Rattle in engine.
 

I am a new member with this forum. I have a 1994 SL 2 with the DOHC engine. This car seems bullet proof but has developed a few issues over the years that I'd like to fix but can live with. Ok back in 2008 I was involved in a small fender bender where i rear ended a Ford explorer after a 18 hour shift. Damage was minimal knocking the front plate off of the car and causing no real damage to the truck.After this accident the car developed a rattle in the engine that I thought was a exhaust rattle. I have had the entire exhaust replaced converter too AND THE RATTLE REMAINED. I have replaced the timing chain and guides and tensioner and the rattle remains. The car only rattles under a load A/C on at idle and goes away when driving. All the motor mounts have been replaced as well as the transmission mount. Rattle remains. Last week I replaced the idler pulley and the rattle is still there. The following is a last of thing I have replaced trying to get rid of this rattle:

Timing Chain
Timing gears
Timing guides
Timing chain tension-er
Motors mounts
Trans mount
Entire Exhaust System
Belt tension er
Several complete tune ups(including wires and fuel filter)
Vacuum lines to the Canister

So I can only think now that it's either the water pump which has been replaced but not since the rattle started Or maybe there is a vacuum switch or line that i have missed that is causing the idle to be maybe to low which is causing the rattle. It' sounds like the timing chain but the rattle was the same after it was replaced. The engine runs smooth and has plenty of power so i don't think it has a compression issue. I have checked the intake for a vacuum leak and it does not. Anyone ever had this problem. Any input would be great.

Thanks

Ray Fields

Oh yeah i took the serp belt off of the car last week and the rattle went away it seemed. But was not sure if the just reduced the load on the engine or if the rattle was caused by something that the belt was turning. All of the pulleys seemed good. a little play in the idler pulley that's why I replaced it.

Well, I was going to suggest the idler pulley, but since you replaced it, I won't. You really need to check each pulley with the belt off. I'm guessing either the a/c compressor pulley or the alternator. BUT, I'm not a mechanic. If you have a mechanics stethoscope, use it on each accessory and listen to them while you spin them. And don't forget the power steering too.

When was the serp belt last changed? It's not on the above list.
If the rattle goes away I would strongly lean towards the AC pulley -- esp if that is the only time you hear the noise (A/C under load)

OR

The aux cooling fan that comes on with the AC (or its shroud), which could have been displaced in the fenderbender.

Stand betw AC compressor and aux fan as a pal starts the engine with the AC OFF, then turns it on.

Use a stethoscope. There's too much mechanical noise around there to necessarily sort it out by ear.

Also, make sure the AC Compressor is mounted firmly to the bracket and the bracket firmly to the block

Any service engine soon light /codes we should know about?