So, after having the engine apart for the last month and a half, we finally got it back together and this weekend was the first decent weekend so far to have the car out and cruise around. Saturday-didn't notice any issues. Sunday, I went to put transmission fluid in (I knew I was low, but forgot on Saturday) and couldn't hardly get any fluid in the dipstick-it just overflows instantly. After church we had lunch, then we all loaded up and drove around for a bit and had no real issues.

This morning while on my way to work, I turned onto the state route I always take and as I get up past 50, I happen to look in the mirror and notice quite a bit of smoke. Thankfully, nobody was behind me so I just kinda cruised it in to work. I texted Pops to ask if he could see if he could swing by (he lives pretty close to my work) and we could go over things to make sure it wasn't something obvious/something preventing me from getting the car back to the house and he noticed a few things underneath:

1. Oil around the pan rails. Probably due to loosening up the pan to get the front seal in place. That's going to more than likely be a nightmare to deal with, but unfortunately it's not a surprise.
2. Oil around the filter. I have a tendency to over tighten filters, so when I changed the filter I was adamant in not doing so. So I'm curious if I just left it loose. I did put a bigger filter on it (more similar to the Wix filter that it came from the assembly shop with) but it spec'd out for the engine.
3. Oil on top of the air cleaner pan. I'm guessing this is due to the new oil cap. I wasn't 100% sure it'd seal, but I'll clean it off, put the old one back on, and see if that helps.
4. Transmission fluid "all over the place". This one baffles me. We went ahead and checked the fluid level *per instructions on dipstick* and he said the fluid was barely registering on the dipstick. I can't for the life of me figure out why I can't seem to get fluid in the dipstick, unless the funnel I'm using is preventing it from venting as I pour. Even still, I have checked to ensure the vent tube is clear multiple times before (it is) yet I still have leaks.

I think once it gets home, I'm going to address the couple of things I can do for sure, but ultimately just go ahead and schedule in to have the oil pan leak/trans leak addressed. I fought with the transmission leak all summer last year (not nearly this bad) and considering its a pretty fresh rebuild-I can't imagine seals should've gone bad but anything is possible. I was hoping to schedule exhaust/dyno stuff today, but that'll have to wait.

Hopefully your Monday is starting off better...

 

That's a bummer.

 

Check the vent on the transmission, make sure nothing has made a nest around it. If it’s a rubber vent hose, make sure it hasn’t fallen on the exhaust and melted.

If air can’t get out of the transmission, fluid won’t go in.

 

So, last fall I believe I hooked a handheld vacuum pump up to the vent tube and I couldn't get it to build vacuum. I'm not above saying I didn't have it in there correctly as I was on my back and unable to see anything/feel much..but I was pretty confident I was successful in verifying it was clear. However shortly before Nationals, the yoke on the transmission end of the driveshaft was leaking substantially out of the vent hole in the yoke. I called the shop that rebuilt the transmission in '21 (before the engine was completed) and he confirmed the suggestions of the internet which was to plug the hole in the yoke with silicone. It had an issue last winter where fluid was coming up the dipstick tube, but it hadn't done it since. I will also say that the modulator has always been wet, as have portions of the pan as well as the cover between the bottom of the trans and bottom of the engine (starter shield?)

It was on my list of things to address as the leak hadn't been this bad, but based on today..this has jumped to the front of the line.

 

Alright, I had some time this evening and climbed underneath..sure enough the filter was pretty loose. Tightened that up, snugged the drain plug and pan bolts up, and we'll see how it acts.

As far as trans fluid..its all over the place. I'm gonna need to first game plan how best to get to the vent tube, but once I verify that's clear (hopefully by clearing it and resolving the source of the issue altogether) but then Ive got plenty of cleaning to do.

 

Oil filter 101:
Spin on the filter until it contacts the housing then go 3/4 no more than 1 full turn past contact...lube the square gasket with engine oil first if that's not already common practice.

As for the trans, are you using a trans funnel? You have to pour somewhat slowly.

Typically if a TH400 pushes fluid up out of the fill tube the first place to look is the vent circuit. Next is fill level,
If the vents clear and level is at spec then air could be getting in between the filter and or pump. The additional air (froth) will come out of the fill tube.

Check the filter and pick up gasket for integrity (cracks) and correct installation. Is the filter attached to the valve body with the correct bolt with the metal spacer tube?
Make sure there isn't two filter o-rings up in the valve body,

Is it still under any kind of warranty? If so don't touch it until you speak with the builder.
A whole bunch of other things could be causing the pan to be pressurized, if that is the case. Next look at the pump and/or valve body. That means tear down & inspection, Do the simple diagnostics first. The diagnostic factor tree gets complex quick.

Check the trans blood pressures....Test the line pressures to see what they are. Take it to a guy that knows TH400s before yanking it so he can trouble shoot in the car.

