Cleaning intake valves on the engine

[djwarner]

While replacing the head gasket and de-carbing the combustion chambers, I also cleaned the back side of the #3 intake valve because it was open. It had some .030-.045" layer of hard coke on it. Only later did I realize that there was no easy way to get to the closed intake valve without disassembling. Since this was beyond the scope of repairs as planned, I put the engine back together with only the #3 intake valve clean.

 

I didn't think the extra clearance would make a significant difference, but the engine has a distinct lumpiness now. So I'm wondering about how to remove the coke from the other valves while installed on the engine.

 

I've been using TECHRON but I'm still seeking other methods since the hard coke is not going to allow speedy results.

 

I've heard of people using crushed walnuts with a sand blaster nozzle and seen some photos showing promising results.

 

Has anyone tried removing the intake manifolds and blasting crushed walnuts with the engine in the car?

 

Open to other suggestions.

[dexter72]

Look up Seafoam or any good Intake deposit cleaner, that can be sucked into the intake manifold, through an engine vacuum hose.

 

I used to work with some old school mechanics and they would pour water, in small amounts into the carburetor while revving up the engine, to boil out any intake deposits.

 

I would never suggest walnut blasting, glass, sand or anything close to that, on an assembled engine. You will ruin it..

Edited November 24, 2013 by dexter72

[djwarner]

I had already used Seafoam three times shortly before pulling the head. The build up on the valves are not spongy or porous, but rather a hard coke. On the #3 valve that I could get to, the coke just laughed a hard wooden probe.  

 

Coke is actually like an amorphous glass, breaking through the outer layer to gain access to the coke/metal junction is almost impossible.

[Josh280z]

Removal and a wire wheel work wonders.

[Xnke]

Run Shell gasolines. It works, I don't know the hows or whys, but it DOES work. I've found both soft and hard deposits removed just by three to five tanks of Shell fuels, both on my Z and on the fleet trucks at work.

[steve260z]

Look up Seafoam or any good Intake deposit cleaner, that can be sucked into the intake manifold, through an engine vacuum hose.

 

I used to work with some old school mechanics and they would pour water, in small amounts into the carburetor while revving up the engine, to boil out any intake deposits.

 

I would never suggest walnut blasting, glass, sand or anything close to that, on an assembled engine. You will ruin it..

 

This method is actually used successfully on assembled direct injection motors, BMWs for example.

With regard to L series motors, I think taking off the head would be the easier route.

[NewZed]

This method is actually used successfully on assembled direct injection motors, BMWs for example.

With regard to L series motors, I think taking off the head would be the easier route.

Which method, three were mentioned?  Seafoam, water or walnut shells.

[steve260z]

Walnut shell blasting.

[djwarner]

Removing the head has as a prerequisite the removal of the intake manifold. It also requires removing the exhaust manifold, draining the cooling system, replacing the head gasket and affecting the timing when you remove the valves for cleaning. Can't help but think the opportunity for something unfortunate happening would be much greater, especially since I've already de-carbed the combustion chambers.

[Josh280z]

You don't have to remove the intake manifold and exhaust manifold to pull the head. However, it does make it easier. Yeah it is a pain in the butt. Although do you really want to run the engine like that? They do have a tool available to hold the timing chain in place.

 

Also when removing the valves you should probably replace the valve seals, because they are probably 30+ years old anyways. You can use the Ford seals which have been documented on here that are made of better material and last a long time.

 

It is up to you though, your engine and peace of mind not mine.

[djwarner]

I have already replaced the valve guide seals with the head on the engine. The head was rebuilt in 2002 and is pulling 19.5" of vacuum and I pulled the head for de-carbing because I was seeing 210-215 psi on the compression check. Sorta hate to mess with a head that's performing that well.

[NewZed]

What's cylinder pressure now?  Did you clean a lot of carbon from the piston and combustion chamber?  Curious.

