Clogged Intake Manifold Cleaning (jakeru's project #2)

[jakeru]

Some diesel intake manifolds are notorious for getting clogged up by sooty exhaust gas recirculation, especially when it comes into contact with oily vapors recirculated in the intake tract. This one is from a 2001 Volkswagen Golf TDI I did some work on recently:
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I cleaned it by igniting the hydrocarbon mass with a propane-powered "weed burner" torch:
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...followed by compressed air (once the embers were hot enough air is all that was needed to spread the flames, and blow the hot embers out.)
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Here are some of the charcoal bits that came out:
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...in hindsight, I should have positioned the manifold so gravity would help the charcoal bits fall out, (but more on that in post #2.)

The torching (followed by scraping) was very effective in getting the inside of the manifold clean of all the heavy residue. Here are what the inlet and outlets looked like afterwards:
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More pics coming in next post (due to 10 pic post limit)

[jakeru]

I had a bit of an "oops" moment when I blew a hole right though the back side of the (cast aluminum) intake manifold. But luckily, I have an AC TIG welder, (and knew how to use it.) And even on the positive side, it actually proved a useful and necessary "access hole" for manually cleaning out all the charcoaly residue from the inside of the plenum. (I bent a welding rod and scraped, and inspected interior surfaces with a "mirror on a stick" to check progress.)
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Believe it or not, after all this, the manifold's mating surfaces were not warped. They were amazingly, perfectly flat!

After I got the inside scraped out all clean, I prepped the hole and a patch piece to plug the hole, and TIG welded it back up. I made the patch out of two pieces. It was I think 1/8" or 3/16" thick 6061 material.
(first piece tack welded, and crack vee'ed out for welding with carbide burr: )
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(first piece welded in: )
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(second piece welded in: )
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Now the welding certainly warped the manifold's mating surfaces, so I surfaced it using ~60 grit open coat sandpaper wrapped around a flat piece of granite I have around just for this purpose. I also put a finishing touch on it by taping all the holes shut, and bead blasting the exterior.
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If I did it over again, I would position the manifold when flame-cleaning it, so the embers/coal would get blown out downwards instead of upwards. That would help the hot embers fall out with gravity assisting them, and not just sit there and "pile up" against the back wall of the manifold (which is what caused the back wall to melt.)

Kind of funny how the access hole ended up working out. It is extremely useful to have a TIG welder sometimes. :D

[SeanMurphy265]

Was the car still running before you started the repair? Nice work, you would think the manufacturer would come out with a re-designed intake to help with the problem.

[sportbike]

I have a 2002 TDI Jetta and have cleaned mine as well. Now has 183,000 miles on it and doesn't have nearly as much of a problem with the sludge since I turned the EGR valve duty cycle way down.

the cars will still run like that. That one is just getting to the point where it starts to decrease performance. These things only make about 90 HP and they are turbocharged. Doesn't require a very big air passage.

I believe the new diesels have a filter to prevent the sludge. There are a few people that make one for the engines that have the problem, but turning down the EGR operation in the ECU works as well.

Jakeru, if you do the burn out method in the future, use a very wet rag on the outside of the manifold and continually wet the rag as you go to prevent melting it. I don't think I have seen anyone melt one that much! OOPS!

[DaveO]

Now the welding certainly warped the manifold's mating surfaces, so I surfaced it using ~60 grit open coat sandpaper wrapped around a flat piece of granite I have around just for this purpose.

You can do this manually, the flat granite piece acts like a sanding block? I'll have to keep that trick in mind. How long did that take, and how did you check to make sure it was flat enough?

When people post pictures I always check into the background to see what else is going on in the picture... and I think I'll check our ironing board to see if it is expanded metal. That was an excellent find!

[sportbike]

You can do this manually, the flat granite piece acts like a sanding block? I'll have to keep that trick in mind. How long did that take, and how did you check to make sure it was flat enough?

When people post pictures I always check into the background to see what else is going on in the picture... and I think I'll check our ironing board to see if it is expanded metal. That was an excellent find!

I have surfaced the cylinder head and the block deck by hand on motorcycles. Actually, the head and cylinder currently on the bike was done in my basemen by hand. I go up to 600 grit. Has worked for almost 200 dyno pulls and probably 60 passes at the track.

