TTV test results.......

[boyt911sc]

In reference to the post below, I did some testing about the TTV operating temperature and compared the results. Six (6) different TTV's were used and tested for vacuum. See test results below.



Quote:
Originally Posted by snbush67 View Post
PS- these are only found on 77-79 CIS cars. Also, not to be confused with the thermo Switch. The following is an excerpt from Jim Williams CIS Primer@

Untitled Document

Thermal Valve;

Holds off vacuum from the warm-up regulator when engine is started cold ('77 - '79 engines). Power is applied to the thermal valve when engine is started, and approximately 30 seconds later, the valve opens. When the valve is open, vacuum to the WUR is then determined by the intake manifold. --The vacuum holdoff results in a mixture richening at warmup. The inner hose connects to the intake vacuum source and the outer hose to the WUR.

Failure mode: An open circuit in the internal heater will keep the mixture from properly leaning out as the engine warms.
Quote:
Originally Posted by snbush67 View Post
The thermovalve works is in a closed state (no vacuum) when cold under 68 deg. F and open (vacuum) when 68 and above, which means I have absolutely no use whatsoever for it here in paradise.

As T77 points out above it can simply be bypassed to create an open vacuum source between the WUR and the Auxiliary Air Device, but the vacuum circuit should not be capped at these locations as that would create a continuous "cold" state and a very rich condition.

How it works

The Thermovalve when cold, blocks vacuum from the Air Auxiliary Valve to WUR by a pressured metal disk against the small white rubber washer shown above (this creates an enriched fuel mixture when "cold" to prevent backfiring).

When the engine is started power is transmitted to the Thermovalve which heats the metal disks (to 86 deg. F within 10-30 seconds) and causes the hollow disk to collapse opening the seal, allowing the vacuum to pass through.

The Valve remains in an open state as long as the disk is above 68 deg. F.


How it goes together

Exactly in the order I have shown above, however there are some key points to this- The hollow circular metal piece has two sides, a shiny chrome like side and a dull copper ish side. I am not sure what side goes toward the white rubber washer as but it does matter. I'll run some test in my refridgerator tomorrow to find out (it only got down to about 72 F here tonight).


How to test it

At a temperature above 68 F. blow into it and air should pass. Put it in the fridge for a few minutes and blow into it, air should be blocked.


*Although it is not necessary to seal the two plastic pieces together it will prevent accidental disassembly.

* if you have a car with a rich condition and the idle can not be adjusted correctly you may have a blocked thermovalve, check power to the connection or take it of and apply 12v power to see if it heats up.
_________________


Pictures of the set-up:

The six (6) TTV were heated at different temperatures:
a). 65°F
b). 80°F
c). 90°F
d). 130°F


At temp. 65°F, 80°F, and 90°F all six (6) TTV's registered vacuum readings indicating that the valves were closed contrary to the above post. However, when you apply low pressure air to them, all exhibited air flow and you could see bubbles coming up. So the test using pressurized air is invalid because the valve works for vacuum (negative pressure).

At temp. 130°F, all six (6) samples did not hold vacuum indicating open valve/s. At exactly what temperature they open is subject for another investigation.



When the six (6) samples were placed in the freezer for 15 mins. all samples had vacuum readings meaning closed valves. But, when you apply low pressure air into the inlet tube air passes through verifying that using pressurized air is a flawed test for this type of experiment.



Findings: To test a TTV, you need to use a vacuum source like hand vac pump and using pressurized air is not recommended.



Findings:
Ambient temperature up to 90°F resulted to a fully closed valve (TTV) and able to register steady vacuum reading. But applying low pressure air to the inlet opens the valve. But not through the outlet tube.

Findings:
Applying low pressure air (3 - 4 psig) to the inlet allows air to pass through the TTV regardless of temperature. On the other hand, applying pressurize air to the outlet locks the valve closed regardless of temperature.

The thermotime valve does not block vacuum from AAV because the AAV does not supply vacuum. Instead, the vacuum supplied to decel valve and TTV comes from the throttle body (vacuum side) as a common source.


Conclusion:
Pressurized air should not be used or applied for doing a TTV evaluation. A vacuum source like hand help vacuum pump does a good job in evaluating if the TTV is working or leaking.

This is a technical forum, whatever differences we have in our ideas, tests, procedures, etc. should not be taken as a personal attack or discredit someone. We are here to discuss concepts, ideas, and principles based on facts and data.

Tony

[Bob Kontak]

Tony,

Thanks for the fine work.

Tirwin needs to grab onto this and plug the link into his CIS for Dummies.

If you had been a chemist I would understand the toil. Any chemists in your family?

[theiceman]

reminds me of trying to balance the carbs on an aspencade..

