Hello group
I seen a few threads mentioning the EGR valve and the one post where it was explained that this was the reason why there are blown head gaskets.
Has anyone done a basic write up on cleaning out the EGR system?
I came upon this idea when looking for parts to buy and wondered if the EGR was worth replacing or just cleaning it out.
BG makes a cleaning tool and solution for professional use... I don't know how it works and I'm pretty sure it's mad money
there's probably cheaper options out there, and given how the previa's engine is mounted, anything like this will be way better than taking off the pieces and hand cleaning
I unfortunately can't say much due to not having my van right now. I was just going over many of the threads and seen it blips and pics from various people talking about it.Originally Posted by TheMAN
So I looked on youtube for videos, but nothing for previas, just other rides.
I have not seen a diagram of the EGR system as well, so I wondered if anyone else had done some type of cleaning as maintenance for their vans.
After reading Zenseeker's previa maint page and seeing the thread on here for 97 s/c head gasket replacement summary with parts (http://www.toyotavantech.com/forum/s...mmary-W-part-s) by Klisterkicker
"-the most common culprit to headgasket failure was a clogged return cooling line. He had mentioned that the majority of Previas he had worked on had crud in the cooling line that ran from the reservoir back to the engine... causing insufficient coolant flow.
- Supercharged Previas have a long ventilation tube which connects the oil filler neck under the driver's seat to the air tube connected to the mass air flow sensor. This ventilation tube is double walled with hot coolant flowing from the throttle body to the top of the outer part of the ventilation tube to under the Previa on the left side of engine and then connects to a hose on its way to the EGR(???). The inner part of this ventilation tube brings crankcase gasses to the air tube connecting the mass air flow sensor and throttle body. Black flakes will collect in the upper "T" where coolant enters this ventilation tube. This can clog the tube and lead to high idles when it's cold out since warm coolant isn't flowing through the throttle body. The solution is to clean out the black flakes and blow out any clogs from the bottom with compressed air. If this fails, you may need to replace the tube altogether or reroute your coolant lines. If you reroute your coolant lines, you may need to frequently clean out the ventilation tube with SeaFoam or other solvent safe for your engine. If once you unclog your coolant lines, you may wish to consider a in-line filter to protect your coolant system"
I believe this has to do with the "black flakes in coolant lines", which I've seen on toyotanation's forum after they got it from the yahoo group.
cleaning_out_tee.jpgcoolingtubeventilation.jpg
I was at a Toyota/Lexus/Scion salvage yard this morning getting those roof garnishes from a previa they posted for parts on craigslist. I started to snap pictures of the van taken part for myself and remembered to try and look for this tube.
Low and behold:
IMG_3572[1].jpg
I saw the tube and even the BLACK FLAKES coming out of it!
I mentioned this issue to the shop and it was kinda brushed off as the guy said that people on the internet"dont really know and just speculate". I planned on check out this issue anyway and do the inline filter, but reading and seeing it just convinced me this might have been the issue with my van.
Well, As soon as I get my van smogged and running good, a check engine light popped up. And it is the p0401 code.
Annoyed because I did not push the shop to do more, I realized it will give me a chance to get my hand dirty.
And I am glad I waited.
After research and only getting blips here and there, a few blogs updated with more information.
So I want to thank these folks in advance:
theMan - again, I cant remember where I saw the pics, but your did a post on the IACV.
Uri - he runs Previa diaries (http://previadiaries.wordpress.com), he provided some more info and pictures.
and Zenseeker - famous zenseeker.net previa maint page. Recently updated with pictures of what to do with the egr valve, air inlet and where carbon builds up (http://zenseeker.net/Previa/PreviaMa...nce-Engine.htm) and pictures zipped here: http://oldweb.jordheim.us/egr_cleaning.htm
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I want to say these maint instructions should be automatic if you buy a previa. I just started working on it an hour ago at 2am.
I was planning on doing the "flake filter" anyways, but once I read the above posts and knowing my IACV was not touched, I figure mind as well clean those and install the filter. So I got down to it.
Removed the air ram.
Removed the big air hose going to the air box.
Disconnected all hoses, 2 tiny ones and 3 main ones (one going to the radiator, one going to the ventilation pipe, and a slightly bigger hose).
Disconnected 2 sensors.
Loosen throttle body cable (12mm wrench) and disconnect end.
Removed 4 12mm bolts that hold the throttle body.
Take out.
IACV held by 4 screws.
At this point, these are he parts I got/need:
G15 inline filter (flake filter)
2 hose clamps for that filter
Throttle body gasket
set of 4 screws for the IACV (3 were easy, 1 stripped)
IACV rubber gasket
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Started to go after the EGR valve.
After disconnecting 6 or 7 small vacuum hoses and 2 12mm bolts, EGR modulator came off.
Then went after air inlet.
Removed air hose clamp, pulled off hose.
Removed 4 studs, set aside bracket with throttle cable.
Removed air inlet. *major carbon build up comparable to those in the pictures above.
Parts:
Air inlet gasket
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I figure tomorrow (or I should say later today) I will order the throttle body gasket, air inlet gasket and 4 screw set. Will also see what additional gaskets to get (EGR gasket).
I will need to get that stripped screw off and clean the IAC Valve and I hope I can get that done tomorrow.
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To be continued.
Last edited by cvtroger; 10-13-2014 at 06:04 AM.
Oh boy, lots of fun. Thanks for sharing your research and posting those links. Always good to have multiple sources of information for a particular task all in one place. Tim
Yup Tim. Since I am not super mechanical, I need some straight forward instructions. All I know is that it is good that information with pictures and that is what helps me.
