transmission

Transmission Oil Cooler

for 2017 Dodge Viper 8.4L V10 · RWD

Difficulty

Moderate

Time

2.0 h

Tools

Steps

🔧Does this apply to your car? On most cars the transmission cooler is built into the radiator side tank, not a separate part — this job most likely doesn't apply to your vehicle (cooler service happens with radiator replacement). Standalone auxiliary coolers are typically found on trucks, vans, and vehicles with a tow package.

✓Fact-checked. Built from OLP's spec database, then independently fact-checked line by line with every correction applied. Master-tech sign-off by Chris Hackleman is queued. Cross-check torque values against the factory manual, and stop if anything looks unsafe. How our data is made.

This procedure covers removal and replacement of the transmission oil cooler on a 2008 Dodge Viper with 8.4L V10 engine and manual transmission, including coolant drainage, radiator access, and cooler line disconnection.

Warnings

⚠️Allow the engine and cooling system to cool completely before beginning work. Hot coolant can cause severe burns.

⚠The transmission oil cooler is part of the radiator assembly or mounted adjacent to it. Coolant and transmission fluid will drain during removal.

⚠Transmission fluid may be hot even after the engine has cooled. Use caution when disconnecting cooler lines.

ℹ️Mark or photograph all hose and line connections before removal to ensure correct reassembly.

Tools required

Floor jack and jack standsEssential

Drain pan (minimum 5 gallon capacity)Essential

Socket set (metric)Essential

Wrench set (metric)Essential

Pliers (standard and needle-nose)Essential

Line disconnect tool set

Torque wrenchEssential

Coolant funnel with adapter

Shop towelsEssential

Safety glassesEssential

Hose clamp pliers

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Parts

Transmission oil cooler assembly × 1 — Use OEM specification
Transmission cooler line O-rings × 2 — Use OEM specification
Engine coolant (if needed for top-off) × 1 — Mopar HOAT coolant 50/50

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Fluids

coolant — 19 qt

Preparation

Ensure the vehicle has been sitting for at least 2 hours with engine off to allow complete cooling of coolant and transmission fluid
Park the vehicle on level ground and engage parking brake
Place wheel chocks behind rear wheels
Raise the front of the vehicle using a floor jack and support securely on jack stands rated for the vehicle weight
Open the hood and remove the radiator cap slowly to release any residual pressure in the cooling system
Position a large drain pan beneath the radiator drain plug location

