I have a 2000 XJ. I was doing some preventative work on it and decided to replace the fan clutch, thermostat, and upper radiator hose this morning.

All went well but when I went to top the radiator off with coolant, I noticed some very fine light grey sediment with very tiny shiny fleks in it, way smaller than glitter pieces, on the little ledge right under the cap.

The sediment are very tiny grains, not an actual 'mud', but similar in consistency. If you stir it with your finger, it disperses and eventually settles again.

It does not look like the sludge you get with a blown head gasket (which I've had before on another car).Could it be some sort of radiator fix stuff that the PO put in?

I paid a shop to flush the system just a month ago, but I believe they only drained and refilled the radiator instead. I've since quit using the shop as they were dishonest on some other work. But the fluid is bright green, not dirty looking at all.

Thoughts?

The engine runs fine, no noise, no smoke, power is ok, mileage is ok.

 

Could be Silver Seal radiator fix or something similar. If the metal particles don't feel like shavings I wouldn't be concerned.

 

If you want to do your own system flush sometime here is a procedure I saved that was posted here. Can't remember who though.


"Remove the top radiator hose and top heater hose from the t-stat cover. Remove the bottom radiator hose from the water pump (very easy if the plastic air filter box is removed 1st). Stick a garden hose in the heater hose and flush. Stick the garden hose on the heater hose nipple on the thermostat cover and flush. Stick garden hose in the top radiator hose and flush. All areas are now flushed without crud moving from one place and lodging in another."

 

They don't look / feel like metal shavings, which is what made me think it was maybe a radiator seal thing. This is a replacement radiator installed right before i bought it though (had been wrecked) so I'm guessing this may be sealant put in before it was replaced, and just never flushed out.

As to the home flush, I'd love to - but in a townhouse community with no water faucet or yard to do it in :-/ I really, really wish I had a yard and a real house.

 

That's what friends are for.

 

Its 2000, are you sure your head isn't cracked?

 

The fresh clean coolant could be picking up stuff and depositing it at the top of the radiator neck. The smallest particles are probably landing in the bottom of your coolant reservoir. I am going through the same thing. When I bought the Jeep the coolant was green, but not translucent. I drained and refilled it, and then again after I did the head. By then it was translucent and that's when I started seeing deposits in the top of the radiator neck. It could be a bunch of stuff, like casting sand, any previous stop leak, rust, etc.

 

might be water pump impeller, they get eaten away sometimes

 

I would do a cleaner/full flush of the system including the heater core. Then a fresh fill of coolant run it for a few hundred miles and see if it shows up again. If so you may need to do some more checking.


I think it is a sealer also but my question is why was it used.

 

I would say it's some sort of stop leak product. I'll concur with Fred. You may need to do several flush and fills to get it all out, but again, as Fred said, WHY was it used? With the year of your Cherokee it makes it highly suspect that it was an attempt at a "cheap fix" for the 0331 issue. How long have you owned this rig? Has the head ever been replaced? If you don't know, have the coolant tested for combustion gases to see...you can get the kit for around $25-50, rent one from your local parts house, or have a mechanic check it.

Also, have you had any coolant loss? Checked the oil cap for the milky bearer of bad news? Have you inspected under the cap for the casting number of your head, or for any cracks?

I would definitely start by doing a complete system flush, including a reverse flush, make sure you get the heater core, stuff likes to hang out there, LOL...let us know how you're progressing...

 

Yeah if it is some kinda stop leak stuff get it out of there fast,That stuff will clog up coolant passages causing more problems then good.

 

I used a bottle of Prestone Radiator cleaner and flush and drove for 1 week and then took it to a shop that did a proper radiator flush on their radiator flush machine with their cleaner and refilled with new coolant and has been good since.

 

Just an FYI but GM added Silver Seal at the Factory to a lot of their engines in years past. A Cousin of mine worked for GM for 30 yrs is how I found out. For the last 15 of those yrs he was President of the Local UWA in the KC area and traveled to a lot of different plants.

 

I don't have any reason to think so yet. My last car (Dodge pickup) had a blown head gasket, so I know the signs to look for.

At this point, no overheating (and I've been driving it daily for 2.5 years), no oil loss, no coolant loss, no milky coolant or oil, no funny smell in the oil.

IF someone used sealer before i got it, my guess would be this. Before i bought it, the right front passenger side had been wrecked. They replaced some of the suspension, the radiator and a few other things before I bought it. It is possible that the radiator damage was minimal and they thought it could be patched up with some sealer, and then after adding it realized it couldn't.

 

My radiator showed signs of old leaking, and the head gasket was weeping out the passenger side. It would not surprise me if my junk is from some old block sealer effort. I plan to let it accumulate a little more before flushing out the radiator (again). I don't think flushing will fix it by itself. My engine seems to release this more on long drives in hot weather than just driving to work.