EGR Blanking, pro's n cons ?

[briwy]

A few pics of before and after.


nasty and oily



pretty obvious where the oil leak was coming from, knackered gasket





the elbow after cleaning up



the pipe on later models (mine anyway) has a an extension which means the blanking plate can't be fitted without cutting the extension off. Also makes it necessary to lift the pipe out of the elbow.



gunge in the pipe



blanking plates in position and all cleaned up





access to side of the engine better without the egr pipe

[maxheadroom]

well done that man briwy

[rhino-wayne]

FANTASTIC briwy

Thanks for all the great photos.. .........like some weirdo, I just had to go out in the dark & rain to look at my Bongos innards!
I am yet again so happy with Bongo, so nice 'n' to find & fix things!
.......... Unlike my previous Espace. ..needed multi-jointed-extra-long-super-slim-fingers with eye ends to do anything

better get my blanking plates now!

[Driver+Passengers]

Good job, Brian. Mine feels rushed after looking at yours. Will reassemble intake manifold tomorrow and hopefully get her back on the road.

[bikerbob]

Has the EGR blanking resulted in any benefits as I`m considering doing so however the Jury appears to be out on the benefits achievable???????

[Driver+Passengers]

Has the EGR blanking resulted in any benefits as I`m considering doing so however the Jury appears to be out on the benefits achievable???????

From what I understand, the average air intake temperature will be lower, the air will be cleaner and the inlet manifold should never get that manky again, nor will the joints continue to weep over the drivers' side - all of which I understand to be 'good things', including but not limited to addressing one cause of black smoke under acceleration. The combustion chamber will be subject to less acidity (citation needed) but the expense of higher combustion temperatures and increased emmissions (nitrates?). Anecdotal evidence suggests vans can be a bit perkier after a clean/blank.

A badly constricted EGR pipe/elbow/manifold may well benefit from a good clean-out (perhaps even periodic), but that has little to do with whether the EGR is refitted or blanked. Some might say "might as well blank it while you're in about there", but that's not necessarily a compelling reason.

I did filters, oil, ATF and exhaust at the same time as blanking EGR and there is certainly an improvement in performance and noise. Can't saw what part the blanking played, though.

[Northern Bongolow]

does blanking extend the warm up time and therefore use more fuel to run efficiently on short runs,or does the egr not operate until the engine is already warmed up.
where does all the gunk now go, down the exhaust.
the solids are carbon deposits from the burn, but where does the oil come from,breather pipe maybe.
just a few more answers needed before i blank mine .

[mikexgough]

The best chap to ask Q & A on EGR blanking/Removal was sadly banned from here last year over some coolant bleeding "misunderstandings".... he had done his and could have given you his experiences... a resource lost

[Driver+Passengers]

does blanking extend the warm up time and therefore use more fuel to run efficiently on short runs,or does the egr not operate until the engine is already warmed up.
where does all the gunk now go, down the exhaust.
the solids are carbon deposits from the burn, but where does the oil come from,breather pipe maybe.
just a few more answers needed before i blank mine .

I have never really read up enough to understand when the EGR is operational or not. I would have thought that engine warm-up times (low revs, low exhaust pressure) would have had to involve the exhaust warm-up valve (winter pack) to be effective, otherwise not that much exhaust gas would 'choose' to transit the EGR.

So without an exhaust valve, warm up time might not be so relevant. If it is, and if you use the warm up switch daily, then including inlet manifold and EGR pipe into a periodic service might be the right answer for you, as opposed to 'blanking and forgetting'. I get the impression most blank the EGR to eliminate crud, so if you're manually removing crud every year or two and getting the benefit of the faster warm-up times, you're laughing.

I suspect the lion's share of oil in the intake manifold (mixed up with the soot), comes from either the rocker cover breather or the turbo oil seal, either way transported via the intercooler through the air intake hoses/pipes. Too much is really bad - a small amount doesn't seem to be, but in another thread, I hope to assess the performance of the intercooler before and after removing all oil traces.

Something I still don't have an answer for is whether or not it is a really bad idea to operate the exhaust valve with the EGR blanked. I can't see how it would be a good idea (be like having a boot/potato up the exhaust).

Ady - you probably know all this anyway.

[scanner]

does blanking extend the warm up time and therefore use more fuel to run efficiently on short runs,

Not that I've noticed - but why should it? EGR is designed to lower cylider combustion temperatures. So if anything it increases warm up time.

where does all the gunk now go, down the exhaust.

Yes exactly where it should go.

where does the oil come from,breather pipe maybe.

Exactly.

