C5 Hdi Inlet manifold cleaning

[KevMayer]

A while back I reported good results on my C5 2.2 Hdi after spraying Wynns EGR3 spray into the inlet manifold.

The car went from being sluggish and always returning 36 mpg to being much more responsive and returning anything from 38 to 44 mpg.

This increased performance lasted quite a while. I eventually decided to try re-fitting my tuning box which previously had little to no effect.

With the tuning box my C5 came to life. Very rapid with good economy, but I decided to only use it for 1 day. I took the tuning box off because the performance was good enough without it, but, the engine reverted straight back to being sluggish and returning 36 mpg.

This didn't improve so I eventually considered using some more EGR3 spray. EGR3 is over £8 for a 200 ml tin. I had some 'Wynn's Fuel Injection & Carburettor Cleaner 500ml' which is a larger can and much cheaper and from all accounts it is good for spraying into a petrol engine.

So, I tried the Injection cleaner. I sprayed around a dozen times into the pipe leading from the intercooler to the inlet manifold. The effect on engine speed was just the same as when using EGR3 spray.

The results were that my C5 is now pulling much better and the latest calculation gave 42.5 mpg.

So, The Injection cleaner has produced the same results as the EGR3 spray.

I'm trying to work out what the spray is actually doing because it's making one hell of a difference.

[cachaciero]

My best guess is that it dissolves the soft oily carbon crap that chokes up the inlet tract which then goes through the engine. This of course will open up the inlet passages and generally improve air flow.
I say that because I have noticed when using EGR3 that there is often a "pinking" noise I wasn't sure if this was the EGR3 causing pre-ignition or lumps being squished and burnt in the combustion space. However the last time I did an EGR3 session having finished the treatment and put the car back together i finished for the day, the following morning after starting I heard for a few seconds the same "pinking" type noise. My logic says that any volatile components left after the treatment would have dispersed over night so the pinking could only be caused by something else, I believe that this was lumps of carbon that had been liberally soaked previously now coming off and going through the engine.

But I could be wrong . Whatever, having used two cans of EGR3 my experience is that it does improve consumption, I reckon the two cans have improved my fuel consumption by 3-4 mpg but this has taken time to develop i.e there is a little immediate improvement but it takes another week or so to see the real difference.

cachaciero

[steelcityuk]

I think that on a diesel (fitted with EGR) it's a good idea to strip the induction system, clean the pipes, soak/clean the intercooler with diesel (red is ideal for this use being very cheap) and blank off or thoroughly clean the EGR. Blanking off the EGR on my C5 (2.0 110) wasn't really the right thing to do because it provides extra heating to warm the car faster on cold days. The amount of gunk that accumulates is significant and can't be good for efficiency.

Here's how the 2.5s inlet valve looked-


This car used no oil between changes but look at the carbon build up-


Steve.

[KevMayer]

It would be good to remove the inlet manifold, but, on the 2.2 Hdi you have to remove the injectors before the manifold will come off, so, it's a big job.

If the injectors come out ok you then, when you're re fitting them, have the worry of getting them to re seat on new copper seal rings.

[KevMayer]

I just remembered that a few years ago I had the inlet manifold off from my 1.9 turbo D Xantia. The inside was coated with a thick layer (1/8 " to 1/4 ") of black oily gunge. I used sprays and pipe cleaner brushes to clean out as much as possible.

The black goo which collects inside the inlet manifold on a diesel appears to be a significant problem.

It's well worth using an aerosol spray to clean it out (as much as possible) on a regular basis.

I'm going to give my air intake a dozen blasts every 3000 miles or so and the cheaper 'Wynn's Fuel Injection & Carburettor Cleaner 500ml' appears to be ideal.

[cachaciero]

I do wonder if paraffin or white spirit would do as well, sprayed in with a plant sprayer.

cachaciero

[mongoose100]

I'll probably get blasted for this question, but will ask anyway.

Would heating inlet manifold (assuming its not plastic) with a heatgun or a gas torch burn off the crud inside? Or will this cause more drama than good? Was thinking that with engine idling, there is no major risk of a huge bang.

Sorry if this is a daft question

[Xaccers]

There are some impressive videos on youtube of inlet manifold cleaning with a blow torch and air line. Off the car obviously!

[cachaciero]

The real objective should be to prevent the build up in the first place. The oil does not come from the EGR the EGR only adds carbon particles which stick in the oil. The oil comes from...? the main source I would guess are breathers which get connected directly into the manifold maybe some kind of oil trap in the breather lines might be an idea. Of course it might be that a lot comes from the turbo, the turbo seals work best at high speed at lower speed they might let some oil past, unfortunately this would coincide with the EGR open regime.

cachaciero

[steelcityuk]

You're right the oil doesn't come from the EGR but the cooler oil mist (from PCV, etc.) meets the hot EGR gases and they get baked onto the induction system.

Steve.

[DickieG]

There are some impressive videos on youtube of inlet manifold cleaning with a blow torch and air line. Off the car obviously!

I've just looked at some of those, boys having fun

[KevMayer]

My last 3 fill ups gave me 40.2, 42.5 and 41.8 mpg.

I always, always only got 36 mpg. And my C5 2.2 Hdi now pulls realy well.

Get in there and clean out your inlet manifold...

[KevMayer]

It's been a while since my last post but I'd like to ask a question.

My performance slowly dropped off back to what it used to be. Another application of EGR3 spray and it pickedc up again.

My inlet manifold seems to become dirty far too quickly.

So, I've looked at my crankcase breather pipes and there's no inline filtet and all the oil mist is going straight into the air ducting.

Do you think the breather system would benefit from and inline filter? or maybe even an oil mist bottle trap or anything to let the engine breath but stop the oil getting into the inlet manifold?

[CitroJim]

This is a very interesting thread Missed it until now

Do you think the breather system would benefit from and inline filter? or maybe even an oil mist bottle trap or anything to let the engine breath but stop the oil getting into the inlet manifold?

It's an interesting thought but I can't help wondering if the oil mist in the inlet tract might help turbo life by lubricating it a bit. Just a thought..

One thing I'd caution against is using diesel (red or otherwise) to clean out an intercooler. There's a risk of leaving too much in there and then the engine might start burning it as un-metered fuel leading to an engine runaway.

This used to happen on big diesels years ago that used oil-bath air cleaners. If a careless mechanic over-filled the bath the results could be spectacular

[Deanxm]

Im not sure oil misted into the turbine helps but if you guys are getting trouble with oil baking onto the inlet tracts why not fit an oil catcher instead? ok its not a fantastic solution but it will keep the inlet clean, you just have to remember to empty the catcher every now and again.

D