Auggie

I am the original owner of a 2003 Chevy Express 6.0L One Ton Cut-Away Van suffering from the dreaded coolant loss that can't be found. This has been going on for quite a while. I do not drive the vehicle that much so I keep putting off dealing with it and just make sure to have extra anti-freeze with me. It has gotten worse though so it's time to make time to try and find out what's going on. It’s my understanding that the 5.3, 4.8 and 6.0L GM engines are different from the 4.3L 5.0 and 5.7L engines, so I am assuming that the issues the 4.3L 5.0 and 5.7L engines are having with coolant loss and cracked heads/intake manifold gaskets may not apply to the 5.3, 4.8 and 6.0L GM engines, but that is an assumption.The van starts right up and runs fine. The oil is fine, not milky or foamy at all. I am a fanatic about changing and using quality Amsoil oil and MotorKote in my vehicles and equipment. This Chevy Express has 189,000 miles on it and uses much less than a pint of oil between oil changes. Except for a few quirks, it's been a good machine.

Has anyone experienced loosing coolant in a G.M. 6.0L but are unable to find any leaks? Did you find out what was causing the coolant loss?

Thanks!

William Kisselstein

Mine seeps a little from the hose under the passenger side going up to the rear heater.

I never did fix that. I haven't even noticed a puddle under it in a long time. If I do fix it, the solution is to buy the hose for a non rear heat van and install it. You have to take the alternator off on mine to get to the hose connections but other than that and care to not break the plastic the one hose mounts to it looks much easier than laying on my back messing with whatever hose is down there.

Auggie

After messing with this issue for quite some time, I finally took it to a local shop that had a good reputation for diagnosing problems. This proved to be a good move on my part. I wished I would have done it sooner. To make a very long and agonizing story short . . they approached the problem systematically and ended up adding dye to the cooling system, because they could not see antifreeze leaking anywhere either. After driving the van to Lowes to pick up a few things I needed and then back to the shop, which was about a 35 mile round trip, it was very obvious where it was leaking from. The shaft on the water pump! The dye they put in made it very easy to see where it was leaking. I never would have thought it possible to be loosing so much coolant and not be able to tell that it was leaking from the water pump. Apparently because the engine was hot, it would burn off the antifreeze so it was hard to tell if it was leaking. But with the dye in there, you could easily see where it had leaked. In my case it was all over the front of the engine. All I had to have them do is change the water pump.

Prior to this I was pretty well convinced that I would have to take the heads off and have them checked for cracks but am so glad I took it to these guys to check out. I learned a valuable lesson from all this.

Thanks for everyone's interest and reply's.

mountainmanjoe

Well that's the second Express van water pump leak in this forum section this week. Good to know.