Bad throttle valve cable

[Philip]

Line pressure at idle is not controlled by TV pressure but rather by the pressure regulator settings.

This is true. Base Line Pressures settings are preset around 100 PSI give or take a little. But there is no settings for high side pressures. This is controlled by the throttle valve. In forward movement only. The throttle valve only comes into play after the vehicle i moving this is when the higher pressures are needed.



Lets define line pressures a little better here. I am talking about clutch pack / band apply pressures that is what the throttle valve is controlling.







Mr Peters if they did not find that temp sensor for you. Have them look under a gasser with a towing package. Dodge was cheap around this time and used sensors aross both lines of trucks. If the diesel listing doesn't show it I bet the gasser section does in the parts book.

 

[PPeters]

Part Numbers and Prices



Second go round with the dealer parts counter, found some stuff, including the sensor, all under the coolant lines. Soooo... ...



Transmission Oil Cooler (mount to side of engine, under turbo)

Part Number: 4746216 (replaces 4720005)

Price : $280

Availability : No dealer stock, 14 on backorder as of 3/30 No manufacturing orders placed. My guess is this part is going bye bye



Oil Cooler Hold down clamps

Part Number: 4428128

Price : $18. 00 each

Availability : In stock



Transmission Oil Cooler Line, front position

Part Number: 4428355

Price : $26. 00

Availability : In stock.



Transmission Oil Cooler Line, rear position

Part Number: 52117602

Price : $110. 00

Availability : In stock.



Transmission Oil Cooler Line, return from front of vehicle to transmission

Part Number: 53009018

Price : N/A

Availability : DISCONTINUED.



Now somebody straighten me out, but isn't the line coming from the front position of the oil cooler (motor mounted) the one that then travels to the air exchange cooler (long run)? And the rear position goes to the transmission (shorter run). I think that is the way it works (memory fails me), so the price between the two lines attached to this cooler makes no sense. I would think the longer line would cost more, not the shorter one.



I'll post the discontinued part number in the other forum.



Pat

 

[cerberusiam]

Ppeters, I don't think the 1st gen coolers are available anymore hence the back order. A 2nd gen cooler can be adapted to work if si needed. There was a post somewhere about that a while ago. Considering the cost of the lines and pieces I would seriously consider an alternate under-bed cooler with a thermostat on it. If I remeber right the cooler, thermo, and fan was around $250 on the summit site. You would still have to build the lines to it but high pressure hose and fittings is not that expensive to have made up.



The reason I have for bypassing the liquid-to-liquid cooler is its tendency to vibrate loose internally and bleed into the various liquids. There were several post a while back about oil in the cooling system and anti-freeze in the oil from the cooler having gone south. The liquid-to-liquid will give you better cooling but that air-to-liquid cooler is worthless if you do tow heavy. Considering the cost and length of the lines it I think it would be much more efficient to use an aftermarket cooler that is controlled by a thermo instead of replacing all the lines and pieces. Just another idea you might want to consider.



Philip, yes that is what I mean also. Line pressure is the apply pressure available for bands, clutches, and in the later trans the TC clutch. I believe the line pressures ran from 40 psi low to around 70 or 80 psi high in a stock application. The throttle valve was used to affect the pressure in this range for apply pressures so if you drove sedately you did not shake the dust off the headliner on every shift. There has to be a way to set the upper pressure limit because a performance rebuild ups the line pressures. If you do not limit the upper pressure you run into the same problem DTT did. Mainly, the clutch apply pistons and band apply pistoms were not engineered to work correctly at that level and they caused major issues. Thats why I say there has to be a way to control line pressure independently of the the throttle pressure. In a full race valve body the TV is completely eliminated and apply pressures are set to a constant level as well as the throttle pressure. You then tune your shift points using the springs on the shift valves. If you do it the cheap way then you just tie the TV valve all the way open and you get the same effect.



The reason I have a problem with saying the throttle pressure controls the line pressure is that leads to the thinking raising the throttle pressure will raise the line pressure and that is not the way to solve shift problems or slippage in the trans. Its more of a semantics thing than anything else because it can be misinterpreted and I really hate having somebody yelling at me because he misunderstood what I said and now his trans is a pile of fused aluminum. Come to think of it, there are some builders that still don't get the relationships correctly either. LOL.

