start up in park or neutral ?

[mr gtx]

going to start a new rebuilt motor, car was sitting and fluid drained back into pan plus putting a brand new torque converter in. added about a quart to the new converter before i put it in. i want the the fluid to go into the converter on start up. will be breaking in cam for 20 minutes, should i start it up in neutral, will that put the fluid back in the converter better then in park. thanks

 

[Davea Lux]

going to start a new rebuilt motor, car was sitting and fluid drained back into pan plus putting a brand new torque converter in. added about a quart to the new converter before i put it in. i want the the fluid to go into the converter on start up. will be breaking in cam for 20 minutes, should i start it up in neutral, will that put the fluid back in the converter better then in park. thanks

On the 727 transmission, the pump is disengaged in Park, so start the car in Neutral.

Dave

 

[Big_John]

Yep, start in neutral. The pump doesn't work while in park.

 

[mr gtx]

great thanks guys. i know on the dip stick it says check in neutral i just didn't why lol

 

[CBODY67]

Be SURE to have the parking brake fully ON, too! When the trans is in "N"

 

[HotDodge]

Respectfully to other comments, the 727 TF pump is not "disengaged" when in park, and you are perfectly fine in the context you provide firing the engine in park. The pump is mechanically attached to the crank via the torque converter hub, so it is always engaged and pumping whenever the crank spins. When in park, the valve body diverts the majority of the converter line pressure back into the pan, but some fluid still flows into the converter. For your specific situation, fire the engine and break in the cam with the transmission in park. The converter will get plenty of fluid for rotating in park, especially with the pump turning at 2,500 - 3,000 rpm. You are also fine breaking in the cam in neutral, but it is unnecessary. Have someone on hand to pour in more ATF if needed as the system fills.

 

[CBODY67]

I'm not sure of the concern with the torque converter as you're not going to drive the car until after the cam is broken-in. If the trans was completely overhauled, there is a fluid-fill spec for that, from which you can deduct the amount of fluid you added to the converter before it was installed, for the "initial fill" amount of atf.. That should get enough fluid into the trans to not hurt itself during the cam activity. Then, after the cam break-in period, when the idle speed is back to normal, everything will be fully up to operating temp and you can do a good check on the atf level, adjusting as needed.

In "P", atf is flowing everywhere, just not at the same pressures as it might be if the trans was in "N". Which is why, on a fully-cold transmission, in the colder times of the year, it's best to start the car that first time in "N", so that when you put it in "R" of "D", it moves as it should. Rather than being initially lazy if it was started in "P".

Enjoy!
CBODY67

 

[mr gtx]

the tranny was not rebuilt. old converter was in there for 5 months not sure how much drained back and the fluid is way high on dip stick. like i said i put in maybe 3/4 of a quart in converter. my concern was to have fluid in converter so not to do any damage. i think i will start in neutral for 10 seconds and then put in park. with keeping the rpms up and down between 2000-2500 checking timing and leaks won't have time to check tranny fluid till i get it back to normal idle. as long i don't hit reverse going into park. lol , I always have a lot of anxiety before and during break in, one time i forgot to put any water or anti freeze in had to shut it down got to over 200*

 

[stubs300]

i think i will start in neutral for 10 seconds and then put in park. with keeping the rpms up and down between 2000-2500 checking timing and leaks won't have time to check tranny fluid till i get it back to normal idle. as long i don't hit reverse going into park. lol , I always have a lot of anxiety before and during break in, one time i forgot to put any water or anti freeze in had to shut it down got to over 200*

I wouldn't even do that, you're just asking for trouble! What happens if you miss Park & hit Reverse at 2500 RPM? Even with bigass chocks and the parking brake fully engaged, I wouldn't want to see what happens! You're over thinking **** and looking/asking for trouble, just start it in Park and you'll be fine.
If you decide to do it your way, make sure you have video rolling and post it up so we can all laugh at the carnage! Good Luck

 

[mr gtx]

