Does fluid drive create oil pressure issues?

[rcb]

I was reading an article that mentioned that fluid drive equipped mopars can have oil pressure issues. I think they were inferring that the fluid drive taps the oil system. I thought that the fluid drive was its own system. Can anyone educated me? I'm still on the search so I don't have one yet, but all the desoto suburbans I've seen are equipped with fluid drive. I imagine I'll be going through the engine on anyone I might wind up with but was curious if that was the case.

[Plymouthy Adams]

fluid drive is a sealed unit, all oil is internal and not shared with any other device, not sure where you are reading your info, could you provide that link.   The Hy-Drive of 53/54 fame did indeed use the engine oiling system but it was a true torque converter, not a coupler....

[rcb]

I see. I'll have to wait until I get home to dig the link back up. The article was mainly concerned with swapping input shafts between a fluid drive and non fluid drive if I recall. I had been looking up rebuild tips/tricks for flat 6's when I came across it. Of course this is all daydreaming at this point, but I was also looking up how much one of the 251s could be warmed up reliably. Everyone seems to have different opinions of what "power" is. Then I got to thinking about the 4.0 I've had in several Jeeps. To me they are my favorite engine built in the last 20 years. Some people say they are dogs too, but I love them and find them to be plenty strong, even in a Cherkoee that I towed with all the time. The one in our wrangler is great. I've towed quite a lot with it too, even over mountains. The flat 6 is pretty close to them in output so it's put it in a better frame of mind for me. sorry, getting off topic.

[knuckleharley]

3 hours ago, Plymouthy Adams said:

fluid drive is a sealed unit, all oil is internal and not shared with any other device, not sure where you are reading your info, could you provide that link.   The Hy-Drive of 53/54 fame did indeed use the engine oiling system but it was a true torque converter, not a coupler....

How big was the oil pan on those engines,and where was the sump located>

[Plymouthy Adams]

10 quart pan, 11 quart with oil filter change....the book does not go into details of the oil pan shape or for that matter the address of the oil pick up tube...in engine, lube or Hy-drive section

[knuckleharley]

Thanks. This is the first I have heard of a combined base and trans oil system.

[Plymouthy Adams]

Knuckle I currently have 5 cars and 2 spare engine/tranny setups here at the house where the entire transmission be it the 4 speed automatic or a 4 speed manual including the third member ...that is located INSIDE the engine oil pan, the manual is dry clutch and works reverse of what you would say is normal......this is nothing new....long back a certain metro police department made it a requirement that the automatic trannies and engines share the same oil and only Mopar could meet the requirements.  Very little new under the sun...many things are hashed about and reborn out of necessity.

[knuckleharley]

7 minutes ago, Plymouthy Adams said:

Knuckle I currently have 5 cars and 2 spare engine/tranny setups here at the house where the entire transmission be it the 4 speed automatic or a 4 speed manual including the third member ...that is located INSIDE the engine oil pan, the manual is dry clutch and works reverse of what you would say is normal......this is nothing new....long back a certain metro police department made it a requirement that the automatic trannies and engines share the same oil and only Mopar could meet the requirements.  Very little new under the sun...many things are hashed about and reborn out of necessity.

"Worked the reverse of normal"?  Do you mean the shifter was on the left side of the wheel?

Mopar had 4 speed auto trans back then?

[greg g]

http://www.allpar.com/mopar/fluidrive.html

[Plymouthy Adams]

clutch,  not shifter...shifter is a single rod change with dual fork and has been modified by me to a shorted throw of a mere 4 inches from first to second through neutral...as compared to being able to manually work the throttle with your pinky when shifting with stock set up...and who said it was Mopar.....?????????? 

 

 

Edited June 19, 2017 by Plymouthy Adams

[dpollo]

HYDrive cars use the same  pan as any other, the extra oil  is contained in the Torque Converter which must be drained separately.

A bit of a chore but with the extra volume, oil  needed to be changed less often.   Better performance than the Fluid Drive for sure !

[Plymouthy Adams]

thanks dpollo...I had seen a hy-drive and did not recall a distinguishing feature in and about the pan...the fact the book did not cover these items should have been enough to say they were stock..but I have assumed in the past...and only gotten egg for my efforts...

[dpollo]

I have owned two Hydrive vehicles and have some technical info should you want it.   The M6 semi automatics also used the engine fed torque converters in 53.     A bit of a mechanical boggle but they worked well enough and certainly worked better than Fluid drive.

The engine blocks for HyDrive needed two machined bosses to mate with the bell housing adapter plate.  One at the oil  gallery and the other for the drain-back into the pan which had a  tube  to put the returning  oil to the bottom.    

