727 cooling

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Jr90
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727 cooling

Post by Jr90 »

I have an 83 waggy beater that i take offroading a couple of times a year, running 31s but other than that all stock and has 2.72 gears so i know that doesn't help. Are there any tricks to cooling the trans? I already have a "stock" cooler in series with a small aftermarket one but it still starts puking fluid from the bell housing after running a while.

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Re: 727 cooling

Post by Nikkormat »

With only 31's you should be fine as long as you're using low range when you should be. But also making sure you've got a good fan clutch, having good airflow across the rad. As long as you aren't in super hot weather you should be able to hold onto the lower radiator hose. There should be that much temperature drop unless you are really pushing the jeep.
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Jr90
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Re: 727 cooling

Post by Jr90 »

This weekend it was in the 80s, i used low range, fan clutch is tied to stay engaged and i dont have a thermostat, engine temp seemed good. Id been playing a little which it had no trouble with but had to try to pull someone a little when it started leaking. May just have to take it easier and install a gauge for a better idea.
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Stuka
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Re: 727 cooling

Post by Stuka »

There are other reasons it can puke besides getting hot. Have you ever had it serviced? Filter change and such?
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Re: 727 cooling

Post by rocklaurence »

Bypass the radiator. I had a Ford Explorer that did this until I bypassed the radiator. I run mine through a cooler [biggest GVW that will fit]. Under normal conditions my trans dont exceed 180 and under heavy load only climb to 210. For me, I dont like the idea of intruducing engine heat into the trans.

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Re: 727 cooling

Post by SJTD »

Bearing in mind that I haven't had an auto since I can't remember when, seems to me if you're loosing fluid from the bell housing you have a leak at the torque converter seal or the front cover gasket???

Maybe caused by a plugged vent? These have vents right or is the dipstick the vent?
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Jr90
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Re: 727 cooling

Post by Jr90 »

It probably needs a filter change, for some reason i didnt think of doing that, ill probably do that and bypass the radiator before the next trip out. I replaced the seals about 6 months ago and it stops leaking after it cools so i dont think its that but it could be, sound right?. There is a vent and its in the bell housing so im thinking thats the source.
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Tatsadasayago
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Re: 727 cooling

Post by Tatsadasayago »

I'll add that while bypassing the radiator coil works great for the warm season, it can disable your rig if you operate in cold country. I bypassed the radiator coil and went with an aftermarket cooler, and while running up a pass at -20f the trans literally stopped working due to the cold oil. Cardboard covering the entire core support opening solved the problem.
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Stuka
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Re: 727 cooling

Post by Stuka »

If you need to run through the rad, run through it first, then a big cooler.
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Jr90
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Re: 727 cooling

Post by Jr90 »

Im in north tx, cold isn't a big issue here usually. I only run this twice a year in march and october and its trailered to and from there. Its worth a shot to bypass it and see what happens.
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Tatsadasayago
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Re: 727 cooling

Post by Tatsadasayago »

Jr90 wrote:Im in north tx, cold isn't a big issue here usually. I only run this twice a year in march and october and its trailered to and from there. Its worth a shot to bypass it and see what happens.
Yes, TX shouldn't be a problem. I was stationed at Fort Hood for a while and the coldest it ever got was during an ice storm in 83-84. I doubt subzero temps are going to be an issue for you :P
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Jr90
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Re: 727 cooling

Post by Jr90 »

Just a thought i had, if i cant keep the 727 cool i have a th400 from a 77 waggy that i could put in which had a qt before. Would that be a better trans? To make it work i would need to change the output and tailhousing correct? Or is there a bolt on dhd tcase that will work?
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Re: 727 cooling

Post by Stuka »

The swap won't work, as the transfer cases wont swap. Well, unless you want to dump a lot of money into adapters and such.

But a TH400 wont stay any cooler than a TF727. If you have cooling issues with one, you will with the other.
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Jr90
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Re: 727 cooling

Post by Jr90 »

I meant swapping any tcase to go behind it, like maybe a later chevy that had a dhd, didnt know if any inputs were the same or not. Thats true about temp, also wasn't sure if 400s would hold up better or not though.
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Stuka
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Re: 727 cooling

Post by Stuka »

The TH400 is arguably a better transmission, but certainly not worth all the work for your situation.
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Cecil14
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Re: 727 cooling

Post by Cecil14 »

The transmission is definitely not *causing* your problem. While you might inadvertently address the problem during the swap by fixing something you didn't know was really wrong, as Stuka has stated it is not worth the trouble. You would be way further ahead to address whatever the problem is with your current setup than trying to band-aid it with a trans swap. Odds are you'd end up with the same problem honestly, and then you'd be out all the time/effort/money for the swap and still having problems.


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Re: 727 cooling

Post by 78 Arizona Chief »

If you recently added trans fluid when the trans was thought to be fully warmed up, but actually wasn't, the 727's vent is part of the front pump/cover. If the trans is overfilled and vents fluid out, it will come out the front and appear to be a converter or front seal leak, when in fact it is just venting the fluid below that vent line. Get the trans good and hot then check the fluid level. I wonder if it is just overfilled.
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Jr90
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Re: 727 cooling

Post by Jr90 »

Im hoping it is just the vent, can it get too low just from getting hot and running out of the vent? It was not very hot when i filled it but it was losing what seemed like quite a bit of fluid when it did get hot.

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Re: 727 cooling

Post by candymancan »

Tatsadasayago wrote:I'll add that while bypassing the radiator coil works great for the warm season, it can disable your rig if you operate in cold country. I bypassed the radiator coil and went with an aftermarket cooler, and while running up a pass at -20f the trans literally stopped working due to the cold oil. Cardboard covering the entire core support opening solved the problem.

I've heard that before, my 5.9 ZJ the trans is bypassed into a 3 loop cooler and i for 7 years havent had issues in winter. But the coldest it gets here is about 10-20f. But even driving to west virginia when it was 2f out on freeway in mountains i still had no issues.. I have debated installing it back to the radiator but since it works i just leave it alone.

And no you wont run low on fluid if its puking out of the vent.. eventually it will drop to a normal level and not go out the vent anymore. Check it when you drive for a few miles. in neutral running, pull wipe, put it back in and push it in all the way pull it out and check both sides.. One side might be higher then the other use your thumb nail to mark and flip it over to see where it compared to other side.

If the transmission is on the low line its 1 quart low exactly to get to the top of full. If its on the dipstick but barely its about 2 quarts low. 2 quarts low isnt going to blow up the transmission, but 2 quarts too high can cause it to froth like foam and cause shifting issues
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HeavyMetalThunder_81
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Re: 727 cooling

Post by HeavyMetalThunder_81 »

Just a thought.
You are checking the fluid with the engine hot and the transmission in neutral, correct? The 727 won't circulate fluid in Park and you can unintentionally over/under fill it while in Park.
Another thought.
Is your TV cable adjusted correctly? If not it could cause slippage and overheat your trans causing it to vent.
Just my .02
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