I've been keeping track of the coolant fluid in my stock '89 with 70K, miles but now the coolant fluid is looking pretty bad. It has a milky light brown color, and certainly has a slickness to the touch.

I'm sure this isn't good new but wanted to get some feedback on where to begin with this trouble. I'm assuming I have oil reaching the fluid somewhere and not trans fluid with this color but not sure?

I think I've seen things in the past the suggest problems in the motor I'm prepared that this might be something like this.

Has anyone else had this problem? What is the best method to diagnois?

 

Doesn't sound good. How's the engine temp? The first thing I would do is a compression test. Are you getting any water in your engine oil? Is the engine missing?

 

how long has that coolant been in there? when coolant ages it will lose its protective properties, promoting rust. rust can also color the coolant brown.

 

I'll go with the "rust" theory. Glycol is "slick", old or new.

 

Flush that system.

I'd drain the oil and look at it closely for coolant. That'll rust up things inside the motor.

The likely culprit would be a blown gasket.

 

Compression may be normal and a leak down test inconclusive. Since most seem to fail at #7, pull that plug and look for rust on the threads or an electrode that looks different from all the others. You can have the coolant checked for the presence of exhaust gasses too.

 

Great advice all around guys, as for the current performance I just finished a SCCA Autocross today finishing 2nd in A-Stock and the driver was the issue with not being a 1st, plenty of power no missing.

The coolant is not real new at least 3-4 years old. I'll go ahead with a flush, I also have plugs sitting on the bench to go in so I'll double check #7 as directed. I guess I could also do a compression test at that time. I believe with all plugs out is the best method.

One question? How do you get rid of coolant at home? Do you take it to a shop or just dump, I know it's very harmful to "critters"

 

Another question, how will I tell if water is in the oil??? I know they don't mix but not sure what to look for. I use Mobil-1 so not sure if that will effect what I'm looking for?

 

Coolant is lighter than the oil and if you drain it cold, it'll be the last to come out - of course fresh coolant helps you to really see the color difference. However, this is more probable with a major leak and that isn't what happens right off the bat with the early aluminum head motors (and with your engine running ok, you don't have that).

According to GM's early Bulletin on the subject, the head gasket was incompatible with the coolant which eats away enough of the gasket material to allow exhaust gasses to leech into the cooling system. This sets up galvanic corrosion which eats away at all of the aluminum parts - particularly where they come into contact with a dissimilar metal - the thermostat bolt being welded to the manifold is a good example. It also plugs up the radiator and heater core (that usually goes first), so after awhile, cooling temps rise (or if your Vette has the aux fan option you'll note that it's coming on with normal driving). So all these things, along with crappy looking coolant within a short time after a decent flush are worth keeping an eye on.

Since you haven't changed your coolant in awhile, you might want to make sure you get everything out of it. The only way I know to do that is to remove the knock sensor and pull off oil cooler hose at the filter. You can take a sample to a chemist (or some radiator shops can check it) to see what's in it. Check the Yellow Pages and make a few calls to find out what's available.

As far as disposing of coolant, I've never found anyone (on a regular basis) in this environmently conscious State that will take it. The parts store will take oil and filters, but most don't even want tranny fluid. You can drain it into a shallow pan and dump it into the toilet, but some seems to get on the ground regardless of what you do - just flush/dilute it really well with a garden hose to keep the stray dogs and cats happy.


[Modified by SunCr, 1:50 PM 6/27/2004]

 

It's looking like I have a new project for the upcomming holiday weekend. Great input everyone, I need to do some work to find this problem but maybe it's not as bad as I may have thought.

But then again what's more American the spending the 4th working on the Corvette :flag

 

Well you know what oil looks like, especially when its worn, its a dark brown-to-black color.

If its getting coolant in it, it'll look like a murky brown, and youll notice the consistency change. If its really bad I'd say it looks like diarrhea

Likewise youll see black/brown spots in the coolant if you drain it all.

 

Did a bit of work on the car, changed the oil and flushed the cooling system and replaced fluid.

Take a look at the fuilds that came out



As you can see the oil looks pretty much ok, couldn't see any coolant/water in the oil, the coolant on the other hand looks ugly , but I can't tell for sure if this is oil or just bad corrosion. I talked with a couple shops today but no one has seen the fluid yet, I saved a bit of the oil and coolant. One shop said that the GM system are bad on corrosion, he own a 86 TA and recommend flushing any GM product every 6-12 months???? This is about 3 year old plus from my car.

I know photos are though but anyone seen this in there car? Good or bad news?

 

that looks like rust to me. mine was rusty was well when i flushed this year (1st time since i got the car), and my water actually looked darker than what you have. i had absolutely no green tinge. took me about 20 fill/refill cycles to get the water coming out acceptably clear.

i plan now to change mine annually.


[Modified by tempest, 9:40 PM 7/2/2004]

 

Not to be a butt - for future reference. Oil Floats in water. The water will be the first thing to come out when you loosen the oil plug.

 

definitly rust in the coolant. When you refil use only distilled water(50/50 mix with coolant), not tap water. Tap water is a no no in engines. Causes all kinds of problems with corrosion.

 

My plan now is to watch the color of the fluid for a couple months and then do another flush to get things as clean as I can. I have to change plugs and I'll be checking for any rust on the thread and such that could tip me off to things as well.

Hope it is just a reglected coolant problem, coolant is cheap! Motors aren't!

 

tap water also will create crusty build-up over time - just like you see around your water fixtures at home. some of the coolant galleys are not very big and can easily be clogged by the build-up.

 

You'll find postings elsewhere about this; APPARENTLY GM put pellets (Anti-rust or something) that make a brownish sludge in the expansion tank...Normal by what I've read so don't PANIC!

 

pellets were used on my early LT1 (don't know about the later years). the part number (3634621) is a GM part number which leads me to believe it is commonly used. these "cooling system sealer" pellets are about four times the size of an alka-seltzer! the service manual calls for six of these when you refill the system, but i have gotten away with two.

the ingredients of these pellets are quite interesting. most of the contents can be found on your spice rack.

 

...Do tell...