88 coupe, 56k miles, normally has green coolant. I opened up the little plastic tank to the side that I assume is the overflow, and it's brown and looks gross. What's up with that?

Should I just clean it out?

 

flush system

 

Yes, by all means clean it out!

It probably is not anything to worry about. Fluids do get contaminated. If you haven't drained and flushed your system in a while this might be a good wake up call. The older "green" type anti-freeze was not intended to be extended life.

You should change it according to the instructions in your owners manual. However, since you have only 56K on an 1988, you need to switch to a time based interval as mileage won't work for you. Probably every 2-3 years a good flush and refill will be in order.

 

Yes you should.

 

PO hardly drove the car. It's my DD, so I've been putting miles on it.


Good, I had a flush on my to-do list.

 

Here in Florida because of the summer heat I do mine every year for what it costs it's great insurance to know the system is clean and working well.

 

Don't forget to use distilled water to mix with your coolant to a 50/50 mix.. This is much better for the system....you wouldn't believe whats in tap water......WW

 

 

I have had the same problem, I have flushed it and clean out the reservoir when I can, but it comes back every couple of years.

 

If you started with green coolant and it looks brown, hopefully it is rust and crud most of which can be flushed and cleaned out as previously mentioned. It could also be oil and antifreeze which would mean your motor is doo doo. Hopefully it is the former.

 

It looks like rust and crud, and not oil. I severely hope the motor isn't bad, I can't afford that right now...

 

PO may have added the GM cooling system sealing tablets - those will also turn the coolant brown.