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Vacuum line routing for '83 Turbo?


DrieStone

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I have a US spec car, and for the life of me, I can't figure out how the vacuum lines should be routed. As with most cars, the air pump and emission control stuff has been removed. A bit of back history: I had a crack in the block and pulled the engine a long time ago (I hate to admit that it was 15 years ago). It took another 7 years for me to start to put everything back together, then I ran into some life issues so the car sat for another 6-7 years. I'm finally getting back to it. The engine ran, but I knew I didn't have the vacuum lines run correctly.

A few things that are head scratchers for me:

1) I finally figured out that the A.C.U. is the Air Con. It looks like it's still hooked up to the Diverter Valve (there's a really thin line going to the top), but the rest of that vacuum circuit is (obviously) gone. 

2) So, I think I just hook the Air Bleed and Flap Valve to the other side of the ignition solenoid. Then on the other side of the solenoid I have a one that goes to the distributor, and I have a line that goes to the rear carb, but I can't seem to see where this line would go on the carb.

3) I have two clear lines that come through the firewall on the passenger side. One is the boost gauge... I can't figure out what the other one is for. (edit: looks like it may be a vacuum line for the the air vents?).

4) Luckily the fuel pressure side of things seems pretty straight forward.

My plan is to replace all the vacuum lines with fresh lines, so I kind of wanted to build my own diagram so I know exactly where everything goes. A few years ago I asked for the UK manual (thinking that it's probably the best thing to follow because it doesn't have the air pump), but when I started to do my research, the only vacuum diagram in that manual is for the HCI, which is totally different.

Any help someone might be able to provide in untangling this would be greatly appreciated.

 

Screen Shot 2021-12-20 at 12.52.43 AM.png

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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After thinking about this a bit more, I think the right way to do this is to route the A.C.U. line over to the ignition solenoid ignoring what's left of the diverter valve entirely. 

Additionally, I must be missing the connection to the carb (it's in a difficult location to see), so I'll just keep searching there.

The only last thing is figuring out the two vacuum lines that look like they're coming from the firewall. I tried to follow them a bit further back and it appears as though they might branch off. My hope is that the boost gauge actually crosses to the driver's side before entering the firewall.

I'll try to check all these theories tonight when I work on the car a bit more.

The only real question is where the line for the HVAC solenoids go. My thought is that it must route into the flap valve/air bleed circuit since that's the one that should be pulling a vacuum.

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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Hi Jonathan,

I am fairly certain the 2 lines through the firewall are for boost gauge and ACU for it's various airflow control doors/flaps. Don't see solenoids as pertinent to AC operation. As to lines routing they'd surely be along the tunnel top along with wiring, throttle and choke cables, and the oil gauge line. The 2 vacuum actuator capsules are fitted to the main casing and to the fresh/recirculate flap control in the plenum, trunk/boot side of the forward bulkhead. See the attached screen grab of the Service Parts Manual.

Cheers 

GG_TURBO_HVAC_VACUUM.PNG

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@drdoom, I saw that page in the manual. Interesting that your diagram is different than mine (maybe for the S2.2?). I don't think my car has the vacuum canister. It explains why there's a black box on the car diagram that didn't make sense when I was looking at it.

I did dig in further, and I think that the line (on my diagram at the top) to the ACU is not a vacuum line. I dug around a little more with the diverter valve and there's a green line that goes up and along the roof through the bulkhead. I think this is the ACU line (and I think it is a cable that opens/shuts the valve at the top of the diverter). I think this line is hooked up to the Air Con and must open a valve so that the diverter would see a vacuum when the Air Con was on? 

My guess is that none of that is important.  There's also a vacuum line attached, but I need to get under the car to trace it, my guess is that it goes nowhere.

I think the vacuum line that you show in your diagram is different. This has to be pulling a vacuum all the time, and I think the source of that has to be the line that comes off the airbox since that's the only place where I think we could be assured of seeing a vacuum. I just don't understand why it's not in the diagram.

It looks like I need to see if I can chase the pair of plastic hoses to figure out which is which. My guess is that one is going to go up the passenger side to the HVAC, the other is going to go up the driver's side to the gauge cluster. They are slightly different colors, so maybe I can find the line under the dash and see what color it is (one is yellowish, the other is more white).

Screen Shot 2021-12-20 at 1.52.54 PM.png

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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Hi, I have a US spec '84.  I have just refitted the engine and have it wide open with all the vacuum lines to show.  I have each one marked up as I disconnected them.  I am happy to take photos but for some reason I have little success posting them on here but I will try.  Alternatively send me a PM if its possible through here.

 

IMG_6789.JPG

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Jonathan, that diagram I posted is from the Turbo Service Parts Manual. Your reply reminds me that a boost gauge is fitted, bonehead oversight on my part, and so one of your lines must be from the carb entry plenum casting ( where boost but no vacuum may be found ) to that gauge. For vacuum, I know the Turbo's were at some point equipped with an engine driven vacuum pump so perhaps check on that as source for your HVAC controls actuation.

