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Safety wire pressure sensors?

rv8ch

rv8ch

Well Known Member
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My build advisor flagged that there is no safety wire on my fuel and oil pressure sensors.

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It does seem like a reasonable thing to do. I can think of some ways to do this, but wanted to check with the VAF brain trust to see if there is already a best practice. My googling has not turned up anything so far. Thanks!
 
I was wondering something similar. I get the feeling that the sensors with NPT threads don't need it because they are friction locked. But I also have some fuel fittings on my EFI that are O-ring sealed threads. I think those should be safetwired for sure, but none of those have any kind of holes for safety wiring.
 
Find a new build advisor, and no need to purge the lines either!
You may also want to throw away those VDO senders now and replace with Kalvico.
 
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Just as a sanity double-check... look at the two visible socket head cap screws installed in the unused ports of that manifold block. Are they safetied with lockwire? Nope. Now go look at every other NPT fitting on your engine, like all the primer connections, the oil pressure fitting, the MAP fitting... Are they lockwired? Nope. And they're right on that vibrating hunk of metal we call an engine!

No need to safety wire the sensors. But as Walt pointed out, the VDO sensors are quite prone to premature wear on their resistive sending element. You'll not be happy when you see your oil pressure and temperature going to zero then bouncing back to life... Very frustrating indeed!
 
A second observation... the two ignition leads coming from the P-Mag appear to be touching both the engine mount and the oil cooler line. The angle of the photo gives this appearance which may not in fact be accurate.

EMagAir recommends these ignition leads be isolated from any contact with metal since that contact could result to arcing through the lead to the ground potential represented by the metal.

It would perhaps be a good idea to secure the leads to the engine mount using non-conductive clamps. (MS21919DG- clamps are specifically NOT recommended by EMagAir for this application.)
 
If you really think about it some of the things we safety and some of the things we don't borderlines the absurd.

For example: it only takes a small amount of turning to break a flared fitting loose where it would leak profusely but very rarely is that done.

But we safety drain plugs that have NPT threads which are impossible to loosen with proper sealing and torque.

Bottom line, anything with a taper thread or tapered sealing surfaces aren't safetied.

Things that have straight threads get safetied, such as the vernatherm and screen cap.
 
Kalvico - part numbers?

Hey Walt,

Do you have suggested part numbers for Kalvico oil and fuel sensors? And where would you typically purchase them? I'm using GRT.

Thanks in advance!

Cheers, Sean
 
Two things stand out to me from your photo:

(1) you don't need to purge the lines to the sensors (air transfers pressure just as well as liquid).

(2) Take the sharp corners off the SkyBolt tabs or you'll draw blood when replacing the oil filter!
 
Canadian_JOY said:
... the two ignition leads coming from the P-Mag appear to be touching both the engine mount and the oil cooler line.
... EMagAir recommends these ignition leads be isolated from any contact with metal since that contact could result to arcing through the lead
Click to expand...

Please elaborate... breakdown voltage for silicone is something like 20KV/mm
(https://chemistry.mdma.ch/hiveboard/rhodium/pdf/chemical-data/diel_strength.pdf) while air has only ~3KV/mm. You would need roughly 10 times more air than silicone to at least match silicone. Assuming at least 3 mm of silicone insulation around the core you would need around 20mm clearance to all metal parts which is insane and not realistic.

One need to avoid running two ignition wires in parallel or along a flat metal part, but for a different reason.
 
About purging air from the sensor lines.....

True that it is not necessary, but if you like to see your oil pressure indication rise quickly on engine start, purging the air will certainly help that.

With air in the sensor head space, it can take several seconds to pump enough volume of oil through the pin-hole restricter on the crank case to compress the air up to pressure.
 
Thanks

Thanks for the feedback. This is a kind of old picture but the best one I had of these sensors.

I did decide to not purge the air as suggested, and it seems to work fine.

The tip on the sharp corners is a good one - will check that. I have not removed the oil filter yet - I think I have enough space, but will confirm.

I think I have pretty good clearance on all the ignition wires now - they have gone on and off a few times since this photo was taken.

I also would love to hear about better pressure sensors - these VDO sensors seem to be really for what they do, but they are what GRT recommended. If I change them, I'd like to use something that GRT support. I am currently faced with changing the temperature sensor since the one I used is for a different software version on my EIS 4000. :S

Thanks again for the tips!
 
I have a couple of VDO oil pressure transducers on Subaru engines, mounted on the engine, that are almost 20 years old.
 
svyolo said:
I have a couple of VDO oil pressure transducers on Subaru engines, mounted on the engine, that are almost 20 years old.
Click to expand...

VDO - 800 hours, 12 years. First I have heard they are junk. Guess I didn?t need to know..... and will be in no rush to remove them. (Provided by JPI as part of their EDM930 package).

In regard to getting a new advisor, I would rather have one who is over the top than one who misses stuff. You can always do your sanity check here. The safety wire thing is a bit surprising though. Makes one think where he got his ?qualifications?.
 
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