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Another new issue. I've got black sludge in my coolant. It does not appear to be oil. It was thick on the cap, almost like a paste, and dipping a rag into the radiator, it came out blackened. Any ideas what this could be? I'm concerned for my engine. I flushed it out not that long ago, it was a bit rusty then but this black stuff is within the last 200 miles or so.
are you losing radiator fluid ? I am starting to wonder if you don't just have a blown head gasket or other serious issue with all the symptoms the car is having
run the car with the radiator cap off and see if you are getting bubbles coming up through the coolant/radiator. if you see bubbles, that is a pretty good indication
Another new issue. I've got black sludge in my coolant. It does not appear to be oil. It was thick on the cap, almost like a paste, and dipping a rag into the radiator, it came out blackened. Any ideas what this could be? I'm concerned for my engine. I flushed it out not that long ago, it was a bit rusty then but this black stuff is within the last 200 miles or so.
I scraped this off the radiator cap
this was from dipping into the radiator
It could be a world of things First Thing that comes to Mind BARS-LEAK
Thanks for the replies here-I'm starting to wonder if I should just do the head gaskets to know that they are done, rather than guessing. I've checked compression on all cylinders and it showed good all around-granted that's been about 2 months ago, but not much has changed on the car since then.
An update-after I initially started to panic, I pulled the lower radiator hose and drained the coolant that way-not really a FLUSH, but wanted to see what it looked like. It was very clear-the black tar substance wasn't in evidence anywhere. There must have been a little bit in the radiator, but it certainly wasn't everywhere. I don't see any evidence of oil in the coolant-good sign for no blown head gasket, right?
That said, I ran the car for about a minute from cold, not enough to even get the engine hot, and I then popped the radiator cap off. There was a slight hiss of air, like it was under pressure. This points to exhaust gasses getting into the cooling system-that would be a sign of a head gasket issue.
Car runs very cool-with AC on full blast on a 90 degree day, I don't break 200 degrees even at stop lights. I've got a 160 degree stat and a manual fan switch which i tend to flip on when I'm sitting at a light just to keep from getting too hot, both of which helps, but even so that's pretty cool I think.
I'm not losing radiator fluid, or burning oil. Both are holding quite nicely. My exhaust is clear after it warms up (first minute or so of idling on cold start it's slightly white, but nothing that would normally cause me concern). On top of that, other than the knock I've mentioned under another thread, the car actually runs REALLY well.
I don't know that much about engines, other than what I've learned so far working on this car, so I tend to panic a bit when something seems off. I don't want to overreact, but I also don't want to ignore bad signs and blow up my car. I tend to post everything on this forum that I find that looks out of the ordinary, in the hopes that those far wiser than I can guide me. Some of it is probably just 30-year-old-car stuff, and nothing to worry about, but I don't really know how to tell the difference yet. Thank you for all your help
I honestly may need to take a break for a little while from this car. I love it, but I've got a baby on the way in a few weeks and I need to focus on that. I'm not sure that I CAN leave the car alone though(I'm a bit OCD).
Well I just wrote a book and got pretty far off topic. Back on track: the black stuff looks like it's probably not a huge issue, but would love feedback on this. I may just break down and do the head gaskets to know they are done, anyone have thoughts on this? Thank you.
Any kind of oily residue (Maybe from your flush?) will float on top.. Possibly making a nothingburger look like a serious problem?
After my initial concern, I actually don't think this was really even worth a post. Like I said, after draining the lower radiator hose, the water was coming out clean. I'd expect that if it were serious, it would be throughout the cooling system.
After my initial concern, I actually don't think this was really even worth a post. Like I said, after draining the lower radiator hose, the water was coming out clean. I'd expect that if it were serious, it would be throughout the cooling system.
My gut tells me you're okay.
You spill a little oil in a bucket of coolant? It looks like it's ALL oil.. But it's a film that rides on the surface..
