Many aftermarket gauges and data acquisition systems use VDO pressure sensors because they are inexpensive, yet accurate and reliable. Unfortunately, two things that can dramatically shorten the life of a VDO sensor are heat and vibration -- two things you'll find a lot of around a racing engine!
Protecting your VDO pressure sensor is as simple as locating it a little distance away from the heat source, with a flexible connection to absorb the vibration. That may sound complicated, but in fact just four parts (plus some basic shop supplies) will do the job.
What you need
You will need one each:
- Premade 3AN Brake Hose, Part No. 3-Length-Ends
- 1/8 NPT Male to 3AN Male Adapter, Part No. 3250-02-03S (assuming a 1/8 NPT female port)
- 3AN Male to 1/8 NPT Female Adapter, Part No. 3254-02-03S (assuming a 1/8 NPT male fitting on the VDO sensor)
- 1.5" Lined Support Clamp, Part No. 4350-1.500 (a snug fit on the 40mm OD of the VDO sensor)
- Pipe thread sealant (such as Loctite 565 PST Thread Sealant, Part No. LT-37396) or PTFE tape
- 1/4" mounting screw or bolt
What you need to do
First, pick a convenient spot for the sensor. We recommend somewhere on the bodywork of the car (assuming a steel body shell) such as the firewall or an inner fender panel. The distance from the engine is not critical because we offer our premade brake hoses in a wide variety of lengths, all the way from 12" to 48".
Next, install the male-to-male adapter in the port on the engine using thread sealant on the NPT threads. Install the female-to-male adapter on the VDO sensor using thread sealant on the NPT threads.
Now connect the hose between the two adapters. Do not use any thread sealant on the 3AN threads. These connections seal at the flare at the end of the male fitting.
Place the VDO sensor inside the mounting clamp and secure the clamp to the car using the 1/4" screw or bolt. Connect the sensor wiring as needed.
The finished assembly should look something like this:
Finally, start the car and check for leaks.
What about other thread sizes?
If your engine block has 1/8 BSP threads, you can substitute our 1/8 BSP Male to 3AN Male Adapter (Part No. 3230-2-3AN) for the NPT male to AN male adapter.
If your engine block has metric threads, use the NPT male to AN male adapter and add one of our 1/8 NPT female to metric male adapters (Part No. AM2265 for M10x1.0 threads, Part No. AM2277 for M12x1.5 threads, Part No. AM2267 for M14x1.5 threads, or Part No. AM2268 for M16x1.5 threads).
If your VDO sensor has 1/8 BSP threads, substitute our 1/8 BSP Female to 3AN Male Adapter (Part No. 3252-2-3AN) for the NPT female to AN male adapter.
What about other sensors and senders?
These instructions specifically apply to the following VDO pressure sensors we carry:
AiM 0-150 psi VDO Oil Pressure Sensor (formerly Part No. MC-320)
AiM 0-72 psi VDO Pressure Sensor (formerly Part No. MC-323)
AiM 0-30 psi VDO Pressure Sensor (Part No. MC-204)
Stack 0-150 psi Analog Fluid Pressure Sensor (Part No. ST745K)
Other VDO sensors may require different adapters as outlined above. Different brands may require a different size or type of mounting clamp, but the basic principle of isolating the sender from heat and vibration still apply.
Note that this cannot be done effectively with temperature sensors. Pressure can travel quickly and efficiently through a hose to a dead end, but temperature does not.
This article was first published on 8/18/2016.