Intake Plenum Interior Crud?
 

Hi all,

I've been tearing into the top of my motor in my 1999 Blazer (see below) with 135k miles to do LIM gasket and fuel injector upgrades. I'm attaching pictures of what I found inside the plenum and on the topside of the lower intake manifold.

In words what I found was a coating of wet-carbon like crud. On one of the pictures you'll be able to see how it is not very thick by where I scraped it with the tip of a screwdriver.

Is this anything to worry about?

Would a degreaser and a brush be a good way to clean it all up?

http://u.cubeupload.com/christine_208/topofLIman.jpg
http://u.cubeupload.com/christine_20...deofplenum.jpg
http://u.cubeupload.com/christine_208/plenumcrud.jpg


Thanks,

Christine

I can't load your pics???.........I tried with two browsers??

carbon build up is better than brown sludge........It should clean up.....carb cleaner .....maybe.....

Thanks Don.

Sorry about the pics not loading. :icon_shrug: I just tried the links now and they worked. The coating is less than a 1/16" thick if not half that.

That is a good hint with the carb clearner. I bet that is the way to clean it all.

I'm also going to do a power-steering fluid replacement now that the air-filter box is out and it is easy to get to the low pressure hose on the pump.

Now time to put the grungy clothes back on and get back to the garage. :-)

Christine

I don't know if i ever mentioned another thing that made it a LOT easier on my old back, was to let the air out of the front tires........;-)

just go slow and easy. and do the job right.....

I guess my blocker must be preventing me from loading the pics ???

I can see them fine.

maybe I need to tweek my security software???

So I didn't get back to the job until the afternoon so all I got done was do a LOT of cleaning of the parts and of the mating surfaces for the gaskets etc.

A degreaser and carb cleaner helped a lot. As I was sitting on the floor of the garage I started chuckling to myself how what I was cleaning would never be seen by anyone. LOL But then I thought how it is so much easier to reassemble a job when everything is clean so that you can see all of your parts. I even vacuumed out the intake ports to the cylinder heads as an extra bit of insurance even though I had plugged them with paper towels.

As to the condition of the LIM gaskets, they looked ok with no deterioration. That said, with the stories of their failure with little or no warning, I'll be glad to have my Blazer driving again with good gaskets and an upgraded fuel injector spider.

Nice job.

And believe me: There are far worse nerds out here.

I tend to:
- chamfer all sharp edges I come by when disassembling. Nice not to get cuts
- Fix paint even if it means to disassemble something, prime, paint, re-assemble
- Check where the sharper side is on washers as that side goes down
- Mount all nuts with the flat side down and the stamped side up
- Grease goes on all threads except where there should be none (very rare) or other stuff goes (Loctite)

So you're in best company.

pitting?
 

So I have some fine pitting around the water passages, outside of the main bead on the new gaskets and inside the secondary beads. In order to check that they were pits rather than ridges of left over gasket, I had to run the the tip of a razor blade to gently over the features to tell if they were recessed or raised above the surface. This is why I describe them as "fine", i.e. not deep at all.

Is this a problem that I should address? If so, how?

The pitting is only on the "downhill" (as defined by gravity) side of the openings.

http://i.cubeupload.com/Ve9Wia.jpg
http://i.cubeupload.com/Q7yCxS.jpg


Thanks

Christine

Pretty normal, actually looks quite nice. Nice job scraping.

This can happen at the edge of the gasket. I could show you some impressive pitting corrosion... ;)