VW T25 1.9l oil pressure switch

[Phil1080]

Just wanted to check incase I create a lot of unecesssary work but I think what I'm saying is the only option.

My T25 was red lighting on the oil light on startup. It would go off after approx 5 mins.As such I figured pump or pressure switch. The blue switch I think which is fit to the location used to check oil pressure was going to be changed first to quickly check if it was just a switch issue. I looked in some doc which said 30nm torque but socket took it off with very little pressure and oil was on the termination external. I put a new pressure switch in but lo and behold it does not tighten and just spins and spins. Is it now a case of either remove the cylinder head and fit helicoils or replace the cylinder head at around £400 (forgetting all the seals etc)?


Any help/confirmation that this is the only solution would be great.

Thanks

[937carrera]

First post, so welcome

On your issue, it might help if you said what engine is in your van , even better if you put the details in your signature

[Phil1080]

Cheers for the ad. Apologies, engine is as per the title. Had to enter twice and then forgot to add everything again.

Its basically a VW 1986, autohomes komet, with a 1.9l waterboxer engine. Its been getting refurbed for the last year and just as I thought everything was done and with mot just passed was bit gutted when the red light popped on. I've a couple garages who are going to have a look next week but thought I'd ask you all first as you'd be more clued up.

[937carrera]

OK, so the oil pressure switch you are referring to is the one between the pushrod tubes on cylinders 3 & 4, left hand side of the vehicle.

You can test the wiring easily by simply putting the ignition on, engine not running.

Spade on the switch, light should be on
Spade dangling in free air, light should be off.

You can still test the wiring out by earthing the spade on the engine

If the threads have gone on the crankcase then you have a couple of choices.

Try and helicoil in-situ. The risk is some swarf finds its way into the crankcase which would be a bad thing
Engine out and stripdown - to completely avoid the swarf issue it's actually a crankcase split,

What would I do ?

Try and helicoil in situ. You can do things to minimise the risk of swarf entering the crankcase. Fiddly job, but it's only aluminium that needs to be cut, so I think with the right experience it is possible.

The oil pressure going off after 5 minutes makes no sense at all. As oil gets warmer it gets thinner and so pressure reduces.

I assume both switches are "blue" 0.25bar switches, both have the same thread.

What happens if you try and put the old one in ?

[kevtherev]

Helicoil it, in place
The alloy won't cause any damage.
M10x1

[Cobra88]

Hopefully you have oil pressure as waiting five minutes with no oil pressure will me your engine is now scrap

[937carrera]

Hopefully you have oil pressure as waiting five minutes with no oil pressure will me your engine is now scrap

As there's no mention of "knock knock who's there" I took the view that it was a false warning

An oil & filter change probably would not be amiss, with an opening up and examination of the oil filter when removed

[Phil1080]

Yeah blue one between push rod tubes. Hoping it's the switch that's gone. Is there an easy way to test the original one standalone Vs the new one or would that involve me having to apply pressure to it. Or is it easier just to deal with the fitment of the new one then see if issue still exists or not? Not up to speed at all with those little pressure switches. If it became a strip down I think I'd prob need to look at selling as I'm at my wit's end. Bit gutting with the amount of time and money spent on it so far. At this rate my couple chassis fixes will be an entire rebuild ha ha. The joys of old vehicles. Cheers for all the help on this. It's very much appreciated with my limited engine knowledge.

[937carrera]

You can test the wiring easily by simply putting the ignition on, engine not running.

Spade on the switch, light should be on
Spade dangling in free air, light should be off.

You can still test the wiring out by earthing the spade on the engine

You can test the wiring as indicated above. The switch is "normally closed" which means if you were to do a continuity test with a meter between the spade and the threads you should see zero ohms. The oil pressure opens the switch, so if the light does not go out there either isn't enough oil pressure, or the switch is faulty.

Just confirm, there was no knocklng from the engine when you were letting it warm up ?

Do you have the ability to do the helicoil yourself ?

[Phil1080]

Ok cool. No knocking. Sounds real good at all times. I'll get a meter and check the original one out.

I don't for the helicoil but can hopefully find someone local. There's a garage local that my dad knows someone at. They should manage

[937carrera]

It's more important to test the wiring out.

Then when you get a new switch fitted you know it will behave correctly

[Phil1080]

Ok cool. I'll check the wiring out this week sometime once I get a meter from work. No doubt I'll find the issue isn't even where the switch was rotating. The way it's gone so far with this thing

[Phil1080]

Ok so I went out to the van at my parents. The switch removed was a dead short between the spade and threads. Compared with the new ones I bought and they're all open circuit. So like you said, so cheers for the info on the switches. So basically no low pressure in the system in theory and should just need the helicoil done. Good news though. I was expecting the worst!

Thanks so much again for all your help! Especially for me, someone who knows little on the T25 engines.

[Phil1080]

I'll buzz out all the wiring too before I fit just incase there is anything else wrong in the circuit.

[937carrera]

The switch is "normally closed" which means if you were to do a continuity test with a meter between the spade and the threads you should see zero ohms.

What you called a dead short is a closed switch or zero ohms. That's normal / correct.

If the replacement is open circuit then it's faulty / the wrong one