Continental Mark 3 transmission vacuum problems

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markusfrank
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Continental Mark 3 transmission vacuum problems

Post by markusfrank »

Hi Lincoln Forum,

I come from Berlin / Germany and have a Continental Mark 3 Coupe from 1971 and a problem with the transmission and the vacuum system for controlling the transmission, which I have not been able to solve for over 1 year. Myself and my workshop don't know what to do next.

1st + 2nd gear work normally

In 3rd gear it only drives in 1st gear and does not shift into 2nd or 3rd gear.


We did step by step:

- Vacuum modulator on the gearbox exchanged,

- Step by step 7-8 found and repaired vacuum leaks in the whole vacuum system

- Spark plugs and ignition cables exchanged, after that it also ran much better with more power

- Another 2-3 leaks in the vacuum system were found and repaired with a fog printing machine

- Entire vacuum systems disconnected to rule out further problems and leaks


And after EACH of these repair steps (10-12 steps total) the gearbox has worked for 5-10 miles.

After that, no more, regardless of whether the car was warm or started cold again the next day.

I checked and adjusted everything in the periphery of the transmission - shift linkage, kick-down and everything else that can be adjusted from the outside.

We are faced with a mystery, mainly because the car works after individual repair steps and then after a few miles (regardless of whether it is cold or warm) it no longer works.

I also need a vacuum diagram, but after hours with google I can only find a wiring diagram for Mark 3 1971 and the vacuum diagram is only for heating and air conditioning. Is there no vacuum diagram for the Mark 3 for the whole system? I have the Ford 1969 service manual and the 1969 Mark 3 wiring diagramm, but there is not the complete vacuum system inside.

I would be very happy if you have any advice for me!

Thanks a lot and many greetings from Berlin

Markus
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TonyC
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Re: Continental Mark III transmission vacuum problems

Post by TonyC »

Markus,

I have seen these symptoms myself before. I do have input, but you may not like to hear it. If the vacuum shift control has been thoroughly checked out and the fluid level is where it's supposed to be (and the fluid is purely Type F, not any amount of Dexron mixed in), the problem is likely far more involved. Once the simpler diagnoses have been exhausted, the only option left is rebuild. I hope somebody near you has experience with American C-6 transmissions, an easy job in the States but I don't know about your part of Germany.

---Tony
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action
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Re: Continental Mark III transmission vacuum problems

Post by action »

Just for clarity, you are posting that there is no 1-2 up shift in Drive after operating correctly for a short period of time???

You are correct it is the vacuum modulator's job is to make the C6 transmission up shift. But there is more than just the modulator that makes to upshift happen.
First ..
The vacuum to the modulator comes from a hose that goes to a vacuum tree or tee just behind the engine and then goes to the intake manifold
The vacuum routing is almost identical for all full sized Ford, Lincoln and Mercury vehicles of the era.
The engine needs to develop at least 17 inches of vacuum at warm or curb idle speed. (800 to 1200 rpm) That 17 inches of vacuum signal has to be at the modulator. If not there may be a restriction in the line.
Some modulators are adjustable, more problems have been created by owners adjusting the modulator.

Fluid level and type (F) are very important. Check level when fluid is hot and as stated above if the incorrect fluid type is used, the transmission will not function correctly.

Other factors that control up shifts
The governor (location is on tail shaft) operation is needed for an upshift. Most common reasons (in order) for governor issues is dirt or debris. Or drive ball not in place if it has been removed recently. Or loose tubes on distributor
Valve body, (1-2 shift valve) valves not moving or stuck because of dirt or debris or physical damage. Fluid type is a factor as well.
Intermediate band servo not applying.
One-way clutch defective or improperly assembled

Work from easy to difficult.
Check vacuum at modulator after engine is warmed up
Check fluid after fluid is warmed up

Action
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1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
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Re: Continental Mark III transmission vacuum problems

Post by Dan Szwarc »

The modulator should be fed by a dedicated 7/32" (~5.5mm) vacuum line from the intake or Teed off the booster.

Have you tried cleaning out the valve body? It should be removable without pulling the trans. You must have some sticking valves.
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Re: Continental Mark III transmission vacuum problems

Post by markusfrank »

Hi Action, Tony and Dan,

I published the topic twice by mistake, Dan also replied to the other post.

He says: The modulator should be fed by a dedicated 7/32 "(~ 5.5mm) vacuum line from the intake or Teed off the booster. Have you tried cleaning out the valve body? It should be removable without pulling the trans. You must have some sticking valves.

First of all, many thanks to you for the quick answer and the competent advice!!!

I add to the questions:

- The transmission shifts normally in 1 + 2 gear. It doesn't shift normally in DRIVE, it stays in first gear. When I take the throttle off, it's like freewheeling, the engine doesn't throttle. If I have the transmission in 1st gear manually, the engine throttles when I take the gas off.

