From what I've read, the Tundras seem to have this leak almost exclusively on the driver's side. Which side is yours leaking on?

 

[virtualfriday]

From what I've read, the Tundras seem to have this leak almost exclusively on the driver's side. Which side is yours leaking on?

The exhaust leak was on the drivers side, same as the Tundras. My lazy/cheap repair was simply placing 2 hose clamps in the form of an X across the junction and cinching things up to the limits of the hose clamps capabilities.

After having the heat exchanger coolant leak fixed I continued to see coolant leaks under my truck 4 weeks later and assumed that something was missed. After pulling all the skid plates off the bottom I found the leak diaper was completely soaked and was randomly dripping a bit of previously leaked coolant.

 

[sdnative]

I am fixing mine now, and also the cracked radiator as well as WP, serpentine belt, thermostat, etc. So far not too bad, just taking my time. I am stuck on the back bolt of the air injection pipe on the passenger side. I called it quits for tonight will re-evaluate tomorrow. Any tips getting this bolt off?

I had leakage on both sides, but not much going down the backside of the engine except a little on the passenger side.

I noticed some markings on the intake ports. Any idea what this means?

 

[Ratchey]

I am fixing mine now, and also the cracked radiator as well as WP, serpentine belt, thermostat, etc. So far not too bad, just taking my time. I am stuck on the back bolt of the air injection pipe on the passenger side. I called it quits for tonight will re-evaluate tomorrow. Any tips getting this bolt off?

I had leakage on both sides, but not much going down the backside of the engine except a little on the passenger side.

I noticed some markings on the intake ports. Any idea what this means?

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This thread was a huge help for me. If you remove the 2 bolts on the right side, you can move the valves far enough over to get the left side loose. Just FYI, putting them back in is 4 times harder. Find someone with little hands.

Kind of "Mystery" Coolant leak back of engine (heat exchanger valley leak)

forum.ih8mud.com

 

[bloc]

Make sure you don’t put much stress on the stainless pipes out to the manifolds. The flanges are known to crack and leak.

 

[marques]

Well, it was my turn to reseal the valley cover plate after months of disappearing coolant that eventually left a trail of pink crud all over the passenger side of the transmission bellhousing. 2008 LX with 178k miles. Never got a drop of coolant on the floor, but it was time to get it fixed. The big O-ring on the connecting tube to the block didn't seat properly the 1st time and it wasn't obvious until after I refilled the system and saw the small leak, so I had the pleasure of doing it all over again

The only thing I can add to everything that has already been mentioned is that putting those air injection valves back in is a major PITA job, especially if you don't have tiny hands. The 1st time I was able to eventually put everything back together as has been mentioned here (disconnect from the driver's side tube and tilt/push the valves back a little so the other screw can clear the passenger's side head). The 2nd time I gave up and looked for a better way. It turns out that there is nothing else holding that tube in place other than two 10mm nuts on the flange on the exhaust manifold, with very easy access thru the wheel well under the fender.

So, do yourself a favor next time and don't bother disconnecting the valves from the passenger side tube. Remove them together and don't mess with the little bolts that are nearly impossible to remove, and even more difficult to put back together.

 

[todiy]

Actually, here's everything you need. I'm sure if you bring this to Toyota they can get you the 1282B sealant.

Is there anyway you can share the torque specs of other nuts/bolts too, especially the intake manifold?

 

[todiy]

Does anyone know if one tube of the fipg would be enough or I should order two?

I am going to work on my LX570 tomorrow and ordered only 1 tube which seems like not enough. So before I disassemble the car I want to make sure I have the parts that I need.

 

[Ratchey]

Does anyone know if one tube of the fipg would be enough or I should order two?

I am going to work on my LX570 tomorrow and ordered only 1 tube which seems like not enough. So before I disassemble the car I want to make sure I have the parts that I need.

Make sure you ordered the 1282B gasket maker. One tube would probably do 3 to 5 repairs so you are fine.

 

[todiy]

Make sure you ordered the 1282B gasket maker. One tube would probably do 3 to 5 repairs so you are fine.

Thank you so much for the response. I have disassembled everything thanks to this thread and some other threads here. However, I have run into a problem where I have a hose in the way of installing the valley plate. Does this hose need to be removed? Or is there a technique/trick to move this out of the way?

 

[Ratchey]

Thank you so much for the response. I have disassembled everything thanks to this thread and some other threads here. However, I have run into a problem where I have a hose in the way of installing the valley plate. Does this hose need to be removed? Or is there a technique/trick to move this out of the way?

