DIY Intake Manifold Interior Cleaning

[speedy25]

Someone else posted detailed instructions for this long ago but the cries of no pics have been heard and now answered. The previous poster did a lot of steps that I deem un-necessary. You do it the way you feel comfortable.

Not all exacting details are included. I assume you are at least somewhat mechanically competent and can remove and replace anything else that I may have not mentioned to complete this job.



After removal of the airbox disconnect the the TPS connector. Then remove the 4 fasteners that hold the TB to the manifold. Also remove the bolt holding the vacuum diaphragm bracket to the manifold.



Separate the TB CAREFULLY, separating the diaphragm from its holder. Remove the metal TB gasket and put it in a safe place for re-use.

Remove the 5 fasteners that hold the upper and lower halves of the intake, along with PCV and FPR hoses.



Carefully separate the two halves and once again remove the metal gasket for re-use.

Pretty grungey ehh? Yecccchhhh! I'm sure yours will be similar.

Most cheap-o carb cleaners wont even touch these kind of deposits. I use Berrymans since its easily available for around $4 a can. IT CLEANS! ITS WORTH IT! You may have another brand that works well for you.

Heres a comparison of the clean top to the bottom half.



Fill the cylinder runners with paper towel to prevent all (ok MOST) of the
grit loosened up in cleaning from falling into the engine. Only the small circular hole in the middle right is not blind. It goes to the EGR. Spend some time working out all the crud from that hole. You are welcome to remove the EGR to help that along, but I didnt want to deal with it. They can be VERY difficult since heat and deposits= corrosion and cursing! Use air if you have it to blast out pieces from hard to get at places. It will go everywhere so either cover things up or be ready to clean it up later.

Finished lower manifold.



Make sure the gasket surfaces are clean before reassembly. NO SEALERS NEEDED! Torque the two halves together evenly. 8mm fasteners are 12-15 ft#. Finish assembly reverse of disassembly. Recheck that you replaced ALL the hoses, and didnt knock any others off.

Restart will be slightly difficult because at least some of the cleaner will have seeped into the cylinders. WARNING: if you think you poured a LOT of cleaner down a runner, remove the plugs and turn the engine over by hand, unless you already have a mess and want to clean the inside of the hood too!

Hold the throttle wide open until you get a start. I made a REALLY nice cloud in my neighborhood from all the stuff burning out of the engine.

I didnt get any improvements to how it ran. My engine ran well already, but I have noticed a reduction in oil consumption lately. I cant scientifically relate that to this cleaning, but I cant rule it out either.

Have fun with your car. Work smart!

-SP

[beefer]

Wow, that plenum was disgusting. Nice job cleaning it up.

[Kiwi-Corolla]

Great write-up. I know a lot of people have been asking for this. Nice work

[mcgiiver]

I have been thinking about cleaning mine, and Speedy 25 said he didn't notice any improvement after he did it. That being said, since the intake carries only air and not fuel, and since most of the crud probably comes from the EGR system, why should I bother cleaining mine. I have never seen an intake that restricted air flow to any measureable degree. Even as bad as Speedy25's intake looked, I doubt it really restricted air flow to any substantial amount. Looking for others to chime in and let me know what I am missing. What advantage is there to going through the bother to clean my intake plenum. I am not talking about the throttle body, I have seen that help many times.

[JesusJones]

Originally Posted by mcgiiver

I have been thinking about cleaning mine, and Speedy 25 said he didn't notice any improvement after he did it. That being said, since the intake carries only air and not fuel, and since most of the crud probably comes from the EGR system, why should I bother cleaining mine. I have never seen an intake that restricted air flow to any measureable degree. Even as bad as Speedy25's intake looked, I doubt it really restricted air flow to any substantial amount. Looking for others to chime in and let me know what I am missing. What advantage is there to going through the bother to clean my intake plenum. I am not talking about the throttle body, I have seen that help many times.

Your cars not gonna turn into a power monster after a cleaning. I've done this and noticed a slight increase in mpgs like 1-2 mpg highway. And that is what I expected and why I did it. Was this because of the improved air flow? Maybe. But a better guess is that the egr system is now working properly because your also cleaning out all those passages, which on mine were COMPLETELY full of carbon.

