Greetings,

My 91 Civic's EGR valve keeps getting 'clogged' and dirty. It greatly affects my idle.

Every now and then I have to remove it and clean it, which is a little annoying. Yet after a few minutes of driving, the idle becomes erratic again. And sure enough, it needs to be cleaned again because it accumulates buildup (The more I clean it though the less 'buildup' occurs). But it's still super black.

So finally I took the intake manifold off to give it a good cleaning. I noticed that the cylinder heads have a EGR port, and it's super black.

Do I have to take the heads off to make sure I clear all the passages and end the 'clogging'/buildup effect I'm having? Or will spraying some carb cleaner do the job? Is that safe?

Any other things I should do while I have the intake off? And coolant drained? Sadly I'm a little on the poor side and would like to minimize spending too much $$.....

Thanks!

 

personal opinion... delete the egr. either keep the stock manifold and weld the hole shut where the egr sits... or get a new manifold that doesnt have egr and let the manifold block the hole on the head when bolted down.

regardless, ur car is a 91. as far as emissions go except cali.. u can pass with flying colors. 91 is the last year that cars can run like crap and pollute the air before they got stricter

 

I would love to remove that damn thing, but unfortunately I'm in California......

Lol '91... damn

 

Clean it out with anything you want. It will turn black again really fast. It is only a problem when it becomes plugged with burnt oil and stuff.
Just don't soak the egr in anything. There is a rubber diaphragm that moves with vaccum on the egr port. This lifts a rod to make the valve open.
Pipe cleaners and small wire brushes can get in there. b12 chemtool is a powerful solvent for this sort of thing.

If it's building up really fast, it sounds like you might have other problems in the engine that are creating an excess of garbage.

 

cali damn.. i bid you good luck then. currently running open headers.. didnt get around to putting my test pipe/muffler on.. but still no cat no o2 sensors all emissions like canister/egr deleted, and i still passed inspection for emissions due to being obd0 and a 91.

they just flagged me for no exhaust so 30mins and 6 bolts later ding ding ding *jersey*

 

On most of the cars I've owned (bought used) I've always had an emission issue. They fail or cause most of my problems.. Sucks man.

Yeah, this car was really neglected. It's my gf's car. All she put into it before she met me was gas. It was tough getting it to pass smog. When it finally did, I was at the Max allowable on most measures. That's why I'm getting an early start before it comes back around........

Do you think it's safe to soak B12 in the EGR head port?
Is there any rubber/gaskets I should be worried about in there?
Should I also soak the Intake valves and clean them down with the B12 chem?

That stuff should dry up anyway right?

Thanks guys

 

Maybe stick a rag in the port and saturate the rag. Pouring stuff into the port might just let it get onto the piston rings, dry them out, and maybe get past into your oil.

You should try sea foam. That will clean everything pretty well. Here's an 'ok' video. I have no idea why he disconnects the battery cable. While you are at it, change your PCV valve. You will likely need some spare tubing to reach the PCV location for sea foam, but don't even have to use the PCV location as you can use pretty much any vacuum line (brake booster is line easy) for it instead.

At that point, it would be a good time to change out the O2 sensor some time after since the sea foam will have blown all sorts of garbage onto it.




Somebody using the brake booster line

 

Good stuff thanks!

Man, I would love to take off the heads but there's too much $$ and work involved for my current financial situation..

I though I saw somewhere that each exhaust port in the heads have a 'hole' that leads to the EGR. I'm afraid that it's super clogged.

Do all cylinders have an EGR port?
How bad does it really get in there?
Is it safe to just spray B12 or pour in some Seafoam in that port?

Thanks again

 

The EGR on this year car is mounted to the intake manifold.
The EGR valve doesn't open direct into the cylinder head as you are describing.
Notice the intake manifold gasket does not have a special hole where the EGR is located. If it did, then it would indicate the gases go directly into the cylinder head, but it does not.
Instead, the EGR gasses just get passed into the intake manifold and pass through along with the normal air/fuel mixture.

 

That intake gasket (from pic above) should be rotated 180deg horizontally (because the EGR is on the right side of the intake manifold from that current view). The larger hole on the upper left of the gasket is the EGR port connecting to the cylinder heads. And I believe that little rectangle below it is a coolant passage.

From what little info I've been able to gather, the exhaust valve ports on the heads have a small hole that 'exhausts' through the heads and back into the EGR valve (I hope that's right). That's how it 'recirculates' the exhaust emissions, and why it gets clogged over time. And my overall worry and question.

I will post a pic of what I'm currently up against.

Thanks

 

Rear view of intake side of cylinder heads.


Closer view of the EGR port on the cylinder head. Key is the pointer.


Intake Manifold wide view:


Closer Intake view. Key is pointing to the EGR port that connects to cylinder head. (I sprayed it with some B12 already, so it looks a little 'clean' compared to how it looked before).

 

Can you see inside that #4 runner in the cylinder head?
Does the EGR port enter into the runner before the valve?
I think it would.

If that is the case, rotate the engine so the intake valves are closed on that runner.
then you can go to town on it with solvents, brushes, drills, jackhammers and whatever else.

Port looks nice on the intake manifold. Cleaned up nicely!

 

Yup I can see in there.. It's pretty dirty. I'm definitely spraying some B12 in there.

Thanks I hope to go through all the ports and clean them out too..

Plan B.
Instead of taking the heads off to clean the exhaust port side of the heads, I'm thinking of taking the exhaust manifold off and spraying B12 through there. I already have the catalytic converter off (soaked it in some soap and water overnight) so the piping should just drop out of the way.

I hope that way I'll be able to clear out those ports of build up. It would have been nice to be able to wipe/clean down the top of the cylinder heads too but....

What do you think of plan B?
I'll be sure to rotate the engine so not too much B12 gets through to the pistons/rings.

Thanks again

 

Oh and you were right 4drEF, the reason there is continuous build up through the EGR is because I have an oil leak through one of the spark plug tube seals. Looks like I'm going to have to replace those damn things........

Thanks man!