Okay, I'll tell you what happened to my 89 Supra Turbo AT when I sea foamed it like over a month ago. I know its long, so Cliff's at the end.
I was reading about how it is a top cleaner, ie it cleans the valves, the cylinder heads, and when used through the gas tank it also cleans the injectors and the fuel lines and what not.
Well any way I decided to give it a go. Went to Autozone and bought myself a can of Sea Foam and waited till twilight (this is because I didn't want people to see the smoke in broad daylight and thought my house/car was on fire when the stuff began to work its mojo and have the fire department come out to my house). Anyways twilight comes and I'm getting ready to Sea Foam the engine. Most people recommend the brake vacuum line because it is the largest of the vacuum lines and most easily accessible.
So I pull the brake vacuum line, open up the can of Sea Foam stick the hose into it, and have my brother start the car. I hear it sucking in the Sea Foam and after about 10 seconds of it sucking, I tell my brother to shut it down. Now people and the can tell you to give it 10-15 minutes so the stuff can work its mojo, so I did went inside to watch some TV for 15 minutes. I came back out and started the car, and it was starting to smoke, but ever so little.
I thought to myself that maybe I didn't put enough Sea Foam into it. On the can, it also states that about a third of a cup will suffice in cleaning out the carbon deposits and what not. So I tried it again and got a tad hog wild, and let the car suck in about 75% of the stuff before I shut it off. Went back inside for another 15 minutes.
When I came out and started the car, the mofo was smoking big time. Thankfully the car was parked in a car port and the windows were all rolled up. I grab my wallet and take the car for a drive and it is now misfiring on at least 1 cylinder. I'm going WTF.
As I'm driving along through my neighborhood, smoke is trailing behind me. I can't tell if its white or blue smoke, because its now getting darker by the minute and I have tinted windows. I probably drove around for a mile hoping it will clear it up, but alas to no avail. I pull back into the car port and pop the hood and smoke is coming from the turbo.
I'm nearly shit myself thinking I ruined the turbo. I grab a flash light and look under the car and I can see what looked like oil dripping from the passenger side of the engine bay and I'm thinking to myself, Fuck, I just ruined the Supra. Well, it was dark so there was no use in fretting over it now since I can't fix it. I cleaned up and took my brothers out to meet some friends and watch Superman Returns.
During the whole movie, I was thinking to myself: No way Sea Foam could've ruined the engine. I poured it into the brake vacuum line like it said on the bottle, the only thing I didn't do right was use a third of a cup--I used almost 75% of the can.
Well, the next day, I get out and hope to have a better assessment of the situation. I turn her on and its missing badly now on 2 or more cylinders. I'm like WTF, did I really screw up the engine and turbo? I take it out for a drive and she's struggling to stay alive all the while blue smoke is coming out the back.
I think to myself, wait maybe the spark plugs got fubared by the seafoam. But how could that be? The plugs were practically brand new. I put those mofos in myself and the car passed smog inspection in California with flying colors. I made less smog than most of the younger cars on the road! But the car was misfiring so bad, it had to be the spark plugs.
I was arguing with myself what could be the cause of the misfires for a couple of days since I didn't have time to work on it during my work week. So the weekend rolls around, and I decide to change the spark plugs. Went and bought Bosch Double Platinums, dielectric grease and anti-seize. and proceed to replace the spark plugs.
When I owned my first Supra, I looked at the mess that was the engine and thought to myself this is gonna be impossible. The first time I changed my spark plugs, it took me nearly 2 hours to do the job cause I was freaking scared of breaking something. This time around it only took me 1 hour to do it.
Pulling the spark plugs, the plugs nearest the brake vacuum line were the most fouled. While the plugs furthest from the plugs were the least. But I proceeded to replace them all.
When all was said and done, the Supra was running like a champ again. There was no longer any smoke of any kind coming out the exhaust. There was no longer a leak from the passenger side of the engine bay. There was no smoke coming from the turbo. And most important of all, there was no more misfiring. Holy shit I think the stuff worked.
If you use it, these are my tips and observations:
1. If you want to use it, do so at your own expense. If it does somehow ruin your engine, you have only yourself to blame.
2. The brake vacuum line is the best line to use, but it will feed the cylinders unevenly. If I were to run Sea Foam again, I'd wait until I have to change the spark plugs again. This way, as I'm replacing the plugs, I can pour just the right amount into the cylinders and get an even cleaning. Too much and you may foul the plugs and have to change them again right after.
3. Do it outside and with the windows rolled up. The smell of excess carbon deposit burning is not pleasant.
4. Advisable to get someone to start and stop the engine so that you can monitor how much Sea Foam goes into the engine.
5. After waiting 10-15 minutes, go for a short drive as this will help in burning off the carbon.
Cliff's notes:
-- Decided to Sea Foam the Supra.
-- Used too much Sea Foam and thought the Supra was fucked up.
-- Went to see Superman Returns and thought to myself that there was no way for Sea Foam to fuck my engine and turbo since it couldn't have gotten the chance to attack seals.
-- Car was fubared, misfired on multiple cylinders.
-- Changed plugs and now the car runs like a champ. No longer any signs that the Supra was ever fubared.