3rd Gen Idler Pulley #1 Removal

From what I can tell, the #1 idler pulley cannot be removed without removing the oil filter/cooler assembly (shown in the borrowed photo below). Can the oil filter/cooler assembly be removed without draining the oil? It appears to have two studs and a bolt holding it in place. Is there an oil passage between it and the engine block or is it just a mounting bracket and the oil only flows through the lines attached to the cooler?

 

There are oil passageways. Drain filter housing first...

 

Did you wind up going this route or taking the top off?

 

I fixed my noisy 2018. Mileage 41K. I had taken this truck to the dealer at 20K assuming a warranty repair...they said the noise was fine (and I drank their Kool-Aide). This is the only issue I have ever had with this Tacoma...a daily driver that stays in 4WD 7 months of the year. I replaced the 4 Pulleys, the belt, and changed the oil.

Pulley notes:
Pulley Idler #1

$70 Gates 36174 Idler Pulley

Gates 36174 (2 row bearing) *Before you start remove the oil filter and the 4ea 12mm nuts/bolts holding the sandwich oil cooler to the filter housing. No gasket worries on the cooler flange, there's only 2 reusable O-Rings inside. The original Pulley I removed was the same part number as the tensioner Pulley 16603-0P030, but #1 uses a RH threaded cap screw. Be careful removing this bolt...a steel bolt that has been in an Alum block 7 years is subject to breaking and would ruin your day if snapped. Torque is 40 ft/lbs.
Idler Pulleys #2 (2ea)

$40 Gates 36173 DriveAlign Belt Drive Idler/Tensioner Pulley

Gates 36173 These are the 2 easy pulleys to replace. Torque is 29 ft/lbs
Tensioner Pulley Toyota "Idler Sub-Assy" 16603-0P030 (2 row bearing). Don't buy the tensioner assy...it's not the problem and changing it would be a real pita.) I was led to believe this Pulley required a

$44 FEBEST 0187-GRJ200 OEM 16620-31012

FEBEST 0187-GRJ200 with the KOYO Japan 5203 2RS bearing (to avoid getting a POS chinese bearing). My order was late so I paid-up and bought the $100 OEM 16603-0P030 from Toyota. What I found is that Toyota used the exact same pulley as they used for Idler #1 but the tensioner Pulley uses a LH threaded cap screw. If I do it again I will order the 1/2 price Gates 36174 and reuse the LH threaded bolt. Torque is 39 ft/lbs.

Parts Summary (all available from Amazon)
2 each Gates 36173 or Toyota 16604-31030 Pulley
2 each Gates 36174 or Toyota 16603-0P030 Pulley
1 each

$47 Toyota 04152-YZZA1 by Toyota

Toyota 04152-YZZA1 Oil Filter Element
1 each Gates K070835, Toyota 90916-A2037, -A2025, Contential 4070834, or Goodyear

$20 7PK2120 OEM Quality Serpentine Belt

7PK2120 Serp Belt (7-rib 83.4"-83.5")

Avoid Frustration:
- remove the plastic cover over the intake manifold (no tools)
- remove the drivers side frame to radiator support brace (17mm)
- remove the oil cooler B4 attempting Pulley #1 (12mm)
- change your oil at the same time you do this job
- a 15-18" long 1/2" Breaker Bar or Torque wrench will work where other tools won't
- Coors Light...save the IPA for post start-up