1999 Mercury Marquis mud?

MMI

MEMBER
1999 MERCURY MARQUIS
V8
2WD
AUTOMATIC
97,000 MILES

I flushed the cooling system about 10,000 ago it looked like it had mud in the overflow. It took 4 time to get it all out. Now its over heating again and l took it to a shop. I told them when it had been flushed and that it had a new thermistat in it. The told me it was the intake manafold had a leak and that it needed replaced. $1,522.00 I said no thanks ill take care of it. I got the parts and replaced it. And yes the old one was bad. But it would still over heat. So got new water pump and instilled it. And still the samething. >.< I pulled out the thermistat and ran it that way last week. No over heating :) but the mud came back? It looks like mud and is sandy looking. Can you help be plz. Also what way does the theremistat need to be instilled on this car its the 4.6L. The book didnt say and the pic had the long side down. That is the way I installed it. I didnt check it when I took it off.
thanks for your help
Brian

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,244 POSTS

Brian:
At any time was the wrong type of coolant mixed with what the OEM was? For example, was GM Dexcool added to your coolant?

As far as the t-stat, it sounds like you have it correct. I would, however, recommend flushing the system again to clean it out. Also, the thermostat should be in the vehicle so it runs at the correct temp. For the price of a new one, you may want to replace it again incase it was damaged. The old one can be checked. Here is a how to for checking.

https://www.2carpros.com/dia/test_thermostat.htm

Let me know what you find.
joe