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1983 300TD Wagon
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14 Posts
Discussion Starter #1
When I was cleaning the ALDA banjo bolt on the intake manifold of my '83 300TD, I saw that my ALDA unit is directly connected to this bolt, and the ALDA sitchover valve has been by-passed. I'd like to reconnect the circuit to run through this valve

1) Which line on the valve is the intake (from the ALDA) and which is output (to Banjo bolt) from this unit?

2) What type of hose should I use?
Can I just replace the hose (and keep the original fittings) using something a vacuum hose like this: Cohline W0133-1714718 Vacuum Hose | Auto Parts Warehouse
Or should is stick with the original parts (I found this on another forum: the line from the intake to the switchover valve is 617-070-07-81 and from switchover valve to the ALDA is 617-070-06-81). I'm wondering if "pressure line" is different from "vacuum hose".

Thanks!
 

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2001 Volvo V40
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2,954 Posts
Check the switchover valve and overload sensor first, they might have been bypassed for a reason.

1. There is no specific input or output.

2. Pressure line has a bigger gauge than vacuum line, but apart from that there is no difference. The pressure difference is about the same. Any line will do, as long as it is a hard line. I don't know how the line is attached to the fittings, but a little gentle heat probably does the trick.

 

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1983 300TD Wagon
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Discussion Starter #3
More questions

Thanks for the reply Govert70227! I have a few more questions.

1) How do I check the switch-over valve and overload sensor?
2) Where is the overload sensor?

The car was incredibly sluggish when I bought it. So I'm wondering if this system was bypassed in an attempt to get a little more power, rather than because it was malfunctioning. It's driving better now since I tracked down some leaks in the hand primer and the 3/2 transmission vacuum valve and have done the standard maintenance related to clean up of clogged fuel filters, screen, lines and valve adjustment.

Maybe I'm not understanding the purpose of this system, correctly. Now that the car has more power, and I do a lot of driving in the mountains, I'm worried that I may need this protection from excess fuel to the engine. Do you have an opinion on the necessity of this system?

I attached a picture of my valve, which looks different from what you have attached to your message. It's located on the firewall to the left of the brake booster when viewed from the front of the car.
 

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2001 Volvo V40
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The overload protection valve is added security in case the wastegate of the turbo does not keep the boost pressure to 0.8 bar. The sensor on the intake manifold senses that and powers the overload valve, the valve vents the boost line in consequence. Under normal conditions the valve doesn't do anything.

My picture of the valve is of a later type, yours is the earlier type, the function is the same.

The sensor sits on top of the intake manifold with a electric wire connected to it.

You can check the vavle by measuring if boost pressures makes it past the valve. If you have a hand vacuum pump you can also measure it with that, using vacuum instead of pressure.

The sensor can be checked with a multimeter. It must not connect to ground if I remember correctly.
 
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