Transmission question - pretty basic.

Reply Subscribe

Thread Tools

Search this Thread

Sep 22, 2015 | 02:51 PM

#16

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,738

Likes: 2,666

From: SE Florida

Quote:

Originally Posted by Dan V

That sounds like the pump is compromised. But Mark will chime in.

Quote:

Originally Posted by Tugly

The truck "pulses" with the torque converter locked, and I feel it's in lock-step with the RPMs - not the driveline speed.

I have never seen one with symtoms like this be a transmission problem. It's ALWAYS been an engine problem.

Quote:

Originally Posted by Tugly

I have confirmed there is no torque converter slip with the TC locked.

Another clue that it isn't the transmission.

Quote:

Originally Posted by Tugly

The pulsing feels like a partial injector miss when the torque converter is locked,

Another clue that it isn't the transmission.

Quote:

Originally Posted by Tugly

but I can find nothing wrong with the engine or the injectors.

I recommend looking harder.

Quote:

Originally Posted by Tugly

If I shift into neutral while rolling down the highway, the ride is smooth at idle, but rev it up and I get the tiniest of pulses with the RPMs.

Another clue that it isn't the transmission.

Quote:

Originally Posted by Tugly

I just figured that since the crank and the transmission are mechanically connected, I should provide that possible troubleshooting clue.

They are not mechanically connected when the torque converter is unlocked, and especially not connected when the trans is in neutral.

Quote:

Originally Posted by Dan V

He'll likely ask if you can measure the pressure the pump is making. I'm just spitballing here, I have really no experience other than changing filter/fluid in these things.

Probably not. I'm nearly 100% sure this is an engine problem, not a trans problem.

Sep 23, 2015 | 05:15 AM

#17

Tugly

Thread Starter

Hotshot

Joined: Jan 2011

Posts: 18,849

Likes: 179

From: Puget Sound

I just had to ask, didn't I. OK... I have a game plan for the engine.

I'll also check the fluid for drainback.

Thanks for all the feedback everybody!

Sep 23, 2015 | 09:20 AM

#18

BadDogKuzz

Postmaster

Joined: Dec 2010

Posts: 2,951

Likes: 4

From: Gary,Indiana

Quote:

Originally Posted by Mark Kovalsky

I don't see that at all.

The delay in engaging when cold is often a drainback valve that is leaking. As mentioned above, check the trans fluid after it's been sitting overnight. Check it BEFORE starting the engine. If it shows overfilled, the torque converter has drained into the pan. The delay is the pump refilling the torque converter.

They are not mechanically connected when the torque converter is unlocked, and especially not connected when the trans is in neutral.

Probably not. I'm nearly 100% sure this is an engine problem, not a trans problem.

Mark thank you for confirming what I was thinking might be the problem. It was the only thing I could think of as far as being able to hear trans fuild flowing? I would think the metal sound IF it was the drainback valve would be the stator being unbalanced due the TC NOT being full of fuild. Now on Sonnax web page for the drainback valve it says that "OD planetary failure" but I would think that it would also cause premature wear on the TC stator and stator bearing. If it is a stock TC the stator only has a bushing and not a torrington bearing.

So my question for you is what kind of damage would you think could happen if a drain back valve went bad and not replaced?
Thank you as always for your input it is much appreciated!!

Quote:

Originally Posted by Tugly

I just had to ask, didn't I. OK... I have a game plan for the engine.

I'll also check the fluid for drainback.

Thanks for all the feedback everybody!

Rich I have found in working on boats with inboards and I/O's that harmonic vibrations can sometimes feel like a pulse at just the right rpm's. And as odd as this might seem I have had where changing the harmonic balancer cured the problem. I know I have suggested to you before a Fuildampr and I still think it would help with some of the minor issues you are having.
The problem is you are too astute.

Ford Powerstroke

Sep 23, 2015 | 09:59 AM

#19

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,738

Likes: 2,666

From: SE Florida

Quote:

Originally Posted by BadDogKuzz

I would think the metal sound IF it was the drainback valve would be the stator being unbalanced due the TC NOT being full of fuild.

I think that's possible, I hadn't considered that.

Quote:

Originally Posted by BadDogKuzz

Now on Sonnax web page for the drainback valve it says that "OD planetary failure"

Maybe they know something I don't (and that is CERTAINLY possible!) but I can't imagine a way that the drainback valve could possibly impact the OD planetary.

Quote:

Originally Posted by BadDogKuzz

but I would think that it would also cause premature wear on the TC stator and stator bearing. If it is a stock TC the stator only has a bushing and not a torrington bearing.

I can't say that is impossible. I don't think it is likely because the converter can never drain below halfway. Within a second or so of engine CRANK, not start, the converter starts filling again. So the bearing and stator should have fluid almost all the time.

Quote:

Originally Posted by BadDogKuzz

So my question for you is what kind of damage would you think could happen if a drain back valve went bad and not replaced?

None. I do not believe it will hurt anything if this isn't fixed.

If the drainback leaks, in my opinion, the only downside is that after it's sat for enough time for the converter to drain you're going to have to idle before the torque converter will allow the truck to move. That's it.

Sep 23, 2015 | 10:06 AM

#20

BadDogKuzz

Postmaster

Joined: Dec 2010

Posts: 2,951

Likes: 4

From: Gary,Indiana

Thank you Mark for your insight !!

Sep 23, 2015 | 02:08 PM

#21

Tugly

Thread Starter

Hotshot

Joined: Jan 2011

Posts: 18,849

Likes: 179

From: Puget Sound

Quote:

Originally Posted by BadDogKuzz

...Rich I have found in working on boats with inboards and I/O's that harmonic vibrations can sometimes feel like a pulse at just the right rpm's. And as odd as this might seem I have had where changing the harmonic balancer cured the problem. I know I have suggested to you before a Fuildampr and I still think it would help with some of the minor issues you are having.
The problem is you are too astute.

Ford Powerstroke

I remember the Fuildampr conversation, it's been on my mind. I need to be sure the pulse is at full RPM and not half RPM. If it's half RPM, then it leads big time to an injector flow imbalance, since the compression checks out.

As astute as I might be - I need to be more "asstute" to sort out vibrations... my butt makes a lot of mistakes.