1Z/AHU into 78 Bus

markd89

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1978 VW Bus 1Z TDI
Why re-invent the wheel? VW used the same coolant reservoirs for so long that they can had for next to nothing and you can integrate the wiring easy enough.
Yep, I'm using the stock coolant reservoir. My question is how to interface to the stock sensor to drive a light. It's not a simple on-off switch, but something that varies it's resistance based on fluid being present. I'm hoping there's an easy circuit or workaround I can do?
 

markward

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Loxahatchee, Florida
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82 Vanagon and 2011 JSW
Mark are you sure it is a varying resistance switch? I think you could add a bulb and a relay somehow. The relay would get it's ground through the stock sensor switch to keep the light off. When the fluid level dropped the relay would loose the ground and the light would come on. You would need a 5 prong relay. Not a fog light relay, but one that transfers between the two working tabs when energized.

Seems to me the switch has two prongs that hang down into the coolant. At least on the tank I am using from a Jetta.
 

markd89

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1978 VW Bus 1Z TDI
Mark are you sure it is a varying resistance switch? I think you could add a bulb and a relay somehow. The relay would get it's ground through the stock sensor switch to keep the light off. When the fluid level dropped the relay would loose the ground and the light would come on. You would need a 5 prong relay. Not a fog light relay, but one that transfers between the two working tabs when energized.

Seems to me the switch has two prongs that hang down into the coolant. At least on the tank I am using from a Jetta.
Thanks Rxsr, I'm trying to figure this out. I had read somewhere that the sensor worked by resistance. I'm also using the two prong coolant sensor. I do have all of the stock relays or can put together something custom if a relay is all that's needed.

Are you saying that the presence of coolant makes the prongs grounded and absence of coolant makes the prongs an open circuit?

Thanks,
Mark
 

markward

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Think of it as a switch. The coolant makes the circuit. So if one wire went to ground, the other wire would run to a relay that would control the warning light. That is why you need the type of relay I describe. At rest, the light would be on. With proper coolant level, the relay would be energized, so the bulb would be off. Mark
 

markd89

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1978 VW Bus 1Z TDI
Think of it as a switch. The coolant makes the circuit. So if one wire went to ground, the other wire would run to a relay that would control the warning light. That is why you need the type of relay I describe. At rest, the light would be on. With proper coolant level, the relay would be energized, so the bulb would be off. Mark
Super, that helps a lot. I'll rig up a relay to do that and report back with how it goes..
 

markd89

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Super, that helps a lot. I'll rig up a relay to do that and report back with how it goes..
Looking at the wiring diagram, sensor G32 is listed as a variable resistor. I've done lots of googling (and searching here) without turning up any info on the circuit. If I can't find anything, McMaster-Carr has some float switches...
 
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markd89

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Looking at the wiring diagram, sensor G32 is listed as a variable resistor. I've done lots of googling (and searching here) without turning up any info on the circuit. If I can't find anything, McMaster-Carr has some float switches...
So, the float switch idea is challenging because the lid of the coolant reservoir had a pressure release valve. I can't just drill a hole and mount my float sensor.

More searching seems to indicate that the controller for the stock sensor is inside the original gauge cluster, which I have but am trying not to use.

More googling found http://www.circuitstoday.com/liquid-level-indicator which has a simple circuit to measure coolant level. It looks perfect and is based upon a single IC.

 

markward

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82 Vanagon and 2011 JSW
Mark, I am a little confused. What sensor and cluster are you looking at? My vanagon has a warning light built into the coolant gauge, but only activates by an overheat condition. The later vanagons did have the cluster light tied to the coolant level.

The vanagon has two coolant tanks. One is pressurized and the other is more of an overflow/recovery tank. This is stock. The tank is located at the license plate door and is easy to visually keep an eye on. I keep everything up to date and don't worry about the coolant level. A small leak would show up in the recovery/overflow tank and a major leak will result in running hot.

The circuit you picture should work, but looks complicated to me. I wired an Audi 5000 coolant tank on to my race car thinking along your lines. It was simple and could be adapted in your conversion. It uses a float switch. I ended up disconnecting from the racecar, because in corners the light would turn on because the fluid was getting moved around.
 

markd89

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1978 VW Bus 1Z TDI
Mark, I am a little confused. What sensor and cluster are you looking at? My vanagon has a warning light built into the coolant gauge, but only activates by an overheat condition. The later vanagons did have the cluster light tied to the coolant level.

The vanagon has two coolant tanks. One is pressurized and the other is more of an overflow/recovery tank. This is stock. The tank is located at the license plate door and is easy to visually keep an eye on. I keep everything up to date and don't worry about the coolant level. A small leak would show up in the recovery/overflow tank and a major leak will result in running hot.

The circuit you picture should work, but looks complicated to me. I wired an Audi 5000 coolant tank on to my race car thinking along your lines. It was simple and could be adapted in your conversion. It uses a float switch. I ended up disconnecting from the racecar, because in corners the light would turn on because the fluid was getting moved around.
Hi Mark,

Thanks for writing back. I'm using the stock Passat tank.


