hi im new to hummer and this forum. i have bought a H2 with 70k miles about 5 months ago and over the last couple weeks it has developed a rattle that sound like metal to metal for the first minute of start up! sound as if its coming from pass side close to front door area. i have been under it and checked everything and nothing is loose, i changed the oil and used 10w40 and its still there. anyone else have or had this problem? kinda thinking it my be the mains rattling, thanks for any and all info. brian

 

might be a broken exhaust maifold bolt if it quits as it warms uo....common H2 problem.
BTW using 10W-40 oil not a good. idea

 

Why, and I hate to ask because I don't want to know the answer you're going to give, is 10w-40 a bad idea?

 

You should use 5w30 in your H2 and yes I also would say your right rear exhaust manifold bolt is broken.

 

Had the same issue with the rattling with my 03. It was the rear motor mounts had to be replaced. about $600 at the dealer. Sounds like the same problem.

 

Thanks Doberman7892 i would like to speak with you over the phone. i will call you if you will send me your number. brian.maples@ymail.com

 

you can lead a horse to water....but you can't make him drink

 

k ichanged the oil and filter again, ac filter and 530 oil. no difference at all. with a broken manifold should i hear this at all times? the only time i hear this is first thing in the morning on the first start up and it may last 30 sec it may last 1min, its never the same. it sounds like a rod is knocking when it does this

 

the broken bolt...or bolts...allows exhaust gas to escape from under the manifold. As the engine heats up the manifold expands and seals off the leak so you no longer hear it. This is a common problem with H2s and many times more than 1 bolt will break. There are stronger bolts available and it would be a good idea to replace all of them to prevent it happening again.
BTW... putting in a heavier oil might hide an engine noise for a while, but it doesn't solve the problem. Whatever is making the noise is still there and in time will probably only get worse....just my 2c

 

The dealer showed me the mounts he replaced. He told me they were liquid filled and one had leaded down and would rattle against the exhaust manifold. Since it has been replaced, the noise has gone away. I also had to reseal the two corner roof marker lights. They were leaking and running out the grab handles by the front windshield. Hope this helps.