2000 Sierra with a few odd issues

Mike GMC · February 22, 2020

My 2000 Sierra has a few odd issues that I've been chasing ur a while with no luck finding them.

1. The engine warms up very slowly when it's cold out and never seems to want to get up to full temp. It has a new-ish radiator due to the old one leaking, a new-ish water pump and thermostat bout it still does it. The clutch fan is still original but seems to spin freely when the engine off. I'm beginning to wonder if it needs a new thermostatic clutch. Even at idle, the fan moves a significant amount of air. Just not sure since I doesn't feel locked up or overly tight when turned by hand.

2. When it below freezing out, in a cold start I hear a weird clanking sound. It's LOUD and seems to be from the front of the engine area. It's somewhat random sounding and not necessarily following engine speed. Almost like marble being bounced around in an old metal coffee can. It seems to be in the accessory drive as it does not happen with the belt off. But since it won't happen once it's even slightly warmer, I can't pin it down. None of the pulleys, idler or tensioner have any play or noise when turned by hand. Fan clutch? Any one have any ideas on what it could be?

Any ideas would be appreciated. Particularly any ideas on how to test the fan clutch to determine if it's bad.

Thanks in advance.

Mike GMC · February 23, 2020

I through a new fan clutch on it this afternoon. It's not good enough to tell if it fixed the noise or the slow warm up issues, but I should be able to find out in the morning. Hopefully, one or both issues are fixed.

Mike GMC · February 25, 2020

It was colder this morning. So far, no clanking noise and it did seem to warm up a bit faster and closer to normal operating temp. Tomorrow is supposed to be even colder so that will be a better test. Fingers crossed.