Absolute Filth! Inlet manifold carbon buildup and cleaning.

[EDC5]

Earlier today I removed my Air Doser and whilst I was there I decided to peer into the inlet manifold.

I'll let the video speak for itself:



So there is obviously a lot of carbon / oil build-up in the inlet manifold. I shudder to think of what the valve ports look like

This is by no means unusual, the combination of EGR soot with the oil naturally present in the intake forms a sort of tar that is very sticky and probably no good for the engine should a lump detach and make its way into the cylinder.

I cleaned as much out as i could reach however it's clear the whole thing is caked in the stuff. I think it's a good idea to remove the inlet manifold and clean it fully as well as try and scrape as much tar from the inlet ports a possible too.

Unfortunately the inlet manifold is combined with the rocker cover so I doubt if it's a simple job to remove, in addition, I will have to use new seals when reinstalling so it won't be a particularly cheap job either.

New seals around £20 to £30:



I think it will be well worth it and help the engine breathe a bit better.

Guide on repalcing the inlet manifold:

[GiveMeABreak]

I couldn’t help notice that when he was putting those new o ring type seals on, there seemed to be a load of that tar caked inside, so didn’t look as if he had even bothered to clean it up first. Useful video even if half of it was taken up with adverts / channel promotion. Never mind

[EDC5]

Exactly! I can only assume the valve ports are similarly caked on the inside of the head too.

The car hasn't even done 60k miles yet so I wonder how bad it has to get before the performance really suffers?

The channel that has the video for seal changes, Ajusa, have a few really detailed videos about the DW10B engine, quite interesting to watch.

[GiveMeABreak]

Yes all useful Elis, thanks for posting.

[white exec]

An insane amount of clogging deposit. Did those who designed this system not foresee this happening? And how would such be dealt with under a certain other manufacturer's seven-year warranty?

This leaves me almost speechless: how a piece of highly-engineered engine could be (presumably) deliberately designed to compromise itself. I guess that aero-engine jets are not similarly hobbled.

This is all down to EGR, I suppose. If so, it's no wonder a good few of us seriously question the wisdom of it.
One thing's for sure: the ICE is set to literally choke itself to death, as we switch to all-electric power. What a way for a remarkable technology to bow out . . .

[myglaren]

One of my workmates - the one with the Juke, knows someone who has a Hydrogen engine cleaning machine.
Had his done and reports improved performance and economy.
He also mentioned a Corsa the became like a factory fresh model with near-zero emissions.
I remain sceptical but it may be worth a try.

Hydrogen Engine Cleaning

As mine has just gone through it's MOT with no emission problems* (bit of a surprise) it won't be any time soon for me.

*Many, many short trips but it has just been on a Scottish tour which may have helped.

I did have the previous one cleaned - all the pipes, EGR and manifold. Made a tremendous difference.

[EDC5]

It's a very interesting point, a lot of the reliability of the diesel engine has been lost due to EGR. I'd say, as a technology, it's fundamentally flawed. I think the SCR and adblue technology should replace EGR as a concept in the future but for now we're stuck with it

I’m looking forward to cleaning the manifold out but am quite apprehensive about what I might find deeper in the manifold. I'd better get a couple more cans of carb cleaner just in case

[EDC5]

One of my workmates - the one with the Juke, knows someone who has a Hydrogen engine cleaning machine.
Had his done and reports improved performance and economy.
He also mentioned a Corsa the became like a factory fresh model with near-zero emissions.
I remain sceptical but it may be worth a try.

Hydrogen Engine Cleaning

With my chemist's hat on I'm a touch sceptical about this. It certainly wouldn’t be able to clean the manifold up as what's need there is a solvent.

Potentially by injecting hydrogen and oxygen into the combustion chamber it may burn hotter for the duration of the cleaning; potentially shifting the carbon deposits in the cylinder and on the underside of the valve. But it won’t touch the carbon sludge pre-cylinder.

