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Discussion Starter #1
I replaced the rear valve cover gasket and while putting everything back together, I'm stuck at what I thought would be real easy: re-installing the EGR valve. As you can see in the pictures, one of the lower studs on the EGR valve unscrewed (along with the nut frozen on it) while I was removing it and the other is still installed in the EGR valve.

My issue is that I can't get the valve to fit the plenum and the EGR tube at the same time - this is required since there are studs on the plenum and the valve and the upper and lower attachments are at an angle to each other.

It seems to me that the only way to install the EGR valve is to remove the remaining stud from the valve, attach the valve to the plenum and then install the studs by threading them through the EGR tube along with nuts. This also appears to be the reason that after-market EGR valves don't have studs installed. Or maybe just install machine screws rather than studs and nuts?

I'm afraid of shearing the stud in the EGR valve and don't have a machine shop to extract it if it breaks - I'll need to spring $70 for a new EGR valve. Anyone aware of a better approach? Seems like a needlessly complex install?

EGR 1.jpg
EGR 2.jpg
EGR 3.jpg
 

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1999 Solara SLE, V6, 353,000 miles
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I had similar difficulty. dont recall exactly what I ended up doing, but after 30 minutes of trying different positions, ect, I managed to get it on. its possible, I do know that. take a break, have a beer (just one) and try again.
 

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Discussion Starter #3
Thanks for your quick response. Will try again (with just one beer) this evening. If that doesn't work, I will take my chances with the removal of the stud on the EGR valve. I've soaked it in penetrating fluid, so hopefully it won't shear!

For what it's worth, the procedure in the Toyota manual is to remove the EGR tube completely (top and bottom), install the EGR valve and then install the EGR tube. This wat, there's no weird angles to deal with, however, it is more work and I don't want to break anything at the lower EGR tube connection to the EGR cooler.

WIll post another update later ...
 

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1999 Solara SLE, V6, 353,000 miles
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For what it's worth, the procedure in the Toyota manual is to remove the EGR tube completely (top and bottom), install the EGR valve and then install the EGR tube. This wat, there's no weird angles to deal with, however, it is more work and I don't want to break anything at the lower EGR tube connection to the EGR cooler.

WIll post another update later ...
That is what came to my mind during the struggle. But my thoughts were same as yours, what am I gonna break if I attempt to separate.
 

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Discussion Starter #5
I was unable to install it as is with the stud attached (despite the beer - lol), but I was able to remove the stud without shearing it - lots of penetrating oil, gentle taps with a mallet and finally an E-5 inverted torque socket got it to turn and come out.

With the stud out of the way, the EGR valve goes on real easy. Now just have to I put the studs & nuts (which seems needlessly complicated and they're pretty rusted anyway) or simply put two bolts in. Not done yet, but progress for sure.

Resolves the issue of this thread: Remove lower EGR valve studs prior to installing the EGR valve and it will save a lot of time and effort in getting the EGR pipe to attach.
 

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Congrats! That is awesome!
 

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Camreee
'99 Auto V6 Camry
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I was unable to install it as is with the stud attached (despite the beer - lol), but I was able to remove the stud without shearing it - lots of penetrating oil, gentle taps with a mallet and finally an E-5 inverted torque socket got it to turn and come out.

With the stud out of the way, the EGR valve goes on real easy. Now just have to I put the studs & nuts (which seems needlessly complicated and they're pretty rusted anyway) or simply put two bolts in. Not done yet, but progress for sure.

Resolves the issue of this thread: Remove lower EGR valve studs prior to installing the EGR valve and it will save a lot of time and effort in getting the EGR pipe to attach.
Installing the EGR valve assembly and tube is most easily done by first installing the plenum and throttle body, then unbolting but not removing the throttle cable bracket from the throttle body, and propping the throttle all the way open to give you the most wiggle room.

