17 replies to this topic

[Ozymandias]

This may be a criminally dim question (and if it is, forgive my lack of understanding about these things!), but...

 

Can you fit a vacuum gauge to one of the hoses that run from the manifold ---> fuel trap --->ECU/MAP sensor on a '95 SPi to alert you to leaks/poor vacuum?

 

Or doesn't it work like that...?

[pierres]

Hope this helps

http://www.iwemalpg....acuum_gauge.htm

[spiguy]

Don't know what that guide means about T'ing in to the source line from the heater system?  I was planning on fitting one using the red line which normally operates the hot / cold air flap. I have disconnected and plugged mine anyway as the valve it connects to leaks (causing a vacuum leak) and I don't think it achieves much anyway - the car heats up in a few minutes anyway.

 

I think that it would be fine to T into the vac line for the ECU / hot cold flap, though it might need an in line restrictor to avoid violent movement of the needle. I haven't got round to trying this yet.

[Ozymandias]

Don't know what that guide means about T'ing in to the source line from the heater system?  I was planning on fitting one using the red line which normally operates the hot / cold air flap. I have disconnected and plugged mine anyway as the valve it connects to leaks (causing a vacuum leak) and I don't think it achieves much anyway - the car heats up in a few minutes anyway.

 

I think that it would be fine to T into the vac line for the ECU / hot cold flap, though it might need an in line restrictor to avoid violent movement of the needle. I haven't got round to trying this yet.

 

 

My Min has a K&N air filter rather than the standard SPi one, so the air filter to manifold pipe (which I think is the one you mean! ) is just blanked off - so could I run a hose straight from the vac gauge to the connection point for the red "air filter to manifold" pipe?

Edited by Ozymandias, 23 June 2015 - 04:30 PM.

[spiguy]

That was what I was thinking I would do. I can't see how it would affect the running of the car if you went on to that line, there shouldn't be any difference between 'evacuating' the volume of the gauge internals compared to the internals of the hot/cold air flap valve. The only issue I could see would be if the gauge was faulty and caused a vac leak. Also my dad (who's 60's Smiths vac gauge I would be using...) told me you are supposed to use a restrictor to make sure that the vacuum changes are not to sudden otherwise it can wreck the gauge. I think I will just try it and see what happens, it might be fine.

[spiguy]

Well, fitted the smiths vac gauge to the red line tonight and it works a treat. Going to get a pod and fit it properly

[Ozymandias]

Thanks spiguy! I'd better get myself a vacuum gauge, then...!

[spiguy]

Just remember, it's more important to look out the front window than stare at the constantly changing gauge! And don't be concerned when you plant your foot and it drops to near zero - the gauge I have is a 60's Smiths one - I think I mentioned before it is actually my dads and was fitted to his 60's 850 mini van, this is why I am fitting it really for sentimental reasons.  The gauge is marked poor, fair, drive, idle and decelerate. When the foot is down, it is in the Poor range, which I wondered about but after reading the Smiths instructions, this is normal. Idle is self explanatory, as is decelerate, drive is light throttle, fair is medium throttle and poor is going for it!.

[Ozymandias]

I also have a vintage gauge which I'm going to fit, once I've got my dash rail gauge holder sorted... but this is a Machmeter from a 1960's jet fighter...!

 

It won't work, obviously, but it'll look great. And a Mini can dream...

[RooBoonix]

I used a metal T-Piece and due to me using silicone hoses which I cut myself I just T'd in the hose that goes to the ECU. Works well.

[Ozymandias]

Would it be worth having another gauge to measure the vaccum in the breather hoses that go from the advance/retard through the rail on the block?

[FlyingScot]

Would it be worth having another gauge to measure the vaccum in the breather hoses that go from the advance/retard through the rail on the block?

What advance/retard? I think you are mixing up the breather/emissions system.

Fs

[Ozymandias]

My mistake, Flying Scot - I thought one of the hoses from the rail on the cylinder head went to an advance/retard unit. I don't think I meant to say "breather" hose... doh...

[FlyingScot]

No worries, the ignition timing is controlled by MEMS on the fuel injection cars.

FS

[Ozymandias]

Well, fitted the smiths vac gauge to the red line tonight and it works a treat. Going to get a pod and fit it properly

Did you have to use an adapter to get the Smiths gauge to tap into 3mm/4mm ID vac hoses?

 

I've just got the gauge and it looks like the ID of the nozzle the hose attaches to is about 5-6mm...