Coolant leak

'79 GMC w/ab.170,ooo mi.,temp gauge moves to ab the 1/4 line but never gets up to the middle.does this mean the thermostat is bad?.my local oil change franchise uses “pellets” for their stop-leak–any thoughts on this?vs. stop leak–the liquid? would a one-time use damage the engine? the mechanic pressure tested the system & said i had a rad.leak on one side…i’m not going to replace the rad. so he said to just keep the coolant level up…appreciate any advice thnx alot

Since you are convinced you are not going to replace or repair the radiator, you are left with band aid solutions that may or may not work. Sure keep adding coolant and otc remedies to forget about fixing the problem might work, maybe you can even get more miles by other means, but chances are you would save money time and hassle fixing the problem right ie replacing or repairing the radiator in the first place vs temporary fixes that could leave you stranded anywhere, anytime. I saw somewhere black pepper works too! You are probably low on coolant now re temp problem. We like to fix problems not see how long we can go ignoring them, and yes the thermostat needs to be checked.

hi thanks–didnt think about"repairing" vs. replaceing it…i’ll ck into it-i just replaced the rad in my corolla &my mechanic said they dont do fixes anymore–tht’s where the $$ 4 the truck rad went!!

A few places left will recore a radiator. or even just solder off the leaks, just to let you know I empathize with your situation and had even loosened the radiator cap to get by with a leak for a bit, but a good repair is better in the long run.

hi–thanks again–it must be a pretty slow leak because it only drops maybe and inch or 2 from the full position every 40 miles or so. i’ll try to get to the rad shop to get it patched for now.

Replace the radiator and move on.