I wouldn't even do that, you're just asking for trouble! What happens if you miss Park & hit Reverse at 2500 RPM? Even with bigass chocks and the parking brake fully engaged, I wouldn't want to see what happens! You're over thinking **** and looking/asking for trouble, just start it in Park and you'll be fine.
If you decide to do it your way, make sure you have video rolling and post it up so we can all laugh at the carnage! Good Luck

yes sir

 

[Big_John]

the tranny was not rebuilt. old converter was in there for 5 months not sure how much drained back and the fluid is way high on dip stick. like i said i put in maybe 3/4 of a quart in converter. my concern was to have fluid in converter so not to do any damage. i think i will start in neutral for 10 seconds and then put in park. with keeping the rpms up and down between 2000-2500 checking timing and leaks won't have time to check tranny fluid till i get it back to normal idle. as long i don't hit reverse going into park. lol , I always have a lot of anxiety before and during break in, one time i forgot to put any water or anti freeze in had to shut it down got to over 200*

I was thinking the trans/convertor was new and that was the concern. My preference with a new trans would be starting in neutral, but since it's not, just start in park and don't worry about it.

 

[HotDodge]

the tranny was not rebuilt. old converter was in there for 5 months not sure how much drained back and the fluid is way high on dip stick. like i said i put in maybe 3/4 of a quart in converter. my concern was to have fluid in converter so not to do any damage. i think i will start in neutral for 10 seconds and then put in park. with keeping the rpms up and down between 2000-2500 checking timing and leaks won't have time to check tranny fluid till i get it back to normal idle. as long i don't hit reverse going into park. lol , I always have a lot of anxiety before and during break in, one time i forgot to put any water or anti freeze in had to shut it down got to over 200*

I agree with @stubs300 that you're overthinking it, which isn't a bad place to start during the theoretical part of prep but can get you into trouble in practice, such as jamming the transmission from neutral into park at 2K rpm. In park, the converter gets 5 - 30 psi of fluid depending on rpm, and your converter will see the high end of that range since it'll be turning 2K+ rpm. In neutral and all gears, the converter gets around 30 psi at idle for comparison. If you're worried about burning up the converter, it's an unfounded worry since it will fill immediately just like it does when idling in neutral/gear. If you're worried about burning up bushings/bearings, the lubrication circuit of the 727 gets the same psi in park as it does in neutral/gear. Leave it in park and focus on the engine.

 

[HotDodge]

I was thinking the trans/convertor was new and that was the concern. My preference with a new trans would be starting in neutral, but since it's not, just start in park and don't worry about it.

I don't know where you found this information, but it's inaccurate. You originally said the pump doesn't work while in park (it does), and now you recommend starting a rebuilt transmission and/or new converter in neutral. The correct information is that there is no benefit to starting in neutral for a new converter compared to starting in park, and it's actually better to start a rebuilt 727 in park versus neutral. Park applies the same lubrication circuit 5 psi as neutral but at 5 psi line pressure which fills the dry system and apply gentle pressure to new seals before moving into neutral to apply 55 psi line pressure against seals, then into 1/2/3 to actuate the rear clutch, ending in reverse for the highest line pressure of 230 psi and to engage both front/rear clutches and the low-reverse band. Starting a rebuilt transmission in neutral isn't going to damage anything, but the better method is starting in park.

 

[mr gtx]

you wonder why i over think. went to prime motor, yes reverse with the drill not 1 lb of oil pressure, thinking maybe cam bearings in wrong just my luck, called engine builder, right a way he said take the oil filter off it won't be filled with oil because your oil relieve valve is stuck, i said brand new melling stock pump, he said still will be stuck from sitting or a little burr. he was right, i freed it up now plenty of oil pressure.

 

[Big_John]

I don't know where you found this information, but it's inaccurate. You originally said the pump doesn't work while in park (it does), and now you recommend starting a rebuilt transmission and/or new converter in neutral. The correct information is that there is no benefit to starting in neutral for a new converter compared to starting in park, and it's actually better to start a rebuilt 727 in park versus neutral. Park applies the same lubrication circuit 5 psi as neutral but at 5 psi line pressure which fills the dry system and apply gentle pressure to new seals before moving into neutral to apply 55 psi line pressure against seals, then into 1/2/3 to actuate the rear clutch, ending in reverse for the highest line pressure of 230 psi and to engage both front/rear clutches and the low-reverse band. Starting a rebuilt transmission in neutral isn't going to damage anything, but the better method is starting in park.