The arrow indicates where the low-coolant level sensor is found.

Ordinarily, I wouldn't pay much attention to hooking up this sensor as I intend to keep an eye on my fluids. However, all of my cooling system custom -- radiators, thermostat cover, heater flange. In theory, it's going to work perfectly.

However if a failure occurs and my fluid all drains out at speed, I want to know right away!

I bought a cool float valve from McMaster Carr ($10), but I don't think it's going to fit in this tank. I could switch tanks, perhaps to the style you're using, or now that I have the IC coming, might as well just build the little circuit?

I appreciate your thoughts :)
Mark
 

markward

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82 Vanagon and 2011 JSW
I am using the same tank in my Vanagon. It never occured to me that the level sensor was a varying resistor based on coolant level. Must be some fancy electronics that tie it to the factory cluster. With varying resistance, something would need to know how low is to low and then turn on the warning light.
 

markd89

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1978 VW Bus 1Z TDI
Not yet, but soon. I worked on the electrics today. The heater needs to be mounted, then fill with coolant, then fill with diesel, then hopefully vroom!

I'm still trying for this week. Once I get a chance, I'm going to take many more pics and do a better job documenting the project.

Stay tuned!
Mark
 

markd89

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1978 VW Bus 1Z TDI
Tired here, long day. The bus runs!!

There's one issue, not sure of the cause:

In VCDS. Actual MAP is about 2400, even when requested is 900. Actual does not seem to move. It wasn't doing this in the donor car.

I should note that the boost gauge shows "normal" boost. 0 when no throttle and up to 12 psi.

Any ideas?

Thanks,
Mark
 
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markward

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82 Vanagon and 2011 JSW
Mark, is it possible the sensor is in backwards? I had to replace my sensor, but recall it stuck on 500. It had sat out in the elements for a long time though. Congrats on getting this far.
 

markd89

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1978 VW Bus 1Z TDI
Mark, is it possible the sensor is in backwards? I had to replace my sensor, but recall it stuck on 500. It had sat out in the elements for a long time though. Congrats on getting this far.
The MAP sensor is inside the CPU, right? I hadn't removed mine.

It was working in the donor car. I sent the CPU to Canada and back with the wiring harness (bad experience unfortunately).

Maybe the sensor went bad during shipment or when the wiring guy was working on it.. Is there anyway to test it, or just replace?

Thanks,
Mark
 

markward

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Sorry, don't know if there is a test you can run. I think the test is to try a known good one. My ECU is still stock, does the label file in VCDS match your ECU part number after the tune?
 

kooyajerms

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97 B4V (mine), 11 x5 35d (hers) 04 V10 (that one you want), 2014 Q7 (mom's) 74 Shasta 1400
Electronically testing it I'm not sure. If you put a mityvac to put pressure on the nipple of the ecu, Run the car and give it varying pressure up to 18psi and see if that does anything, I have my doubts though. Sounds like it's holding pressure for some reason if that reading is correct.

I've got my old 2.5 that we could resolder if you confirm its bad. Only thing is the pins maybe short/to non existent when I cut it off. I can mail it off today or if you want to come get it if you are in a rush.
 

markd89

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1978 VW Bus 1Z TDI
Sorry, don't know if there is a test you can run. I think the test is to try a known good one. My ECU is still stock, does the label file in VCDS match your ECU part number after the tune?
No tune yet, still running stock, but the tune is soon :)
 

markd89

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1978 VW Bus 1Z TDI
Electronically testing it I'm not sure. If you put a mityvac to put pressure on the nipple of the ecu, Run the car and give it varying pressure up to 18psi and see if that does anything, I have my doubts though. Sounds like it's holding pressure for some reason if that reading is correct.

I've got my old 2.5 that we could resolder if you confirm its bad. Only thing is the pins maybe short/to non existent when I cut it off. I can mail it off today or if you want to come get it if you are in a rush.
Cool Jeremy, that would be great if you could mail it, then I can mess with it early next week. I'll text you my mailing address.

Thanks!
Mark
 

markward

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Sorry, I am giving bad information. On the ALH the MAP sensor is in the intake plumbing and I was thinking about the MAF sensor above. Carry on.
 

markd89

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So Jeremy was very kind to meet up with me tonight and give me his old MAP sensor. Thanks!!

I took it home, took apart my CPU. Inside I found that two of the legs of the existing MAP sensor had cracked away at the board.

I soldered up some jumpers from underneath the board and carefully soldered them onto the legs of the MAP sensor. Once done, I squirted a glue from the thermal glue gun to keep things in place.

I put it all back together and went for a quick drive with VCDS. Actual MAP is now back down to normal. Power is greatly increased. I see 14 psi peak on my gauge, but the seat of the pants indication is drastically improved.

Next up is a Stage 2 tune, not that more power is really needed :D

P.S. Jeremy, thanks again!! I can mail your MAP back to you or keep it until we meet up next.
 

kooyajerms

grocery getter
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97 B4V (mine), 11 x5 35d (hers) 04 V10 (that one you want), 2014 Q7 (mom's) 74 Shasta 1400
Keep it Mark, glad we pushed you into opening up the ecu =)

The concert was great btw. Good timing with the map sensor re-up.
 

markd89

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1978 VW Bus 1Z TDI
An update...

