727 rising fluid level

chermik1999 · Jun 16, 2025

Hi guys. Here's a new one for ya.

New peformance build. 3500 stall, transgo kit, installed a stand alone cooler and kickdown cable adjusted. Here's bullet point procedure

- 8 litre initial oil fill after 1 litre in TC
- startup and warm for say 5 mins
- check oil in N
- bit low.
- Top up another litre and reads under full.
- in the next 20 mins in 5 min intervals it creeps up to 1 1/2" over full.
- take for run and come back to check oil. Even higher. No foaming or leaks.

Disconnect return line and ran for 20 seconds. Got near 3/4 of a litre of oil, so no cooler issues. Blew air into the dipstick tube and air coming from vent. So no blockage there.

Let cool down and with TC drain back, reads below full initially then creeps up once again. Removing the excess and let sit overnight. Check again in am and have to add a litre. Then same thing happens again.

Strange, I go N to D and R a few times and it starts to drop. But back checking in N and starts rising up the stick once again.

So what am I doing wrong that I haven't done in like 40 years in the past. It's getting daunting..

Ideas?

dvw · Jun 17, 2025

We had this issue once. The trans also performed poorly. There was a crack in the valve body next to the converter fill valve. So sometimes the converter filled, sometimes not. If the trans works well have someone hold their foot on the brake and check the fluid in gear. With high idle the internal components will spin at sloshing fluid. This tip was given to me by a very high end race trans builder.
Doug

chermik1999 · Jun 17, 2025

Wow! That's interesting.
It's taken me a long time to dial in the kickdown cable lokar style, but seems to be ok. As for running ok, it seems fine but I do notice for having a transgo, it just doesn't have the hard shifts.
I do have to pop into N for a bit to get it to engage, but for a 3500 stall there is slippage to get it rolling. But seems to hook up at 3500 rpm and I get a good burnout.
I did chock the wheels and with e brake on checked the level in gear. Seems a bit lower in the stick but I didn't try it for longer periods of time. I'll try that today.
Appreciate the advice Doug. But it sounds like you may have a point with valve body here.
As I said this is a new one for me. Im not as seasoned as some of you fellows are, but I have done a few in my time.
Just after playing around for so long one tends to get give up.

Dipstick · Jun 18, 2025

dvw said:
We had this issue once. The trans also performed poorly. There was a crack in the valve body next to the converter fill valve

Was it a '66 or '67 valve body?

chermik1999 · Jun 18, 2025

Wow! Thats obvious..lol.
Didn't open it up yet. But maybe...I have to drop the pan And check.
BuT it runs ok, just oil creeps up.
Originally I thought it was because I had some pressure from the KD lever. One of the motor trend articles said that the first 3/4" of travel doesn't do anything when adjusting a Lokar KD cable. So start there....
So I made some added a return spring to seat it back to closed. It would appear that wasn't it..lol

1KoolBee · Jun 18, 2025

I’ve found that Dexron expands quite a bit in my 727 when hot. Like a 1/2 quart difference on the dipstick between cold and hot readings. So I fill to middle of hash marks on stick when cold and it reads at the top of the hash marks when hot.

chermik1999 · Jun 18, 2025

Am using type F.

1KoolBee · Jun 18, 2025

chermik1999 said:
Am using type F.

It should have similar expansion properties

chermik1999 · Jun 18, 2025

Maybe so, you may be right. But not from add mark hot to 1" above in 15 mins?

dvw · Jun 19, 2025

Dipstick said:
Was it a '66 or '67 valve body?

View attachment 1871243

I was a 65. And yes it was cracked like that.
Doug

chermik1999 · Jun 19, 2025

Wow...well aside for drain back in the TC, it runs pretty well. But doesn't hurt to check.
Im installing the 2nd one from the same builder in a 72 charger right now. I'll fire it up and see if same thing happens. Then I'll have a comparison. Will report soon.
Thanks

chermik1999 · Jul 12, 2025

Ok..
Back at the update.
So my tranny guy got me to do some testing.
So I hooked up a pressure gauge to the servo port. D - 1 I got 70 psi.
But when applying full KD with the lever fully open with a helper im D - 1 again gave the same 70 psi result.

