Ok, I know this isn't a GM product, but I've been on this board for a very long time and I trust most of the responses I get on here.

My girlfriend's car (2000 Celica GT 4cyl 5spd manual with 97k miles) started making a rattling noise from the engine bay. I'm not asking for you all to pinpoint, I'm just trying to elimate somethings.

Took it to a local mechanic, he said it was piston slap due to excess tolerances, told me to try out some 15W-40 oil and see if that changed anything. Next, took it to a transmission shop. They said it wasn't in the transmission. I was convinced it was in the transmission. It also had a heatshield that was rusted and cracking, so that was a possibility.

Last night, I took off the heat shield, still have noise. Put 93 octane in it, still have the noise. Replaced transmission oil with Mobile 1 fully synthetic 75W-90 GL4/GL5, still have the noise. That pretty much rules out that it's in the transmission right?

A week ago I changed the oil (Mobile 1 5000 mile 5W-10 with AC Delco filter) and she said it started doing it soon after that. So last night after I changed the tranny oil, I put in some Quaker State 10W-40 (couldn't find 15W-40??). No change in the noise. What all does that eliminate? Rod bearings? Valves?

I just need to know what I've eliminated in the engine before I can go any farther.

Thanks,

Josh

 

check the belt tensioner, idlers, and exhaust bolts.

Does the rattle stay in touch with fluctuating rpms?

It is a dull or a sharp noise?

 

Looking at the miles on the car, I would look in to a new timing belt. It is common for failer at 100k on four bangers. You will want to check the valve lash as well.

 

I checked all the exhaust bolts too...forgot to mention that.

There isn't a timing belt on these, just a timing chain that is "supposed" to last as long as the engine. The timing chain tensioner is a common problem on them, but this rattling doesn't sound like all the other descriptions of them going bad. I'm not ruling it out though.

If changing to a higher viscosity oil doesn't affect the rattling, that pretty much rules out any internal problems right?

The rattling is hard to describe. It varies quite a bit but the best description I can think of is a dull sounding marble inside a coffee can. Mostly a mettalic noise.

It does it in every gear, can barely hear it in first though, and it does it when coasting with the transmission in neutral (with or without the clutch pushed in).

 

Bump for a new day

 

Do you hear it with engine running and car stopped with clutch in? Also when you rev the engine does the noise get faster? Fan hitting anything?

 

throw-out bearing? that often sounds like a rod knocking