I have a 2004 Toyota 4Runner SR5 V6. And I’m pretty sure I have a head gasket leak or a blown head gasket and I’m trying to figure out some cheap solutions to this fix.
make sure it's actually the head gasket first
https://carkiller.com/scottykilmer/qa/93-toyota-lexus-es300-automatic-234564-miles/#post-106617
if it is, you can try one of those additives, but don't expect miracles. Either rescue your 4Runner with a proper head job, or start looking at replacement vehicles.
Unfortunately the "cheap fixes" for headgaskets don't last. If you want to keep it you will probably end up having to replace the headgasket.
If it really is the head gasket the only cheap fix is to repair it yourself. (Or maybe a friend or relative who will help do the job for a six-pack.) The gaskets themselves are not expensive. Most of the cost is labor.
Sealers are temporary band-aids at best and can also "seal" your heater core and radiator.
Be sure to verify that it's actually the head gasket at fault.
https://www.youtube.com/watch?v=v0U8Iyf0kk4
if you ask me to fix your head gasket, you better show up with more than a 6-pack. If you're a good friend, I would consider it for a nice 12yo scotch.
Point well taken! I do that kind of work myself but never actually had a bad gasket. I have had to pull cylinder heads for other reasons like engine rebuild, cracked valve, and in one case stupidly dropping something into the open spark plug hole that wouldn't come out any other way.