So no change in pressure when WOT KD applied means I have a problem.

Any ideas??

dvw · Jul 14, 2025

chermik1999 said:
Ok..
Back at the update.
So my tranny guy got me to do some testing.
So I hooked up a pressure gauge to the servo port. D - 1 I got 70 psi.
But when applying full KD with the lever fully open with a helper im D - 1 again gave the same 70 psi result.

So no change in pressure when WOT KD applied means I have a problem.

Any ideas??

Pull the pan. Make sure the cam on the throttle pressure shaft is installed correctly pushing the kickdown valve in when you move the lever. If that looks good? Pull the valve body and check the throttle valve, spring, kickdown valve, and guide for proper installation. Good? Look at the throttle bore wall for cracks.
Doug

chermik1999 · Jul 14, 2025

Thanks Doug.
I actually did that yesterday and have it on the bench right now. I'll air test to check seals and if pump is not leaking too.
I have another new trans to install, but I'd really like to troubleshoot this first to figure it out.
I just installed the twin from the same builder in my son's 72 charger as well and its like a different unit. Levels are fine, engages in gears normally and firm etc. Just need to road test. So it would appear its just this guy with the problem.
Will report back later.
Mike

chermik1999 · Jul 14, 2025

So air tested both servos and ports to clutch drums. That's all good. Opened up and inspected the VB. Seems OK as far as cracks but found the line pressure valve may have been sticky being a bit rusty in the bore. Couple others with a slight bit of binding.
Cleaned up with scotchbrite and slides good now.
Ordered a transgo TF-2 and will install once cleaned up. I dont know what kind of shift kit the builder put in, but cant be much as i see no new springs or drilled holes etc.

Then give a shot again. Only thing left would be the pump.

Stay tuned

chermik1999 · Jul 15, 2025

Trans is out and going to inspect and measure clearances in the pump. Seems OK but I'll do it anyway.
I did find some monkey business though. Seems like a home made attempt of a shift kit. Increasing spring tension to adjust line pressure? Could have been the issue?
New transgo kit coming and should have back in on the weekend.
I suspect too many backyard ideas may have been the problem...crossing my fingers

chermik1999 · Wednesday at 9:03 PM

So transgo showed up so getting ready to install. Did some more digging, and I have an old style pump. Did some measurements. Outer gear approx .0025 and inner .0001. Seems a bit worn and looks like has rings. Thinking these gears are done?

chermik1999 · Wednesday at 9:07 PM

So I have a few donor cores. Can I not swap one for a newer style pump even if I have to use the front drum as well due to the wider bushing for a total upgrade?
Aside for checking governor, condition of pump gears and a little cleanup to the PR valve having some rust which i polished, I can only think a proper shift kit install, thats all I can do? Everything else works...

dvw · Friday at 4:55 AM

I've run some pretty grooved pumps. If the housing and reaction shaft support aren't scored never had a pump pressure issue. The outer rotor should have .004-.008 clearance to the case. Clearance from the tip of the inner rotor tip to the outer gear is .005-.010. The end clearance is .0015-.003. New gears are cheap. Not sure what you are saying about early model pump. The bushing changes to a wider unit along with the drum. But the pump gears are the same from 62 and up.
Doug

chermik1999 · Friday at 9:23 AM

Well I dont have that clearance with this one.
What i meant was I have a few donor cores here that are newer. I was going to swap a pump from one of them. I read that if they are a newer wide bushing, I need to use the front wider drum as well as this one now is a narrow one. I could just grab the gears as well.
Remember here im Canada it's harder to get these items without a long wait time..lol

727 rising fluid level

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