View Full Version : Transmission cooler leak / how to remove all contaminated fluid?

06-06-2007, 08:50 PM
I have an 87 Prostar 190 and the transmission oil cooler failed this spring resulting in replacement of the transmission fluid with lake water. I have fixed the problem but am having a heck of a time getting the contaminated transmission fluid out. When it failed the transmission fluid took on a color and consistency of a McDonald's strawberry milkshake. I thought I would be able to drain and refill 2 maybe 3 times and get back to bright pink but as hard as I try to remove all the old fluid it seems that the new stuff takes on the same color. The consistency is the same as fresh transmission fluid but it is milky pink even after about 5 flush cycles.

Are there any tricks to this or is it a matter of a few more flush / refill cycles? I suspect if a person could drain from the bottom instead of pulling out through the dipstick hole I would be better off.

I am pretty sure there is no other leak or issue as the fluid volume is neither increasing or decreasing and the boat works fine but I would like to get back to pink transmission fluid.

Thoughts? Am I missing something?

06-06-2007, 08:57 PM
Hmmm....Lance, not sure. However, I would be concerned about changing it 5x's and getting no improvement. That leads me to believe you may have other issues.

06-06-2007, 08:58 PM
If you do not get a good answer on here I would call Vince at Skidim and get his opinion.

06-06-2007, 09:10 PM
Thanks Brian. To clarify though there is a big improvement in the consistency as it is now the same as fresh transmission fluid but it is the color that is slow to change. I suspect it is a very small amount of water that is causing the color change. I will try vince if I don't come up with something else.

Thanks again.

06-06-2007, 09:11 PM
How much are you getting out on each change compared to the total amount it can hold?

06-06-2007, 09:39 PM
Changing the transmission fluid IS NOT an EXACT Science. you do not need to refill all the way in your case. 1 quart to 1 1/2 quarts are plenty in this scenario. Run the boat and let it sit overnight. Then drain the transmission. You need a SMALL diameter hose to get that last little bit out. Let it sit again for an hour and suck out what is left.

Refilling is not an exact science either. Some transmissions like a little more fluid than others. Any excess will blow out the overflow outlet on top anyway. Be patient 5 changes is not uncommon. Don't worry about putting in ALL THE CORRECT amounts of fluid till the last filling of the transmssion. You can run a QUART low. It won't hurt it! Just do that last change all the way to the correct level

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06-06-2007, 11:49 PM
Hey Lance ,get your head down in back and look to see if you have any
visual seepage around your lower tranny seal, just got my boat back today from the dealer, they put a new seal in, it seems that as the shaft seal breaks down it will allow any water in the bilge to be sucked up through the seal, thus putting water into the tranny to contaminate

06-07-2007, 03:28 AM
Add a bit of kerosene to the transmission fluid, run it and change it again. The kerosene will help to get rid of the water. This is advice I got from someone who worked at Indmar and after doing this, I never got any nasty phone calls from the customer whose transmission was the recipient of a bunch of free water.

The oil cooler should be pressure tested and repaired before running it again. Radiator shops are a good place to take them for repair.

06-07-2007, 09:44 AM
I STILL (after two years) have a bit of residual milkshake lurking just around the top of my trans. dipstick - the bulk of the fluid however is clear, so yeah, it could take you multiple changes to get it back to "normal"...I'd say as long as you're making progress with each subsequent change, you're doing the right thing....chances are you've fixed the problem (imagine that!!) - it's just going to take some time to completely cycle thru...

Good luck

06-07-2007, 11:05 PM
Thanks everyone for the advice and comments. I will be back to the lake this weekend and will drain and refill a few more times. I am fairly certain there is no more water getting in as the volume that I put in and take out each time is the same (a tad over two quarts).

I have heard of using either kerosene or diesel to flush out transmissions and would probably try it on one of my old tractors but wasn't sure I wanted to do it with my old mastercraft but maybe I will if it will result in pink fluid again.

I just bought a new cooler from skidim rather than try fixing the one I had.