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I left it in place but it almost caused issues. I pushed it over as far as I could. But I did hit it with the bottom of the plate and scraped off some of the gasket material. I bought a bore-scope so I can keep an eye on that area. No leaks after a few months.
Practice putting the plate in place to make sure you can do it without hitting anything. And make sure to lube the O ring to ensure you don't pinch it.

 

[marques]

Thank you so much for the response. I have disassembled everything thanks to this thread and some other threads here. However, I have run into a problem where I have a hose in the way of installing the valley plate. Does this hose need to be removed? Or is there a technique/trick to move this out of the way?

View attachment 2377582

I just bent the small horizontal tab out of the way (about 30 degrees). That was enough to keep it from interfering with the cover when removing It or putting it back in place. You’ll of course need to straighten it back when reinstalling the plastic crankcase vent assembly.

 

[todiy]

That is exactly what I ended up doing. Didn't realize how easily it was bending until I tried it. Thank you for the suggestion.

 

[todiy]

Finally got everything done and put back together. It took me a good solid two days worth of work to complete this job(I definitely take my time), I am sure others here are more skilled at this hence the shorter time to complete the job. Few things that I would like to share:

1. First of all this thread and few other threads here were very helpful.
2. This Youtube video helped with disassembling up to the point of removing Secondary air injection pump. After that below post was very helpful in disassembling.

3. As mentioned before, the job is not too technical just kind of hard to remove certain bolts/nuts. The main parts to remove when resealing the heat exchanger is the air intake filter box along with the plastic intake manifold... Then you have to remove the water pump bypass tube (4 bolts, posted pic) in order to remove the the 2 plastic air injection tubes that run from the front of engine all the way to the air injection valves in the back of the engine..Then it's just a matter of removing the plastic crankcase oil separator and then the dual air injection valves...Hardest was the 4 bolts on each side of the dual air injection valves at the very back of engine valley in between the cylinder heads.. The 2 bolts on the left hand side metal bypass was a bitch ( 1 bolt will not allow you to remove/put a wrench etc on because it's a super tight area where that certain bolt will not clear the wall of cylinder head)..... You have to remove the 3 bolts holding the air injection valves/ pumps to the block and then remove the 2 bolts on the right hand metal bypass tube.. This will allow you to grab the air injection valve and slightly bend the left metal bypass tube up and back so you can clear the cylinder head and then remove the 2 bolts from that left bypass tube... I posted a pic to show what bolts to remove in that order.. After that, it's just a matter of resealing and replacing the 2 orings in the union pipe that attaches the heat exchanger to the waterpump iirc... Here's a couple of pics... First pic is the 4 bolts you have to remove for the water inlet tube to remove the 2 plastic air injection tubes.. 2nd pic is the order in which you should remove the air injection valve bypass tubes in order to clear the left hand cylinder head..
   
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4. This post was very helpful in putting the gasket on

5. Actually, here's everything you need. I'm sure if you bring this to Toyota they can get you the 1282B sealant.
   
   

   

   
   

   

   
   
6. If you are new to this like me, then taking lots of pictures at every step is a big help.
7. The gasket glue that came off was much softer and brittle, kind of spoungy texture. Not sure if that was a different kind of gasket glue or it just deteriorated over time. I am not surprised it failed like it did. The new gasket glue dries to a much better rubber like texture. If it is the difference in glue then I think 1282b(08826-00100) should last much longer. I ended up using about 1/4th of the tube. Not sure what am I going to do with the rest. Perhaps donate to some mechanic.
8. I ended up replacing the manifold gasket(17171-0S030) as well since the original was kind of flattened.
9. Also replaced the PCV valve(12204-380100) and union pipe O-Rings(96761-35035). I used extremely tiny amount of brake parts safe grease to lubricate the O-Rings to slide in-place correctly. The total cost of parts was around 105$.
10. As suggested by others here practicing to put the heat exchanger plate back on helps a lot to develop a technique to put the plate back on without messing up the gasket glue:

11. When I did mine about a month ago, I used about 1/4 tube of the normal fipg. And that is putting down a fat bead. I would recommend putting your orings and coolant tube on and practice installing the coolant plate. I did this about 10 times and came up with a good method. Had I not done this, I would have had to clean and reapply the fipg due to bumping into components. Install new intake manifold gaskets and a new pcv valve. I also installed 2 new coolant t's on the passenger side firewall. Good luck and take your time.

    
    
12. After putting everything back together the Traction control(solid), check engine(solid) and 4Lo(blinking) lights came on. Someone on youtube suggested to disconnect battery terminals and short them to reset everything which resolved my issue.
13. Shout out to everyone else who has contributed so far to the information required in getting this job done.