I feel like I have to defend myself here to the new guy.

So, just so you know, I've read everything you've written, thought about it as coming from more experience and working knowledge than I have. You've most likely done a lot more trans work than I've done or even thought about doing. I never worked on cars professionally and your explanation makes sense to me....

My reference to the pump "not working" is very simplified and written with the understanding of what is happening. Yes, it pumps some fluid... That's really obvious. If we were back in my hydraulics/pneumatic class from years ago, we could argue about if the pump is "working" when it's really just "running" to keep fluid circulating.

As far as my "recommendation", yea, that's the way it was suggested to me years ago by someone that knew a lot more about transmissions than I did. He's long dead, so I can't ask him. The trans that I have rebuilt over the years have worked just fine... The best example being a 727 I did 40 years ago (and beat on for a couple decades) that is still doing fine with the car's new owner beating on it on a regular basis, so I couldn't have been too wrong. I twisted a couple driveshafts in that one, but never a trans problem. That said, I'll defer to you as having good working knowledge and starting in park does make some sense as you've explained it. Chances of me doing another trans is kinda slim these days, so it's a moot point for me.

I have started cars that I've drained/refilled trans fluid in neutral... Mostly for ease of the initial fluid level check before running through the gears (and then recheck). I'll probably keep doing it that way because it's my preference. I'll probably dig out my Mopar trans book a little later and see what they say just 'cause.

 

[azblackhemi]

For years now after sitting overnight or longer I start my Mopars in Park and then shift them to neutral for a few seconds before shifting into drive or reverse. That eliminates the hesitation that occurs if I go right into gear. Not sure if it matters but it makes me feel better.

 

[mr gtx]

gm dipsticks says to check in park but Chrysler says to check in neutral, thought i read that the fluid goes back in the pan and you will get a higher reading in park.

 

[Big_John]

For years now after sitting overnight or longer I start my Mopars in Park and then shift them to neutral for a few seconds before shifting into drive or reverse. That eliminates the hesitation that occurs if I go right into gear. Not sure if it matters but it makes me feel better.

I had a couple worn out "beaters" that you had to do that with just to get them to move. LOL.

 

[71FuryGC]

For years now after sitting overnight or longer I start my Mopars in Park and then shift them to neutral for a few seconds before shifting into drive or reverse. That eliminates the hesitation that occurs if I go right into gear. Not sure if it matters but it makes me feel better.

I've been doing the same as you particularly after sitting all winter in frozen upstate New York. I wait until the idle comes down from high before shifting from Park though.

 

[HotDodge]

I feel like I have to defend myself here to the new guy.

So, just so you know, I've read everything you've written, thought about it as coming from more experience and working knowledge than I have. You've most likely done a lot more trans work than I've done or even thought about doing. I never worked on cars professionally and your explanation makes sense to me....

Sorry you feel like you have to "defend" yourself, as my purpose wasn't to attack you but to clear up information. I'm a blunt person, which often doesn't come off as I'd like in written American communication. It's likely one reason why I and the German-American and Australian-American people I know get along so well.

I appreciate your perspective on the pump not doing much work in park at idle (around 5 psi,) and at the OP's 2K - 3K rpm it will be pumping well at around 30 psi.

As for your preference to start a rebuilt transmission in neutral, there's nothing wrong with it since (1) it won't hurt anything and (2) it's your transmission and you may do as you please. I took your recommendation to be more of a universal "it's the right way versus the wrong way," so my apology if I read something else into it. I think you'll find most Mopar factory service manuals assume the overhauled 727/904 will be started in park and don't lay out any special instructions for putting it into service. The 1960's and 1970's factory TF 727/904 manuals I use never mention starting in neutral, although I've seen generic non-make-specific aftermarket instructions (e.g. TCI) specify lifting the wheels off the ground and starting in neutral.