Tranny leak...
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Elder User
Joined: Jul 2004
Posts: 920
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From: Westminster, Colorado
Tranny leak...
I have a somewhat unusual leak coming from my np435 Transmission.....
Around town, driving all day....I have no issues, the outside of the case is a little damp, but no dripping....
However, a long distance/high speed trip (like 2 hours at ~70 to Laramie from Boulder) causes a leak that appears to be coming from the front of the tranny, leaking out of the bottom of the bell housing....
The Shop is thinking it is the front seal of the transmission....does that sound right?
Why does it only have the leak problem on higher speed/longer distance trips?
Around town, driving all day....I have no issues, the outside of the case is a little damp, but no dripping....
However, a long distance/high speed trip (like 2 hours at ~70 to Laramie from Boulder) causes a leak that appears to be coming from the front of the tranny, leaking out of the bottom of the bell housing....
The Shop is thinking it is the front seal of the transmission....does that sound right?
Why does it only have the leak problem on higher speed/longer distance trips?
Senior User
Joined: Oct 2007
Posts: 281
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From: Kernersville, NC
It's very possible that it's the front seal leaking.
The reason for the leak occurring only after extended high-speed driving is probably that the oil never really gets hot around town, but over long distances, it gets hot, thereby becoming thinner.
The reason for the leak occurring only after extended high-speed driving is probably that the oil never really gets hot around town, but over long distances, it gets hot, thereby becoming thinner.
Thread Starter
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Elder User
Joined: Jul 2004
Posts: 920
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From: Westminster, Colorado
Overall, the tranny seems to be in good shape, it doesn't have any shifting problems or pop out of gear or anything....so....should I look at just replacing this seal, or is this something that would be indicative of other problems in the transmission?
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Front bearing retainer seal.. If it gets to bad then it will get a crabbing clutch as your start from a dead stop. You may also need to replace the whole bearing retainer to if it's warn to much from the throw out bearing movement. Also with a real real bad pilot bushing can also cause the seal to fail. But you would notice a vibration that goes away while pushing in on the clutch. Only in rare cases thou.. .. Heck you may want to do a new clutch while your working on the tranny. my 2cents
orich
orich
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Elder User
Joined: Jul 2004
Posts: 920
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From: Westminster, Colorado
Yeah...the clutch needs to be replaced already....it's not bad normally, but on those trips where the leak starts, I can notice slippage as I accelerate....not to mention the smell of the gear oil.....
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
So you'll be looking at, shaving the flywheel. A new complete clutch kit to do it right. But if it's been shaved to much already, now then you'll need to replace the flywheel too. When it's been shaved to much now you'll see the flywheel bolt heads have been rubbed off some by the clutch disc touching them. This will also make the clutch slip not letting it seat down on the flywheel completely..my 2 cent
orich
orich
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Elder User
Joined: Jul 2004
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From: Westminster, Colorado
I guess I'll need to get an estimate on repair pricing....I know Jasper has the tranny rebuilt for around $1000....might behoove me to go ahead and freshen it up if I'm going to go through all the trouble of pulling it....
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Lead Driver
Joined: Aug 2003
Posts: 7,592
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From: **** hole San Jose ca.
Those 435 trannys were hard on the rear output bearings too. I've fixed a few of them Even on the early 1966 3spd trans i've fixed them. When my 435 got shift stick got sloppy again and need fixing. I went to the chevy nv4500 5spd overdrive with the 27% drop in rpm in 5 gear. At 60 mph I'm now taching 1,900 instead of 2,600 like before..It was a smooth install in my 4x4..Plus added a few mpg..IF You do everything right and research how to do's... my 2cent
orich
orich