For the throttle cable bracket nuts use a 1/4 drive swivel head ratchet and/or u-joint with a short 10mm socket to fit it in the awkward location. Once the throttle bracket is loose and the throttle is opened all the way by moving the cable guide away from the egr location. Then slide the egr assembly directly into place by first placing the bottom in and then the top two afterwards. Thread on the nuts partway, then tighten the throttle bracket before finishing tightening the EGR nuts.

As far as the EGR tube you definitely want everything installed and tightened before putting on the tube or its a massive PITA, put the gasket over the bottom two studs by the rear exhaust and the gasket over the egr assembly studs, then gently move the top of the tube over the top studs and just barely rest it on them, then press the bottom of the tube over the bottom two studs, now it should be able to simply slide all the way on. Thread on a nut on the bottom side to hold it on before you let go of the tube, as it will want to fall off.

Once the tube is over the bottom and top studs and you've got at least one nut on at least one thread, the rest is easy, I use a 1/4 drive flex head swivel ratchet connected to a 9" straight extension and a 6" wobble extension with a U-joint and short 10mm socket at end of the extensions. If you don't have a u-joint you can also use multiple wobble extensions or just a ratchet and a 6"and shove your arm down under the heater hoses to reach the bottom egr nuts.

When doing my headers I even put a dab of exhaust gasket maker to hold them in place because they are such a pain to keep on the studs while trying to line up the tube, by sticking the gaskets on the studs and having everything bolted down already, you're able to just hook the egr tube over the top studs, move it over the bottom studs, then move it straight inwards and thread on your nuts by hand with everything in place.
 

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Discussion Starter #8
Thanks for your very detailed reply and instructions. Your process completely makes sense.

I was trying to avoid removing the 2 lower EGR tube nuts near the exhaust fearing that they would shear with so much rust on them. If you don't detach the lower EGR tube connection and leave the EGR tube in place, it's nearly impossible to reinstall the EGR valve with the 2 studs sticking out the bottom of the EGR valve. Hence my solution was to remove the 2 studs from the EGR valve. With these 2 studs out, the EGR valve easily goes on.

However, now the EGR tube won't exactly align with the EGR valve to put the studs back on. It's about 1/16" too low so the studs can't be threaded in. Looks like I will have to remove the EGR tube lower nuts, put the studs back on the EGR valve and then slip the EGR tube over all 4 studs as you describe above. The Toyota service manual instructions also says to put the EGR tube on last. This is by far the most difficult part of the job of replacing rear valve cover gaskets or anything involving removing the plenum.

Again, thanks for the detail.
 

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Camreee
'99 Auto V6 Camry
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Use LOTS of penetrating oil spray from underneath the car (wear goggles) and wear gloves so you don't shred your hands when working from above.

It's easier to undo from above the car leaning over driver side strut tower with left hand braced on transmission case and feel around with your right hand to find the eg recirculation tube. If the studs are connected to a corrugated tube its the wrong one.

Unhook the two heater lines from eachother to give them more wiggle room, then shove your right arm balls deep underneath the heater hoses above the cable/hose, and feel around.

There is the egr cooler tube right next to it so make sure you don't accidently loosen that and give yourself an exhaust leak. When installing the tube on the bottom hook it under the cable/small hose going to the firewall with the insulation on it resting on top of the egr tube.

I hope these pictures help.



302722


302724
302723
 

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Discussion Starter #10
Your pictures are extremely helpful. I was able to get my hand behind the plenum and throttle body and can feel where the EGR tube ends and I can also reach the 2 nuts with my fingers. I will get underneath and spray them for a day or two first in the hope of not shearing them and then try to remove them.

Another thought occurs to me that might be much easier: What if I cut the EGR tube in the straight section after the bend at the top, slide on a metal sleeve over the 2 cut ends, attach the top part to the EGR valve and then hold the sleeve in place by stainless steel zip ties? (thought about grazing, but don't have enough experience to do it well especially with a round tube) This way, there's no risk of breaking anything, I know the EGR tube will easily attach to the valve and the only thing that can happen is a very small leak through the sleeve which I should be able to live with. Know if sounds crude, but I'm not confident I have the skill to do everything you have outlined.