 

I've seen signs that the intake valves were getting cleaner on my old engine, that had obviously sat for many years before I got it.  They were cleaner when I finally took it out than when I changed the manifold gasket, after about 20,000 more miles.  I had seen the same as you and wondered about cleaning up the backs of the valves.  They were nasty looking.  To Xnke's suggestion, modern gas and hard driving to get lots of flushing on the back of the valve might be the way to go.  A good reason to go have some fun.  You're cleaning your valves.

[djwarner]

I'll have to try Shell. There's no station nearby, but worth going out the way if it works.

[steve260z]

I'll have to try Shell. There's no station nearby, but worth going out the way if it works.

 

Don't hold your breath on that solution.

[Savage42]

Our local Costco here in Sarasota, Florida adds a very high level of cleaner to their gas and it's the lowest price in town.  There is definitely something to running good gas and some additives really do work. 

 

I have run XLP fuel additive (about $13 a bottle where you run a high dose the first tank and then just 1 oz per 7 gallons thereafter) in my 2000 BMW 540i 6-speed for several years.  I recall getting down to about 3/4 tank on the first time I used it and could tell an improvement in power & acceleration.  I have continued to use it for years and when I had pull the intake off to replace the valley pan gasket, I was amazed at how clean the valves were with 209k miles on the motor.  Unfortunately, I recently ordered a few more bottles (online only) since it was being discontinued.  Not sure if you can get it now. 

 

Anyway, I am a firm believer in Chevron and Techron, as we had to run a bottle of Techron in our older BMW every 6 months or so when it started to miss a little and would clear it right up.  Have any of you guys seen valves with clean in a motor that has never been opened up with over 200k miles on it?  The little bit of dust/dirt that fell in was vacuumed out before I put it back together. 

[steve260z]

That looks great. Yes, I've always used quality gas but never been convinced the good gas will clean up old deposits. 

Maybe it does.... I just use Shell or Chevron to hopefully prevent the deposits to begin with. 

[djwarner]

I can understand heavy detergent use can prevent carbon/coke build up, but have my doubts about washing away glass like hard deposits like those I found while de-carbing my cylinders. Before attacking with a wire brush, I tried soaking in Seafoam, strong detergents, penetrating oil, and anything else I could find in the shop.

 

For those of you who haven't heard about walnut blasting

 

http://www.youtube.com/watch?v=TMQDdb4szUY

[Sam280Z]

I think you are putting the solution before the problem. If I understand your first post correctly, you replaced the headgasket and while the head was off, you cleaned the combustion chambers. Since the #3 intake valve was open, you cleaned it, but did not turn the camshaft to clean the others. Now you have a lumpy idle which you are attributing to the differences in the deposits on the valves.

 

Deposits will normally affect running by absorbing gasoline and affecting the ECU's ability to control the mixture. It doesn't sound like the types of deposits you have are the normal fluffy type that affect engine running in this manner. I don't think that hard, glassy deposits can affect fuel flow or air flow (especiall at idle) enough to cause your problems.

 

I think it is more likely that you have another problem. I'd start with a leakdown test and checking for intake leaks. I think it is more likely that you inadvertently scratched the valve or seat on #3 or have an intake gasket leak.

 

Sam

[djwarner]

Interesting thought Sam. When I finished cleaning #3, I noticed just how much the passageway had opened from when I first removed the head. If the stock cam has something like .440" lift, .030-.040" reduction in the passage way would significantly reduce airflow in my opinion. 

 

My impression of the lumpy idle was that the odd pulse seemed to have more power rather than less as a miss would have. A leak down test would be in order though. Thanks for the suggestion.

 

Of course, my Series I 240z was an old car when the first ECU was put in a car.

 

 

[Sam280Z]

I couldn't tell from your first post what car or engine this was on. I assume you are running 3 or 4 screw SU's? What have you done to verify the tune and balance of the carbs?

 

"If the stock cam has something like .440" lift, .030-.040" reduction in the passage way would significantly reduce airflow in my opinion."

While that is true, it will not have a large effect at idle. I doubt the effect is even measurable at idle. Think about it... The only thing that is affecting airflow is the throttle. The engine is turning over slowly, giving the maximum amount of time for the valve to be open. I'm pretty sure your problem lies elsewhere.

 

Sam