I'd wash it out real good and refill. If you see more of this, don't freak. Take a big syringe or a turkey baster and pull the top off and I bet you're into good coolant underneath
I agree with BillS when you flush you will awaken things deep in the engine and they will slowly come up and wont pass through the cap. Tend to surface there. I seem to be wiping out some rust occasionally. A good hiding place is the heater core. Clean on.
That said, I ran the car for about a minute from cold, not enough to even get the engine hot, and I then popped the radiator cap off. There was a slight hiss of air, like it was under pressure. This points to exhaust gasses getting into the cooling system-that would be a sign of a head gasket issue.
Water expands a LOT when it gets warm. I think you're OK and what you saw is normal.
When looking for bubbles in the coolant, you start it with the cap off. You don't want it to build any pressure. Pressure is normal, bubbles would not be.
Everyone (including myself) is taking their best guess based on their own experiences and what they have seen in their lifetimes. Myself, on my computer that looks a little like soot/carbon deposits. I have seen rust, even globs of rust and jelled up coolant come out of a radiator, but nothing black like that.
When looking for bubbles in the coolant, you start it with the cap off. You don't want it to build any pressure. Pressure is normal, bubbles would not be.
Everyone (including myself) is taking their best guess based on their own experiences and what they have seen in their lifetimes. Myself, on my computer that looks a little like soot/carbon deposits. I have seen rust, even globs of rust and jelled up coolant come out of a radiator, but nothing black like that.
Ok I'll run with the cap off for a bit, thanks for clarifying.
I definitely understand the best guess. I've never seen black crap like that, either. I'm a little less worried because there was so little of it-but you can bet I'm going to be keeping my eye on this.
The problem with diagnosing with a car like this is there's probably more than one issue going on at all times which can make it confusing.
anyone ever add that sealant in a can (like bars leak)that stuff makes a mess out of the cooling system
I make mostly short (15 minutes?) trips in the car-it's for date nights and weekend errands, mostly. I've been driving it to work (~1 hour) once per week the last few weeks.
No idea if the bars leak was put in. I do know that before I bought it, it had sat in a barn for at least 5 years. I assume from your reaction, you do not recommend it in cases of a small head gasket leak (jury is still out on whether or not I have one).
Hey BF, That black stuff looks like what came out when I ran my finger around the inside of an old heater hose. I think it deteriorates with age. Just a thought.
If you think you have a head gasket leak between the water jacket and cylinder bore just get the coolant system pressurized and see if it slowly bleeds down.
If you think you have a head gasket leak between the water jacket and cylinder bore just get the coolant system pressurized and see if it slowly bleeds down.
That sounds like good advice, but having never torn an engine down to that point, I don't have a good visual of the water jacket/cylinder bore. To pressurize the coolant system, is there someplace you know of to rent the tool I'd need? Also, you need to remove the spark plugs to test for a head gasket leak, right?
Problem is, sealants cannot discriminate between GOOD small passages and BAD ones. Tho I've no hands-on with it, I hear GM sells a good sealant, IF one opts so.
Drive and enjoy it and the new baby, as your instincts indicate. Longer trips are always better than short, as you know.
If your OCD pops up, remove the spark plugs and research how to read the colors and deposits on them; every cylinder. I drilled and numbered 8 holes in a piece of wood, for insertion of each spark plug terminal end. It's a simple aid for inspection/comparison, while retaining which plug came from which hole. Old Motor manuals have photos of various plug issues, but few know even think look at them! If coolant is entering any hole, whether from head gasket or worse, there's probably some rust on the plug's electrode.
The aforementioned bubbles visible when the radiator cap is pulled can indicate higher pressure (cylinder) air, escaping into the lower pressure water jacket.; not good.
Last edited by whalepirot; Aug 7, 2017 at 11:57 AM.
I like your idea for the 8 holes in a piece of wood. I used painter's tape to mark them when I've taken them out before.
They've got a white-brown deposit on them that my research says is probably related to running some crappy gas (I'm no longer doing that) but nothing major.
My next job is probably the balancer, which has the rubber insert coming out. While I started out a novice, I think I will end up being an expert mechanic by the time I'm done with this car...
Black Sludge in Coolant
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- tis a bandage; maybe worse.
