Help identifying part

[mrbeanieca 0]

Hi all, need help identifying a part in a 1994 Esprit S4.

It's located on top of the battery enclosed in a foam box. See attached picture. It's making some weird noise (some motor noise) constantly.

It has part number 003 953 08 and GM and Hella logo on it.

Thanks in advance!

Erik

[slewthy 99]

Great Scott!

Its the Flux Capacitor!!!!!

Sorry.

Where do the connections go and what happens when you disconnect it?

[mrbeanieca 0]

Hi Simon....I haven't tried to disconnect it yet. There is one hose going back to the engine compartment and a wire to get power. I'm guessing it's emission equipment that's only available on USA cars...

[andydclements 271]

Vacuum pump?

[yeller77 17]

Whatever you do, don't cut the red wire!!

(OK, I've got an S4 parts list and will try to look it up. )

[Malc Holmes 2]

Its most definitely your vacuum pump for opperating the heater system controls.

Malc

[Günter 23]

Hella/Bosch-00395308 should be A082M6518F ...the pump for heater-flaps and engine management in your type of car

but why is it not fitted, isn't the box for storage only ?? ..or does it some 'sound insulation work' as you mention it is noisy..

[Sparky 792]

It's fitted inside the foam block for vibration/sound insulation.

[Günter 23]

anything with an electric-motor in it will heat up over time....so this insulation is a part of Lotus engineering, or is it really the meant Bosch type of application -as surprisingly a mounting bracket is clearly shown.

So the noticing of this 'constant noise' means a vacuum leak

-or just strange fun on 1. of April -to test our skills, Sparky ?!

[Sparky 792]

Honest! It should only run for a few seconds at a time to maintain vacuum, so it's unlikely to heat up. If running constantly, there's likely to be a leak somewhere. A fair amount of vacuum pipework runs from it - there should be an explanatory diagram stuck to the inside of the deck.

[yeller77 17]

Hella/Bosch-00395308 should be A082M6518F ...the pump for heater-flaps and engine management in your type of car

...what Günter said. Good luck getting it sorted, Erik!

I'll go back to the G-car room now.

[sailorbob 59]

If it is running constantly then disconnect the electrical connection otherwise it may quickly burn out.

[wookiecj 8]

Disconnect the pipe from the end of the pump unit and put your finger over the exposed pump inlet it when it is running. It should stop running in a very short time 'cos it cuts out when it has created enough vacuum. If it doesn't then that is a good indicator that the sensor mechanism inside the pump is not doing its job.

Assuming that the pump does cut out, reconnect the pipe and then move along to the next joint/component... disconnect that and put your finger over the end of the pipe. It may take a bit longer to cut out as it has a greater volume to evacuate! When you get to the point where the pump does not cut out you can reasonably assume that there is a leak between the last 'good' point and the one you are currently at.

Be aware that if you reach a 'T' junction, you will have to block off the path to the run you are not evaluating or you can get yourself very confused. Of course you may have a leak on both sides of the 'T'... hence only check one run at a time.

Good luck, it's a tedious job and you may discover nooks, crannies and recesses that you never knew existed on the car... been there, done it, got the t-shirt!

[mrbeanieca 0]

Thanks everyone for your insight! As Gary mentioned, it is running for 1-2 seconds, then paused for a few seconds, then run for 1-2 seconds again. It repeats this cycle as long as the car is running. Would that be normal operation?

Erik

[sailorbob 59]

It typically only runs when the heater controls are adjusted causing the flaps to move or at start up when the throttle jack butterfly is closed.

[Newts 16]

Does anyone know why Lotus chose to operate the heater flaps by vacuum instead of the usual cable operated systems ?

[Sparky 792]

Colin - can't answer that, but it's common across many manufacturers. Maybe just a servo assist thing?

If it's running every few seconds, there's probably a minor leak somewhere. These aren't easy to find! As Chris said, just keep tracing it out and exclude circuits, you'll get there eventually. These are pretty robust pumps, and I've seen quite a few that do this and seem to last forever.

[GodFatha 0]

Is it possible to find the 'wiring diagram' for the air-hoses?

Mine was always on, all the time. I located the leak under the front dash, under the steering wheel. What I've done is just to close it temporarily is putting a toothpick on it. But I don't know if, and where, the hose should bee attached?

Any suggestions?

[lotus4s 19]

I believe that vacuum tubing under the dash is attached to a valve on a cam/actuator switch on the back of your a/c controls. The control is used to change the vent settings.