Intake Grunge

[Dr. Jones]

In the FAQ's there is a section on cleaning the intake. Do you have to worry about getting the junk into the combustion chamber? And will carb/choke cleaner affect the valve seals?

[asavage]

When I did mine, I sprayed carb cleaner in each port (with intake off) and scrubbed with a small wire brush. I suppose I should say that I turned the crank so that the intake valve was closed when I was working with it, but I admit that I only did that with five of the holes, I had one valve not quite closed, and I got a lot of smoke on startup.

The junk all runs downhill, of course, so getting the volatile crap (carb cleaner and gunk mixed) out of the port was the trick. I duct-taped a 3/8" fuel line to a Shop-Vac's crevice tool, and would suck a bunch of soupy crap out from on top of the intake valve, then spray/scrub some more. It took quite a while to clean all six, several spray/scrub sessions per valve. I guess I should mention that you're not supposed to use a Shop-Vac for anything that could ignite. The only alternative I could think of (other than turning the car upside down) was to blow it out with compressed air, but can you imagine the mess?

I would try had to keep the crap from running into the CC, but all you really have to do is turn the crank and work on one valve at a time.

The intake valve seals are up above where you're working, so it's unaffected by the carb cleaner. I also used a small pick tool and chipped at some harder deposits right on the lower valve stem. I wish I'd had a better camera when I did the job, I'd have taken better pics, but that camera refused to focus below 4'.

[Dr. Jones]

Well I didn't turn my crank. Do you think it will burn off or should I just go ahead and clean out the combustion chamber?

[goglio704]

Checking and cleaning the intake is on my to do list, but my question is this: Other than emissions does EGR do anything beneficial? I am real tempted to disconnect and plug the vac line to the EGR valve after seeing the pictures of the grunge.

[glenlloyd]

Checking and cleaning the intake is on my to do list, but my question is this: Other than emissions does EGR do anything beneficial? I am real tempted to disconnect and plug the vac line to the EGR valve after seeing the pictures of the grunge.

Environmentally it does help, and I've left mine alone. Peugeot used an EGR system on their cars very early on, and one wonders after they get so old whether they actually function anymore or not.

You can feel good about it by thinking of all the TDI owners, myself included, who have horrible cleanups on their intakes because of EGR. The blockage on the LD28 is nothing compared to the blockage on a TDI. I'm talking about a 2" diameter hole constricted down to about .5"..now that's bad.

my .02

sa

[asavage]

It'll burn off. Because liquids are (nearly) incompressible, you will want to hand-crank over the engine a full two turns before trying it with the starter. I've bent a rod before, when I had liquid in a cylinder and cranked it up. Other than that, stand back for the smoke!

goglio (sorry, you didn't fill out much in your profile, so I don't know your name yet), the sole function of the EGR system is to reduce peak combustion temperature and pressure, thereby reducing formation of oxides of nitrogen (NOx). That's it, on a diesel.

On a gasser, the rest of the engine is calibrated/tuned to accommodate the EGR system, and disconnecting it almost always leads to pinging, which is very harmful (and is also extremely formative of NOx, much more so than normal operation), but on a diesel I can't think of any downside to disconnecting the EGR system other than increased NOx emissions. You will note that about half of the plumbing and a good part of the visible annoying wiring on the LD28 is the EGR system including that vacuum servo operated throttle in the air filter box. Though at least that thing does damp the idle air intake noise a bit.

I learned about the diesel intake clogging problem when I was reading about it in the FAQ on Fred's TDi forums about 1.5 years ago. Apparently, it's a big problem on TDis.

[asavage]

My take on vehicle emissions is that I like to be able to breathe where I live, and for others to be able to, too.

That said, there has been a lot of discussion about NOx recently, esp. in the biodiesel world, because although BD burns quite a bit cleaner than petrodiesel (HC & CO are way down), NOx emissions are generally a bit higher. Some studies show parity, some show as much as 15% higher.

Mike Briggs and others have made the contention that NOx is overrated as a bad emission. NOx is largely a non-issue until it's combined with hydrocarbons and the reaction is triggered by sunlight, and then you get ground level ozone, a baddy indeed.

Clean up/remove the excess hydrocarbons, and NOx is harmless. At least, that's what I'm reading.

In the meantime, a periodic cleaning of the intake manifold sections and intake ports is a good idea -- probaby doesn't need to be done but every three or four years on the LD28, I imagine. My 150k load was ugly but nothing (as Steve points out) like what the TDi folks are having to deal with.

[goglio704]

I'm all for clean air. I have enough trouble breathing as it is. I would submit that an LD28 running with a choked off intake and functional EGR is probably more polluting than one with a clean intake and no EGR. So I guess keeping the intake clean is the environmental thing to do, but carb cleaner isn't something you want to inhale either.

[Carimbo]

Brings up a few questions:

1. How to hand crank the LD28 in an AT car.

2. Are there any identifiable symptoms of intake manifold/port buildup or does one just have to open it up to visually verify. (I've had a few times, where, on a long road trip, the engine will momentarily bog and then gob a huge cloud of brownish smoke out the tailpipe, then immediately clear up. Freeway speeds. My imagination paints a picture of a chunk of intake manifold grunge breaking loose and getting inhaled, passing thru the CC and out.)

