What the heck is this?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.


Aug 9, 2005
Cedar Rapids, IA
I have no idea what this greenish/yellow slime is. I'm assuming it's coolant but can't figure out where it's coming from. It's sitting on the water pump below the temp sender(?). Hoses don't have any signs of leaking.

Background, I had the lower rad hose leak last week. Replaced and flushed and filled. Did I push the "weak point" somewhere else?

ImageUploadedByIH8MUD Forum1425247381.487681.jpg
looks like coolant and stop leak
looks like coolant and stop leak
That's weird. I'm the only owner and have never used stop leak on my 80. Radiator is 5 years old. Along with water pump.
Did you do a block flush? Replace radiator cap? Looks like the greyish sedimant most everyone has in their cooling systems...look in bottom of your overflow tank.
I did replace the radiator cap. And I did flush my system. Maybe I didn't flush it good enough? It was the first time I've ever done a flush myself. It makes sense that it's that sludge from my reservoir. Because after I filled it up I had a leak and it sucked everything out of my reservoir. Damnit. Ok. Shouldn't hurt anything then? It can wait until warmer weather when I pull the motor to replace every seal that is leaking and rebuild it.
Likely you loosened up some sludge in the cooling system. Maybe the sludge was partially sealing the leak you see now.
The stuff in res. is usually hard in the bottom BUT it is usually Grey. Its takes some semi heavy washing to get all out. Did you shine a light in the bottom of your OF bottle and see whats in the bottom?

Wierd thing is your sludge looks milky like milky water in your coolant.

Looks like your leak is at that pipe with a hose clamp on it. Drain some coolant. Pull the hose. Wipe dry. Wipe inside of hose and male end with Naptha. Install with a constant tourque clamp. OR replace the hose with an OEM for best case.
Last edited:
I have a bunch a OEM clamps and hoses that I have been picking up so as not to have to incur the full cost all at once. I had just been waiting to replace all of the hoses when I pull the motor this spring. But, I had one hose start leaking. Replaced it then another start leaking. I feel like I'm just pushing the leak to the weakest point which I don't want to eventually be the head gasket. Need to make it 4 more months...

Honestly, I have no reason to think the head gasket is bad (other than it being 22 years old and 233k miles). My oil is good, no white smoke. Truck runs good. I just don't want to push my luck knowing I am pulling the motor in a few months...

Thanks for your help. I'll check the reservoir in the morning. I'm sure it's nasty as hell. I've looked in there and never really noticed anything before but I'm sure it's filled with lime or something.
If you do not use distilled water with your coolant It may look like that from tap water. Especially If your on a well with hard water and minerals. Good Luck . !
I used a garden hose to flush it. Then 8 gallons of distilled water to flush it. The 50/50 premix to fill it. After rebuild I will only use Toyota red and distilled water.

Thanks for your help.

Users who are viewing this thread

Top Bottom