Boost gauge help please

[MistralS60]

Hi all

Just bought a used goost bauge off the bay, alleged to be from a scooby but no markings to confirm that.

Problem is, it reads just over 2psi with nothing connected, and I can suck it down to ~5 on the vacuum side but can blow it up to only about 3psi.

Is this normal ? A mark on the dial suggests someone has already been inside it, but I can't get it apart myself.

If / when I have one worth fitting, is the arrowed joint the right place to which to connect it ?

[LeeT5]

Hi all

Just bought a used goost bauge off the bay, alleged to be from a scooby but no markings to confirm that.

Problem is, it reads just over 2psi with nothing connected, and I can suck it down to ~5 on the vacuum side but can blow it up to only about 3psi.

Is this normal ? A mark on the dial suggests someone has already been inside it, but I can't get it apart myself.

If / when I have one worth fitting, is the arrowed joint the right place to which to connect it ?

Do not use that gauge. It needs to rest on '0' psi, otherwise any reading will be false.

You could connect it to where you originally pointed, but it's far easier to connect it here:



.....Although, there is a one way valve in that hose and my question to Tim would be...

Which is the best location to T into the vac line, left of the valve between Plenum and valve or right of the valve, between valve and other one way valve further round the side of the block?

Will it make any difference to gauge readings?

[Gold 'N' Brown]

Lee, wouldn't it be better plumbed between the turbo and the first valve (which is beside the block)? That way the one way valve is not interfering with readings. If plumbed after the one way valve, would the gauge stick at the highest boost reading and not fall back when off boost, due to the 1 way valve doing what it is supposed to do?

[LeeT5]

You cant have a + and - pressure at the same time, so the gauge will be either reading boost or vacuum, not both.
For the gauge to stick at a high reading it would be either knackered or on permanent boost.

I just wanna know if the gauge will work better in a certain location in relation to the valves? I'll check to see where mine is again, and I may consider moving it to see if it works better.

[Gold 'N' Brown]

Maybe I wasn't clearly explaining my thought process.

With no 1-way valves in place, the gauge will read either boost or vacuum depending on the conditions at the time. It will react either way. Now if you stick a 1-way valve BEFORE the gauge, a valve that will allow air to travel only one way, would it not be the case that upon boost the gauge will shoot up to whatever boost value it sees but then the 1-way valve prevents the boost from bleeding back out of it, hence the gauge stops at that reading and does not fall away as boost reduces?

In my mind it's like any other sort of pressure gauge - take a compression tester for example - you pump it up to a certain + value and then it stays at that reading until up press the valve in to release the air back out again. That release valve is like the 1-way valves we are talking about here.

EDIT: And after typing all that I've just realised that the boost can still "bleed away" back through the intake, so I'm talking ££££££££. haha

[M-R-P]

Plumb it into the recirc pipe.

[MistralS60]

Thank you, Lee, that's what I thought, but didn't want to make a fool of myself returning the item, unaccustomed as I am to Volvos and goost bauges.

And thanks to all who've joined in !

M-R-P - Isn't the recirc pipe down under t'mill ? Can't get there ! If where I originally pointed is on the plenum as I think - see below - I'm quite happy to plumb a boost gauge to there, always assuming I can find a suitable tee, of course.

I've seen the horrid little offtake arrowed in green, but it's a bit awkward to get at

[M-R-P]

That's the recirc pipe

[MistralS60]

Arrh, thank you . And that's the recommended offtake, or can I use my fave spot ?

[960kg]

As above ^^^^^^what MRP says it should be connected as near as possible to the manifold on the recirc. hose.

You have no picture of the guage but if to 30psi or to 2 bar ....these cheaper gauges are not calibrated properly and do not rest on "0" ....maybe why the previous owner of it took it to pieces?

I wouldn`t use it as if your at the top of your boost pressure reading you use what is to say too much and bang?

I had to start with on my V70 T5 a 0-20psi and i felt it was boosting more than that according to how i adjusted the actuator so i took mine to pieces and found a stop at 20psi so it was over boosting and it still said 20!!

I bought about 3 or 4 0-30psi gauges and they were returned as they were all faulty and different suppliers.......in the end i bought a digital 0-30psi which was spot on and with a battery conditioner inbuilt for the same price as the faulty ones.

If your fav spot is nearer the throttle plate then use it......it should be as near to this plate as possible for accurate boost.

[Harvey]

Have a watch of ipd fitting a guage.

[MistralS60]

And the video is spot on, even for RHD ! Thanks again, Harvey, what a relief

If you want your gauge near the middle of the dash just remove the steering column shrouds and instrument panel surround (not the panel itself), then the black cover over the panel, and you can route the tube without having to stand on your head and ££££ in the footwell.

NB the cover has 4 screws, two of which are at the back. Try not to drop them in the works !

[MistralS60]

.....Although, there is a one way valve in that hose and my question to Tim would be...

Just realised who Tim might be.

TIM wasn't the manufacturer of the faulty gauge. I now have a TIM gauge which shows zero when not connected .

[LeeT5]

Just realised who Tim might be.

TIM wasn't the manufacturer of the faulty gauge. I now have a TIM gauge which shows zero when not connected .

...and who might that be then?

[MistralS60]

Time Instruments Ltd, as if you didn't know

[LeeT5]

Time Instruments Ltd, as if you didn't know

Actually, I didn't.

Thought you were referring to the forum Master!

[MistralS60]

Ah, I didn't know about Master Tim .

My gauge is now plumbed into the recirc pipe as recommended by M-R-P and working fine.

Thanks chaps.