Scary sight in my overflow tank!!!

fxpthl

Member
Well today I was going to topoff the coolant reservoir when I noticed a brownish fluffy-looking stuff instead of coolant! I siphoned out this fluid and then re-topped with coolant. Upon close inspection, this goo looked like watered down oil. I have been adding oil to the crankcase at about 1/2 quart every few hundred miles but no water is showing up on the dipstick. Could this be a sign of a blown head gasket? God I hope not. Being semi-retired and trying to live on SS doesn't leave much for major auto repairs. Anybody out there know about what I have described? Give it to me gently if it is a bad omen. This is a 97 with 165K miles on it.
 
what does it look like under the radiator cap

Agree with Signature Sound post a hi res picture
 
I've seen some nasty OF tanks. Water will sometimes stagnate in there and build up all sorts of goo. I wouldn't assume it's oil off the bat.

Clean the tank a few times and keep an eye on it. Remove it, toss in a bit of crushed ice and clorox and shake it up as if it were a mixed drink. The crushed ice acts as an abrasive to scrub the sides. It'll obviously melt away making overall cleanup easier.
 
Well folks, just got home from a great "ride" out to Death Valley, CA in my dirty water 97 Miata. Didn't have any overheating issues but checked it out at each fill-up. Having the radiator cleaned out is high on my list of "things I need to do"! I did notice what sounds like a "spark knock" at low rpm's during acceleration from a stop. That is the best way to describe the sound It only made it when getting on it from a stop or during slow uphill climbs. Checked oil at every stop as well. After the first 450 Mile leg I had to add one full quart! Haven't checked it since I arrived home but will later tonight. This car came with lots of new friends and enthusiats. I joined the So.Calif. Miata Club as well as "miatafun". We all have a sickness about our little sport cars and share some fun times on these rare overnight journeys. I recommend anyone with a Miata to look up their local club(s) and get involved.
 
I checked the dipstick and I used about one half quart on the homebound leg of my drive to Death Valley. Still getting that "spark knock" sound occasionally. Purchased a new thermostat and will clean/flush out the radiator soon. I guess when you have a car of this vintage you should expect things to go wrong-wear out or just break! I love a challenge and this little car is going to be just that! OK, it is the next day and after a trip to the local auto parts store, I have new thermostat, some radiator cleaner and more 50/50 coolant. I get home, jack up on side of the car just so I can see underneath, and take a look at/for the draincock for the radiator. No luck in finding that but I did find the lower radiator hose. Of course there was no way I could get my hand up in that little space let along have the proper tool for the odd spring-loaded hose clamp holding in position! So I buttoned it back up,took back the cleaner and coolant and made an appointment with my local garage to do this chore for me. The days of being able to easily work on your own vehicle are long gone for most of us and that is a sad thing for us old shade-tree mechanic types. OK then, it's the next day AFTER visiting my local mechanic. He flushed the radiator and cleaned the coolant reservoir. The diagosis is once again scary.....there was oil in the coolant tank but none in either the crankcase or the radiator itself! This only opens up more questions as to where this oil came from. Film at eleven!
 
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