What do you think?
 

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Camreee
'99 Auto V6 Camry
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Your pictures are extremely helpful. I was able to get my hand behind the plenum and throttle body and can feel where the EGR tube ends and I can also reach the 2 nuts with my fingers. I will get underneath and spray them for a day or two first in the hope of not shearing them and then try to remove them.

Another thought occurs to me that might be much easier: What if I cut the EGR tube in the straight section after the bend at the top, slide on a metal sleeve over the 2 cut ends, attach the top part to the EGR valve and then hold the sleeve in place by stainless steel zip ties? (thought about grazing, but don't have enough experience to do it well especially with a round tube) This way, there's no risk of breaking anything, I know the EGR tube will easily attach to the valve and the only thing that can happen is a very small leak through the sleeve which I should be able to live with. Know if sounds crude, but I'm not confident I have the skill to do everything you have outlined.

What do you think?
I would absolutely not open an exhaust pipe in my engine bay without gaskets and bolts or welds to seal it again.

The process I described is not very technical or hard, I just added all the useful stuff I learned doing it and I write in too much detail.

You could ostensibly spray the nuts, drink a beer, then go back out and be done 5 minutes later. I reeealy recommend trying to undo those nuts before seeking alternative solutions.

Worse case scenario grab some 1/16th or thicker sheet or scrap metal and one of the old gaskets, drill 2 holes in it through the gasket holes and then run m8 x what thread type you want flange bolts and nuts with washers through the sheet metal, gasket, and tube flanges to properly seal and secure the gas inside.
 

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Discussion Starter #12
Agreed - don't create a new problem!!

Attached is a picture that shows that I have 3 different offsets between the valve and tube flanges: tube is 1/8" to the right, tube is 1/8" lower and there's a 1/4" gap between the flanges. Looks like I might have inadvertently bent the tube while getting it out of the way during the replacement of the rear valve cover. I may need to get a new tube from the local junk yard.

First step is to remove the nuts at the bottom of the tube, realign and attach. If that doesn't work, I will make a custom gasket as you've suggested from a 1/4" piece of scrap metal and drill 4 holes - 2 to align with the valve flange and 2 with the tube flange and a larger center hole to allow the exhaust to flow through and bolt everything down.

Appreciate your guidance with this issue and any additional thoughts you may have.

EGR 41.jpg
 

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Camreee
'99 Auto V6 Camry
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As far as whether or not the tube is damaged - if it's wobbling around then someone was bent or broken - could a stud pulled loose or bent, a nut came off or loose, or the tube deformed at the flange - the tube itself is extremely stiff and I have a hard time imaging you bent it before bending or breaking a stud or the warping the flange connection.

When I was installing headers I ended up bolting on the bottom first and assumed the top would just slide on, but it was way misaligned and with just one end torqued down it had less play than would be required to move it to line up in that picture. It's really quite sturdy as it has to survive thousands of hours of extremely hot NOx and engine vibrations without deforming or losing a seal. There shouldn't be more than 1-2mm max of wiggle at the top of the tube if the bottom is secure.

Maybe you can manage to force it with the studs already out of the EGR valve, but I think that's asking to break something down below with the amount of gap in your picture.

I agree that it's big pain to remove the bottom nuts if they're rusty, especially the furthest back one, but a 6" extension over a 1/4 ratchet or even a 3 inch extension with a deep 10mm socket will fit on just fine once you manage to get the socket on by feel with zero vision of what you're doing.

If I were you I would commit to go ahead with removing the bottom nuts after spraying them with penetrating oil and committing to removing the bottom end before trying any other options, I think you will be fine because you can't get much rust on the tiny thread surface area of those nuts but on the other hand - people have broken these studs off when they are rusty in more than one thread I've read. I'm guessing the people that broke the studs off or pulled them out had significant rust between the flange and nut instead of just surface rust on the nut and a little rust in the threads.