3. Could one chuck a long skinny flexible honing ball brush in a drill to clean the runners?

[glenlloyd]

Brings up a few questions:

1. How to hand crank the LD28 in an AT car.

2. Are there any identifiable symptoms of intake manifold/port buildup or does one just have to open it up to visually verify. (I've had a few times, where, on a long road trip, the engine will momentarily bog and then gob a huge cloud of brownish smoke out the tailpipe, then immediately clear up. Freeway speeds. My imagination paints a picture of a chunk of intake manifold grunge breaking loose and getting inhaled, passing thru the CC and out.)

3. Could one chuck a long skinny flexible honing ball brush in a drill to clean the runners?

For 1. Al may have another suggestion, but when I replaced my timing belt I cranked the engine by hand by putting a socket on the crankshaft bolt and using a 1/2 rachet. It should move pretty easy since the drive isn't engaged and the torque converter isn't doing anything, so essentially de-coupled. You'll have to pull the cooling fan but that should be it. Since you're in there, if your belts need replacing do them. You can't replace the ps belt with the fan on anyway, and the alt belt is easier with the fan off.

For 2. I think that the build-up is not indicative of a malfunctioning EGR system, it's just the nature of the stuff it's putting back into the sytem. What you mention when driving, I have experienced with past Peugeot vehicles and I assumed as you do, that it's probably from some build-up that's been suddenly passed through the system...Al may have better tips on this.

For 3. For TDI intake cleaning this is the easiest method to follow. close off the intake runners with plastic bags and rubber bands, or a board clamped over all the runner ends. Then pour in clean nuts, bolts, or stream pebbles, then pour in chemical cleaner, cap off intake inlet and then shake shake shake, tipping back and forth to make sure the nuts and bolts inside go into all passages. Once you think it's fairly clean then dump the contents into a bowl and check the inside. If it isn't thorougly clean then pour cleaner and nuts back in, cap and repeat. Repeat as necessary until clean.

For the head inlets it is wise to close the valves prior to cleaning the inlets so as to avoid the chemicals entering the combustion chamber. You'll have to pull the valve cover but it's better than a bent rod.

I have to do my TDI again, and it isn't as easy as the LD28 since the engine is transverse mounted and the head ports face the cowl. A mirror is about the only thing you can do in this case.

good luck

steve a

[glenlloyd]

This link shows the difference between a dirty and clean TDI intake. I'm not endorsing the product, because I don't necessarily believe their claim.

http://www.concept1.ca/LM%20Diesel%20Hi-Test.htm

Here's a better link, scroll down about 2/3 of the page to see two very dirty intake manifolds. Mine was actually a little worse than these, mine had never been cleaned and it had 96k miles when I purchased it. You can see that the LD28 grunge is nothing compared to TDI.

http://www.stealthtdi.com/TDI-Problems.html

sa

[asavage]

1) I think that I used a 27mm 1/2" drive socket on the front crankshaft bolt, and something to turn it. I can't recall if that something was a breaker bar or ratchet.

If, as Steve implies, you can't get to the crank bolt (I honestly can't recall), my favourite trick is to overtighten the alternator belt, then use a wrench on the alternator sheave's nut.

[later addition: alternator nut is 22mm, and it works well to turn the engine over, if the alternator's belt is tight.]

2) I don't know if there's a good way to determine whether it's time to clean the intake tract. The top of the intake plenum comes off pretty easily, though, and you can probably see a good way in from there. I, too, have see a sudden plume of smoke while driving down the highway at steady throttle. I don't know if I can attribute it to something in the intake tract coming loose and being consumed or not.

3) A honing tool (especially) would be a poor choice for cleaning, because regardless of how much gunk is in the intake tract, it's better being there than a single hard abrasive bit scoring a cylinder!

Having done this job, I can't think of any effective way of doing it other than the way I did, and even then I didn't clean the intake manifolds themselves. I started to, then decided that my time was better spent elsewhere, so I paid to have them "jet cleaned", which was 98% effective -- I did have to spray a tiny bit out that they'd missed, but it was very minor. I paid about $40 for that service; had I known that price beforehand, I would probably have bucked up and cleaned them myself -- I'm cheap for that kind of work. No fooling, though: it's a damned messy job any way you look at it. If you don't plan your moves carefully, you'll have black sticky gunk detritus all around you, and probably on you too!

My engine's pretty tight, doesn't use any oil etc., and it still had a pretty good accumulation. I imagine that the higher-miles rigs might want a cleaning more often (I speculate).

One only needs to have the intake valve closed on the cylinder one is working on, and valve cover removal is not necessary (I've never had my valve cover off , that's how I know). Just turn the engine until the intake is fully up. Spray the carb cleaner wand at the junk in the port (with a rag over the hole), remove rag & wand, grab vacuum and suck it all out, repeat over and over. I used a small wood-handle brass wire brush on the ports' sides and the bottom of the valve, and that helped a lot. It's messy, but do-able.

[Dr. Jones]

Al hit the nail on the head. It is indeed a 27mm and it can be turned as is. Also a good indicator if your car needs the grunge removed is to remove the hose(plenum?) from the intake and stick your finger in there and see if you can scrap the goop off or just look inside. As far as paying $40 dollars to have them cleaned I'm not so sure thats a bad idea that stuff is horendous, but I haven't tried the cleaner and bolt method. I was thinking all day of a way to do it w/o spending the rest of the afternoon cleaning the up mess. I don't feel so alone now my cars not the only one that farts. The first time it scared the crap out of me I thought I blew the engine, now I try to do it in front of A-hole drivers.

[glenlloyd]

Additionally, if I remember from my TB replacement, it's easier to access the crank bolt if you remove the fan shroud too, which can be done fairly easily if you temporarily move the radiator resevoir out of it's present location.

sa