Some say that seafoam does not work.
MVS forum member vlv850 shares his seafoam horror story with the hopes of helping other members see the potential risk. vlv850 says – Just did a Seafoam treatment on my 94 850 NA. Sucked it through the intake tree into manifold, let sit 15 min., started it back up. Tons of smoke, and a horrible clicking/knock from the engine. Drove it a few miles, until smoke subsided, but knocking continued.
MVS Forum Member Maxbaby replied:
Can’t say I’ve experienced it, but it’s certainly something I’ve heard of a number of times, and it’s been talked about here and some of the other non-volvo forums that I’ve been on. It’s just one of those things that could happen when you do such a treatment, and usually will correct itself by, as you’ve already learned, burning off.
MVS Forum Member MadeInJapan says:
Keep driving it and see what happens. I doubt you’ve bent a rod from just using seafoam.
MVS Forum Member vlv850 replied:
The Seafoam Saga Continues…
Drove it to my Volvo mechanic this morning, with people looking at my broke a$$ car, so he could here the noise in person…NOT GOOD. He didn’t think was a bent rod, to high pitched of a knock he said. Didn’t think was a piece of carbon either, but something was stuck in the cylinder or broke in there. Checked all the plugs, oil pressure, compression, all good to go. Next step…remove the head. I ended up leaving the car there, and taking a cab home.
I’ll keep you posted as to how it turns out, Seafoam beware.
MVS Forum Member vlv850 added:
Okay, so the head came off, #1 cylinder was shot, and wet per my mechanic. no use really fixing (so he says) and it’s new engine time. Engine wasn’t hydrolocked nor a bent rod, i don’t know what happened….
Maybe the vacuum line I used only fed into the #1 cyl. not all of them…used one of the throttle body tree.
Called Seafoam, they basically said tough shit, you applied it incorrectly. Sue us if you want us to fix it.