EGR valve

Technical questions and answers about the Mazda Bongo

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Post by scanner » Fri Nov 02, 2007 7:11 pm

Had to do a slight mod to the cruise control today to cure a "clicky" throttle pedal so as I had the seat up thought I'd check the air filter.

I found that had a huge black patch of gunge opposite the inlet so changed it for a new one (will get a K&N for next time) and thought I might as well do the EGR whilst at it.

Having done it on a previous car and seen just how much gunge had collected in the manifold I disconnected the little EGR pipe and then unbolted the connection between the inlet pipe and the manifold itself.

Sure enough there was a huge collection of thick black gunge in the inlet pipe where the EGR enters it. I sprayed the inlet pipe and manifold with engine cleaner and after letting it soak in made a HUGE cotton bud out of a hammer handle and some rag and cleaned everything out.

If you want to see what is left behind if you don't clean the manifold after blocking off EGR - some pictures can be seen here http://www.dervhead.com/xmb/viewthread. ... 1#pid92361[/url]
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Post by dandywarhol » Fri Nov 02, 2007 8:45 pm

Thats amazing - I wonder how the tree stump got into the EGR system................. :? :wink:
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Post by missfixit70 » Fri Nov 02, 2007 8:50 pm

mikeonb4c wrote:Rather than spend hours looking it up (lazy me) can you remind me v quickly Missf what the pros/cons are of the £12 Allens kit and the £18 NickSkidmore kit. Maybe this is a job I should get done on my Bongo. Have you noticed much change in performance and/or fuel consumption?
Allans kit I think is 2 blanking plates fitted with the egr & pipework left in situ, therefore easy to reinstate, quicker to fit & slightly cheaper.

Nick Skidmore's kit consists of a blanking plate & threaded plug to fit the outlet form the turbo. This allows complete removal of the egr v/v & pipework which clears a pile of scrap metal from around your engine, which consequently takes a bit more work & knuckle skin. Can be removed in such a way that it could be refitted, but most tend to go for the quicker destructive method :twisted: as I did. I can't see that it's doing anything useful anymore, it was a retrofit item on the engine to satisfy legislation, so the engine will run fine without it (in my & many other's opinion).

Both kits do the same job in sealing offthe egr system completely.

As regards consumption, its difficult to say as mine is pretty cack anyway thanks to lots of short runs, I would say it felt slightly better after removal performancewise, but that could just be wishful thinking :roll:
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Post by Ralph » Fri Nov 02, 2007 9:15 pm

I read up on the EGR system for another car not the Bongo and
on it the EGR only worked with the engine at running temp and
small throttle opening, it is intended to cut nitrogen oxide "I think
it's a wile back" emissions by lowering the combustion temperature.
If it goes wrong and works at higher throttle openings the reduced
oxygen content leads to unburnt fuel and black smoke.
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Post by dandywarhol » Fri Nov 02, 2007 9:31 pm

missfixit70 wrote:
mikeonb4c wrote:Rather than spend hours looking it up (lazy me) can you remind me v quickly Missf what the pros/cons are of the £12 Allens kit and the £18 NickSkidmore kit. Maybe this is a job I should get done on my Bongo. Have you noticed much change in performance and/or fuel consumption?
Allans kit I think is 2 blanking plates fitted with the egr & pipework left in situ, therefore easy to reinstate, quicker to fit & slightly cheaper.

Nick Skidmore's kit consists of a blanking plate & threaded plug to fit the outlet form the turbo. This allows complete removal of the egr v/v & pipework which clears a pile of scrap metal from around your engine, which consequently takes a bit more work & knuckle skin. Can be removed in such a way that it could be refitted, but most tend to go for the quicker destructive method :twisted: as I did. I can't see that it's doing anything useful anymore, it was a retrofit item on the engine to satisfy legislation, so the engine will run fine without it (in my & many other's opinion).

Both kits do the same job in sealing offthe egr system completely.

As regards consumption, its difficult to say as mine is pretty cack anyway thanks to lots of short runs, I would say it felt slightly better after removal performancewise, but that could just be wishful thinking :roll:
But my point is you can get the same results by a 5 minute job blocking off the vacuum pipe (unless the EGR valve has seized open)
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Post by scanner » Fri Nov 02, 2007 9:42 pm

Mine now has a strip out of the top of a sardine can sandwiched into the joint.

