CranMaro99

iTrader: (10)

Just wondering what this could possibly mean, if anything.

My friend and I (he is a member here) seafoamed his car. Crankcase, fuel tank, and induction.

We put the seafoam in the brake booster just like the write up told us to do. Waiting 20 minutes and started her up and the seafoam did the job. However, right after start up after seafoaming he had a huge knock going on and it gave us a bad feeling. After revving it a little bit and having all the seafoam carbon build up clear up, it stopped knocking.

So before the seafoam, no knock. During there was a lot. After, none again.

What could this mean?

I have video of a portion of the seafoam we did. You can hear the knocking in the beginning when the engine idles a few times.

It is uploading now and will post when it is done.

FMX05

iTrader: (3)

My blazer knocked while I was adding the seafoam and then directly after. It cleared up and I chalked it up to the seafoam combusting after the fuel did. Like the seafoam in the cylinder fired when the valves were open. If it isn't knocking now I wouldn't worry about it.

CranMaro99

iTrader: (10)

Yeah it seems to be ok now. Just didn't know if we temporarily messed something up.

Video for those that want to hear/listen to us be nubs.

DWZ28

My car did the same thing
but i figured it was just the seafoam mabe causing a slight misfire
after i reved it up and the smoke stoped the knock was gone

CranMaro99

iTrader: (10)

Yeah same thing happened here. Just making sure it is fine for when I do it to mine I know it won't catch me off guard.

FMX05

iTrader: (3)

Yeah man my blazer continued to run on like 3 cylinders for about 10 seconds after I turned the ignition off. Talk about getting caught off gaurd...

98trans-am

iTrader: (4)

yeah seafoam wil cause youre car to misfire depending at the rate it is put in. the knocking is most likely misfiring from the engine being overly rich. what i do is hold the rpms up and let it all just brn off and its back to normal. i would also recommend checking youre spark plugs for fouling. it will happen everyonce in a while when you use seafoam.

CranMaro99

iTrader: (10)

Glad to hear.

tici

iTrader: (1)

Mine knocked too and when I turned the ignition off it didin't stop! It ran like a diesel for 10 sec...

zman1969

iTrader: (91)

this is something "normal" after doing a combustion chamber cleaning like this - could be carbon breaking loose and knocking around - back in the day you used to do this with a large glass of water- just pour it slowly down the carb,you dont want to hydrolock a cylinder- liquid dosent compress! can do bad things to connecting rods, bearings and generally ruin your week ive seen techs do this before

2000KnightRider

iTrader: (21)

Pardon my ignorance but, what is Seafoam and how do you use it?

jmm98LS1

iTrader: (28)

https://ls1tech.com/forums/general-maintenance-repairs/534376-how-seafoam-your-car.html

Z Fury

iTrader: (1)

Gah, beat me to it...

Anyway, read through that sticky in the General Maintenance section. Choco does an excellent job of explaining what SeaFoam is, an how to properly SeaFoam your car.

CranMaro99

iTrader: (10)

Yeah he does. We did everything by the book on how he said to do it, and so far so good.

tici

iTrader: (1)

On another forum they suggested to do first a chemical treatement (Seafoam, GM top engine cleaner or other) and then a water treatement.

I can imagine that the solvents first remove the oily dirt, then the water will remove the hard stuff...

What do you think about this combined treatement?

Shawn MacAnanny

iTrader: (12)

I've seafoamed 20 or so of the cars ive had and everyone of them knocked. I let the cars sit for 30-minutes to an hour and always do it when the car is warmed up.

CranMaro99

iTrader: (10)

Yeah sounds like it is common. It's just funny that this is never mentioned in any write ups and can give a newbie a heart attack lol.

Shawn MacAnanny

iTrader: (12)

Yeah or when it backfires through the brake booster line, or you're leaning over the carb looking down it while pouring it in and it backfires all the smoke and seafoam in the intake into your eyes or when your car will not shut off. It's always fun to use.

tici

iTrader: (1)

While decarbonizing I noticed the fuel trims going -15%, this is the max those cars are able to do.
I can imagine that when restarting the PCM is still reducing fuel like hell and it takes a moment to get back to a normal situation. During this adaptation time the engine is probably running lean causing some knock.
After the cleaning I drove 20 miles on the highway at 60 mph in 4th (3000 rpm). at the beginning it knocked everytime I tried to accelerate.
A couple of days later I took a scan and was amazed to see that there is much less KR than before. Really much less At WOT I used to have a couple of degrees, now it's 0 (zero)