Subaru EJ25 timing belt guide 13145AA021 You need it for a manual transmission. HD 720p

This video demonstrates the purpose of the Manual Trans MT Belt Guide (Subaru part 13145AA021).
It's an EXTREME test, for demonstration purposes. Turning the engine backwards with the cam "LOCKED" by a vise grip does not happen in real life.
I've been driving an auto engine in a manual VW for 25 years with no belt guide. But my belt slipped last week so I studied the mechanism and found one way it can happen. It requires several bad conditions to happen at once.
I had parked with the gearbox in a forward gear, using the engine to hold the (heavy) van from rolling backwards. Which turned the engine backwards very slowly. The parking brake was not set.
This video shows how the Subaru Manual Trans MT Belt Guide 13145AA021 prevents belt slippage. There are other faults that can cause timing belt-slip, including failure to replace belts on time, idler roller bearing problems, water pump failure, over-rev, perhaps others. But the belt guide positively prevents slippage at the crank gear thus is a good item to have on your engine.
At the end of the video I probed a Smallcar engine with a nail, confirming that Smallcar installs the Subaru Manual Trans MT Belt Guide to their conversion engines. And likely others do as well.
If your engine has no belt guide, think carefully about which gear you choose when parking on a hill. If pointed downhill, use a forward gear (1st) . If pointed uphill, put it in reverse gear.
=========== Tom Lengyel of Syncroshop, Oregon ==========
He's a small Subaru-Vanagon shop said he's seen belt-slip four times over the years, all with no belt-guide. There could be other reasons the belt skipped, but he hasn't seen it on engines with the guide.
=========== note from Richard Jones, engineer at RJES.com ==========
In 20 years of working on this stuff, you’re the only person I have ever heard from who has had their belt slip due to not having a guide fitted. But I bet you’re not the only one.
Richard Jones,
R J Engineered Solutions Ltd www.rjes.com
Quality Components for Subaru Powered VW Conversions

[@MisterRisk]

Looking forward to meeting you at syncrofest and seeing your trans cooling presentation

[@richardjones38]

Subaru started fitting the cam belt guides in MY98, on manual models only (at least, in European model Subaru's). They changed the design of the oil pump at the same time (for manual and auto models), adding the two bosses that the cam belt guide screws in to. So to fit a cam belt guide to an earlier engine, you'd need to fit the later oil pump. But to fit one to an MT88 or later engine from an auto when being sued in a manual application, you just screw the guide on to the existing pump. Be super careful if taking the crank position sensor out to check for the presence of a cam belt guide. The stainless steel sensors are very probe to corroding the surrounding aluminium, trapping them in the bore. When the screw is removed, the top of the sensor often moves a little bit, encouraging you that it's loose, so just needs prying a little. When the stainless sensor housing is trapped in the casting by corrosion, this movement is not the sensor moving in the casting, but the plastic senser internals moving in the stainless casing. Prying at it, even lightly, can break the top off an otherwise good sensor.

[@mishaft]

The only helpful video I've found about what happened to my engine!!!! Thank you! How do I rectify tho?

[@manolid]

Replaced my timing belt today on a 2012 STI hatch and was wondering what the guides were for. It had them over the crank as well as over the right exhaust cam pulley and left intake cam pulley. I used a thin piece of cardboard to set the gap between belt and guides. Is there a special tool for adjusting the gap?