I'm probably biased because I removed them all without even spraying a few of them first, at the end of the day its your car and your call. I hope you get it taken care of without any further problems :)
 

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Discussion Starter #14
Thanks again for your very detailed and thoughtful reply. The tube is very difficult to bend or move other than a little bit side to side - there's no way to adjust for the up-down gap. The good news is that I've not broken anything else.

For testing purposes, I temporarily blocked off the EGR tube with a piece of sheet metal bolted on to the flange so there's no exhaust coming in to the engine compartment. Car runs very well and the oil leaks from the valve covers are gone. I'll ignore the expected P0401 for now.

When I get some time, I'll attempt to remove the lower nuts and bend/adjust the EGR tube on the vice until it fits well on all 4 studs without the use of force. That's clearly the right thing to do.

Again, I appreciate your patience and help with this.
 

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Camreee
'99 Auto V6 Camry
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Thanks again for your very detailed and thoughtful reply. The tube is very difficult to bend or move other than a little bit side to side - there's no way to adjust for the up-down gap. The good news is that I've not broken anything else.

For testing purposes, I temporarily blocked off the EGR tube with a piece of sheet metal bolted on to the flange so there's no exhaust coming in to the engine compartment. Car runs very well and the oil leaks from the valve covers are gone. I'll ignore the expected P0401 for now.

When I get some time, I'll attempt to remove the lower nuts and bend/adjust the EGR tube on the vice until it fits well on all 4 studs without the use of force. That's clearly the right thing to do.

Again, I appreciate your patience and help with this.
Glad to help,

Many people have blocked off EGR that way without running into issues leaving it like that permanently on various engines. This is certainly an option if you don't need emissions testing or care about losing a bit of HP, it's easy to add back in if it turns out you want it. I would just grab a junkyard tube in that case - probably easier than trying to bend it to the millimeter tolerance it has.

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I know you didn't say you intend to do this; but for the sake of this thread I personally wouldn't recommend deleting it permanently on the 1MZ. Reason being the knock sensors are super sensitive, and removing EGR will increase the likelihood of knocking;

End result being the engine bogs down all the time and you lose power on hot days or when the engine is heat soaked. This is due to insignificant predetonation being registered as significant predetonation by virtue of overly sensitive sensors generating a signal for minor predetonation that is not damaging the engine. This signal tells the ecu that it actually is, and tells the engine to make reduce timing of the engine so the cylinders don't get as hot and the engine doesn't break. This reduces power.
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Basically EGR splits off a small percentage of the exhaust mix, cools it down a little bit relative to exhaust temps - still around one thousand degrees lol, then sends it back to the intake - for the explicit purpose of reducing nitric oxide emissions which are produced mainly at high temps and with excess oxygen - however it has other side effects.

When exhaust gasses are sent into the intake chamber they prevent that amount of atmospheric oxygen from entering in its place, resulting in a mix of roughly 20% exhaust, 73% atmosphere, and 7% fuel at high rpms; rather than 93% atmosphere and 7% fuel you get without egr. This mix varies using engine sensor feedback to control how much exhaust the egr valve puts in the intake. It closes at idle, and sends the most in at high rpms when the engine is hottest.
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Mo air, mo power right?

Let's say right now your engine is sending in 93% atmosphere + 7% fuel, this WILL result in more frequent and more powerful pre detonations and more timing retardation in response. Basically what will happen is this fuel explodes when injected but before it's that cylinders turn to fire off, this causes a vibration in the crankshaft due to the cylinder trying to move the crankshaft a little bit before it's supposed to when another piston is still working that shaft.

The overly sensitive knock sensors pick up these vibrations in the engine which are very normal, and thinks there is a ton of fuel exploding because they're overly sensitive. If there was a ton of fuel exploding when its not supposed and sending the opposite forces into the crankshaft at the same time as another cylinder it can cause serious crankshaft/rod/piston damage, thats why knock sensors exist and where stock EGR comes into play as a net benefit to the 1mz when not using forced induction.

