I took off the intake manifold from my 300SDL last night. Scraped out the gunk out of the inside of it as best as I could - it's now soaking in the tub of biodiesel...

When I shine a strong light inside the exposed intake holes in the engine head I can see that the whole intake area is just covered in carbon and black soot including the valve stem - I can't tell ya how much that bothers me and how much I wanna scrape all that off and vacuum it out, but I'm resisting temptation to do it out of fear that I may be doing more damage to the valves ability to close properly with all the gunk getting stuck in the wrong place... should I just let it go, or should I attempt to scrape/vacuum out?

I can post pics if need be later today....

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Pics please!! I am about to remove my intake manifold and clean mine out. I removed my crossover tube to remove and test my injectors and it was filthy. I did what I could and it actually helped a lot. Most of what I cleared out was on the fitting on the passenger side with an oring on either side. It had a 1/4 inch of crud all around the inside. Seriously, my engine breathes tons better now just with that crud scraped off with a screwdriver. Here is a pic with the crossover removed where you can see how dirty everything is past the EGR:

1987 300TDT @ 175,000 miles

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Ok, I'm going to post some pics tonight... you're showing the top of the turbo going into the crossover tube - mine was bad though not as bad as in your photo but I cleaned it out too.

I then proceeded to remove the intake manifold to clean that as well... what I'm asking about is whether or not I should clean as much as I can inside intake opening in the engine's head... but got mixed feelings about doing anything there - what have others done?

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

His valves were OUT and the HEAD was OFF,and I believe I remember he used a small wire wheel on a Dremel.



before and after:

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'84 300SD sold
124.128

How much of this crud do you think diesel purge removes? I'd love to open mine up and clean it out, however I'm scared to death of messing something up...

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1986 300SDL - 116K
2014 Prius Plug-in (company car)
2014 Q5 TDI (wife's car)

A diesel purge simply cleans the fuel system out. The is the air intake system and is not related. So a diesel purge does nothing for this.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Duh...I guess I wasn't thinking... ;-)

So I guess there's no way to clean the soot/carbon from these areas other than removing the intake manifold?

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1986 300SDL - 116K
2014 Prius Plug-in (company car)
2014 Q5 TDI (wife's car)

Correct. Gassers can be cleaned out a bit with products like Seafoam, but this should never be done with diesels. And there is no way something like that would clean out our EGR sooted manifold.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Here is the picture of the opening holes with the intake manifold removed - showing two of the 6 holes, but they all have this heavy crud in it... do I dare to scrape/vacuum this stuff out as best as I can?!

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Hey guys,

With the head on the engine, I would be careful when cleaning the intake ports on the head. A little crud dropped into the cylinder won't hurt anything but you don't want a lot. As mentioned above, when I cleaned mine, the head was off the car. A vacuum and compressed air gets the debris out after it's scraped off.

If you REALLY wanted to clean this out... you could turn the engine until the intake valve is closed for that cylinder, and then clean it up. When that one is done, turn the engine until the next valve is closed, etc. Don't spray too much solvent in there as it will likely seep past the valves into the cylinder, and again, you don't want too much in the cylinder.

Final comment: Although the crud buildup looks bad, it has very, very little effect on performance unless the intake port is significantly blocked (say, 50% or worse). If you do clean it out, do not expect any increase in power or MPG, just a warm fuzzy feeling inside that your intake valves are shiny!

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Dave
Boise, ID
Check out my website photos, documents, and movies!

That's what I needed to know - thanks!

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

My intake and crossover were both thick with crud. The local machine cleaned them both for $20. If you go the DIY route be careful not to leave any chips of crud loose inside the manifold. You might have to shop around for a machine shop that will put diesel parts in their soak tank. Have you dis-connected the EGR system?

Hopefully... I plugged the vacuum line leading to the EGR system... I'll know better when I finally start the engine - I plan on keeping the crossover pipe off for the first start to blow out some unfortunate bits that fell down into the turbo while cleaning... I'll be keeping my eye on the hole from the EGR to see if I can spot a hint of exhaust...

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K