[jakeru]

SeanMurphy - the car was running, but was severely "disabled" on power output.

DaveO - that's indeed it's an old ironing board, stripped of its fabric cover. It's worked very well for me for many years doing the bulk of my small oxy-acetylene welding jobs, and many general torch heating duties, etc. When it's not needed, it easily folds up and stores out of the way, taking up almost no space.

I've used hand files to surface things flat as well. Really works well when you can clamp what you're working on in a vice, (or clamp the flat file in vice) and stroke the piece across the file (or file across piece) consistently. You need to be attentive, don't want the edge of the file "digging in". On aluminum, stroke backwards with some pressure as well, to help clear the shavings/chips out of the file teeth. Sometimes how you orient the piece and file, can allow gravity to help clear the shavings as well. Alternating directions of filing can be helpful as well. For example if you file or sand for a while with strokes in a "/" direction, change and do it in an orthogonal "\" direction for a while.

You can get a pretty reasonably accurate assessment of flatness of a long surface by simply viewing down the surface and observing if ends are sticking up beyond the middle, or if middle is sticking up beyond the end.

For more precision, you can do ti with a precision straightedge, using the same procedure you use to measure engine block or cylinder head flatness. Lay the straightedge across the surface, and slips various thicknesses of feeler gauges underneath the gage the flatness. (You can also observe how much light shines underneath the straightedge.)

I had to put some spacers under the granite piece, and clamp it down to bend it completely flat. (Maybe because the table I had it setting on was not completely flat.) But I know there are pieces of thick rock that are pretty flat out there. It does help to have a flat table to set them on (if they are not extremely thick.) Big pieces of metal, surfaced flat on the one large surface, work well for surfacing things flat also. The ideal scenario is to have your "flattening tool" be of larger dimensions than the piece you are trying to flatten. I've heard of some people using spray-mounting adhesive to bond sandpaper to the flat surface. That would definitely keep it from slipping around.

You can either move the flat, abrasive tool against a stationary workpiece, or move the workpiece against a stationary, flat abrasive tool.

I've actually straightened surfaces that were milled warped by careless machinists. If a machinist pre-stresses a part excessively, they can easily machine the surface flat as long as it' stays bolted/fixtured to the milling table... but if they do it wrong, as soon as they release the bolts, the work can spring into a different shape and the freshly machined surfaces may not longer be flat.

sportbike - I'm planning on removing the EGR in this VW TDI. I have an innovative method in mind for it. Stay tuned...

[Haywire]

I believe the new diesels have a filter to prevent the sludge.

That's good to hear. We just bought a 2011 Golf TDI a couple weeks ago.

Ian

[yotarover]

that is awesome i'll have to give it a try. my 22re's intake has the famous black goo again. might be time to convert to pan but that's a 800$ price tag hardest part is finding a place to get the tanks filled. right now mine is soaking in 3gal of seafoam

[jakeru]

That's good to hear. We just bought a 2011 Golf TDI a couple weeks ago.

Ian

I was at the VW Dealer getting parts for the car I was doing the intake work on recently, and decided "what the heck, let's take a 2011 Golf TDI out for a test drive!" It was a 6-speed manual. It was a blast, very cool car. I noticed a "clunk" over bumps I complained about. Turns out they hadn't "prepped" the car yet... (which means it still had big, long plastic spacers stuck inside the front springs! I guess so the shocks wouldn't get worn out as it was transported over rough seas by boat?)

The funny thing is, I thought the car actually handled very well. I wonder if might actually handle worse with it "prepped?" (with those spring spacers removed) I did note it had a funny, nonlinear behavior when transitioning abruptly into braking, and from braking into cornering. I'm sure it was because of those plastic spacer blocks.

I researched the EGR system on that powerplant however, and it sure seems "complicated"!!! It seems like there is a lot that can break to me (servo motor controlling an EGR-specific throttle valve?) But I guess it's all necessary nowadays to get diesels to pass emissions. At least they are selling them in California again, and at least it doesn't need the "liquid urea additive" (like some other competing modern diesel designs use.)