Do you have the correct dip stick? If the dip stick is too short you could be inadvertently over filling it.

 

Yeah, I was always taught to snug by hand, then give it a 1/4 turn with the wrench. Worked fine for 15 years..just the last few in doing that they'd get stuck on the housing. I thought I was being proactive this time..not quite..lol. I always put oil on the gasket, and around the housing. That helps make sure the gasket is on there securely, and the old gasket came off (I've dealt with both of those being issues before too)

As far as the transmission, I am using a funnel. I had wondered if having the funnel practically sealed on the dipstick tube while pouring was creating a problem..but every time I keep it somewhat up and not sealed to the tube, fluid comes out quicker.. lol.

I dont beleive ita still under warranty. I feel like I'd looked at it at one point and it was a 1 year warranty, which essentially expired 2 months after it was installed (just based on the engine taking longer than anticipated). With that being said, I don't have an issue taking it back to the builder..Id just hate to go through that if it's something simple enough I could fix at home (ie vent tube blocked). The dipstick is the original one, so I feel fairly confident in that.

 

With the 400 trans, it’s common practice to use 2 o-rings on the filter tube. No problem there.

If fluid won’t go in, most likely either the dipstick tube is restricted or blocked, or the trans can’t vent. Check the vent first, then drop the pan for an inspection. If you don’t see anything obvious, I’d suggest talking to the builder before doing anything else.

 

Yeah, probably Sunday after church I'm gonna get underneath it and try to fish around for the vent tube and hopefully do a better job at clearing it (I'm super hopeful that it's just blocked) however if it's clear, I'm going to call the rebuilder first thing Monday morning and try to get it scheduled in. I've stumbled my way around a lot of things in my life..but I've never been bold enough to try a transmission.. lol

 

Just went out and stuck a electrical wire up the tube, only was able to get maybe an inch to an inch and a half in before it hitting something. So safe to say it's blocked. Now..how to remove it.. lol

 

You may have just hit the bends in the tube or in the case casting. Its a hard place to gain good working access...as you know.

Id put a vacuum hose on the vent tube. Suck on it. Get resistance?

 

May have to see what I've got laying around in the way of vacuum line. Not sure I've got anything that size, or if I do it's not very long. Even still, how do I remove said debris other than just shoving into the transmission?

 

You are not removing anything at the moment just verifying you can actually feel suction...or not. Or not means there is an obstruction somewhere in the vent circuit.

Go to the nearest house of china and buy 5 ft of vac line. Hook it to the vent suck n blow.

I cant get to my TH400 stash at the moment. Someone will be able to measure a vent tube to get you the proper sized line.
Or if you can reach it now with a short length you have laying around just for sizing.

Steve

 

Copy. I know elsewhere I'd asked the question of the size, and it was either 1/4" or 3/16". Now that I'm home, I'll check my stash of hoses and see if anything will fit..that'll at least give me a for sure size. I'm pretty sure I hit obstruction, not the bend of the tube as I was able to see what I was doing (though obviously not the end of the wire inside) and it didn't seem to be close to the bend.

 

Its a press fit and can be hard to get out of the case while its in the car. If you can get on it in a gentle manner with a fresh set of small vice grips it may wiggle out.
But its a finesse feel thing not a bull in china shop (gah) approach. Ya dont want to deform it or worse break k it.

Maybe gently thread a fine thread bolt that just fits the ID as far into the tube as you can to assist with removal. Give ya some grip and not risk collapse.
Shooting out ideas here as Ive never had to pull one out.

 

The later model plastic tubes can’t be removed with the transmission assembled. It has a step on the end, it slides into the hole in the case then the pump is installed.

Later model plastic tube

Early model pressed in tube.

 

I'm fairly certain I've got the metal tube.

 

Well, I went out and attached hose to the tube, and then attached it to a duction pump on the other end. You could actually hear the fluid in the pan as it was suctioning (?) So that tells me the obstruction is gone. I went ahead and wiped everything up, and may take it for a spin tomorrow (weather permitting) and see if/what anything is still leaking. Hopefully, that was the problem..and not something like a seal.

 

Got off work last night and got the car out to see if the leaking had stopped. I drove it around under normal circumstances, as well as pushed it harder than I did when it was pouring out last week and managed to not see any smoke.

When I got home, I put some blankets down beneath the car then backed in and shut it off. After dinner I went out and checked..ive got some fluid on the filter (couldn't tell in the moment if it's oil or if it's trans fluid from the amount of times it'd spilled out) and then the bottom of the dust shield/front of pan/modulator look a little wet. Nowhere near as wet as they were last week..actually about what they looked like last season when everything was good.

I may go ahead and put a narrow oil filter back on if it is indeed leaking pil, to see if that cures that issue. Not entirely sure on the dust shield.