My engine is being a jerk!

[saforwardlook]

I respectfully disagree, I've done a few, and with videos, and a book, find it pretty simple. Even my 8 yr old daughter helped!

Simple tools except the forward clutch piston tool to compress the piston. I made mine, but c clamps could be used. Check all clearances!

I have done about 20 rebuilds of these transmissions, so I have a pretty good idea of how difficult they are or are not to rebuild - I said they weren't all that hard but that the first time through one, there are plenty of details that could be overlooked and not having some special tools makes things more difficult - not that it couldn't be done without them. But I appreciate the ease of the special tools rather than resorting to C clamps every time I do one, so I bought them since I knew I had plenty of them that I was going to do.

It just takes one simple screw up potentially and the trans has to come back out.

My intent was to caution the self-declared "newbie" that it wasn't a walk in the park the first time through one and to be prepared for the need to be vigilant - of course, I was assuming, respectfully, he wasn't going to have an 8 year old to help him through it though.

I appreciate when I am told to expect some difficulty when doing an important task in a project rather than being told it is really easy and then find out that yes it is after doing a few, but the first time through you need to be ready to think through all the steps you do and not be casual about it all. Doing otherwise isn't being helpful in my opinion.

 

[marty koirtyohann]

I have been gradually working through the issues on my new to me 1970 300, which was inop for 30 years. The car now starts and runs reliably. Ive been very gentle driving it around the neighborhood, just light throttle, no W.O.T. starts.

That's a good thing, as the driver side motor mount was sheared. Just a moderate throttle
would at times send the fan into the fan shroud. All mounts are now new.

I checked the new mounts the other day by opening the hood, standing on the brake, and giving it a bit of throttle. Engine torque would make the driver's side of the engine "hike up" against the load. (BTW, it's impressive to see that bonded rubber block in the mount stretch to control the engine against load. No surprise that they want to break.)

During this load test, the engine would sometimes "unload", fall down, and then jerk back up, even though throttle was constant. I think this has also happened while driving with moderate throttle after a stop. There's sometimes a "clunk" or "chuggle".

This makes me think that the transmission plates must be slipping ,momentarily . I have not touched the trans yet, other than confirming the level is correct. On the plus side, the car has only 44K original miles. The minus side is, of course, that it's 50 years old. I'm going to change the fluid and filter. Maybe the filter is "pasted" or restricted, resulting in starvation, and low clutch circuit pressures?

Also, if the car sits a couple days, is started and put into gear, either forward or reverse, the car doesn't move until i give it a bit of throttle. Maybe another indicator that it's "starved", or has "drained back". Once the car warms up, the trans is normal. Drop it into gear, and it will creep.

I saw a good looking 727 book on Amazon. Looks like it could be rebuilt with only a couple special tools, like slide hammers.

I don't know if I can make it run acceptably until rebuild time.

get a good factory sevice manual u can get used ones from ebay or new reprints from Bishko Books, Repair Manuals, Owners Manuals, Parts Books & Sales Brochures

 

[68PK21 440.6bbl]

The kits were a part of a safety-related recall campaign, just as the later improved inter-locking lh motor mount replacements were.

The main problem was that transmission would go into gear mainly the automatics IIRC. Also the auto trans indicator would be off and not represent what actual gear it was in causing some to back into something thinking they were in drive. It was a big issue if I recall, not just for GM but also Ford, and I take it someone got killed when the car went into reverse instead of forward, may have been a little child. Anyways I'm sure it was Lawyer inspired.

Me on my 440's when I tore up the left mount I just got a auto parts store replacement, and it was of a good quality back in the 70's, but I tore that one right apart so... down to the hardware store for some strong thin chain. I did the same with my $100 DD Fury III, lack of maintenance by previous owner had the mounts deteriorated by engine oil gunk so I just chained it, same for the rear transmission mount, think I blew that one out from the many times I was stuck in the snow doing the forward & reverse jacking to get unstuck. A SureGrip rear end gives you evil ideas in the snow.

