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Transmission leak

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JimF
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Transmission leak

Post by JimF » Thu Jan 15, 2015 9:23 am

I have a Velvet Drive transmission on a 350 engine. The transmission fluid level mysteriously drops but there does not seem to be a leak. I keep wiping under the housing but nothing is there. Is it likely that there is a leak in the transmission cooler and I am blowing the fluid into the cooling water and then out the exhaust? It would be fairly difficult to replace the cooler but I am afraid that is probably the culprit.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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drrot
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Re: Transmission leak

Post by drrot » Thu Jan 15, 2015 10:02 am

Bypass the cooler and see if it still happens
Jim Staib
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1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

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JimF
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Re: Transmission leak

Post by JimF » Thu Jan 15, 2015 10:13 am

Would I just disconnect the hoses from the transmission and put in plugs?
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Transmission leak

Post by Peter M Jardine » Thu Jan 15, 2015 8:43 pm

The old CC oil coolers, and a lot of of the others, have solder joints that hold the cooling tubes inside together. They will occasionally crack from vibration, and yep, the pressure in the transmission is usually higher than the raw water side, so the transmission fluid will go out the exhaust. A radiator place can pressure test it, but you could bypass it too.

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Re: Transmission leak

Post by jim g » Fri Jan 16, 2015 7:15 am

If you bypass the cooler you need to connect the trans cooler lines together. Also it could be the front seal. If the trans is on a flywheel forward engine and the front seal is leaking the trans fluid willl be leaking into the engine oil.

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drrot
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Re: Transmission leak

Post by drrot » Sat Jan 17, 2015 1:00 pm

jim g wrote:If you bypass the cooler you need to connect the trans cooler lines together. Also it could be the front seal. If the trans is on a flywheel forward engine and the front seal is leaking the trans fluid willl be leaking into the engine oil.
Jim,
Do as Jim says.
JIM
Jim Staib
www.finewoodboats.com


1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

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JimF
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Re: Transmission leak

Post by JimF » Sat Jan 17, 2015 5:36 pm

I have disconnected the lines from the cooler and connected them together. I also have two plugs to screw into the vacant holes on the cooler. I am thinking of not installing them just yet but instead, waiting until I run the boat in the lake. If I see water coming out those holes, I will know that there is a leak between the water side and the oil side of the cooler. What do you think?
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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drrot
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Re: Transmission leak

Post by drrot » Sun Jan 18, 2015 7:27 am

Sounds like a good idea to me.
Jim Staib
www.finewoodboats.com


1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

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Re: Transmission leak

Post by evansjw44 » Sun Jan 18, 2015 10:04 am

Keep an eye on the transmission temperature while you're testing. It needs the cooler or you wouldn't have one. You don't want to cook it and warp the clutches or damage the seals.
Jim Evans

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JimF
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Re: Transmission leak

Post by JimF » Sun Jan 18, 2015 10:15 am

Could I assume that if the housing were not too hot to touch that it is not overheating?
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

jfrprops
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Re: Transmission leak

Post by jfrprops » Sun Jan 18, 2015 10:52 am

all good advice above.....temp? shoot the housing with one of those laser t-meters....will at least let you know if she is heating up fast and high.

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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JimF
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Re: Transmission leak

Post by JimF » Sun Jan 18, 2015 11:43 am

I just did a driveway test. Ran the engine for 15 minutes with the transmission hoses connected together. Looking in the cooler I saw no rise in the standing oil level due to water coming in. However, I don't think that proves that the cooler is good. The higher pressure of oil might push through pin holes into the water but the water is under very little pressure and would find it easier to just push on into the engine. The cooler is located between the thru hull and the water pump.

Also, the transmission case got quite warm, approaching hot. It was hot enough that I am concerned about doing a lake test without the cooler. Just for fun, I reconnected the hoses to the cooler and ran the engine another 15 minutes. The housing was barely warm and the hoses almost cool where they had been very warm before so the cooler, even if leaky, definitely makes a difference.

It turns out that the cooler would not be hard to remove and, if I can find a match, simple to install a new one. Then if the problem remains, I can pull the transmission to check seals.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Chad Durren
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Re: Transmission leak

Post by Chad Durren » Sun Jan 18, 2015 11:18 pm

Is it this style Jim? If so, I have one for you.
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1952 CC 18' Sportsman
1969 CC 19' Commander Super Sport

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JimF
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Re: Transmission leak

Post by JimF » Mon Jan 19, 2015 10:09 am

get-attachment.aspx.jpeg
Thanks Chad but mine seems to be unusual in that the ends are at 90 degree bends and at 90 degrees to each other. I am going to rig up a pressure test today with air and determine if it really does leak.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

jim g
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Re: Transmission leak

Post by jim g » Mon Jan 19, 2015 5:01 pm

Jim,

If you end up needing a cooler. I have a place I can send yours to and they replace the cooler section using your ends. I doubt you will find a new one like yours. Do not ever use a used cooler. They can not be cleaned out very well and you never know what trash might be in them that will destroy your trans.

jfrprops
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Re: Transmission leak

Post by jfrprops » Mon Jan 19, 2015 5:45 pm

correct on do not use a used one.

That one in your pic is a rare bird I think, mostly the looked like the one in the other pic posted...the straight through model.

The straight shot ones were available some years ago?

You could plumb a straight through with some fiddling and hose elbows etc.

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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JimF
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Re: Transmission leak

Post by JimF » Mon Jan 19, 2015 6:01 pm

get-attachment.aspx.jpeg
I have good news and bad news. I rigged up pressure test on the cooler (see picture). I put fluid in the cooler and applied a lot of air pressure, so much so that air and fluid was coming out around the other plug. It was tight but did not have teflon tape. I fully expected to see fluid coming out the water pipe ends but none did so my conclusion is that the cooler is good. I have re-installed it and test run the engine in the driveway and the transmission stayed nice and cool.

So the bad news is that it must be the inside front seal of the transmission. I am going to do some lake testing and carefully monitor how quickly the transmission level goes down. I have also changed the engine oil because I have no idea how much transmission oil might be in it already.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Transmission leak

Post by jim g » Mon Jan 19, 2015 7:05 pm

What model conversion is your engine?

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JimF
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Re: Transmission leak

Post by JimF » Mon Jan 19, 2015 7:09 pm

It was built by a friend of mine 15 years ago from a1975? Chevy truck.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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