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So this stuff gets a lot of hype around here, so i figured id get some good numbers on it. Our test subject will be one 1990 ej22 with 98k miles. Runs like a 100k mile engine would be expected to- idle hunts between 50 rpms occasionally, and can hesitate when the engine is cold, otherwise, no problems.

initial compression test- 172 175 173 177

I'm pretty happy with these numbers, but hey, if it ain't broke, fix it until it is...

I used a throttle body vacuum hose (with a longer vacuum hose as an extension) and held the engine at high idle. with the hose dipped in the can. Engine swallowed the stuff in ~1.5 minutes. Big loads of ass-smelling smoke billowed out of the exhaust during the process and for the few seconds it took me to run out to the ignition. Waited 15 minutes, as per instruction. Puffed a moment on startup, and cleared up.

Went for a drive. I really wanted to, but i didn't notice anything different. Nothing. Idle is the same, no perceptible gain in power, nothing.

Took it back for a final compression test- 174 172 170 173

Generally a slight loss in compression- i'll attribute it to loss of carbon buildup. I must have had a bad reading on #1 at some point, but its all still close enough to keep me satisfied.

Conclusion- The stuff does break down a little carbon, but it's not earth shattering. I can't tell a difference driving the car. Will i do it again? Sure, when i hit 200k miles. I wouldnt expect it to solve all your troubles though.

I think how much seafoam helps the engine depends on the current condition. More then likely the engine was fine.

I've been told that carbon builds up on these motors, however when I had my intake manifold off, I looked down at the intake valves, and everything was really quite clean for the kind of mileage I have. Is that contributed to my driving style, and/or seafoam or other cleaners....I couldn't say.

I think the carbon builds up inside the combustion chamber since the back of my valves looked clean, but when I took the heads off, I could see all the carbon. Below are some pics of my head and block.

http://www.thawa.net/petridish/legacy/head.jpg
http://www.thawa.net/petridish/legacy/cleanblock.jpg

Andrew

Yeah, the bulid up's more n the inside, where it's more dangerous. I blame it for my engine's melted valve. That was a few months after using Sea Foam.

Steve

so how do you clean all that crap??

Beats me. Sea Foam's supposed to do it. Maybe keeping a regular schedule of it?

Steve

Take off the heads, hit with steel wool, replace. Or, dont drive like a grandmother.

Take a look at my compression #'s. Avg 1-2% change in compression. That could just be scott not reading very well. I am of the opinion seafoam is so much snake oil. If you melt a valve at 250k miles, the engine served you well.

The car was far from grandmother-driven. Not a drive goes by without redline hit multiple times and frequently held on it around long on ramps or waiting to pass slow massholes. Mileage builds up carbon no matter what.

Steve

I wouldn't conclude anything from those compression numbers, aside from the fact that the engine has good, even compression.

Comparing compression numbers from one gage to the other, and one car to the other, even one set of results to the other is not very useful, even atmospheric differences will change the numbers up to 20%

it is the eveness across the cylinders you want, and your readings are as perfect as a new engine would be

I know that when I ran seafoam through my engine (it was probably around 195k at the time I guess) I noticed a diffence. My acceleration was a little smoother and I got a couple mpg's . My brother's car (95 Aspire, with a lot of miles) was having troubles when it was wet outside. Engine misfiring, rough idle, just having a hard time. I got him to run some seafoam through it and it cleared up the rough idle and all the misfirings and stalling. My dad's Altima (95' 140k) showed a difference in smoothness when I ran some through it. I'd say it definately depends on the engine condition to start with, all of my experiences were with high mileage and at minimum slightly problematic.
As far as cleaning the inside, I thought seafoam was supposed to take care of that too.

My car has 230,000 miles....no problems whatsoever with the engine(ej22 NA ). Smooth as can be...idle-redline without a hessitation no matter what.

Would seafoam help it at all? I'm thinking since it has so many miles it would help clean it up a bit. whata u think?

if it aint broke, dont fix it