 

[CBODY67]

The problem, which basically went away when throttle cables replaced the rods, was that when a driver throttled-into the engine to hit a gap in cross-street traffic (for example), the throttle would hang in that "power on" position as the motor mount came apart. That did cause some traffic accidents, but when it happend to the wife of a Chevrolet corporate person, that got everybody's attention (IIRC). No issues of mis-selected gears were mentioned, back then.

The issue of "the gears" might have been the differences in the selector quadrants between Chrysler/Ford and GM? Prior to the federally-mandated standardized selector quadrant sequence for 1965+ model year vehicles, all GM automatics had "R" at the opposite end of things from "P", which would have been a plus for drivers who might get stuck in snow or mud, rocking the car "out" by shifting between "R" and "L", which were next to each other in the GM automatics (PNDLR vs PRND21). I remember the justification for the 1965+ models having the PRND21 was that some people who had previously had a GM car bought a Ford or Chrysler product and "ventilated" their garage when they started to leave, putting the gear shift where they used to put it to back out, but went forward instead. Yikes!

Which also put the Pushbutton TFs out to pasture as "gear shift levers" were all that could be used, it seemed. Of course, that new Chrysler owner would have had to look at the button being pushed, so they'd know which was the car would move, being different than what their prior GM car had.

Enjoy!
CBODY67

 

[C Sickness]

Well, today I changed the fluid and filter. New fluid is ATF+4. What came out looked just like liquid chocolate. Filter was also pasted with it. Couple quarts came out of the pan, but a couple gallons (almost) came out of the converter.

I drove the car, and it drives like new! No more skips, mis shifts, or "chuggles". Gear shifts are so smooth, it's almost like having a one speed, continuously variable transmission. The greatest improvement for the least amount of money, so far.

In the morning, I'll level the car ad top off the fluid. Thanks for all your help.

 

[azblackhemi]

Well, today I changed the fluid and filter. New fluid is ATF+4. What came out looked just like liquid chocolate. Filter was also pasted with it. Couple quarts came out of the pan, but a couple gallons (almost) came out of the converter.

I drove the car, and it drives like new! No more skips, mis shifts, or "chuggles". Gear shifts are so smooth, it's almost like having a one speed, continuously variable transmission. The greatest improvement for the least amount of money, so far.

In the morning, I'll level the car ad top off the fluid. Thanks for all your help.

That's great that it's fixed! It might be a good idea to do another fluid change pretty soon since it was as you said "liquid chocolate" There's still probably quite a bit of gunk in there.

 

[C Sickness]

Yes, Intend on driving it a bit to circulate, then change again.

One cooler line has a rubber splice from where someone twisted it off at the radiator. Getting a new set of stainless lines.

Maybe there’s a lesson here. When buying some old “barn find”, care for the transmission first, before you tune up the engine and start driving it hard. Might save you an otherwise useable transmission.

 

[tallhair]

Yes, Intend on driving it a bit to circulate, then change again.

One cooler line has a rubber splice from where someone twisted it off at the radiator. Getting a new set of stainless lines.

Maybe there’s a lesson here. When buying some old “barn find”, care for the transmission first, before you tune up the engine and start driving it hard. Might save you an otherwise useable transmission.

Very good plan. Definitely don’t think about power flushes though.

 

[C Sickness]

A “power flush” is done on an engine running car, or dead car?

 

[tallhair]

A “power flush” is done on an engine running car, or dead car?

Running, machine flows new fluid til it comes out clear. Problem is it dislodges stuff that would have stayed where it was which is really not good for a older, grunged up auto.

I did once on a Dakota, after about a year, it finally started performing correctly going into reverse.

 

[tallhair]

And it wasn’t even that old, 1993, flushed with 112k on it, in about 2000.

 

[C Sickness]

I saw a flush on the vw forum-

Break the return line at the trans, add hose to cooler side tubing to flow into bucket.

Connect a hose to the trans. Get a good size “pump up” garden sprayer at H.D., connect (with a valve)to trans hose. Fill with fresh fluid, pump it up.

Start car, watch flow into bucket. Open valve enough so flow rate is “matched” and doesn’t change. Stop when you see fresh clear fluid going into bucket.