Everything pretty much works. I've been driving around. I did about 60 miles since I filled the tank and it just moved off full. My gauge is optimistic, but that wouldn't have happened with the gasoline engine.

The cooling fans have never come on. Peak temp has been 191F.

I'm working out bugs then will do some more pics and writeups.

Here's the bugs. Few questions in here are bolded and I'd welcome any suggestions!

1. Gearing. I got my trans re-geared .70 for 4th and 1.18 for 3rd. I'm kicking myself that I should have got 1.08 for 3rd. 1.18 is only an 8% overdrive from stock.

1st and 2nd gears are stock.

1st, 2nd, 3rd get a little buzzier than I'd like. I shift at about 2700-3000 in 1st and 2nd.

My solution is to increase my rear tire size from edit: 25.5 inch diameter to 28 inch diameter. I'm looking at [FONT=&quot]16" steel wheels and 215/70R16 or 225 tires[/FONT] This will give me a 10% overdrive and help 1st, 2nd, and 3rd.

The only issue is that it will make 4th taller as well. At 70 MPH, it'll put me at 2700-2800 RPM, not the 3000 RPM that people seem to recommend for happy EGTs. I'm planning on a Malone Stage 2 or 3 tune with stock turbo. Any thoughts if the 2700-2800 RPMs will make a difference with EGT?

(P.S. for others doing a swap.. It is possible to go to a 15 inch wheel and then up to 31 inch diameter tire will fit.)

2. Vibrations. Things get a little annoying at higher RPMs (3000ish). I'm using the hydraulic mount on the rear and rubber mount on the front of the engine. The transaxle is suspended from the front mount only. (Note to others: losing the rear trans mount works fine!)

We're going to revisit the mounts. If the issue is on the front (non-hydro mount), maybe I can use a hydraulic rear mount on the front? The dimensions are the same but it's meant to be pushed on by the torque not pulled.

If the vibrations are coming from the front (solid) trans mount, there may not be much that I can do. There's really no space there to do anything custom.

3. Noise. Inside, it's loud, especially at higher RPMs. I'm not sure how much noise is vibrations and how much is other stuff. Any ideas on isolating where the volume is coming from?

I'm running a CAT only, no muffler. I could add a muffler? Other than that, I can get some sound-deadening panels and glue them in the cargo, rear-seat area.

4. Clutch actuation. The Kennedy Stage 2 Clutch takes a stronger left leg than stock. It puts more stress on the cable, clutch arm, etc. There's little bits of play in the clutch arm, clutch shaft bushing, and as a result, the clutch disengages very close to the floor.

I've got a new clutch arm and a bronze shaft bushing on order. These should take out a little more play and make the clutch a little more comfortable to actuate.

5. IAT. I've got a 7" fan mounted on a Saab Blackstone intercooler. The IC sits in the left rear of the engine compartment. It should be getting air from the vent above, but it's not sitting directly in airflow. I know it's helping, but it's not ideal. I'm hoping it's enough.

6. Oil Leaks. I've got at least one oil leak, probably two. I'm waiting to put the bus up on the hoist again to figure it out. Possible candidates are the oil pan and oil cooler. If the oil cooler is leaking, I'll upgrade to the bigger one. Any deals on a new one that you might see, please let me know.

P.S. to Jeremy, hoping to make the Dec 3 GTG later in the afternoon :)

Mark
 
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Digital Corpus

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'97 B4 w/ 236K mi body, 46K mi soul
Mark,

Sounds like you've got a gem in the making. If you make it to the GTG, I can help you track down sounds and vibrations. Also, Jeremy tells me that you might be looking at a turbo upgrade. If you're interested, hit me up.
 

markd89

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1978 VW Bus 1Z TDI
Mark,

Sounds like you've got a gem in the making. If you make it to the GTG, I can help you track down sounds and vibrations. Also, Jeremy tells me that you might be looking at a turbo upgrade. If you're interested, hit me up.
Thanks for your message. I'm hoping to make it to the GTG -- probably will be there in the afternoon if it's not raining.

As for the turbo, it sounds like a great deal. I'm trying to resist though ;-) I think I'm going to be OK with my stock turbo + injectors + tuning. I'm finding the power is pretty good and if it's even better with the tune, I'll be happy.

This is a bus, so maximum power isn't the goal. If I'm getting 30 mpg, able to climb a hill at 2300-3000 rpms, I'll be very pleased :)
 

markd89

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1978 VW Bus 1Z TDI
Did a nice freeway run today. EGTs got up to about 1100 *F peak, well below the 1400 that should be safe.

IAT's reached over 170 *F which I'm not happy about. Clearly I need to rework/relocate the intercooler so it gets more cool air. Right now it's in the engine compartment. It has a fan, but with sustained boost of 10+ PSI there's not enough cooling.

Jeremy -- I was pretty likely to join for Saturday, but now having second thoughts. I'd be running at high IATs for an hour there and back. Am I risking damage?

Mark
 
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