Its common for the oil cooler to fail due to its poor design and the cooling fins within the unit furring up / corroding causing it to rupture. As the oil cooler is submerged in coolant, the cooling system becomes contaminated with oil.
The V6 oil cooler is located between both cylinder heads in the V and is surrounded by coolant. This means when it does decide to fail it contaminates the cooling system with engine oil.
The job to replace the cooler is very time consuming due to its location and having to strip everything away to get at it … then theres flushing the cooling system to get rid of all that oil.
1. Before you start get the front of the car up on axle stands, then drain the coolant and the oil.
2. Unclip the five hoses and remove the front part of the plenum assembly.
3. Disconnect wires & pipes from the centre plenum bridge assembly, then remove it.
4. Unbolt & unclip the five hose’s on the rear plenum assembly.
5. The inlet manifold mid section can now be removed from the flange, undo the six Torx[12] bolts that secures it. There are fuel lines connected to this that feed the injectors and I found it best to leave these on and maneuver it to the right next to the battery.
6. Remove the inlet manifold flange … twelve Torx[12] bolts.
Once removed the oil cooler cover plate is at last visible. Put the inlet manifold flange somewhere safe … its only ABS plastic!
There are rubber gaskets on both sides of this, its debatable if to replace these with new, I did not.
7. Remove the coolant bridge on the right side from the two heads.
8. In order to remove the oil cooler, the oil feed pipes that attach to the block either side of the oil filter housing need to be disconnected, but as space is limited for a spanner, the oil filter housing must be removed first … remove the oil filter and undo the hex bolt [12mm] on the inside (in the middle) that secures the housing.
9. Unbolt the oil feed pipes from the oil cooler and push them to one side. Unbolt the eight Torx [12] bolts from the cover plate … remove the cover and pull out the oil cooler … what a mess!
You can test the old oil cooler by using an hose pipe on one end, and blocking the other it should show a leak if its a big enough one, if not you may need it professionally pressure tested to be 100% sure it as failed.
10. Flush the whole system out as much as possible with my recommended coolant flush. This step can take a while as the engine oil would have been distributed around the whole of the coolant system. Ensure you dispose of all fluids responsibly at your local recycling centre, and avoid pouring it down the drains. Antifreeze is nasty stuff for the environment.
A new oil cooler kit can be purchased from www.courtenaysport.co.uk which includes the oil cooler, cover plate, securing nuts, sealing washers and a tube of sealant.
11. Get everything together including a torque wrench then apply the sealing compound (GM part 90511124, now changed to Elring Dirko HT) to the cover plate. Place the oil cooler in the recess with the two sealing washers in place and then the cover plate over it. Torque all 8 bolts to 15lbs/20NM, and the two securing nuts to 22lbs/30NM.
Here’s the new and the old … the design has change for the better by the looks of things … less to fir up anyway.
To reassemble, its a case of working back in reverse using a torque wrench on the important parts, and not forgetting to replace any gaskets, washers and seals with new ones … as you don’t want to be doing this job again due to one leaking! A new thermostat may also be worth fitting while you can get easy access to it, these are all one with casing and are £40 from Vauxhall.
I did also buy a flushing agent for the cooling system, and flushing oil for the engine just to be on the safe side.
This guide will also be useful for the following vehicles :
2.5 V6 – C25XE – Cavalier/Calibra
2.5 V6 – X25XE – Vectra B
2.6 V6 – Y26SE – Vectra B/Omega
3.0 V6 – X30XE – Vectra B/Omega
3.2 V6 – Y32SE – Vectra B/Vectra C/Signum/Omega
Torque settings
Coolant bridge = 22lbs/30NM
Inlet manifold flange bolts = 15lbs/20NM
Inlet manifold mid section = 15lbs/20NM
Oil cooler cover plate = 15lbs/20NM
Oil cooler inlet/outlet unions = 22lb/30NM
If this guide has been useful for you, please let me know.
Find the GM recommended sealing compound for the Vectra V6 oil cooler cover plate along with the coolant system flush by clicking the photo links below …
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Vauxhall Amigo oilcooil
Awesome Blog, all that’s missing is the part number for the cooler.
Thanks Adam
Yes I’ll dig that out for the blog.
Dave