Thought about doing it on my Phaeton ZF trans.

 

[LeBaron1973]

As tallhair mentioned - a transmission is likely to have bits of band friction material etc which won't affect its operation, but power flushing will likely move it somewhere it could/will interfere with smooth operation.

Please don't risk your (probably expensive) Phaeton transmission, just drain and refill.

 

[Big_John]

I saw a flush on the vw forum-

Break the return line at the trans, add hose to cooler side tubing to flow into bucket.

Connect a hose to the trans. Get a good size “pump up” garden sprayer at H.D., connect (with a valve)to trans hose. Fill with fresh fluid, pump it up.

Start car, watch flow into bucket. Open valve enough so flow rate is “matched” and doesn’t change. Stop when you see fresh clear fluid going into bucket.

Thought about doing it on my Phaeton ZF trans.

I wouldn't do anything like that with either car. As said, it can dislodge the crap and cause more issues.

 

[C Sickness]

I've been thinking about this all afternoon.

Yes, I can see where people have had bad experiences with a power flush "dislodging crap".

Here's what I think I know-

The transmission pump picks up fluid from the sump, through the filter. Fluid is pressurized to a high pressure to operate the clutch plates. Once it's done that job, it then exists at a much lower pressure. From there, it goes through the lines to the radiator cooler, and maybe aux cooler, then returns to the trans, where it simply drops into the sump. If it takes whatever pressure, maybe 150-200 psi, to operate the trans, those pressures don't exist in the cooler lines. (Otherwise, "front end" car crashes would be really spectacular, with hot 150 psi fluid spraying onto hot engine parts.) Maybe 5-10 psi there?

I'm guessing that the "power flush guy" breaks the line before the cooler, and injects pressurized clean fluid through the cooler, and back to the trans through the return line. He's trying to clean the cooler, and install fresh fluid.

I don't believe it's possible to "pressurize" a 727, or most any transmission. Transmissions have vents, either in the form of a physical vent at the top, or the dipstick tube, with the (non airtight) dipstick handle at the top. If a transmission didn't have a vent, it would, upon heating from operation, push its fluid out through the seals, resulting in leaks. Upon cooling , a vacuum would be created, sucking in moist air or water, if present, resulting in accelerated contamination. All these "breathing" cycles would leave you with an oil-less transmission full of moisture.

If you tried to "pressurize" a 727 with fluid, ( I'll say 50 gallons of fluid, for the sake of this argument), the excess fluid will simply shoot out the vent (dipstick).

Based on the above, i don't see how it's possible to pressurize a transmission by a "power" or "force", (if you will), flush. "Power" is really a marketing term, not an engineering description. The average person who owns a car will say "$150 for a "flush"?, aah, it's not worth it".
"Oh, it's a "power" flush? Do you take American Express?"

The pump picks up irregardless, the plates see their normal pressures, the valve body sees its normal pressures. "Power" will not over pressurize the internal circuits. The only place I see the opportunity to break loose gunk is in the cooler. Maybe the "pressurized" fluid hitting the sump bottom stirs up (to a small degree) whatever is sitting on the floor of the sump, which could include metal particles and band material.

What am I missing?

 

[68PK21 440.6bbl]

the excess fluid will simply shoot out the vent (dipstick).

The vent on a 60/70's era BB 727 is in the pump housing (plate) at the 12 O'clock position and needs a cover plate which is sometimes missing.
Also note the FSM about 'Flushing'.

.

 

[Big_John]

I've been thinking about this all afternoon.

Yes, I can see where people have had bad experiences with a power flush "dislodging crap".

Here's what I think I know-

The transmission pump picks up fluid from the sump, through the filter. Fluid is pressurized to a high pressure to operate the clutch plates. Once it's done that job, it then exists at a much lower pressure. From there, it goes through the lines to the radiator cooler, and maybe aux cooler, then returns to the trans, where it simply drops into the sump. If it takes whatever pressure, maybe 150-200 psi, to operate the trans, those pressures don't exist in the cooler lines. (Otherwise, "front end" car crashes would be really spectacular, with hot 150 psi fluid spraying onto hot engine parts.) Maybe 5-10 psi there?

