I recently bought a '98 Blazer. It looks like it's in reasonably good shape, but I don't know who the prior owner was or have any idea of how well it was maintained. Among other things (check/replace usual parts, flush all fluids, etc.), I'm thinking of adding Seafoam to the crankcase and, a little later, through the TB. Afterwards, I plan to change the oil & filter.

The problem is, I have no idea whether this kind of thing has ever been done on my "new" Blazer before. Specifically, I have no idea how much stuff is being held together by gunk. This is my DD, so I wouldn't want to have to spend the next few days fixing unplanned stuff. Among other things, I have a couple gaskets with slow leaks that I plan to replace in the next couple weeks.

Am I better off doing all the usual stuff and replacing the bad gaskets before I do the Seafoam routine and replace the sparkplugs? Are there any parts that are likely to need replacement soon after I do this?

 

Seafoam down through the throttle body (the only way I use it) will not disturb any gaskets. This will clean out the carbon in the intake track. To be able to pour the product down the throttle body, you will need to remove the intake duct, remembering to unplug the MAF sensor (the engine won't run if the MAF is still plugged in). Start the engine and dribble the product down into the throttle body while keeping the engine running with your hand on the throttle linkage, maintaining a high idle. Once you get to the last 1/3 of the bottle, be more generous with the amount you are pouring in. You will want to let the engine die when you pour in the last bit of seafoam. Let it sit for a half hour or so and then drive the crap out of it with some spirited driving until the smoke clears.

Once that is done, it's on to atleast checking the spark plugs and definitely changing the oil.

 

Just go for it. I have run seafoam in every vehicle I have since 01. When I replaced my LS1 intake on the Z after 70k miles, it looked brand spanking new with hardly any residue on the inside.

I have done the TB like Swartlkk mentioned to get the throttle blades clean (especially when I first got the blazer it stuck so bad), but mostly I do the Brake booster line into the intake before every oil change, pour another can straight into the crankcase every other oil change, and a full can in the gas tank every third oil change. And smoke out the neighborhood (although the Z stays clean enough to hardly smoke anymore).

 

Never have used it in the oil and never will. Using a quality oil should render that step not necessary. If buying a used vehicle with unsure maintenance, then you may contemplate doing so. I also do not use seafoam in the tank as there are better products for cleaning the fuel system, IMO.

 

Thanks for the advice, swartlkk. I plan to do as you've suggested. I'll do the oil change and then just replace the plugs afterwards. When I bought it the plugs looked ok, but not great. Tomorrow (hopefully), the MAF sensor gets cleaned.

I wonder about the "drive it like you stole it" part of the process though. The cops around these parts are... not understanding. And DMV hasn't sent me plates, yet. Does the engine need to run with a load after the last shot of Seafoam and stalling, or do you think I'd get the same cleansing if I just run the engine at higher RPM for the duration of the smoke show?

 

Doesn't really need to be loaded up. It just needs to be cleared out.

 

You would be surprised. Seafoam will help the whole system regardless of your oil or changing intrevals (Proven on LS1 motors anyway, so I assume the rest as the same).

I don't really believe in the fuel system cleaners, I just run sea foam as a bit of security and a why not since I keep so much of it around. But in the crank once in a while (even with Amisoil or Royal purple in race engines that are changed often) is a good thing to do once in a while.

 

Well, I removed the air cleaner assembly and pretty much followed the advice here on putting it directly in the TB. It wasn't any extra work since I already had that apart to clean the MAF sensor. There was some really nasty carbon build up there, which I wiped before applying the Seafoam. It looks much, much better now.

Of course, it could have something to do with the fact that the factory distributor cap, rotor, wires, and possibly plugs were all still there. After changing all of that (except the #3 plug which will have to wait a couple days), the engine is noticeably smoother at idle speed.

I noticed that there's no photographic how-to for using the Seafoam, and the topic comes up often enough that I can whip something together with the photos I snapped, if that would be of benefit (at least for the TB method)?