Understanding the vacuum system

[Bijan]

Hi Dinoisti,

the other day when I was taking my Dino 2400 Coupe for a spin I noticed lots of blue smoke out of my
right exhaust pipe. I first thought that my engine is broken and the next step would be to withdraw 15k EUR from my
bank account to finance a complete overhaul of the engine, but when I looked at it more closely I realised that the vacuum
pump was the reason for the the trouble. The engine bay was full of oil that dripped out of the vacuum pump on the exhaust
manifolds causing the smoke. Also I think some of the oil has been sucked into the 3rd cylinder where it was burnt.

The result of a deeper analysis was:
- There is an override switch installed for my pump, so it works all the time or not at all.
- According to the repair manual it is supposed to work only 10 seconds constantly at maximum

My Questions:
- How can I test if the vacuum switch that controls the pump is working or not?
- Who can tell me what the correct wiring for the system is? Please note that there
is no information at all about the vacuum system in the official wiring diagram.

Thanks guys

Bijan

[Dario]

Hi Bijan,

Maybe this comes too late, but there is a vacuum-operated electrical switch attached near to the pump. It is connected to a small relay and operates whenever the vacuum is below a set point. There is a screw behind the dust cap that allows you to set this point. Ideally, the pump will turn on when you turn the key and stay on until the correct vacuum is reached (ca. 10s if all is well). Then, it turns off by itself and stays off provided you do not pump the brakes a lot at idle. There is a vacuum canister in the front fender to smooth out the system. I'm away from my car, but I can take pictures for you it you need me to.

Good luck,

Dario

[ebrown5686]

Hi Dario and Bijan,
I too am having a problem with the vacuum brake system on my 2400 spider. The pump works fine if I put current directly to it...actually surprisingly smooth and quiet! It's never worked when the car runs in spite of being wired up and connected to all of its oil and vacuum connections. I quit messing with it to work on the engine, clutch, diff, driveshaft, brakes, etc.
I've never been sure of the correct wiring, and have left it the way I got the car. I have looked but never found a wiring diagram that covers the pump system. In my car there is also a silver relay below the pump, as well as a device sitting against the firewall (temp sensor?) wired into the silver relay in addition to the components you mention Dario. When I remove the dust cover on the vacuum sensor/relay the adjusting screw is coated with some very hard material presumably to avoid tampering.
Now that I have a little time to come back to the vacuum system, I'd love to work with you guys on learning more about the system and maybe get mine running.
To Bijan...when I was cleaning up the engine bay, I pulled the vacuum pump off, removed the top cover on the pump and cleaned some corrosion in the chamber where oil flows through. What a fragile-looking little gasket under the cover! Can you tell where the oil is coming from? The oil fittings or perhaps that top gasket?
To Dario... many thanks for your explanation of the pump's proper function! It's the best one I've ever read. So this little pump should come on every time I start the car? Do you happen to know how to adjust the screw on the vacuum sensor? Could we perhaps compare notes on wiring? I'd be glad to shoot a few pictures of mine for comparison.
Good luck to you Bijan on the oil problem and hope it's already remedied. Keep us posted. Thanks again Dario and if you've got any further input on this frustrating little system I'd love to hear from you.
I wonder how many other 2400 owners actually have correct-functioning systems?
Thanks again,
Ed

[Dario]

Hi, I've had a request for pictures of the vacuum system, so I shot some this morning when I took the car out to go to work

Here is a front pic of the system. I drew yellow circles on the oil lines (the small one is the oil delivery, the large one is the oil return line). A blue circle on the vacuum line to the system, a blue "X" on the line to the pump vacuum switch

On the next pic, you can see where the vacuum pump connects to a metal pipe through a T junction. The front connection goes to a large canister in the front bumper. The back connection goes to the brakes and vacuum switch

On another pic, I drew a circle around the relay and disconnected the wire from the vacuum switch for you to see. It's not the original relay (obviously) but I think it's the correct location judging from the length of the wires.

Lastly, you can see where the metal pipe goes along the back of the engine bay and separates into a vacuum take-off from the engine and a rubber hose to the park booster.

Sorry for not imbedding the photos, it's not working too well for me and they move all over the place...

Hope this helps,

Drop

[maduno]

Dario,
I attach some photo's from a friends Dino.In one you can see a round device with two wires.You don't have on your car it would appear.Is this the fuse you refer too? What purpose does it serve? As I have a Superformance modified 2.3 litre alloy block engine ,I presume I could add an oil tank to supply the Vacuum Pump for lubrication for the 2 smaller flow and return lines, rather than connect to the engine.Then add a powered relay to supply the Vacuum Switch and Vacuum Pump

[Dinoswede]

Hi guys,

Here are some Fiat original workshop manual pages that might help you solving your servo pump issues. Note that the 2.4 litre
electric diagram really shows the pump, pressure switch and safety switch wiring.
As far as I can understand, there is no oil feed line to the vacuum pump...?

Dinoswede

[maduno]

Dinoswede, There are oil pipe connections not shown on the schematic drawings. See the pictures sent by Dario and look for the 2 small pipes with the orange markings.
Regards
Leigh

[Dinoswede]

Maduno, you are absolutely right! When looking at page G1.03 there is no trace of any oil lines -
probably because they are shown at page A3.01 !!
I owned a 2,4 Dino Coupe for 10 years in the eighties´, and once had a vacuum leaking problem
with the servo pump system, but - obviously - didn´t remember anything about the oil feeding
system...

Dinoswede

[maduno]

Dinoswede, Thanks for adding the 2.4 spider page. I have only the Coupe schematic pages and the oil connections are not shown there.I have found the electrics on the other page you posted, now to see if I can make it work. The only problem I have is determining what item 75 on the elecs is.Vacuum Pump Protector??????? What is this? Is it a fuse seeing that the elec feed is direct from the battery. I am not familiar with the symbol.
Regards
leigh

[Dinoswede]

Maduno, if you search for an old post: "Electrical problem, fuse keeps blowing"
by "sveckan" 15 September 2014, you will find all about the safety switch no 75 !

Please note, when I refer to the safety switch as "no 73", I found that info in the
2,4 Spider Electric diagram. The 2,4 Coupe Electric diagram has a slightly different
numbering...


Dinoswede