FLCV Mod

flman · **Posted:** Mon Aug 23, 2010 9:29 pm

FLCV Mod (Flman check valve mod)

Many CRD owners are plagued with air in the automatic transmission lines at start up, this causes many problems, slow initial engagement, and even a binding situation that causes stalling when switching from reverse to drive. Others on this forum have stated in was the valve in the front pump and a poor casting, and you either need a new front pump, or a repair kit, doing this requires removal and tear down of the transmission, but does it work? Or does the new spin on filter installed during the tear down give the illusion that this did work?

I came to the conclusion that ever since I did a filter change this problem started for me, I even blew into the spin on filter to insure it had a check valve, it did but it must not be very reliable. So do you pull the pan and repeatedly change filters and hope you get lucky, or do you make a permanent repair?

Here are the parts:

http://www.grainger.com/Grainger/APOLLO ... Pid=search

http://www.grainger.com/Grainger/PARKER ... Pid=search

So order the check valve and 2 compression fittings, use Teflon tape or a suitable thread sealant then tighten the fittings into the check valve. Go under the Jeep and cut out enough tubing from the lower transmission return line and install on the line, you can locate it any where you want, just be sure the flow direction to the check valve is correct. Fluid loss is minimal, you will only need to replace about 1/3 of a quart of fluid.

Here it is on the line, but not secured.

Here it is secured, I slit a piece of 3/8" vinyl tubing and put it on the top line, then tied the two lines together with a nylon tie, this prevents metal to metal from rubbing together, and stops vibration.

I have put 500 highway miles on my mod with no adverse effects and more confidence when I put it in gear.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Nice hack.

dgeist · **Posted:** Thu Sep 30, 2010 2:58 pm

Interesting solution, so that basically prevents backflow from the tranny cooler up front back down into the pan, right? Is there anywhere else that something like that might fit, like perhaps right a the coolant outlet from the cooler?

Dan

jrcstudios · **Posted:** Fri Oct 01, 2010 7:55 pm

Hey, I think this may be what I need to do.. I have not replaced any tranny filters since I have been the owner, but I have been plagued with a worsening problem;

First start of the day results in no movement either forward or reverse for about 15 seconds (getting longer) Then, after moving at about 5 MPH, occasionally when you hit the brake, it turns into a 'manual' transmission with no clutch, resulting in either surging forward, or choking the engine down..

After it does this once, it doesn't do it any more for the rest of the day. Even after 3-4 hour rests.

Now that the weather is cooler, it seems to be worse (or is the problem just getting worse with time?)

Tranny fluid checks fine at operating temp.

greiswig · **Posted:** Wed Nov 17, 2010 5:39 pm

Hi,

Looking for any updates to this mod. I have this exact problem, and it does seem to be getting worse. So has the apparent fix that this made to your vehicle lasted?

Thanks!

flman · **Posted:** Tue Nov 30, 2010 7:29 am

greiswig wrote:

Hi,

Looking for any updates to this mod. I have this exact problem, and it does seem to be getting worse. So has the apparent fix that this made to your vehicle lasted?

Thanks!

It works perfect, it does what the internal spin on filter is supposed to do. I have been running it for 3 months in 2 vehicles so far.

grsjax · **Joined:** Sun Oct 03, 2010 7:26 pm **Posts:** 61

Trying to put the back flow valve in today and ran into a problem. There is a plastic piece connecting the two tubes together. I assume it is there to prevent them from rubbing. Question is how do I remove it? With it in place there is not enough room to mount the valve. Will it just slip off after I cut the pipe?

After thinking about it for awhile I think I will just cut the dang thing off with a saber saw. I can't see any harm it would do and I can't put the valve in with it there so cutting it off seems the best approach. :idea:

flman · **Posted:** Wed Jan 05, 2011 2:27 pm

grsjax wrote:

Trying to put the back flow valve in today and ran into a problem. There is a plastic piece connecting the two tubes together. I assume it is there to prevent them from rubbing. Question is how do I remove it? With it in place there is not enough room to mount the valve. Will it just slip off after I cut the pipe?

After thinking about it for awhile I think I will just cut the dang thing off with a saber saw. I can't see any harm it would do and I can't put the valve in with it there so cutting it off seems the best approach. :idea:

I just took some pliers and worked it until it opened up. The valve and some vinyl tubing to prevent chafing take takes the place of the spacer.

JcGilmour · **Posted:** Wed Oct 24, 2012 8:15 am

Anybody got any new ideas. It has been some time since this topic was updated.

John

MtnClimber · **Posted:** Sat Nov 03, 2012 11:43 am

Great idea - I'll have to order up the parts and give this a shot as I am having the drain back issue after she sits for several hours.

JcGilmour · **Posted:** Sat Nov 03, 2012 5:18 pm

This external check valve in the cooler return line had no effect on my vehicle.
It puzzles me that the trans will work normally sometimes.

dieseldog · **Joined:** Thu Sep 30, 2010 1:41 am **Posts:** 2

Did this mod lasted week . It worked. Just make sure you point the check valve arrow toward the back of the jeep.

JcGilmour · **Posted:** Sat Dec 22, 2012 11:58 pm

I for one will be interested in your report a few weeks down the road.

John

flman · **Posted:** Thu Feb 28, 2013 12:42 pm

JcGilmour wrote:

This external check valve in the cooler return line had no effect on my vehicle.
It puzzles me that the trans will work normally sometimes.

This will help with a drain back issue, if you are using any transmission fluid other then ATF+4 you will have similar symptoms.

Amsoil ATF will cause all kinds of problems with the lower RPMS of the engine that cause lower pump pressures.

Both of my Jeeps were plagued with tranny problems until I got rid of the Amsoil and put the ATF+4 in.

darinb · **Posted:** Wed Aug 07, 2013 9:58 am

This is great. I hate when I put my Jeep in gear I the morning and nothing happens. Going to do this soon.

What's the best tool for cutting the tranny line cleanly?

jayleonfb99 · **Joined:** Thu Apr 04, 2013 12:24 am **Posts:** 9

Can anyone suggest the best tool to cut the line? How have the long term results been on this mod?

CATCRD · **Posted:** Wed Jul 30, 2014 11:03 pm

I would use something like this

http://www.homedepot.com/p/RIDGID-101-T ... /100075014

jayleonfb99 · **Joined:** Thu Apr 04, 2013 12:24 am **Posts:** 9

FYI, this didn't help my issue.

flman · **Posted:** Mon Dec 15, 2014 3:42 pm

jayleonfb99 wrote:

FYI, this didn't help my issue.

Well, you must have a problem with the front pump valve instead of drain back?

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