[boyt911sc]

Did a vacuum and heat test on these TTV's and the data collected were:


TTV .....................#1.......#2..........#3..........#4.........#5........#6

Test #1..................19".......24".........17"...........X..........19"........20"
Test #2..................21".......25".........19"...........X..........21"........21"
Test #3..................20".......23".........18"...........X..........19"........20"

Ave. time (sec.).....20".......24".........18"...........X..........19"........20"


Procedure:
Applied 20-mm vacuum to the inlet tube, connected the electrical plug with 12-volt, and recorded the time when valve released the pressure. TTV #4 could not hold steady vacuum and omitted in the test.

Note:
The valves do not hold the vacuum at steady state and there was very slight change in vacuum reading as you observe the gauge. Some valves make a popping sound when pressure was released and some didn't.

Tony

[Vereeken]

To add to this test:

TTVs are found on EURO SC's up to the last run of the SC's (1983). They come in combination with WUR 089.

Manufacturer is PIERBURG and they are NLA (at least in Belgium, but over here a lot is NLA except taxes). I have found them on the first generation VW Golf as well.

The mounting of the TTV is important. It 'hangs' above the left cilinder bank, I believe this is to catch the radient heat from the engine.

Where I do not agree is that it receives its vacuum from the AAV. On the EURO SC I still believe the vacuum is received from behind the TB T-ed into the Decel valve (the pear shaped one) and then on to the WUR. But this is based on my investigation in EURO SC's only with a sample of three.

Michel

[boyt911sc]

Originally Posted by Vereeken

To add to this test:

TTVs are found on EURO SC's up to the last run of the SC's (1983). They come in combination with WUR 089.

Manufacturer is PIERBURG and they are NLA (at least in Belgium, but over here a lot is NLA except taxes). I have found them on the first generation VW Golf as well.

The mounting of the TTV is important. It 'hangs' above the left cilinder bank, I believe this is to catch the radient heat from the engine.

Where I do not agree is that it receives its vacuum from the AAV. On the EURO SC I still believe the vacuum is received from behind the TB T-ed into the Decel valve (the pear shaped one) and then on to the WUR. But this is based on my investigation in EURO SC's only with a sample of three.

Michel

Michel,

How are doing these days? Been a while since we last discussed CIS matters. Could you elaborate the highlighted line above? I also 'do not agree is that it receives its vacuum from the AAV'. Or you believe it gets vacuum from AAV? Not sure what you meant. Are we in agreement or disagreement? Thanks.

Tony

[wacko]

So can the TTV be taken apart, cleaned and put back together?

[Vereeken]

I do not think so.

I believe you would destroy the outside when opening it up.

It is not that hard to find in a breakers yard with older cars. Mercedes, Volkswagen, Saab,...all had it at one time.

And since it looks small and no-one knows what it is they ask little money for it.

If you have a few you can repeat the test from Tony.

[patkeefe]

You are truly the Guru of K-Jetronic!

[snbush67]

Originally Posted by wacko

So can the TTV be taken apart, cleaned and put back together?

Yes, be careful and note the order of the internals, the shell is snapped together from the factory.

My Thermal Valve came apart and I need help putting it back together

[Vereeken]

Shane that is impressive. I could not be bothered with it.

The WUR makes sense because of its price but the TTV...not sure.

So how do you separate it when it is still one piece?

BTW I found out that some companies still have a few in stock (In belgium). This was last year at a Bosch Diesel Center. The piece is not exactly Bosch but Pierburg but anyway.
They still had it in their stock and wanted if I remember well, about 150€ for it ;o)

I picked up two old ones from an old VW Golf for 10€.

I also suggest you check the opening and temp listings by Tony. It took me a long time before I agreed with him that the opening time is also important. Mine worked fine from a vacuum perspective but it took the thing almost 60 seconds to pop. So it seems they can become lazy. And when they do you are slightly flooding the engine I have the impression.

[snbush67]

It is hard to pull apart bit it snaps apart. I think a test of a NOS TTV would determine the intended effectiveness of the factory part. Testing old worn out units might not illuminate the intent of the design.

Under 68 deg. F it is used to enrich the cold start and open within a minute of the car starting. Over 68 deg. F. it is intended to have no effect.

By removing the TTV from the system or having an inoperable TTV could likely be the cause of many cold start issues, idle issues, or even other issues.

[boyt911sc]

Originally Posted by snbush67

It is hard to pull apart bit it snaps apart. I think a test of a NOS TTV would determine the intended effectiveness of the factory part. Testing old worn out units might not illuminate the intent of the design.

Under 68 deg. F it is used to enrich the cold start and open within a minute of the car starting. Over 68 deg. F. it is intended to have no effect.