Cheers 

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I think I figured most of it out.

1) one of the lines is the oil pressure line. I thought I had mistakingly hooked it to the distributor, but there's a spot behind the distributor that the oil pressure line hooks up to, but it's hard to see and I probably felt it incorrectly.

2) The vacuum hose that is attached to the diverter valve I followed across the engine bay to the other side where it's capped off.

3) I also found the connection that hooked up to the carb and it looks to be capped off.

4) I found the vacuum pump under the engine. I completely forgot about the need for vacuum for the brake booster. I feel completely stupid for not thinking there was a vacuum pump. Most of the diagram for that is 33.03A and I can see the T which is labeled "Emission control take-off".

5) Since I don't see any evidence of the HVAC flapper valve vacuum lines, they must be attached elsewhere in the car since they need to pull vacuum. It would make most sense to pull that from the thicker lines that go up front.

In conclusion

The vacuum diagram is actually very close to what I need. The only thing that should be affected by the emissions control is the diverter valve. I should be able to simply take hose #5 and run it right into the "T" off the vacuum pump and everything else gets plumbed as seen.

The only thing that still confuses me is where the vacuum lines for the heater are. I don't really see any evidence of them around the engine. They must be wired into the vacuum pump elsewhere. Either way, I think I'm not going to worry about it right now.

I'm going to replumb everything as in the following diagram.

Screen Shot 2021-12-20 at 11.30.59 PM.png

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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Seems you're moving in the right direction. It's a very thin black nylon line used for the HVAC controls on my car, likely remains the same for most Esprit. On the non-Turbo cars there's a vacuum take-off fitting on #1 runner of the inlet (intake) manifold which passes through a 1-way check valve and on to a reservoir tank mounted in the area above the right side wheelarch. There's a tee fitting there where the slender vac line for HVAC controls connects before heading forward through the firewall, along the tunnel top and on to the HVAC unit under the dash.

Cheers  

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4 hours ago, drdoom said:

Seems you're moving in the right direction. It's a very thin black nylon line used for the HVAC controls on my car, likely remains the same for most Esprit. On the non-Turbo cars there's a vacuum take-off fitting on #1 runner of the inlet (intake) manifold which passes through a 1-way check valve and on to a reservoir tank mounted in the area above the right side wheelarch. There's a tee fitting there where the slender vac line for HVAC controls connects before heading forward through the firewall, along the tunnel top and on to the HVAC unit under the dash.

Ok, that confuses things a bit more for me then. I found the black nylon line. I thought that was where the T on the vacuum pump but now I'm second guessing this. It seems that the nylon line goes to the heater vents (which makes more sense anyway, it would be stupid to be applying a vacuum from the pump to the purple line). 

It does look like the purple line goes to the vacuum pump, and the diagram that @snowrx posted seems to be clearer than the one in my manual. I think my diagram I drew is correct, but there must be a second fitting on the vacuum pump that I didn't notice.

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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I'm no authority on the Turbo but have gathered that vacuum for the brake booster is the pump's primary function. Also clear is that the line for the booster is considerably bigger than that for those wee actuator capsules in the HVAC system. Perhaps that may help a bit? The emissions system is a whole 'nother ballgame, don't have any insights on what Lotus cobbled up in support of that exercise. 

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2 hours ago, drdoom said:

I'm no authority on the Turbo but have gathered that vacuum for the brake booster is the pump's primary function. Also clear is that the line for the booster is considerably bigger than that for those wee actuator capsules in the HVAC system. Perhaps that may help a bit? The emissions system is a whole 'nother ballgame, don't have any insights on what Lotus cobbled up in support of that exercise. 

Ok, it seems like if I just keep digging (then going out to the car and checking) I slowly understand this more and more. 

I'm not worried about the emissions system, since most of it is missing off my car. Before I started this whole pursuit, I thought that was my trouble area, but in the end, I don't think it matters.

You are absolutely right, the vacuum pump has a fat line that go through the center frame that is obviously for the brakes. There is a small nylon hose that is comes off the T near the pump which I can't chase (easily). It would seem silly that it's HVAC related (why not T it off at the front where everything is needed?).

I pulled one of the solenoids off the car and put it on the bench to better understand how it functioned. This helped some, but I also found some relevant write ups in the manual. What concerns me is the following in regard to the ignition solenoid:

Quote

Located beneath front of plenum chamber. Function is to advance ignition on operation of choke. A micro-switch operated by the dashboard end of the choke cable (which also operates the choke tell tale lamp) energises the ignition solenoid. The signal to the distributor vacuum advance capsule (normally connected to No.1 cylinder throttle edge drilling) is then switched to the vacuum pump, and thus full ignition advance is achieved, together with an increase in engine idle speed.

