coolant questions
 

I'm new to Chevy and just bought a 96 s-10 with a 4.3L (x) 5spd with 160k. I gave it a tune up(plugs, wires, dist cap, rotor, oil, air/oil/fuel filters) complete with a new distributor since the last guy cross thread the old rotor on both screws.

Anyway, it runs great. Has the very very slightest stumble at idle sometimes. Stays pretty constant at idle between 710-750 rpm. The coolant though in the coolant reservoir is dark. Almost black. It's not oily, there's no shine. There's no coolant or water in the oil and there's no moisture in the exhaust pipe. I haven't used this dex cool coolant before so I'm not used to it or how it looks. Reading on here I've seen that that stuff can get pretty gross and sludgy overtime. The engine temp is great though. Just a little over a quarter of the way warm (I forget the temp range on the gauge).

I also have a leak coming from the crank pulley or the water pump above it(I haven't looked at it that deep yet). I never see any leaks on the ground but it's definitely wet under there. It's seems like water. Reading on here I see that it could be an indication of an intake gasket problem.

I guess my question is, is the dark coolant a symptom of the intake gasket or do you think it's just nasty and the system needs to be flushed? It could be the original coolant as far as I know. I'm thinking about flushing the system out tomorrow I'm just hesitant because if it's the intake I'd like to do that all at once. I won't be able to do the intake for 2 weeks though but then I'll have 2 weeks to do it and since the temp is running well now....... Any ideas?


Sorry for the novel here. Thanks in advance.

If the leak is water then it is likely to be the weep hole on the water pump that is leaking. You should also change the water pump at the same time that you flush the system and add new coolant. Dex Cool is Orange in color and is supposed to be more environment friendly and more expensive. There are now coolants that mix well with Dex Cool and are green in color.

It seems that he back of the h20 pump is leaking? It's a little wet where the lower radiator hose meets the pump and where the heater hose meets the thermostat housing also so I'm definitely going to just replace all the hoses and looks like the water pump too. It doesn't seem to be leaking out of the weep hole though so hopefully the water pump will last a couple weeks until I have the time to do it. Are there any good write ups for the water pump? I don't have any manuals yet.

I'll double check the weep hole while it's running. Time to get the nasty crap out though until the big job.

BTW I don't smell any exhaust in the coolant either.

What are some recommended green coolants to use on these Chevy's that will mix with dex in case I don't quite get all of it out?

Update: I pulled the overflow tank out to see the fluid in it. What came out was just water. Mostly clear. The tank itself was covered inside by think back. I scrubbed what I could but the water that comes out is clear. That only make we worried about how dirty the rest of the system. At least I know it was just water flowing through.

As for the water pump I was able to get a combo wrench up there and all 6 bolts on the back of the pump were loose by at least 1 full turn. It felt like eating soup with chop sticks but I got them all tightened and the pump doesn't leak any more. In a couple weeks I'll probably flush the system and replace the hoses thermostat and pump.

With just water in the system, you probably have a lot of rusty water in there. I had that problem when I had a leak. I was just putting water in until I had time to fix the leak. When I did fix the keak, I flushed the system and a lot of rusty junk came out. Also the heater core got clogged, I had to back flush that also. Now when I have to add coolant, I add antifreeze.