Since these were pretty much untouched by the shop I had my work done, I figure I'll just do it myself. I was just going to do the flake filter, but then saw that there was IACV that needed to be looked at and when Zenseeker linked those pictures... that helped tons.
Once I took of the air inlet and saw the carbon build up... I am glad that info was posted up because I would have taken my van back to the automotive shop to track down that code.
Taking tons of pics, unfortunately my carport/garage has very dim light.
I'm surprised you can work that late without your neighbors complaining. I assume you're in a complex?
the screws wouldn't be so stripped if you used a JIS screwdriver... I didn't know this when I cleaned my throttle body, but now that I do, the right tool makes a huge difference
I replaced the A/C idle up valve a couple of weeks ago and there was a VSV attached to it with one screw.. if I used a regular Phillips screwdriver, it would've gotten stripped because it was rusty and seized... but my JIS screwdriver just gripped into it good and the screw came out without a scratch
Yes Tim,I'm surprised you can work that late without your neighbors complaining
My parking spot/ carport is under our apartment complex. I did it late at night so people dont get curious and complain. If it is kept discrete, nobody complains.
3 screws had no problem, but 1 did and I just took a channel lock to the side and it was able to budge.
To my surprise my IACV was clean! Well atleast now i know.
IMG_4522[1].jpg
I cant say the same for my EGR system! The problem I am having is that in Zenseeker's photos, he used a 1" crow foot to loosen a fitting for the EGR valve, which I do not have or cannot find. Gotta try my channel locks again.
IMG_4515[1].jpg
IMG_4519[1].jpg
Is this the same engine you had just spent a few grand on? I thought they rebuilt it............but they didn't clean this stuff up?
Same shop. I mentioned it when they were building the motor, so I dont understand why it wasnt done. I told them to check out the ventilation pipe and IACV and they didn't believe it to be an issue.
At any cost, it would have been nice to have everything taken cared off, but getting the motor running, then the cat and 02 sensor needed to be replaced, then brake/lamp inspection...
After I got the van smogged and all, then the CEL poppped up. I'm just glad that info was posted so I can be able to do it myself. I like working on a car as long as I understand what I am doing.
So I followed the pictures and steps that these resources offered.
The parts I ordered:
For under the hood:
Fram G15 inline filter - did this for the flakes going into the ventilation tube.
2 small hose clamps for the filter.
Throttle body gasket - 22271-76020
IAC valve rubber gasket - 22215-76010 - gasket between the IACV and Throttle body
IAC valve screws (set of 4) - 21821-25180 - holds the IACV to the throttle body
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EGR intake gasket - 25628-76010 - this is on the far right side next to the exhaust.
EGR valve gasket - 25627-76010 - used for the EGR valve to the intake manifold.
Air inlet duct gasket - 22273-76010 - this is where the air goes into the intake manifold and where the EGR can get plugged
1 container of coolant
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After detaching hosing to the Throttle body and removal (4 bolts, 2 tiny hoses, 3 big hoses, 2 sensors), I immediately cleaned out the ventilation pipe. There was some flakes and carbon build up. I then cut the hose and installed the inline filter.
I cleaned the throttle body and IAC valve a bit and checked function.
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I started off with detaching all the small hoses to the EGR modulator matix and 2 bolts to remove.
I then went to take off the air inlet duct (4 nuts, with throttle cable bracket). As you see in the above picture, it was plugged and dirty.
With the EGR system and dis-assembly, I followed zenseeker's info to the T. I didnt have a 1" crow's foot for the EGR pipe union nut, so I ended up buying a set just for it (Craftsman - $50) On a side not, I think the shop I went through put anti seize on this, which was helpful.
I dont know why, I had issues with the nuts for the EGR valve itself, especially the one underneath. 2 hoses and getting a coolant shower and it was out.
My EGR valve wasn't dirty and the EGR modulator worked fine.
Also took out the temp sensor and cleaned of the tip.
Worked on the plugged portion with 50 state legal carbon cleaner (I am environmentally conscious), which means this stuff wasn't as powerful. Pulled out the turbo snake and got some gunk out. Blew carb cleaner and canned compressed air through the other side to get as much as possible out.
Reverse and everything is good to go. Test drove and no CEL and a bit smoother as far as idling.
I have a bunch of pics, but for some reason, my iphone and desktop computer and work dont like each other, so I'll have to do it sometime after I get midterms and thesis papers due this coming week.
hey CVTROGER
I m looking to find out what size crowfoot wrench i need to get EGR off PREVIA
i have it soaking with the JB Blaster and need to reach in to undo nut... did you take EGR off?i can barely see it and I cant hardly reach it lessin i remove motor mounts again and drop engine...i read 15/16 or 1" will do the trick without lowering motor.
Last edited by tbkilb01; 02-25-2015 at 06:02 PM.
Sorry for the late reply my friend. Been busy with school and fixing my subie wagon.
I used a 1" crowfoot as it was mentioned in the write up by zenseeker. I did not take off any motor mount, but I did use a universal joint to reach it... I had my soaking in WD40.
ended up buying both sizes on ebay
neither fit.. first too small, second too big..? so just skipped it for now!
Found another post where this guy says he used a 24 mm? i may try that size
I just want a sure fit so as to not strip it!
I didn't try other sizes, so got a set with that included. I was glad that zenseeker put up a walk through with pictures... because that just made more sense than anything to me. I think these issues need to be put up front and center for anyone that is pick up a previa and fixing it.
Absolutely....well finally!
I got my hands on both sizes (again) of wrenches only this time they are FLARE NUT crowfoot and the 15/16 fits perfect! I had purchased open end type and they just weren't made for this JOB...(lower picture) my bad.......I just didnt snap in time.... thought they'd work
.
Last edited by tbkilb01; 04-05-2016 at 02:51 PM.
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