So I feel like I'm beating a dead horse at this point. I understand a lot more about this then I thought I would (not a bad thing), and I think I'm down to this last mystery.

My last theory is that the tiny little vacuum line coming off the T near the vacuum pump is my mystery line and it must go into a T behind the fuel tank. The line being so tiny might be so that it never scavenges too much from the brakes.

Unfortunately, I don't think I'm going to be able to investigate this further until after the new year. I'll pull the plywood "shelf" off the driver's side fuel tank and see if I can figure out where those vacuum lines go.

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1997 Jeep XJ | 1983 Lotus Turbo Esprit

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After more digging, I think this verifies that the "T" right off the vacuum pump is the hose I'm looking for (item 94 is labeled " 'T'-Piece, Emission control take-off". If it was HVAC related, I would have expected that it would have said "Heater vent". I will still chase it down to verify. My guess is that it leads to a "T" that sits behind the fuel tank, and there's a vacuum line that goes to the (now defunct) diverter valve, and the other is supposed to be hooked into the lines on the other side of the car.

Of course, a lot of this is caused by the fact that I don't think most of this was hooked up correctly in the first place. Maybe it doesn't matter (someone smarter than me might know a better way to have set them up). 

Of course, now I wonder where the heater flaps get their vacuum. Maybe there's something I'm missing under the air intake which is the most likely spot to find that. 

Screen Shot 2021-12-21 at 10.52.30 PM.png

Edited by DrieStone
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1997 Jeep XJ | 1983 Lotus Turbo Esprit

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I think that #94 tee is labeled emissions because it would have originally first gone to the air injection diverter valve before it continued up front to power the HVAC controls.

In your diagram I would tee the boost gauge feed from your "Blue" line (#12) before the solenoid, not the orange one after it.

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4 hours ago, snowrx said:

I think that #94 tee is labeled emissions because it would have originally first gone to the air injection diverter valve before it continued up front to power the HVAC controls.

In your diagram I would tee the boost gauge feed from your "Blue" line (#12) before the solenoid, not the orange one after it.

Oh... that makes perfect sense. I assume that the line coming off the top of the diverter was a control line, but that doesn't make sense. I feel like the label "TO A.C.U." is confusing, since  it's not really specific to the Air Conditioner. (fresh air flap and mode flap). I guess I don't know what I might have expected it to be called.

This also explains why the diverter valve is still in the car (easier than finding a T fitting that would fit). I still don't understand why the vacuum line is capped. I have to imagine the timing wasn't retarded as much as it should have been because it wasn't seeing a vacuum on start.

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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On my car there were two vacuum lines, one to the front intake manifold runner, and one to the carb(orange in my diagram).  The carb one is probably ported, in that the throttle plate uncovers the port as you add fun pedal. That's the one you want for the distributor advance solenoid/capsule

 

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  • 3 months later...

I'm finally onto cleaning up my vacuum lines and I'm not more than two lines and I'm confused (in retrospect, this is probably why I originally was confused by this routing).

I made a diagram with all of the various lines that need to be run. I felt like it was all settled, but as I started working my way around the engine starting with the HVAC line on the left of the engine, I found that the vacuum line that was supposed to connect to the ignition solenoid and flap valve has been capped.

This was obviously a choice by someone, but I don't understand enough about how the various systems interact to understand the effect of capping the vacuum line.

I've uploaded a pic of my vacuum diagram with the location of the capped line. Any insight would be appreciated.

 

screen_shot_2021-12-22_at_8.49.00_pm.png

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1997 Jeep XJ | 1983 Lotus Turbo Esprit

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I can see someone wanting to disable the Intake flap, but it would seem to me some vacuum advance would be nice for off throttle. I don't know how the balance between the Boost retard and the Vacuum advance would work out.

Not to say the system was necessarily optimized for other than passing emissions requirements on a Federal car.

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On 30/03/2022 at 22:26, snowrx said:

I can see someone wanting to disable the Intake flap, but it would seem to me some vacuum advance would be nice for off throttle. I don't know how the balance between the Boost retard and the Vacuum advance would work out.

Not to say the system was necessarily optimized for other than passing emissions requirements on a Federal car.

I discovered this is only on the Federal car, which makes me feel a lot better. I'm going to disable it, since it was obviously only for US emissions.

Other changes (for anyone reading this thread in the future), I'm going to make:

  1. The vacuum pump line only supplies vacuum to the HVAC line and the brakes.
  2. I'll be removing the internals of the intake flap
  3. The ignition solenoid has been removed 
  4. Instead of a vacuum line going from the top of the distributor to the ignition solenoid, it will go to the back of the front carb.

This removes the flap valve portion of the vacuum circuit. It also removes the vacuum advance on the distributor when it's cold and the choke is on. 

The previous owner of my car didn't have any vacuum lines on the distributor, my guess is that the pressure differential under boost dials in some timing.

 

1997 Jeep XJ | 1983 Lotus Turbo Esprit

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