- The first thing I did in the past was swap the modulator, after that it ran fine for 5-10 miles. I have a modulator with a white ring, but I am not sure if it is correct ??? I also tried to set this, but I only tried.

- I also changed the transmission oil with type F, what was in it before I don't know, I tried to let out as much as possible, but with automatic transmission usually part of the old oil remains in it.

- Whenever I have found and repaired a vacuum leak or other problem (see first post) the transmission shifts normally for the next 5-10 miles. Then it only stays in 1st gear again on DRIVE, regardless of whether I drive on or park the car and start again cold. So I hope that the problem must be with the vacuum, otherwise it would not switch after the individual vacuum repairs .... ???


Or it's like action and Dan also says that something sticks or is dirty.


My questions:

- The governor sits in the gearbox directly behind the modulator? How can I expand it, check it and clean it up? Take off the oil pan?

- Dan suspects that I have sticking valves and I should clean the valve housing, which valve do you mean? Modulator, governor or is there another valve (for example a check valve?)

What jobs that you mentioned can I do without dismantling the transmission? What can I do with the oil pan removed? I will now continue as Action says, check all the simple things again and measure against the hints you gave me. I haven't actually measured the negative pressure yet.

Again the question about a vacuum diagram for the whole car: Is there one and where can I buy it? I also still see the possibility that there is still a leak somewhere - and if I have less than 17 inches of vacuum I have to look right there ........

In the past I had a Lincoln Continental 1969 sedan with Suicide Doors, everything went well with this one, I sold it better I would have kept it, I bought the Mark 3 without a test drive because it was not possible, I have never done that before done and I will never do it again ......

But the people here in Germany love the old Lincoln, but it's very difficult to run them here, that's definitely a lot easier in the USA, and I can't find a workshop that really knows the C6.


Thank you in advance and best regards Markus
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Re: Continental Mark III transmission vacuum problems

Post by TonyC »

Markus,

I am presuming that you don't have any shop manuals to refer to your car. This is where such a manual will come in very handy; not only does it explain the vacuum routing, which is actually very simple; but it also shows in great detail how to tear down and reassemble the whole wretched mess. I advise getting shop references for your car; there are a lot of online sources that can hook you up. Possibly the Forum here can offer more specific sources to check first. Now, for the Mark III, I'm not sure if there is one book that exists to use as a reference; it could be that it would be a series of Ford manuals. But somebody here should tell you what to look for.

I can tell you that Dan's recommendations are fairly easy to diagnose, although access to the governor is somewhat more difficult. The valve body that he was referring to is visible when you remove the oil pan to the transmission. It is a piece that contains its respective shifting valves inside it, and it's screwed into the transmission. It is fairly easy to remove, but for disassembly you really need shop reference material, to make sure you put in some of the smaller parts back where they should go. Some of those parts have springs on them, which will send them flying once you take the casing apart.

The governor is located at the rear of the transmission, at the base point of the output shaft. To access it, you need to remove the tail-cone piece of the casing, which I don't recommend unless you happen to have a replacement gasket set on hand. It too is screwed into place and can be removed for cleaning; its mechanics are fairly simple.

Now, all that said, I clearly remember going through all of these spots when my transmission first showed those same symptoms in 2004 that you're having now; and, despite all my efforts to clean and diagnose them, nothing fixed the problem. The only thing that cured the problems was a full rebuild, which I understand is a very difficult venture at best where you are. However, I would dare say that a reputable transmission rebuilder should be able to apply the standards of rebuilding a transmission to a C-6, one of the most commonly-known Ford transmissions in history, even if he's never done one before, as long as he has shop manuals to go by. And if he doesn't have one but the customer does, he should accept a customer's willingness to help by loaning out his reference material. At least I would if I were a professional rebuilder. But, I may be just too idealistic for my own good.

---Tony
Last edited by TonyC on Fri Jul 23, 2021 6:05 pm, edited 1 time in total.
"Don't believe everything you read on the Internet, just because there is a picture with a quote next to it." (Abraham Lincoln, 1866)
"Question Authority!"

1966 Continental Sedan, affectionately known as "Frankenstein" until body restoration is done (to be renamed "General Sherman" on that event)
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Re: Continental Mark III transmission vacuum problems

Post by frasern »

There is a small rod which is inserted in the vacuum modulator, when it is installed. Did your mechanic loose this part?
It is not included with a new modulator, and must be removed from the old one and re-used.
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Re: Continental Mark III transmission vacuum problems

Post by markusfrank »

Thank you for the good explanations from Tony and the additional information from fraser!
I still hope that the problems can be solved without rebuilt and will do the many suggestions to check and repair the simple things first. This will take 3-4 weeks as I am now on vacation and the car is not near me. I will report to the forum when I have done further work.

if the forum has any further hints for me please give them to me

Thanks a lot!

Markus
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