Nice post Speedy,

Cheers

[kickfli12]

ill probably be doing this within the next week cause im sure the carbon build up in my car is terrible. the previous owner drove it 11 miles a day. no highway... they had a different corolla for that. ill clean the throttle plate at the same time i guess with a fuel system service as well. and nice write up man!

[mcgiiver]

I did my plenum cleaning yesterday. Pretty much went the way Speedy25 said it would. He did state he did not include all the steps. I found a stumbilng block was the necessity to remove the EGR valve. One nut is easy but the other , toward the pass side of the car, has a shorter than normal head on the nut and must be removed using a socket with a universal joint, very litte room to swing rachet, fine tooth ratchet helped. Another necessary step was to remove the bracket which is under the engine lifting hook that sandwichs between throttle body and plenum. Not real hard to remove, just another step, the nut beneath the throttle body for it is a little tough to get at.

All in all the job went smooth. With only 38,000 miles on the car I did not expect too much crud. But there was a fair amount, even though the car has been meticulously maintained.

It appears most of the crud comes from the soot from the EGR valve and the crankcase oil being pulled into the manifold. I was amazed to find about 3 teaspoons of oil pooled in the dimples in the manifold.

I cleaned the throttle body while it was off. This is a stupid system whereby crankcase vapors are routed upstream of the throttle body, a sure way to foul the throttle body.

The only difference in performance might be a slightly better, smooth idle, which I would attribute to the TB cleaning.

It does not seem that even over the life of the car, enough crud could accumulate in the plenum to restrict air flow, plug a passage, maybe.

I fail to see how flooding the plenum with cleaners like Seafoam or Techron would ever clean out the crud. It really needs to be disasembled.

I will definitely be looking to install a catch can in the near future. Why this is not OEM is beyond me.

[speedy25]

Originally Posted by mcgiiver

This is a stupid system whereby crankcase vapors are routed upstream of the throttle body, a sure way to foul the throttle body.

Despite the fact that it seems dumb, PCV systems have ALWAYS been routed into an air filter or intake pipe.

Typically the vapors do NOT cause a big problem, and I personally dont think the PCV system has made all that sludge, but it had to come from somewhere.

-SP

[kickfli12]

Originally Posted by speedy25

Despite the fact that it seems dumb, PCV systems have ALWAYS been routed into an air filter or intake pipe.

Typically the vapors do NOT cause a big problem, and I personally dont think the PCV system has made all that sludge, but it had to come from somewhere.

-SP

i thought the same thing until i put a catch can in line of the pcv system. after about 6000k (2 oil changes) i dumped about 1/4 of a quart of oil out of it. for me thats 2 gallons of oil that has passed through it in its current time on the road (my car has 192k). since the oil is travling so slowly it has time to attach itself to things and gum up. well this is at least MY experience with these pcv systems. this is my 3rd 1.6L corolla and my previous 2 were full of oil as well. to ME this makes sense lol

[mcgiiver]

Originally Posted by speedy25

Despite the fact that it seems dumb, PCV systems have ALWAYS been routed into an air filter or intake pipe.

Typically the vapors do NOT cause a big problem, and I personally dont think the PCV system has made all that sludge, but it had to come from somewhere.

-SP

I probably used the wrong word "Crud". At 38,000 miles mine had a coating of carbon/varnish inside the intake manifold. the oil that was pooled at the bottom of the plenum, was basically clean oil. Since the PCV valve is not a very refined mechanism as far as making a good seal, I can certainly see how oil gets by it, not enough to show as a loss on the dipstick.

[Shuttlepod One]

At 187K I removed the plenum and the intake manifold. The route to the EGR was 95% blocked by buildup. Most of the passages were just as blocked. Only the intake runners were not clogged, but they had a solid black varnish. T-body was pretty dirty as well.

I agree that Seafoam or MCCC won't do squat to clean this system. You have to tear it down and use Carb Cleaner.

I saw a solid 2mpg avg increase in fuel economy from 32 to 34.

[astroboy224]

can you explain how to turn over the engine by hand again? what plugs were you referring to?

[speedy25]

use a socket on the front pulley to turn it over.

plugs= spark plugs.

If you dont do it by hand you will spray black gunk all over the place.

-SP

[hokeymcf]

I've combed through this thread, and the other DIY thread and neither of them say what tool to use for cleaning the intake manifold. what did you guys use?