I'm guessing that the "power flush guy" breaks the line before the cooler, and injects pressurized clean fluid through the cooler, and back to the trans through the return line. He's trying to clean the cooler, and install fresh fluid.

I don't believe it's possible to "pressurize" a 727, or most any transmission. Transmissions have vents, either in the form of a physical vent at the top, or the dipstick tube, with the (non airtight) dipstick handle at the top. If a transmission didn't have a vent, it would, upon heating from operation, push its fluid out through the seals, resulting in leaks. Upon cooling , a vacuum would be created, sucking in moist air or water, if present, resulting in accelerated contamination. All these "breathing" cycles would leave you with an oil-less transmission full of moisture.

If you tried to "pressurize" a 727 with fluid, ( I'll say 50 gallons of fluid, for the sake of this argument), the excess fluid will simply shoot out the vent (dipstick).

Based on the above, i don't see how it's possible to pressurize a transmission by a "power" or "force", (if you will), flush. "Power" is really a marketing term, not an engineering description. The average person who owns a car will say "$150 for a "flush"?, aah, it's not worth it".
"Oh, it's a "power" flush? Do you take American Express?"

The pump picks up irregardless, the plates see their normal pressures, the valve body sees its normal pressures. "Power" will not over pressurize the internal circuits. The only place I see the opportunity to break loose gunk is in the cooler. Maybe the "pressurized" fluid hitting the sump bottom stirs up (to a small degree) whatever is sitting on the floor of the sump, which could include metal particles and band material.

What am I missing?

OK, what it comes down to is the "power flush" is another money making machine for the garage to do exactly that... Make money from the unsuspecting/uneducated public. It all sounds good, "flush" the old out, replace it with new.

In the real world of the 727 (and 904 for that matter), the filter catches all the crap that flows through the trans. Of course, the filter doesn't prevent varnishing of internals and burning fluid.

So... your guy hooks up the "power flusher" and keep in mind, it's a guy that is probably not a candidate for being a rocket surgeon, it's the guy they make change oil and... well... do power flushes... and he pushes some fresh fluid through the lines and into the pan. The filter isn't gonna catch everything and what happened is all the crap on the bottom of the pan and maybe even in the filter itself is now in suspension in the new oil. Ummmm...

The best way and the only way to do this is to unbolt the pan, draining the fluid (yes, it makes a mess) and change the filter. An option is to adjust the bands while you're in there. You clean the pan and, of course, look at what's in the bottom... and if the filter is gummed up. Drain the convertor (if it has a drain plug, some newer ones don't) while you're at it.

There are some things in this world that are just the way they are. This is one of them.

 

[tallhair]

You will likely regret it you do. Small particles that are happily stuck where they are will likely be unstuck and now flowing through the tranny to get lodged in a valve, passage, or wherever else and probably cause problems, whereas that’s much less likely with a repeated normal fluid changes.

You are more likely to experience problems than gain anything if you flush it though.

But it’s your choice obviously.

 

[C Sickness]

The point of my above post was- I don't think my procedure is "power" or "pressure" anything. I'm just supplying it fresh fluid at the same rate it naturally pumps it's old fluid out. No "drama".

It is a fluid change, not a "flush".

If I had just changed the filter, pulled the pan, and washed the pan, there is no "sludge" to stir, or "particles" to disturb.

The alternative is to drop the pan and drain the converter "10 times" to get all the way back to fresh fluid.

If a "particle" goes all the way through a brand new filter, I think you have a filter problem, not a particle problem.

 

[LeBaron1973]

I would think the "power/pressure" aspect refers to the "effort" required to "purge and replace" the transmission fluid by the machine compared to draining and removing the pan and refilling via a funnel.

Reading the factory service manual made me wonder whether, having "flushed" any remaining solvent, the 2 quarts of fluid (and solvent remains) should be removed and replaced with fresh fluid?

I'm sure we'll be interested to learn how your Mopar/Volkswagen operates should you decide to flush. I should think it less risky to "flush" the Mopar transmission without all the electronics.

Good luck whatever you decide.