Diagnosis of ugly noise at start up

[95ToyCruiser]

Thanks for the link, I may look into this!!!

 

[BigDaddy96]

Lately I have noticed a "rumbling" sound that lasts for about 5 seconds when the truck is started (never occurs during cold starts). Used to happen about one in twenty times, seems to be much more frequent now.

'97 w/ 195k miles on the vehicle.

The sound is low and "rumbly".
At first I thought it was exhaust, but ruled that out because it goes away.

Could it be a belt that's too loose? Have replaced all three and they're within spec from what I can tell.

Could it be water pump?? Have replaced all other cooling system components - skipped the pump because the bearings felt time at the time.

Could it be the fan clutch??

Idle is smooth, rpm's are normal - during the rumble and after.

Thanks!

Hi just came across your post. Had ERG valve replaced about 150 miles ago. No CEL back on yet and running great. Then last two days I've had the identical rumble you mentioned. Making me nuts because it is intermittant and so brief that it is tough to even ID the source. Thanks!

 

[jmkfzj]

Thread resurrection. Just started experiencing this. Anyone else? Was this ever solved?