By removing the TTV from the system or having an inoperable TTV could likely be the cause of many cold start issues, idle issues, or even other issues.

Shane,

I disagree with your data. 68°F is below room temperature and there is no such a device in the Ketronic (CIS) system that operates or control at this temperature. Maybe you misunderstood the thermal valve test in "Troubleshooting Guide K-Jetronic" booklet on page 41. It says that at 20°C (68°F) - 30°C (86°F), the valve must open after 10 - 30 seconds. Don't forget that the heater must be working, otherwise it would take a much longer time to open the TV from the engine heat.

At ambient temperatures between 80°F to 90°F the thermal valves were all closed. See test data. Do an investigation and show your test results. Or find an article about this subject. Keep us posted. Thanks.

Tony

[snbush67]

Tony,

I am hearing you, and I am probably and confusing everyone. I mistated the AAV, is connected to pull vacuum, can you clarify as to the right connections to the throttle body?

Also the hose connections to the TTV? Which connection goes to the WUR and which one goes to the throttle body?

I have more questions than answers.

I am not even sure if my TTV is put together right, can you describe the proper way, order and orientation, of assembling the internals?

I believe that, when cold, the TTV blocks off the vacuum between the throttle body and the WUR to provide enrichment. To do this does it have to be closed, or open? And is it a one way (check) valve when opened?

Shane

[snbush67]

I pulled the valve apart again.

The bimetallic disc has a shiny side and a dull side.

The disc is flat at temps 86* F and below.

The disc curves out to the dull side above 87*F.

I reassembled the valve with the shiny side of the disc facing the rubber washer.

The valve is shut at temps 86*F and below.

The valve is open at temps above 87*F.

The closed valve opens within 30 seconds of applying 12v power.

With this information it implies that for 10-30 seconds, valve induced enrichment occurs in starting conditions when the ambient engine temperature is below 87*F. A working valve is of concern during most cold starts.

[boyt911sc]

Originally Posted by snbush67

I pulled the valve apart again.

The bimetallic disc has a shiny side and a dull side.

The disc is flat at temps 86* F and below.

The disc curves out to the dull side above 87*F.

I reassembled the valve with the shiny side of the disc facing the rubber washer.

The valve is shut at temps 86*F and below.

The valve is open at temps above 87*F.

The closed valve opens within 30 seconds of applying 12v power.

With this information it implies that for 10-30 seconds, valve induced enrichment occurs in starting conditions when the ambient engine temperature is below 87*F. A working valve is of concern during most cold starts.

Shane,

Use a good thermal instrument to check the opening temperature of the TTV. And use many samples of good working TTV in your test and tabulate the results. I have more than a dozen of TTV's tested in the experiment and none of them was opened or operating below 90 deg. F except for the one that did not hold vacuum. Secondly, the temperature of a person having a slight fever is about 101 deg. F (?). I am not a doctor but has more than 10 medical doctors in my immediate family circle.

A heater is incorporated in the TTV design and by the time the TTV opens up, you could feel the heat and warmness of the TTV. In my next investigation, I will include the operating temperature to shed light to this controversy.

Shane, thanks for your data because it broadens our data base by sharing our experiences (good or bad). It would be nice for other enthusiasts to share their knowledge and information.

Tony

[snbush67]

Hi Tony,

I think that using 30 year old valves is unlikely to provide accurate data as the valves are worn well beyond factory specs and likely have outlived their shelf life.

I think that a new, or nos factory part will probably perform within specs as specified. And I think that a valve that is within factory spec will enhance starting capability.

I only have one valve to study, and my interest has diminished as I have downgraded to carbs.

I appreciate your research as well. Thanks, Shane

[Vereeken]

How cool is this. I was just wondering what the opening temp of the ttv would be and look an old thread got revived and I have my answer. Talking about service.

I do not see much use for a TTV when you live in Hawaii ;o)

If I am not mistaken it was introduced for cold climate cars to make sure that the control pressure was low enough so to not cause backfires as a result of a too lean mixture when starting from dead cold.

[bossing]

Reviving this relic thread but good info on it regarding the TTV (part # 17a in the pic).... I have a quick question.

In a hot climate, like FL, is it okay to leave the TTV electrical connector unplugged? And then just leave the vacuum lines (1 to the WUR and 1 to the TB) plugged & intact?

[SkiVT]

What do you mean by “plugged and intact”. The lines need to allow vacuum to the wur after the ttv would have opened, so like 45 second after engine starts. The vacuum then controls your afr across the throttle range.

The ttv itself can be stuck permanently open, particularly In warm climates, and have very little impact on How the engine runs in those first 30-40 seconds. Question would be: why not fix it as its easy to have a working ttv without breaking the bank.