Very slight transmission leak?

andrew4321

Original poster
Member
Jan 28, 2012
50
Good evening, today I was contemplating changing my transmission fluid considering I recently hit 56,000 miles. I decided after reading a "how to" on the subject to spend a few minuets familiarizing myself with the undercarriage of my Trailblazer. Whilst inspecting the underside I noticed what seemed to be a bit of fluid coming from the transmission area; I always park in the garage and have never noticed any puddles (there are still not any puddles present). My question is, is this a leak and if it is will it get progressively worse or is it normal to have a slight buildup in this area? Just for the record I checked the level of the ATF today about four hours prior to crawling under the truck. Could this somehow be related? I should also add that it has not been driven today only started.

Thanks for your time,
Andrew
 

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Lima Tango

Member
Dec 4, 2011
242
Well, any fluid really shouldn't be seeping out of anywhere, no. I would re-torque those bolts down if nothing else.

50k miles is pretty early to change your trans fluid unless you have a reason to think it's had a hard life up 'til now. Do you offroad, tow, drive in tons of traffic or up and down inclines? Official answer is 50k for severe use, 100k regular use. I went with 90k to be on the safe side and did a full drain using the trans pump. If you want to extend your trans life, spend the money on an external trans cooler. I was really happy with the pcmforless trans cooler kit on sale for less than $200 shipped.

If you do want to change the fluid and filter, you can change out the pan to a Dorman easy drain pan at the same time so you can drain the ~5qts in the pan at shorter intervals more conveniently. I had good luck with my Wix filter and walmart SuperTech Dexron VI fluid for $4 each qt instead of $8.
 

andrew4321

Original poster
Member
Jan 28, 2012
50
Lima Tango, I have never towed anything with the vehicle nor do I off road a whole lot (the occasional dirt road, sand patch, dirt hill) as I have a 2WD. I purchased the vehicle with 41,000 miles and thought that perhaps changing the fluid would not be such a bad idea considering I don't know what ind of life it had before me and especially since it seems so many on the OS recommend the fluid to be replaced with new fluid at 50K. I really have no complaints about the transmission, no slipping gears and the like. With that said I have noticed that when the engine is cold the trans makes a rather loud (best described as a) "whining noise" or low pitch "hissing" noise; but this goes away after it warms up.
 

Lima Tango

Member
Dec 4, 2011
242
It's not a bad thing to replace the fluid especially if you don't know how it was treated before 41k miles. It's cheap insurance if nothing else. Total cost incl filter and 14 qts of supertech dexVI was something around $100.

You definitely do NOT want to pay for a shop to do a flush where they forcibly backflow the system. Since the miles are fairly low, you can drop the pan and see how the fluid looks - if it looks fresh and reddish pink then just replace those 5qts in the pan and the filter and pan gasket (comes with the filter) while you're in there which may solve your minor fluid seepage if I am understanding your pictures correctly. If it looks dark or brownish, then replace the whole mess of it.

Many people do choose to replace fluids at a more rapid pace than the manufacturer's schedule, but most of them are enthusiasts who use their trucks more aggressively than the typical grocery getter demographic. Up to you. I would review your owners manual and decide. Personally I did my fluids and other 100k service about 10k miles early. The appearance of the fluids was such that I am glad I didn't wait until 100k, but wasn't jet black either.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
andrew4321: You may also get a good idea of how dirty the fluid is by wiping the dipstick with a clean white paper towel. And check for a burnt smell.
 

Wex

Member
Dec 4, 2011
124
My fluid had a slight leak similar. It was the transmission oil pan bolts needed re-tightening.
 

andrew4321

Original poster
Member
Jan 28, 2012
50
Thanks for the input everyone! I checked the fluid and it is a reddish pink color which I would consider "good". I will need to the find time to check for loose bolts and tighten them down... can't have the DD not running in perfect condition!
 

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