Wish I had all this stuff now.    Hydrive with Overdrive .  Possible but I have never seen or heard of one.

[Plymouthy Adams]

I know of one hy-drive with overdrive...

 

expounding on the above, the introduction of the hy-drive and the 2.6 torque multiplication of the converter allowed ma Mopar to reintroduce the fast second similar to earlier times and at the same time also get a higher ratio rear gear under the unit.  Adding OD is just a bowl of gravy for the  ole boat...

Edited June 20, 2017 by Plymouthy Adams

[Bobacuda]

My B4B has Fluid Drive.  I have seen that using it affects the oil pressure, but I think that is caused by affecting engine rpm.  Normally, when warm the engine has just about 40 lbs oil pressure.  If I don't put the clutch in and come to a stop, the engine will "load," rpm's drop and the oil pressure will drop to about 5 lbs pressure.  Based on this, the Fluid Drive in my truck has an impact on the oil pressure, but not in the way a Hy-Drive system would.

[Jerry B]

Recently found out that the engine oil  suplied trans uses diferent rear main bearins. Any info on this will help.

[Plymouthy Adams]

editing post, found the statement...there is not a special bearing only a note to use a rear lower shell without oil groove and return hole.....

 

Edited December 6, 2017 by Plymouthy Adams

[Dodgeb4ya]

A different H-duty rear main bearing is required on the fluid drive 23" smaller engines.

A loss of oil pressure if the rear main end play is excessive.

[Merle Coggins]

21 minutes ago, Dodgeb4ya said:

A different H-duty rear main bearing is required on the fluid drive 23" smaller engines.

A loss of oil pressure if the rear main end play is excessive.

What's different about the rear bearing for a FD 23" engine? I didn't know anything about this when I built my engine 12 years ago. I haven't experienced any issues to date.

[Plymouthy Adams]

24 minutes ago, Dodgeb4ya said:

A different H-duty rear main bearing is required on the fluid drive 23" smaller engines.

A loss of oil pressure if the rear main end play is excessive.

I know you deal with these cars a lot, if there is a running change or service bulletin issued since my book was published I would like to know the specifics as I think many here would also.  There is in my mind a need to annotate that change and requirement in the service manual.  No retailer I found had a note for this requirement on the bearings they sell might I add. Can you post that information for our benefit...thanks...

[Plymouthy Adams]

1 minute ago, Merle Coggins said:

What's different about the rear bearing for a FD 23" engine? I didn't know anything about this when I built my engine 12 years ago. I haven't experienced any issues to date.

FD which I assume is fluid drive and the hy-drive are not the one and the same.  The hy-drive is an actual torque convertor that operates on engine oil and multiplies the torque greatly.  So great in fact that the hy-drive got a taller rear gear stock, and taller gears in first and second as the torque really got these cars rolling easily.

[knuckleharley]

SO.....since no one mentions the 25 inch engines,is it safe to assume this is not a problem with any of them?

The "Hy-Drive" sounds like a Plymouth name to me for some reason. What cars were they in,and what years?

If you adapt a fluid drive/hy drive trans to a 25 inch block,will there be any problems? I have a 51 DeSoto engine with some sort of auto-trans that I bought,so I am interested in hearing about this.

Edited December 6, 2017 by knuckleharley

[Don Coatney]

15 minutes ago, knuckleharley said:

SO.....since no one mentions the 25 inch engines,is it safe to assume this is not a problem with any of them?

The "Hy-Drive" sounds like a Plymouth name to me for some reason. What cars were they in,and what years?

If you adapt a fluid drive/hy drive trans to a 25 inch block,will there be any problems? I have a 51 DeSoto engine with some sort of auto-trans that I bought,so I am interested in hearing about this.

Do a forum search. The  hy-drive has been discussed many times. Surprised you don't recall??

[knuckleharley]

12 minutes ago, Don Coatney said:

Do a forum search. The  hy-drive has been discussed many times. Surprised you don't recall??

The only thing that really surprises me anymore is  not having to use my GPS to get back home from the grocery store.

[dpollo]

Hy Drive does not fit just any block 23 or 25 inch.  The block must have the machined surfaces to mate up with the  adapter  plate to provide oil to the  torque converter and return it to the pan.   Blocks cast in 53 and 4 and possibly some later ones have this feature but on later blocks the return hole was not drilled.  The supply was from the back of  the  oil gallery and would have a threaded plug if there was no Hydrive.  Same for the semi-autos with engine-fed torque converters.