Brown Mud like residue in Coolant Overflow tank

[Test]

Hi,

I have a 88' Honda Prelude with about 138K Miles.
There is a Brown Mud like residue on Coolant Overflow tank dipstick.
I also noticed some white gunk on the inside of radiator cap.

I had one of the coolant hoses replaced a few weeks back. Is there a
connection
to the above problem ? Or is there any thing broken ???

Thanks for any inputs.

[MaxB013]

Sounds like you have been adding only water to your system, try adding some
comercial flush from the Auto Parts store,
follow manufacturer instructions. Add a 50-50 mixture of Coolant or Antifreeze.
If the system is very derty you might have to do it twice

[GOCORCORAN]

>There is a Brown Mud like residue on Coolant Overflow tank dipstick.
>I also noticed some white gunk on the inside of radiator cap.

IT's ALIVE!! Actually it's possible to grow bacterial gunk in the cooling
system if the thermostat fails open. It looks just like your description.
The coolest places in the system are the radiator cap & the overflow tank. The
overflow tank "breathes" in & out as the car heats and cools, pulling in
bacteria, mold, dust, pollen, whatever... If the T-stat has failed open, the
top of the radiator & the overflow tank never get hot enough to kill off this
bacteria. It lives on the glycol converting it to sugars (& I believe, acid?).

Perhaps more importantly the engine never fully warms up causing loss of fuel
mileage and possibly catalytic convertor damage.

Been there, done that. I learned the hard way.

gocorcoran

[meg...@pacbell.net]

Does the radiator have a ATF cooler built in? If so,
it could be ATF fluid is contaminating the coolant
water.

On 24 Sep 1999 00:44:21 GMT, shr...@aol.com (Shrub7) wrote:

>sible to grow bacterial gunk in the cooling
>>system if the thermostat fails open. It looks just like your description.
>>The coolest places in the system are the radiator cap & the overflow tank.
>>The
>>overflow tank "breathes" in & out as the car heats and cools, pulling in
>>bacteria, mold, dust, pollen, whatever... If the T-stat has failed open, the
>>top of the radiator & the overflow tank never get hot enough to kill off this
>>bacteria. It lives on the glycol converting it to sugars (& I believe,
>>acid?).
>>
>>
>>Perhaps more importantly the engine never fully warms up causing loss of fuel
>>mileage and possibly catalytic convertor damage.
>>
>>
>

>If the t-stat fails to oen I am sure the engine would get plenty hot enough to
>kill bacteria.
>

[Shrub7]

[GOCORCORAN]

Hi shrub,
Always good to read the entire thread and understand it before replying. The
engine will get hot enough to kill bacteria. That's not what the post says.
The overflow tank and the radiator cap, which are out of the heat producing
area, and in the air turbulence under the hood can be a good 50 degrees F
cooler than the coolant in the engine. If the t'stat failed open these two
areas may never get above 120 F and bacteria can live. The overflow tank is
vented to the atmosphere when the level falls it pulls in outside air. Glycol
is a suitable food for some anerobic bacteria. Warmth, moisture & food equal
thriving bacteria.
Remember you have to boil water (212 F) to kill some bacteria and most t'stats
are in the 195 F range IF they are working.

Don't take my word for it, look it up, call the Car Guys on NPR, whatever. I
have personally experienced it in my '92 Taurus SHO. May not be a possibility
in Texas, or Florida, but I lived in Chicago, so there was a lot of cold air
blowing around under the hood at highway speeds. Had about a 1/4" layer of
light brown slime coating my expansion tank. Think my t'stat was failed open
for about 6 months before I figured it out.

Best regards,
Greg