[myglaren]

Agreed.

I think this looks a much better approach

[white exec]

When XM diesels acquired EGR, official company fuel consumption figures worsened by about 2mpg, apparently, although this was never acknowledged officially in Evolution pages.
Have seen enough of older PSA diesel engines to know that inlet systems, and combustion chambers, could run for topside of 180,000 miles (in the case of our BX19RD) virtually clean, with only the lightest of soot deposit 'decoke-able' with a simple wipe with a cloth, and nothing that wouldn't shift itself with a good motorway run with decent fuel.

[EDC5]

Blowtorch / flamethrower looks to be very effective... shame the inlet manifold is plastic on these engines

When XM diesels acquired EGR, official company fuel consumption figures worsened by about 2mpg, apparently, although this was never acknowledged officially in Evolution pages.
Have seen enough of older PSA diesel engines to know that inlet systems, and combustion chambers, could run for topside of 180,000 miles (in the case of our BX19RD) virtually clean, with only the lightest of soot deposit 'decoke-able' with a simple wipe with a cloth, and nothing that wouldn't shift itself with a good motorway run with decent fuel.

That doesn't surprise me, it’s hard to justify the lower economy for the lifetime of the vehicle along with the reduction of performance from the clogged intake system for a marginal reduction in pollution.

In addition, all of that soot passing straight into the cylinders is going to wear the engine out really fast due to simple abrasion, and that's before some of the soot gets dissolved in the oil and makes its way around the engine wearing every metal to metal surface (bearings, cams, etc.)

Ask yourself: what is the point of having an air filter if the EGR is going to pump particles of soot directly into the cylinders.. its madness really.

[wurlycorner]

Ask yourself: what is the point of having an air filter if the EGR is going to pump particles of soot directly into the cylinders.. its madness really.

Different kind of particulates than general air born stuff (exhaust gasses known not to cause contamination/scoring etc).

They really should add a walnut blast/de-coke to the planned service intervals though. At least that's being upfront about it.

[EDC5]

I wish that were the case, unfortunately it appears that soot is not only abrasive, it removes the anti-wear coating layer that the engine oil lays on the metal surfaces.

https://link.springer.com/article/10.10 ... 016-0704-9

That link above has a lot of interesting info regarding EGR and engine wear, it even proposes that the soot can block oil ways throughout the engine. We know this to be true from the failure modes of the 1.4 and 1.6 HDi engines.

[EDC5]

Finally got around to removing the inlet manifold / rocker cover to inspect the sludge buildup.
Overall, not as bad as I feared. Whilst there was a lot of gunk in the manifold, the ports in the head didn't seem too bad, probably only a couple of mm of restriction on the walls.

That said, cleaning the manifold was a horrible job. The carbon sludge had to be scraped out by hand, petrol only helped somewhat as it was that thick that it turned the very thin petrol as thick as motor oil.

I would have liked to have powerwashed it, however, with the oil/air separator being part of the inlet manifold I didn't want to get water in that as it would contaminate the engine oil if not completely dry.

Removing it was a bit fiddly but following the instructions (kindly provided by Marc) I was able to do it within an hour. It requires the removal of the Camshaft position sensor, air doser unit, EGR pipe and crankcase ventilation hoses.

Here are some pictures of what I found.

Below I show how I got to the places I couldn't reach with a toothbrush or my hand. Pulling a petrol soaked rag through every port until no more gunge came through.

All clean, fitted a new set of seals and rocker cover gasket.

Refitting took about 20 mins; a lot quicker as the procedure was still in memory.

After refitting the manifold I took it for a drive to ensure that everything had sealed OK.
I haven't noticed an improvement in performance however I was expecting the gunk buildup to be much worse before starting out so from that point of view I'm not disappointed; at least I know it's clean now.

[GiveMeABreak]

Great post Elis, thanks for taking the pics - bound to be a help to others.