Some people may have remember a lengthy thread quite a while ago about senders, where to put them and thread sizes etc etc. Today i fitted mine.
Now, where do i start? On a standard XE there is a pressure sender/low pressure switch combo (astra gte only) or just a low-pressure switch (all other XE and LET). This lives in the rear of the oil pump and is identified by the green arrow in the picture below. (Low-pressure switch shown) The thread size for this is metric, M14x1.5
The normal route to add an aftermarket sender is to fit a T piece into the rear of the oil pump then fit the standard sensor/switch and the new sender to the T piece. This is what i set out to do, I had a 1/8 bsp oil pressure sender from demon tweaks, the T piece reflected this, M14x1.5 to M14x1.5 + 1/8 bsp. In reality space is tight, and sods law said that when the T piece was screwed in and tightened, the hole for the aftermarket sender would be facing the block and be useless, and this is exactly what happened.
So, what now? Well in the older thread there was mention and picture of 2 blanking plugs in the main oil gallery to the rear of the oil pump. One of the holes is used for the turbo oil feed on LET engines, and that’s pointed out with the red arrow in the picture below. On XE’s it just has an allen head plug wound in it. So, I took this out on my engine and oil dripped out, this was a good sign. It’s the same thread as the hole in the rear of the oil pump, which was even better news. So a new home was found for the standard pressure sender/switch. Trouble is I still have a T-piece with the hole facing the block; so having the T piece in the rear of the oil pump was a no no.
Next I wound out the second blanking plug, which is identified with the yellow arrow in the picture below. Oil also poured out of this hole, good news part 2. I took the T piece out the oil pump, replaced it with the blanking plug from hole 2, and then wound the T piece into hole 2. It tightened just as the side hole began to face the oil pump, just enough room for the after market sender. So, wound the sensor in, used the plug from hole 1 to plug the now redundant second leg of the T piece and its virtually job done.
Lastly I ran a single wire down the bulkhead for the signal from the sensor. Hooked it all up in makeshift fashion to the gauge then started the engine. Pressure registered straight away and a nice healthy 6 BAR cold idle. I left the engine running and had a snoop about underneath for leaks, no leaks from the senders and fittings, but the sump was weaping (shock horror) so nipped up those bolts then let the engine heat up. Engine got up to running temp and by this time the pressure guage was dead on 4 BAR hot idle, rising to about 6.3 when revved. Excellent, packed up, job done.
I’m still not happy with the T piece which is technically redundant, so ive ordered a plain M14x1.5 to 1/8 bsp adapter, then it can go back in its rightful home in the rear of the oil pump.
Just a sub note, I can confirm that the Vauxhall sender range is 0-5 BAR pressure (0-72psi) and each of the 5 yellow bars on the digi dash represents 1 BAR pressure each. So that means before I increased the tension in the oil pressure relief valve I was getting 3 BAR hot idle (5 BAR cold idle), 5 BAR revved, Roughly a 1 BAR increase at all stages then.