EGR mystery ...

Technical questions and answers about the Mazda Bongo

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JulesMartin
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Re: EGR mystery ...

Post by JulesMartin » Thu Jan 09, 2020 3:33 am

My valve fell apart on my resent rebuild. followed advice on here to use a screen washer one way valve and all is good.
Martin
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MyBongoiscalledDave
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Re: EGR mystery ...

Post by MyBongoiscalledDave » Thu Jan 09, 2020 11:45 am

I'm so confused by all this talk of one way valves. Mine doesn't appear to have any stall going to or from the actual EGR valve. I assume, judging by your contributions, that it should have ... ?

We are thinking about the same engine. The 1996 2.5td ...

Does anyone know anything about posting pictures?
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Re: EGR mystery ...

Post by Ian » Thu Jan 09, 2020 12:02 pm

Dave, email me your pictures and I will put them up for you. It's quicker doing that rather than explaning how to link to externally hosted photos etc....

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JulesMartin
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Re: EGR mystery ...

Post by JulesMartin » Thu Jan 09, 2020 2:00 pm

this morning I replaced the gaskets on my EGR valve with solid metal ones :wink: :wink: I must say it runs much better and seemed to get better and better I guess it's clearing out all the crud that's accumulated. much more responsive at low revs and smoother idle. left wiring in place as to the vacuum pipe. Whilst I was there I had a look at the non-return valve we've been talking about and on mine it is in the pipe running from the nearest solenoid to the EGR down into the big black inlet tube running under the EGR valve. The pipe from the EGR does not have a valve in it and looked to be the original tubing.
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Re: EGR mystery ...

Post by plonkatronix » Thu Jan 09, 2020 2:16 pm

Sounds like you found your valve and is in place, there's not one on the solenoid. I did pm you saying send a picture over so we could take a closer look and better understanding of your setup to avoid confusions
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Re: EGR mystery ...

Post by Ian » Thu Jan 09, 2020 4:01 pm

Here's Mybongoiscalleddave's photos:

Image

Image
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MyBongoiscalledDave
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Re: EGR mystery ...

Post by MyBongoiscalledDave » Thu Jan 09, 2020 4:19 pm

So, to recap;

If I have the vacuum pipe connected both ends to the EGR and solenoid, it runs really really bad.

If I have either end disconnected, it runs beautifully.

I've had the EGR off and cleaned it up, it seems like the diaphragm works okay. I pressed it up and put a finger over the vacuum pipe and the diaphragm stayed in place.
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Re: EGR mystery ...

Post by plonkatronix » Thu Jan 09, 2020 4:27 pm

Something not right there, that pipe coming off the left front solenoid isn't supposed to go towards the front and under? someone has been playing around with the vacuum possibly.

Trying to find a good photo to illustrate
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Re: EGR mystery ...

Post by g8dhe » Thu Jan 09, 2020 4:43 pm

Geoff
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Re: EGR mystery ...

Post by MyBongoiscalledDave » Thu Jan 09, 2020 4:51 pm

So I saw this last night. The pipe numbered 93-5104 (top-right of page) definitely isn't 170mm long, doesn't have a one way valve and goes somewhere under the engine block. I don't know where it's supposed to go. Does anyone know what component does 1312 13-341 refer to?
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Re: EGR mystery ...

Post by g8dhe » Thu Jan 09, 2020 5:30 pm

I think you mean 93-5104 pipe ? That appears on this page the 13-314 refers to the bracket;
http://www.lushprojects.com/bongopartsm ... mgno=.html
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Re: EGR mystery ...

Post by plonkatronix » Thu Jan 09, 2020 6:20 pm

As you can see from an early image of my bay, the green one way valve comes off the last solenoid and goes to the big main inlet pipe, just mine snapped off the original lug and was glued in further forward with the snapped one blocked with a tight self tapper, at least you can clearly see it here otherwise its connection to the big pipe is at the back of the head out of sight and behind the EGR almost.

Image
Higher resolution image > http://perlsol.co.uk/bongo/bay1.jpg

Don't shoot me if this is wrong as I have only studied 2 of these bongo's, nieher of them were "untouched" so from my calculations I have mine rigged up like this...
Image
hope this make sense
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Re: EGR mystery ...

Post by MyBongoiscalledDave » Thu Jan 09, 2020 8:43 pm

This is awesome. Thank you! And your arrowed picture will prove to be more than useful, I'll explain below.

The plot has thickened. I contacted the previous owner to find out exactly when it had gone wrong, because something just wasn't adding up. Turns out, when it went in for loads of welding work, they had to strip down quite a lot more than expected. I think they've put the vacuum system back together incorrectly. She even said that the 'mechanics' were scratching their heads trying to work out where all the vacuum pipes went.

So, I will sit down with the lushproject webpage schematics and try to work out the whole vacuum system and put it back together correctly. Is their a specific page that refers to the vacuum system in its entirety?

And does the vacuum system work in a linear fashion? As in, does air start at the vacuum pump and finish in the air intake pipe?

Many thanks for you replies.

This is a fantastic forum to be welcomed in to.
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Re: EGR mystery ...

Post by g8dhe » Thu Jan 09, 2020 10:51 pm

Your homepage for the mech. diagrams is here http://www.lushprojects.com/bongopartsmk2/ choose the year, then drill down to engine type and around the engine for the vacuum system pages. You can also tackle it from the overall diagram pages rather than by system elements, using the righthand coloumn once you know the page numbering there are actually a few pages that are difficult to locate other than by page number!
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Re: EGR mystery ...

Post by plonkatronix » Fri Jan 10, 2020 12:15 am

It certainly is a fair bit of plumbing but hopefully you'll work out what has been done wrong, keep us updated.
I too had/have questions like you... where does the vacuum pump get its air or breath from? Seemingly inside the engine as there is no inlet
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