: 2005 STS loud engine grind/rattle on start up only

04-19-12, 12:32 PM
I have a 2005 STS loud grind/rattle when I start my car, however, it is intermittent. It lasts only a few seconds and then goes away. I have taken it to the dealership several times and they first said it was a heat sensor loose, so they tightened that... didn't work, they replaced the cat converter.... that didn't work.... now they are saying this is a normal sound! If this is normal, then why doesn't this happen every time i start it and why don't all of the cadillac STS do it? Very frustrated! The noise is extremely loud and embarrasing especially when people are around and they hear it... driving a $55,000 dollar cadillac, you wouldn't expect to hear a "normal" noise like that!

Cadillac Cust Svc
04-19-12, 04:22 PM
I'm so sorry to hear that, workmant! I would be happy to investigate this further for you; please send me an email anytime at Katie_Lucille@gmexpert.com and I can research on your behalf.


Cadillac Customer Service

04-19-12, 05:58 PM
You're describing the classic symptoms of an oil change and using the wrong filter that doesn't have an anti-drainback valve. Without the valve the oil in the engine drains back to the sump when you shut the engine off. On a restart it takes a while to build pressure again and the cam followers rattle to beat hell. Try replacing the oil filter with an OEM one that has the valve.