Soafoam Problem

[Mossyoakglock]

I don't know if this is just something with the 07+ Avalanche or Silverado because my sister's 06 Envoy didn't do this. When I disconnect the brake booster line to run some seafoam through our Avalanche, it barely idles and struggles to run. But, when I start pouring the Seafoam through it, it revs really really high. Sounds like probably about 3,000 rpms or maybe more. I didn't put much through it because it was kinda worrying me since it never did that on my sister's Envoy, my old S-10 or my fiancee's Audi.

 

Is this just something that the Avalanche does or should I not bother with with the Seofoam? I cleaned the throttle body and MAF sensor so I figured I would do that while I was at it today since we actually have some decently warm weather.

 

Any thoughts?

[C. Charles Hahn]

How many miles on your Av? Chances are you don't need it.

 

I also seem to recall hearing that with the GMT900 trucks the brake booster vacuum is from a different source, and shouldn't be used to do a top-end cleanout.... but I could be mistaken.

[Mossyoakglock]

just rolled over 90K. Where else should I use the Seafoam at? I thought about the line coming from the underside of the intake tube that runs to the valve cover. Would that work as well?

[RaddHazzard]

I thought about the line coming from the underside of the intake tube that runs to the valve cover. Would that work as well?

 

Thats probably your crankcase vent.

[hockeypro1411]

My dad's truck did the same thing. The only problem I had was getting the engine to shut off. After the Seafoam was sucked in through the brake booster line, I had the key out of the ignition and the engine continued to run incredibly rough. A quick push of the brake pedal turned it off though. Since my truck doesn't have a brake booster line, I just found a random vac line to use. It sucked in over half of the can of Seafoam in about 2 seconds and didn't even shudder.

[Snow White]

how often do you guys do this because I did it on my s10 and it really only did anything the first time i used it, i mean it was like a smoke machine but i did it again later on at 60,000 (first was 30,000) and it didn't do much.

 

i've also heard that is a quick way to clog your cat converter?

 

on topic, i did read recently here not to use brake booster line and to use some other line coming from intake manifold.

[dwhults]

how often do you guys do this because I did it on my s10 and it really only did anything the first time i used it, i mean it was like a smoke machine but i did it again later on at 60,000 (first was 30,000) and it didn't do much.

 

That's probably because the first time you used Seafoam it cleaned it out (the white smoke). The second time didn't have as much carbon buildup. I believe Seafoam only smokes when the engine has buildup inside.

[hockeypro1411]

how often do you guys do this because I did it on my s10 and it really only did anything the first time i used it, i mean it was like a smoke machine but i did it again later on at 60,000 (first was 30,000) and it didn't do much.

 

That's probably because the first time you used Seafoam it cleaned it out (the white smoke). The second time didn't have as much carbon buildup. I believe Seafoam only smokes when the engine has buildup inside.

 

 

Correct. You won't see any smoke if you do it on a regular basis. That doesn't mean it's not doing anything, just means there isn't enough to make a smoke show.

[Mossyoakglock]

My dad's truck did the same thing. The only problem I had was getting the engine to shut off. After the Seafoam was sucked in through the brake booster line, I had the key out of the ignition and the engine continued to run incredibly rough. A quick push of the brake pedal turned it off though. Since my truck doesn't have a brake booster line, I just found a random vac line to use. It sucked in over half of the can of Seafoam in about 2 seconds and didn't even shudder.

 

What truck does your dad have? Where is the vac line that you used located at?

[ken1mod]

Gentlemen,

 

Best place to put seafoam is the kitchen sink.

 

Ken

[mipsco1]

Gentlemen,

 

Best place to put seafoam is the kitchen sink.

 

Ken

 

 

any reason behind this or.....?

[hockeypro1411]

My dad's truck did the same thing. The only problem I had was getting the engine to shut off. After the Seafoam was sucked in through the brake booster line, I had the key out of the ignition and the engine continued to run incredibly rough. A quick push of the brake pedal turned it off though. Since my truck doesn't have a brake booster line, I just found a random vac line to use. It sucked in over half of the can of Seafoam in about 2 seconds and didn't even shudder.

 

What truck does your dad have? Where is the vac line that you used located at?

 

 

2007 Sierra Classic with the 4.3. His truck we just used the brake booster line. I'll see if i can get a picture of the line I used on my truck when I go out later.

[usmc3529]

yes, seafoam is garbage. If you want to clean the top engine(comb chamber, intake etc) get either 2 cans of the gm top engine cleaner or mopar combustion chamber cleaner.

 

Or take it to a dealer that carries "bg" Products and have them do the 3 part fuel system cleaner. One cleaner goes right through the fuel rail, the 2nd goes into your comb chamber via the t body and the last step is in the tank. The stuff works incredible.

[hockeypro1411]

yes, seafoam is garbage. If you want to clean the top engine(comb chamber, intake etc) get either 2 cans of the gm top engine cleaner or mopar combustion chamber cleaner.

 

Or take it to a dealer that carries "bg" Products and have them do the 3 part fuel system cleaner. One cleaner goes right through the fuel rail, the 2nd goes into your comb chamber via the t body and the last step is in the tank. The stuff works incredible.

 

I've used both the GM Top End stuff and Seafoam. To be honest, they seem to work exactly the same. Unless you're running both of these products in identical 100k miles engines and then taking them apart, I'm not sure how you can say one is better than the other.

[ken1mod]

Gentlemen,

 

I do believe in cleaning the MAF and throttle body (although I have not found it necessary to do either even at 160k) but I have never seen a crapped up combustion chamber since leaded fuels went away.

 

I am nervous about dumping liquids into the intake. How close to destruction did the earlier poster come when his engine "ran away" with the key off? Risky stuff guys. I do occasionally use the Italian tune up procedure of full throttle acceleration.

 

Ken