That's no longer a tree stump, that is now my winter fuel.
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Post by mikeonb4c » Fri Nov 02, 2007 11:15 pm

Interesting stuff & thanks MissF - I think - if I get round to it at all - that I'll choose the simplest option. My back you know, my back and my wallet 8)
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Post by missfixit70 » Sat Nov 03, 2007 12:56 am

dandywarhol wrote:
missfixit70 wrote:
mikeonb4c wrote:Rather than spend hours looking it up (lazy me) can you remind me v quickly Missf what the pros/cons are of the £12 Allens kit and the £18 NickSkidmore kit. Maybe this is a job I should get done on my Bongo. Have you noticed much change in performance and/or fuel consumption?
Allans kit I think is 2 blanking plates fitted with the egr & pipework left in situ, therefore easy to reinstate, quicker to fit & slightly cheaper.

Nick Skidmore's kit consists of a blanking plate & threaded plug to fit the outlet form the turbo. This allows complete removal of the egr v/v & pipework which clears a pile of scrap metal from around your engine, which consequently takes a bit more work & knuckle skin. Can be removed in such a way that it could be refitted, but most tend to go for the quicker destructive method :twisted: as I did. I can't see that it's doing anything useful anymore, it was a retrofit item on the engine to satisfy legislation, so the engine will run fine without it (in my & many other's opinion).

Both kits do the same job in sealing offthe egr system completely.

As regards consumption, its difficult to say as mine is pretty cack anyway thanks to lots of short runs, I would say it felt slightly better after removal performancewise, but that could just be wishful thinking :roll:
But my point is you can get the same results by a 5 minute job blocking off the vacuum pipe (unless the EGR valve has seized open)
Judging by the amount of crud in the pipework when I removed & blanked egr, would the egr valve actually be able to close fully & seal 100%, I know there was some debate on this point which was one of the factors that helped me decide to go all the way :wink: :shock:
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Post by brorabongo » Sat Nov 03, 2007 1:04 am

So far I've just blocked the pipe. ( hopefully the right one 8-[ ) I do own a nickskidmore kit, but have been up to now too afraid to stripe the system out.

TBH, I would not know what a EGR valve looks like :oops:
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Post by dandywarhol » Sat Nov 03, 2007 1:06 am

Fair point Kirsty :)
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Post by RobnKathryn » Sat Nov 03, 2007 10:22 pm

Just a quick note, especially to scanner............if you're going to sandwich something where the egr pipe meets the inlet manifold.....make sure it's going to withstand heat/pressure otherwise it'll end up in your cylinders.

Scanner are you sure a sardine can is man enough? (or fish enough for that matter). Ir you don't disable the valve too, you'll get lots of very hot gas build up at that point I think.

I speak from experience, using a coin which couldn't move through the hole, so must have distorted under heat/pressure, ended up in a million pieces in 2 of the pots. A secondhand engine and a truckload of hassle later and everything is fine again.

Rob
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Post by scanner » Sun Nov 04, 2007 12:41 am

Thanks, I'll keep an eye on it - it's a wide strip of quite thick gauge steel.

I will be taking the gasket out and copying that in sheet steel sometime. I take your point about disabling the valve though, I assume that is on the passenger side of the engine?
It will have to wait until Monday, as I'm at the Truck Racing at Brands Hatch all tomorrow.
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Post by mikeonb4c » Sun Nov 04, 2007 1:17 pm

I'd be very careful about a thin metal blank. I suspect it will be subjected to strong pressure based oscillations and there is a possibility it will fatigue, shear off and....over to you Rob :shock:
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Post by Netpest » Tue Jan 15, 2008 11:09 am

Just ordered both plates from Allans in plymouth. Reading posts and what witht he trip this year feel safer knowing it is out of the equasion than any problems comming up.

Says it has fitting instructions so fingers crossed :)

Now time to read up on the treads about fuel consumption.....
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Post by mikeonb4c » Tue Jan 15, 2008 2:45 pm

Sensible chap Netpest - Allens kit is from someone who understands the theory and engineering of the EGR very well from what I've read. 8)
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