LD Intake Grunge

#1

More information about intake goo buildup in the FAQ

Some more pictures of LD28 intake manifold grunge, from an '81 Sedan in the JY:

(click on any image for larger)

#2

Jeez...

That's worse than the worst drains I've had to clean. Guess that engine didn't run too well. I wonder how you'd get the stuff out of there - hi-temp pressure wash?

Rufus

#3

That was a JY engine.

That is not nearly as bad as I've seen on others. In particular, my '82 was worse than that (but my pics are not so hot; see the link in the FAQ in the above post). I learned about the problem when reading about the same problem with VW TDIs. The same conditions exist (EGR + crankcase vapors), so I theorized that my LD28's black smoking could be due to restricted intake, which is why I pulled my '82's intake a couple of years ago.

It is quite gooey. I started to clean my intake & plenum manually, but . . . read the rest of the story in the FAQ. Cleaning the intake manifold is easy compared to cleaning behind the intake valves.

#4

I do not think that the EGR is causing the grunge buildup. More likely it is the throttle. With the throttle closed (idle), the engine is creating a little vacuum and sucking all bypass gases and some oil into the intake. My intake was also plugged badly, not as bad as in the pictures. Cleaning up was a mess. I am going to get rid of that throttle. Never seen something like that on any other diesel engine. I will keep the EGR however. Did some small changes to the valve cover.

#5

The throttle (on the Maxima LD) is for EGR function, and that's its only reason for being there. I assume that the marine and industrial versions don't have a throttle. It's closed at idle!

If you disable the throttle, the EGR will not function -- there is not enough delta P to get exhaust flow into the intake (at least, not enough to make any difference). Meanwhile, the EGR system controller is advancing the IP timing at certain times on the assumption that EGR is occurring. So, if you disable the throttle, disconnect the IP advance solenoid's wires too.

I think the intake goo is EGR soot + some oil vapors. I do not think it's mostly oil, I think it's mostly soot. Diesels I worked with that don't' have EGR but have crankcase ventilation to the intake have not had anything near this level of goo. Oily deposits, yes; goo, no.

#6

goglio704 wrote:How were you going to have it cleaned? IOW, what sort of place were you going to take it to, and what were you going to ask them to do? Also, did you intend to split it into two pieces, or leave it as one?

My local FLAPS also does light automotive machine work, so they have a shop and can clean things. I did separate it into two pieces, then started cleaning it myself, then decided "this is not my job" and sent it to them. Got it back in a few days, sans the EGR Guide Tube. I had forgotten to remove it before giving it to them. Because the Guide Tube is stainless steel, they could not drag their cleaning tank with a magnet to find it, so I had to wait for a couple of weeks until they drained the tank. I did eventually get it back. I've never reinstalled it

but I still have it here.

I paid about $40 for the cleaning, which I thought was quite a bit, but it did come back with about 98% of the crap gone, and if you haven't done this job before, you cannot imagine how nasty it is to clean.

I will continue to pay $40 to have mine cleaned.

The EGR gasket is getting harder to source. You need two of them. Get them in advance. Nos. in the FAQ, Intake Grunge section.

#7

I have seen repeated warnings in the factory literature that the intake manifold should not be disassembled.

An example...

How come, why for?

#8

I have assumed that "there is (normally) no need, therefore don't bother." Maybe I'm wrong. Certainly, there's nothing in there that is matched in a precision manner, or has hidden springs that pop out, plastic tabs that break, or evil spells released.

#9

Reading many posts on different forums points to the crank case blow-by as the main culprit for intake manifold gunk. The solution to this problem is to install an Oil Catch Can/Crankcase breather. Currently there is one available to buy online: http://www.alamomotorsports.com/greddy/ ... chcan.html
At $90.00 plus shipping it is kinda pricey, so I will go the DIY route. Found a few designs online but decided to use this one for it's simplicity:
http://www.diesel-central.com/News/OilAirSeparator.htm

#10

From what I know, You can use a air filter for air compressors, unless you want to make one out of some old cans laying around, I would say that is a good way to go that is the cheapest. Probably can pick one up for about 20 bucks

#11

Kassim503 wrote:

From what I know, You can use a air filter for air compressors, unless you want to make one out of some old cans laying around, I would say that is a good way to go that is the cheapest. Probably can pick one up for about 20 bucks

Do you have a part#, source or web page link?

#12

Scrubbed around on the internet, and found a link to these on grainger industrial supply. If you want to obtain one locally, I would reccomend just going to almost any hardware store and look under the air compressor acessories section.

Filter link

40 dollars for this sounds about right for a quailty made product, you can go cheaper and buy eastern made stuff. I wouldnt see a problem with using 3rd rate products here, b/c you arent actually running pressure through the setup.

A google search found a writeup supporting the notion of using an air/oil filter for a catch can, from photos it appears that it catches waste oil. Homeade catch can

lozLD28 · #13

DO you think those fuel additives do anything to help with this or don't they reach this vunerable area?

#14

The crud comes from the crankcase ventilation system. I don't think you get much fuel additive through there.

Rufus

#15

Fuel additives will not help this problem. It's exhaust soot mixed with crankcase fumes. Fuel does not touch this area, so anything you put in the fuel tank is not going to help.

Cleaning the intake is routine maintenance for the LD28 with EGR.

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