I've cleaned out too much EGR muck from half blocked inlet manifolds to have ANY thought that it could be good for the engine.


Little story from a few years ago...................

A pal of mine had a Perkins Prima engined Maestro TD and took it to Perkins own garage in Peterborough for a service - the first thing the mechanics did there was stick a ball bearing in the vacuum tube that operated the EGR saying "There, that's fixed that, you don't need it anymore."

EGR needs to be fitted so a diesel engine can be sold, once it's sold no further checking of EGR operation takes place and all it ever does after that is bad for the engine.

[briwy]

does blanking extend the warm up time and therefore use more fuel to run efficiently on short runs,or does the egr not operate until the engine is already warmed up.
where does all the gunk now go, down the exhaust.
the solids are carbon deposits from the burn, but where does the oil come from,breather pipe maybe.
just a few more answers needed before i blank mine .

Ady. Since I've done mine it definitely feels a bit more responsive and ticks over better.
I can't comment on fuel consumption as I've only done a few short trips since doing it but I can't see how it could make it worse.
Warm up certainly doesn't seem to be affected ,but I think the Bongo warms up quickly anyway. Compared to my Octavia TDi its great. The Octavia takes forever to warm up and get the heater working properly. I guess it's a much more efficient unit with all its fancy electronics on. Does average 50mpg though. Perhaps a transplant is in order before the contract hire company have it back. Wonder if they'd notice. VW engined Bongo! I'd probably be chucked out of Fury.

[Driver+Passengers]

...VW engined Bongo! I'd probably be chucked out of Fury.

But a Bongo engined VW...

[Northern Bongolow]

thanks for that guys, the questions were slightly retorical as we hear all the time--- blank it off, and maybe dont fully appreciate what it may affect down the line.
it would seem to me to be a good idea to blank/remove it as new/cooler air to burn has got to be better, the link to warm up times is still a bit unclear,and blanking it will do nothing for a worn engine passing oil vapours into the inlet manifold or leaky turbo seals.the winterpack/egr link (if any) still needs to be checked out.
just trying to get some facts out really. .
the winterpack bit is really what im interested in, i work nights and use mine every night to warm mine up, it comes off fast fast idle very quickly,then off fast idle in about half the time of without winterpack, this i recon is better for my motor as it runs more efficiently quicker,and saves fuel,the last thing i want to do is blank the egr if this feeds warm air into the air intake whilst under winterpack warm up as it must take longer .
going back to the carbon deposits found in the inlet manifold,if your engine is running /burning correctly and if the correct, good quality engine oil is used this should not be present in large amounts,what im actually saying is if your engines bad, firing all the crap down the exhaust doesnt make the engine better, it just hides the result.

thanks scanner for the egr designed to lower temp bit, makes perfect sense if you think about it,dirty air with not as much oxy in it.

[M 80NGO]

Ok some great info on this post and i've read it all with great interest, just 2 things that puzzle me :

1) surely the pipe that's being blanked will fill with crud again bearing in mind that the crud seen in the pics could be 16 years worth of crud ?

2) why is it not just as easy to take it all off clean it all out and then refit complete with EGR as mazda intended ?

[Driver+Passengers]

Ok some great info on this post and i've read it all with great interest, just 2 things that puzzle me :

1) surely the pipe that's being blanked will fill with crud again bearing in mind that the crud seen in the pics could be 16 years worth of crud ?

If the pipe is blanked, there will be no further crud deposited within it, as there will be no more dirty air going through it.

2) why is it not just as easy to take it all off clean it all out and then refit complete with EGR as mazda intended ?

If you choose not to blank it, then you may still want to take the manifold and EGR pipe off to inspect, clean and refit - on the assumption that it's not going to be spotless in there, particularly if you're getting the characteristic weeping gunge around the gaskets. Blanking is easier because you don't have to remove and clean, but I'd argue that you'd probably want to remove and clean the inlet manifold and elbow. At which point, it's 6 and two 3s whether you blank or refit. Cleaning out and replacing gaskets is going to be a good job in itself, it's just you may have to do it again a few years down the line.

I get the impression that "as Mazda intended" may be subject to differing opinions. Japan's strict(er) emissions regs require the EGR to reduce nox, and I've read at least one post where the author reckons it 'looks like an afterthought'.

We may be biased towards blanking due to the collective reports that (crud-wise) it "does more harm than good", performance seems better after blanking, it's easy to blank, etc... It is clear, though, that this should not be the final answer.

It doesn't seem like a big deal to include cleaning out and resealing it all into a service regime.

That's what I reckon, anyway. I blanked it because it felt like the right thing to do - who knows?!