Thick snot like black substance in radiator.

[Rangerdan2.3]

I just bought another Ranger, 99 x-cab 3.0L 110K miles. There is a thick snot like black substance in the overflow jug and the rest of the coolant is dark brown. There are no signs of a blown head gasket, and the guy I bought it off of said the dealership put that stuff in to prevent leaks. I don't buy it, has anyone heard of something like this?
Thanks
Dan

 

[Earl43P]

Sounds exactly like the old Barrs Stop Leak (black beads in a molasses-like syrup).

I'd use a heavy duty Prestone flush and remove and clean that reservoir.

You may have to repeat in a year or so. I flushed the Explorer last Dec. and put in coolant. It is already turning that brownish color again. I think that Stop-Leak settles in crannies and is hard to flush out completely.

 

[Rifleman]

Don't know of anyone that uses stopleak for anything but stopping leaks. Never ever seen anyone use it as preventative maintenance. I don't know that in such a case you want to flush it all unless you are looking to find the hole (hope you're not out along the road somewhere when it happens).

I'd dump it all, rinse the system really well with water, then fill it with clean coolant/antifreeze. Check it in 20k miles and if it needs it again, do so again. I don't know that I'd run any of the chemical flushes through it, it may be bad. If the truck isn't overheating and isn't leaking, I'd do as little as possible on anything that could cause either. Getting the stuff out should prevent clogs, and not using a chemical flush should prevent any leaks that are there but plugged with stopleak from beginning to leak again.

 

[SixFoFalcon]

The previous owner is full of it, IMO. I'll bet you a peso that there was a leak in the radiator or heater core, or if you are lucky, something really simple like a cracked expansion tank.

Having said that, the ugly stop-leak stuff does work for small leaks in metal (the plastic expansion tanks and the plastic sides of some radiators are notoriously impossible to seal up once they crack so it doesn't help there). Stop-leak can be problematic when it clogs up the radiator cap or expansion line, preventing the coolant from flowing back and forth as needed during heat-up/cool-down cycles. But if you keep an eye on things, I wouldn't be too worried about it for the short-term. It's not going to lock up your water pump or completely clog your radiator or anything catastrophic like that. It's just going to be ugly and reduce cooling performance a bit.

When/if you are ready to deal with a leaky radiator or heater core, flush it out as recommended above. In the mean time you just have an ugly mess to look at and something to think about putting on your to-do list some day.

 

[Rangerdan2.3]

I already cleaned the overflow jug (whole can of carb clean, that stuff is nasty) and I will probably flush the system this weekend. I have no problem doing a heater core or radiator. I just hate doing head gaskets. Thanks for the imput, haha I'll let you guys know what starts leaking.
Dan