BOV harness connector

[Turftech]

Just what exactly does the wiring to the blow-off valve (BOV) do anyways? Is there a light that comes on while the BOV is active? I have run the engine with that connector off and didn't notice any difference. What does it do?

edit: sorry, should have said it's an engine out of 1990 Jetta TD, MF idi to be exact.

[vanbcguy]

There shouldn't be any wiring connected to the overboost protection valve. I believe the switch in it was only ever used on a few Audi vehicles to turn on a dash light.

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[Turftech]

If it is indeed merely for an idiot light then it will not be missed. I guess they reckoned Audi deserved to know if the boost was routinely too high and relatively bare-bones Jetta owners were best kept in the dark.  Mind you, this little motor is more than capable of dealing with any transient extra boost it might get.

Cheers!

[RabbitJockey]

do you have a picture?

[vanbcguy]

There is a wiring connector nearby that should be plugged in to a small heater on the end of the crankcase breather hose where it connects to the intake pipe... Maybe that's what the plug you have is for.

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[westcoaster]

There is a wiring connector nearby that should be plugged in to a small heater on the end of the crankcase breather hose where it connects to the intake pipe... Maybe that's what the plug you have is for.

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I wondered what that thing was on the end of the crank case breather hose...
A heater? why?
Since my engine is swapped into a samurai I have no wiring for that. Advantages/disadvantages to connecting or not?

[Turftech]

The plug port itself is on the boost valve assy. See item #1 at the following: http://etka.cc/vw/part_single/catalog/vw/markt/USA/modell/JEG/year/1990/drive_standart/110/hg_ug/129/subcategory/42000/part_id/3697443/lang/e

The engine is sans car right now and sitting on a stand in my garage, about to be sent to a new home in an '81 caddy. I am just determining if that bit of function can go unused.

[libbydiesel]

There is a wiring connector nearby that should be plugged in to a small heater on the end of the crankcase breather hose where it connects to the intake pipe... Maybe that's what the plug you have is for.

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I wondered what that thing was on the end of the crank case breather hose...
A heater? why?
Since my engine is swapped into a samurai I have no wiring for that. Advantages/disadvantages to connecting or not?

Increasing the pressure of a gas makes the temperature rise, decreasing the pressure causes the temperature to drop.  The crank vent goes from a higher pressure zone (engine block/head) to a low pressure zone (turbo compressor inlet hose).  That sudden drop in pressure and consequently temperature can actually cause moisture in the gases to freeze into ice crystals in some conditions.  Those ice crystals going through the turbo compressor is bad for it. 

[air-cooled or diesel]

so correct me if im wrong, cause were running a turbo here. the ccbreather hose, will go into intake before turbo;     

[Turftech]

Increasing the pressure of a gas makes the temperature rise, decreasing the pressure causes the temperature to drop.  The crank vent goes from a higher pressure zone (engine block/head) to a low pressure zone (turbo compressor inlet hose).  That sudden drop in pressure and consequently temperature can actually cause moisture in the gases to freeze into ice crystals in some conditions.  Those ice crystals going through the turbo compressor is bad for it. 

Forgive me if I go back to my original question, are you saying that heater or whatever it is should be connected to 12v, even if it means tapping into the harness somewhere? To be perfectly honest, I do not fully recall whether there was a connector connected when this engine was still residing in the donor Jetta, but even if it wasn't, should it be activated in it's new home, the caddy? It would not be much trouble at all to leach power and energize that heater, if indeed that is what it is.

[Turftech]

Hold on a sec here. My mistake, I confused that breather heater in the rubber intake plenum for having been connected to the BOV -- for some reason. Must be some kind of weird flashback to the 70s or something, because upon close re-examination just now it is abundantly clear that what I imagined was a connector is in fact a formed port on the valve that escaping boost takes to atmosphere and not an electrical connector at all! Yes, there is a small heater on the breather and for some reason I got the two mixed up.

I really should have exerted more self control back in 1977, then maybe I wouldn't be hallucinating so much... However I will suggest to the new owner of this motor that he should find a power-source for that heater, assuming one does not already exist on the caddy, and I would bet money it doesn't.

[air-cooled or diesel]

There is a wiring connector nearby that should be plugged in to a small heater on the end of the crankcase breather hose where it connects to the intake pipe... Maybe that's what the plug you have is for.

yea van,guy made this suggestion, i suppose we got carried away with subject; we dont get enough attention here, and the explanation comes out.

[westcoaster]

Ok, back to the CCV heater, just connect that to any old electric source that turns on with the key?

And what kind of draw (amps) does it take?

[vanbcguy]

It's low draw. It's also one of those things that probably needs a particularly specific set of circumstances to be a problem which doesn't come along all that often.

Yep, it's just 12V with key on. It's probably on the fuel cutoff solenoid circuit but I haven't actually verified that.

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[libbydiesel]

I don't recall the circuit it is on, but if retrofitting, I probably would choose a different circuit from the stop solenoid.  The stop solenoid circuit is unfused as it is essential.  I'd avoid non-essential items on unfused circuits.