Resonant Rattling Noise At Front Of Engine..!

June 1, 2018

Hello Everyone,

I am about to carry out some repairs on a 2003 RAV4 2.0L Petrol Manual Transmisison.

I have a resonant bell-like rattling noise enamating from the front region of the engine.
After some investigation, the source has been narrowed down to the Belt Tensioner, the Coolant Pump, or both units and have decided to replace both units, the Drive Belt, flushing out the cooling system and renewing the coolant. The necessary patrs are now being ordered.

I initially suspected the camshaft drive gear; faulty chain tensioner, stretched chain, worn slippers/pads etc.
Then using a stethoscope, everything was ruled out except the Drive Belt Tensioner and Coolant Pump. This was further confirmed by removing the drive belt and running the engine (yes, I know,) for no more than ten seconds. It ran "Silky-Smooth" and surpisingly quiet for 172600 + Miles.

Now I have some simple questions that I hope will be answered:

1.. I have read various posts (not this site) stating that the coolant pump has had several modifications and it is best to get one from Toyota. What is the view here if any?
2.. I plan to use Toyota gasket sealant, or is that ott? What sealant have others used and found to work (or fail) just as well without future leaking or contamination issues (Permatex or Toyota FIPG etc)?
3.. The tensioner part (hydraulic ram) is servieable, but the idler bearing is noisey. Has anyone attempted repairing/replacing the idler bearing(s). I intend attempting a repair just to see if it can be done.

Any other relevant comments and suggestions are most welcome.

Thank y'all..!

Edited June 1, 2018 by Nwuvic
Previous corrections were not included by the system prior to initial submission.

June 2, 2018

There are plenty of decent after-market pumps available (QH, Blueprint, First Line etc etc) less than half the price of the genuine Toyota part. The important thing is that the gasket mating face on the block is fully cleaned up - use something like Liquid Chisel if the deposits are stubborn. It should be fine to fit the gasket dry - but a smear of Hylomar Blue on both sides of the gasket is an added safeguard. Replace the bolts if damaged / corroded. The idler wheel with fitted bearing is available aftermarket - around half the price of the complete assembly - however even though the ram appears serviceable - it's covered a high mileage and may well have weakened. Given that you've got everything apart and given the modest cost, I would suggest fitting a new serpentine belt.