Procedure

1
Drain engine coolant
Locate the radiator drain petcock on the lower driver's side of the radiator. Open the petcock and allow all coolant to drain into the drain pan. If the petcock is stuck or unavailable, disconnect the lower radiator hose at the radiator connection point using hose clamp pliers to release the spring clamp. Drain coolant completely.
2
Disconnect battery negative terminal
Disconnect the negative battery cable from the battery terminal to prevent accidental electrical shorts during the procedure. Move the cable away from the terminal.
3
Remove upper radiator hose
Locate the upper radiator hose connection at the radiator. Use hose clamp pliers or a screwdriver to release the hose clamp. Twist and pull the hose off the radiator neck. Expect residual coolant to drain.
4
Disconnect transmission cooler lines from radiator
Locate the two transmission cooler lines connected to the transmission oil cooler at the radiator (typically on the passenger side). These lines use quick-disconnect fittings or threaded compression fittings. If quick-disconnect style, use a line disconnect tool to release the locking tabs while pulling the line away. If threaded, use a flare nut wrench to avoid rounding the fittings. Have shop towels ready to catch transmission fluid spillage. Cap or plug the lines immediately after disconnection to prevent contamination.
5
Remove radiator mounting hardware
Remove the radiator mounting bolts or brackets. The 2008 Viper radiator is typically secured with mounting bolts at the top corners and lower mounting points. Remove the upper radiator mounting bolts first. Note the exact position of any rubber isolators or spacers for reinstallation.
6
Disconnect lower radiator hose (if not already done)
If the lower radiator hose was not disconnected during coolant draining, release the hose clamp at the radiator end and remove the hose. Move the hose out of the way to provide clearance for radiator removal.
7
Remove radiator assembly for cooler access
Carefully lift the radiator assembly upward and out of the engine bay. The radiator may need to be tilted slightly to clear mounting points and hoses. Have an assistant help with this step as the radiator is heavy and awkward. Set the radiator on a clean work surface with the transmission oil cooler facing upward.
8
Remove transmission oil cooler from radiator
The transmission oil cooler is either integrated into the radiator tank or mounted externally to the radiator. If external, remove the mounting brackets securing the cooler to the radiator. If integrated, the cooler lines will connect directly to ports on the radiator. Remove any clips or fasteners securing the cooler. Carefully separate the cooler from the radiator, noting the orientation and position of all seals and gaskets.
9
Install new transmission oil cooler
Position the new transmission oil cooler in the exact orientation as the original. Install new O-rings on all connection points, lightly lubricating them with transmission fluid before installation. Secure the cooler to the radiator using the mounting brackets and fasteners removed earlier. Ensure all seals are properly seated and no cross-threading occurs on threaded connections.
10
Reinstall radiator assembly
Carefully lower the radiator assembly back into the vehicle, ensuring it seats properly into the lower mounting isolators. Align the mounting bolt holes and install the radiator mounting bolts. Tighten the mounting bolts securely but do not overtighten, as this can crack the plastic radiator tanks.
11
Reconnect all hoses and lines
Reconnect the lower radiator hose and secure with the hose clamp. Reconnect the upper radiator hose and secure with the hose clamp. Reconnect the transmission cooler lines to the radiator, ensuring the quick-disconnect fittings are fully seated and locked (you should hear or feel a click). If threaded fittings, tighten to a snug fit without overtorquing.
12
Refill cooling system
Close the radiator drain petcock if it was used. Using a coolant funnel, slowly refill the cooling system with Mopar HOAT 50/50 coolant through the radiator neck. Fill until coolant reaches the base of the filler neck. Allow time for air bubbles to escape. Check the coolant overflow reservoir and fill to the COLD mark.
13
Reconnect battery and bleed cooling system
Reconnect the negative battery cable. Start the engine and allow it to reach normal operating temperature with the radiator cap still off (use extreme caution around the open radiator). Monitor coolant level and add as needed while the engine warms up and the thermostat opens. Watch for coolant circulation in the radiator. Once the engine reaches operating temperature and coolant level stabilizes, install the radiator cap.
14
Check transmission fluid level
Note: The 2008 Viper is equipped with a Tremec T56 6-speed manual transmission, which is not cooled via a radiator-integrated transmission oil cooler. Verify whether this vehicle actually has a transmission/gear oil cooler before proceeding; if the cooler being serviced is an engine oil cooler or differential cooler, adjust the fluid and procedure accordingly. If a manual transmission fluid check is required, check level per the service manual (level ground) and top off with the manufacturer-specified 75W-90 manual transmission fluid. Note: Add the manufacturer-specified manual transmission fluid (Mopar Manual Transmission Fluid / SAE 75W-90 per service manual) as needed to bring fluid to the proper level.

Reassembly

Ensure all hose clamps are properly positioned and tightened
Verify transmission cooler lines are fully connected and locked in place
Double-check that no tools or shop towels were left in the engine bay
Lower the vehicle from jack stands safely

Verification

Start the engine and inspect all connections for coolant leaks while the engine warms up
Check transmission cooler line connections for any transmission fluid leaks with the engine running
Monitor the engine temperature gauge to ensure it reaches and maintains normal operating temperature without overheating
After a 10-minute test drive, re-check coolant level in the overflow reservoir and transmission fluid level
Inspect the ground beneath the vehicle after the test drive for any signs of coolant or transmission fluid leaks