Forum:
Hi all, I posted a message a while back about a rumbling sound I could hear while sitting inside my sportrak. The thing is the same sound can't be heard while under the bonnet. I'm wondering if the sound can be caused by the big end bearings. Can anyone tell me what to expect or look out for in terms of warning signs such as noises, as far as these are concerned?
Many thanks in advance for any replies 
big end?
If your big end was gone you'd hear a knocking noise. Rumbling noises usually come from a noisey bearing. Try running it without the alternator belt and power steering belt. ( only run it for as long as you need to listen for the noise as the waterpump won't be turning). It may be a noise timing belt idler or tensioner bearing, but you'd have to run it without the timing belt cover on to listen for the noise. The other place to listen is the gearbox, the input shaft bearings could be rumbling so press the clutch and put it in gear. This stops the gearbox from turning so if the noise is still there it's not the box.
If it's not any of them your probably looking at noisey main bearings
Hope this helps, Daz
Sounds like a job for the long screwdriver.
Sometimes the noisy bearing can be located by placing the blade of a long screwdriver on the housing of the suspected bearing and sticking the handle of the screwdriver in one's earhole.
All sorts of horrendous banging and clanging will be heard which is quite normal for an engine. Knackered ball bearings rumble quite noticeably louder than good ones though.
Don't think that this is a precise science, but it sure looks good and sometimes helps diagnosis.