 

[Philip]

there are some builders that still don't get the relationships correctly either. LOL.

Boy you got that right.



The low side line pressure is the pressurer regulator setting in light throttle setting. At WOT the throttle valve boosts it up to around 160 PSI line pressure. I recovered this from some notes I had taken from an advanced auto trans class many years ago.



The good thing about this little talk is now some of the members will be able to understand the function of the TVC cable setup better. Then hopefully they do not unhook them. Both of us has seen to many transmissions blown from low line pressures.

 

[PPeters]

Transmission Oil Temp Switch

One more part number from dealer.



56026720, price $11. Stock available.



Have done some looking at the cooler, and I'm getting that sinking feeling that it is the fitting at the rear of the cooler that is leaking. Hoping that it has just rattled loose, but I've tightened it once already to stop the original leak I had after the garage did the rear seal, only to have it start up again. I used a backup on the fitting when I tightened it, so I *really* hope that it hasn't cracked going into the cooler. Should know more today.



How do I deal with the sensor location if the cooler is trash and I need to install an under bed unit. Can I cut the line with the sensor boss to retain it, then transition to soft line? Or replumb with a copper T for the sensor and thread into new high pressure line? Anybody out there who has done this, now's the time to speak up Oo.



Again, thanks for all the help and support guys.



Pat

 

[cerberusiam]

As long as you keep the sensor fitting as close to the stock place and the tip in the same approximate postion to the flow of fluid you should be able to build custom lines out of pieces availble about anywhere and make it work like stock. If you don't have to worry about others driving the truck and pulling with it you could just bypass the sensor and put a gauge in its place. Computers are just great for keeping things under control for the masses but leave a lot to be desired when they start having issues. A set of gauges and the old Mark 1 is just as effective and a lot less trouble most of the time.



Phillip, I need to have another discussion with a trans guy about the line pressures. I know you can push them that high and have had several discussions about whats good, bad, and ugly and was under the impression max in a stock setup was around 90 to 100 psi but that may have been for a gasser. Too many numbers and my less than adequate not taking probably missed something. Working on too many different trans in too many different vehicles so things are a bit hazy.

 

[Philip]

I need to have another discussion with a trans guy about the line pressures

Let me know what you find out. The last class I had only covered 727's. But going threw the flow charts between the 727 and the 518. The only differnce I see is the extra circuits for the OD.



From talking to people that worked on the assy line where they were put togeter. The springs for all the other valves did not change when they went to the 518 series of trans. ( I have two brother in laws that were working the line when the change to 518's were made). I try to keep up on changes on the line when they happen.

 

[PPeters]

I knew I saw a post about this a while back, here are the pictures:



https://www.turbodieselregister.com/user_gallery/displayalbum.php?&albumid=893



He's using the underbed cooler in conjunction with the engine mounted cooler. Neat setup.



Looked at the fitting in the cooler, that is definitely where the leak is. The fittings are listed in the Dodge computer system, but not for sale (serviced with cooler). Gonna see if the fitting can be pulled and reinstalled/sealed. If that don't work, gonna bypass the cooler alltogether and look into installing an underbed unit like above.



Oh the joy of fixing old vehicles



Pat

 

[PPeters]

Just an update on the adventure...



Truck is back on the road, replaced the OD temp sensor switch with the correct one (part number posted earlier). The leak from the cooler was caused by the rear fitting nearly being unthreaded from the cooler. Don't ask me how. The garage that did my rear seal (usually very good) did this work. I asked the owner how that might have happened. He explained that the tech working on the truck must not have retightened it when he pulled the transmission. I asked why he would have pulled the line from the cooler instead of dropping it at the transmission. He didn't have a good answer, but did credit my bill two hours labor for the trouble. So luckily I didn't have to replace any lines.



The sensor must have been causing my trouble, because no more shifting issues since, running just like before it went in for the seal-ectomy. Thank you all for your help on this.



Pat