So while the overall amount of oxygen going into the engine is actually degreased not insignificantly with EGR, our engines actually make more power and run cooler with EGR still operating.

Another thing worth noting is that even if you don't run a catalytic converter, Carbon monoxide isn't great, but this stuff is bad. EGR reduces the most harmful exhaust emission for the environment by something like 80-90% by virtue of stopping the engine from producing it in the first place.
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Well that was long and not entirely relevant to your reply, but thought I'd share some stuff
I learned when considering deleting EGR o_O
 

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Discussion Starter #16
Wow - that's the most comprehensive write-up I have seen about the EGR and it's benefits for the 1MZ-FE. Great stuff!

I have no plans to run with EGR defeat - I will put in a junk yard EGR tube when I get a bit of time. I will also use 91 octane gas versus 87 or 89 to reduce knocking and sensor feedback. I rarely if ever run the engine at high RPMs and northern weather is cool anyway. We also don't have an emissions check.

The one question I do have with the write-up is how a small 3/8" diameter EGR valve flange opening can contribute 20% of the incoming air when the air intake plenum diameter is 3". Especially since the EGR air is much hotter and lighter than atmosphere air. 20% seems awful high - have you measured this or is it the original Toyota design spec?

Finally, my EGR intake at the plenum where the EGR valve flange attaches was completely clogged with black soot when I took it out to clean - despite all the cleaning, I wasn't able to clear away an opening into the plenum. Where Is the plenum opening? Is it at the circular thing sticking our the top of the plenum or at the bottom and should I be able to put a wire in through the opening?

Thanks again. Your very thoughtful write-up is raising new questions in my mind - lol.
 

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The one question I do have with the write-up is how a small 3/8" diameter EGR valve flange opening can contribute 20% of the incoming air when the air intake plenum diameter is 3". Especially since the EGR air is much hotter and lighter than atmosphere air. 20% seems awful high - have you measured this or is it the original Toyota design spec?
EGR valve is closed above ~4000 rpm and plays no role in maximum power output. You can read about it in the FSM. The 20% is probably true while at cruise, and air flow is low to begin with, so 20% isn't much.
 

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Camreee
'99 Auto V6 Camry
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20% was a random number, it's probably closer to 5-10% on the high end. I have no idea what these are programmed for, it's based on MAF sensor, knock sensor, crank sensor, coolant temp, a/f sensor and downstream oxygen sensor feedback, etc, along with whatever Toyota sets it to for emissions.

It's possible these knock sensors were tuned exactly how Toyota wanted them, simply to reduce NOx emissions at the time by forcing the engines to run cooler by sending in more exhaust, and the timing and power reduction of high sensitivity was just a side effect of their goal; the us was extremely strict about NOx emissions at the time.

Exhaust gas is being sucked in along by vacuum along with forced in by exhaust pressure when the valve is open, so even though the tube cross section is much smaller, the air velocity is much higher, it routes directly into the throttle body behind the butterfly valve to swirl it into the mix as early as possible rather than entering through the plenum.
 

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Camreee
'99 Auto V6 Camry
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EGR valve is closed above ~4000 rpm and plays no role in maximum power output. You can read about it in the FSM. The 20% is probably true while at cruise, and air flow is low to begin with, so 20% isn't much.
EGR absolutely plays into power output for the 1MZ by virtue of lowering the frequency of pulled timing due to knock detection.

Maybe not after hitting the gas once, but get the engine hot for more than 30 seconds and you will bog down without it.
 

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Discussion Starter #20
it routes directly into the throttle body behind the butterfly valve to swirl it into the mix as early as possible rather than entering through the plenum.
Which way does the EGR flow enter the plenum in the attached diagram? I wasn't able to see it even though I poked around inside the opening with an angled pick
EGR 11.jpg
 
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