I have a 01 millenia (2.5L)with 90,000 miles on it. The car just recently began giving off a knocking noise at what sounds like the top of the engine at the side closest to the firewall near the passanger side. It is very prevelant at startup and low idle or as the car is coasting and your not on the gas after 1100 to 1500 rpm the sounds is not noticeable. Anyone have any clues? This is the worst car I have owned after rebuliding the transmission I am hoping this is not anything major.

 

When u say knocking noise do u mean it sounds like it's a diesel engine or somethin? I remeber a few months ago my car had a similar if not the same sound and it was one of my cat converters. The good thing about it was that it was still under the mazda warranty for the cat which is 8 yrs./80,000 miles. U should take it 2 a muffler place it c what it is because it could b sumthen really serious. I'm only 19 and learned that once somethin goes bad on these cars even it's little don't wait and fix it quick.

 

I have a 95 2.5. Rebuilt the trams at 187, now has 210. I had a knocking noise when cold, rear cylinder that got some what quieter as it got warm. I thought it was the hydrolic tensioner. Replaced it the noise went away for a while. Disassymbled the old tensioner and found nothing wrong with it (190 on it). The problem was the idler pullies they had pieces of rubber/oil grime on it from oil leaking from my cam plug seals. (I fixed them by silicon sealing the plugs in.) I fixed the problem by pulling the T-belt covers, spraying "brake clean" on the pullies and the back side of the belt. I used a "dull"screwdriver to clean the pullies while the engine was running. (Be carefull it is easy to get hurt!!!) and the back side of the belt. The motor is now quiet on start up and at idle. The belt currently has 130 on it and runs smooth. Pull the covers and look at the pullies. You know you got it when the tensioner pulliy does not shake at idle. The Tensioner can not recover fast enough when it hits a bump on each idler pulley, so slap, slap..

1/6/2010 Car now has 240k miles on it, T-belt started the noise again after 15k more miles. Found out the t-belt had streched after 145k miles and the hydrolic tensioner was at it's limit and could not take up the slack. Put in a new T-belt, cleaned pullies, all quiet again.

Dennis

 

That's really awesome that you came back and updated on how it worked out over the long term. My best friend and I have owned our Millenia's for about 6-8 years each and just had this symptom for the first time from his 2.5L today. Looks like I'll be taking a peek under that timing cover this weekend