Description

Nissan QR25DE, MR20DE 2009 Service Manual

You’ve been there. Pop the hood on a 2009 Sentra with a QR25DE or MR20DE, and the aftermarket book tells you to “remove the thermostat” – no mention of the liquid gasket prep, no torque value for the housing bolts, and zero warning about the SRS system you just brushed against getting power restored. That’s why this 55-page factory Nissan QR25DE, MR20DE 2009 Service Manual exists. It’s the exact same binder that Nissan techs used at the dealership. Every spec comes from Yokohama, not some third-party compiler guessing at thread pitch. If you’re working on the cooling system of either engine, this PDF stops the guesswork cold.

Precaution for SRS – Why It Matters Before You Start

Page 3 spells it out: Precaution for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT BELT PRE-TENSIONER”. After you disconnect the battery, the manual gives a specific operation procedure for steering wheel rotation – skip it and you’re setting off an airbag while you’re leaning over the core support. I’ve seen it happen. The factory method takes two extra minutes. The manual also covers liquid gasket removal and application procedure so you don’t get leaks on reassembly. This isn’t a suggestion; it’s a step you will follow if you want the job done once.

Overheating Cause Analysis – The Troubleshooting Chart

Both engine sections start with a troubleshooting chart. Not a generic list of “check thermostat, check fan.” Nissan organized it by symptom – coolant loss, slow warm-up, fan not cycling. You trace the symptom to the most likely cause using the factory logic. The chart lives in the SERVICE INFORMATION block for each engine. For the MR20DE, the cooling circuit diagram shows exactly how coolant routes through the water control valve and the heater core. The QR25DE includes a schematic on page 36. If you’re chasing an air-bound system, that schematic is your road map.

Does This Manual Cover Both QR25DE and MR20DE?

Yes – separate SERVICE INFORMATION sections for each engine, starting at page 1 for MR20DE and page 28 for QR25DE. Both include the full cooling component breakdown: radiator, cooling fan, water pump, thermostat, water outlet and water control valve. The spec pages (SERVICE DATA AND SPECIFICATIONS – SDS) for each engine list capacity, thermostat opening temperature, water control valve settings, and radiator core dimensions. If you’re swapping a water pump on a QR25DE, the removal and installation sequence in the manual tells you what to inspect afterward – something aftermarket guides never mention.

Cooling System Specs on Page 55

Page 55 is the SDS page for the QR25DE. Capacity, thermostat rating, water control valve specs, radiator dimensions – all in imperial units. Standard and limit values for each. You need to know the thermostat opening temperature? It’s right there. The MR20DE SDS is on page 27. No guessing. Compare that to the aftermarket book that says “fill until full” without a capacity figure. This manual gives you the exact amount of coolant for a drain-and-refill on the QR25DE (same for MR20DE – check the SDS section).

Original Factory Print – Why Reprints Don’t Cut It

This is a scanned copy of the original 2009 Nissan Service Manual, not a reformatted aftermarket version. The page numbers match the factory binder. If you’ve ever tried to cross-reference a torque value in a reprint that renumbered every page, you know the headache. Here, the Precaution for Supplemental Restraint System (SRS) is page 3 for MR20DE, page 28 for QR25DE. The QR25DE thermostat section starts at page 49. Every link in the bookmarks works the same way the dealer CD did. For a 55-page document focused entirely on engine cooling, that specificity matters when you’re standing at the workbench with the fan shroud partially removed and a drip tray under the water pump.

Need more detailed vehicle-level coverage? Check the [LINK_ID_REL_*: Related Nissan Service Manuals] for the full chassis. The [LINK_ID_INT_*: Nissan Sentra 2009 Workshop Manual] covers the transmission and body sections. Don’t rely on a generic Automotive Industry Overview when you need a factory spec for your cooling system. And if you’re rebuilding the transmission, the Manual Transmission section in the full manual will give you the exact clutch clearance.

FAQ

What engines does this manual cover exactly?

Both the QR25DE and MR20DE engines found in 2009 Nissan Sentra and similar models. The manual is split into two complete SERVICE INFORMATION sections, one per engine.

Are torque values included for water pump bolts?

Yes. The Removal and Installation sections for water pump, thermostat, and radiator all reference the factory torque values in the SDS pages. If you need the exact ft-lb for the water pump pulley, it’s in the procedure – not buried in an appendix.

Does this manual cover the SRS system precautions?

Page 3. The SRS precaution is the first thing in the SERVICE INFORMATION block. It includes battery disconnect procedure and steering wheel rotation warning. If you ignore it, you risk deploying an airbag while you’re leaning over the engine bay.

How many pages and what format?

55 pages, PDF scan of the original factory binder. No reprints, no OCR errors on critical torque tables. The bookmarks match the factory Table of Contents exactly.

This manual is the difference between a cooling system that holds pressure for five years and one that springs a leak at the water pump gasket next month. Factory procedures. OEM torque specs. SRS precautions written by the engineers who designed the system. If you’re pulling the radiator on an MR20DE or replacing the thermostat on a QR25DE, you need the steps that Nissan signed off on. Access the Factory Manual and get the 55 pages of genuine 2009 service data – no fluff, just what the shop manual says.