86 Chevy K10 Checking Transmission Fluid

[lumartin1989]

Hi all,

New to the forum bought an 86 chevy k10 with about 115k on it a little over a month ago and kind of had a silly question but I do not want to overfill the transmission fluid. The tranny seems like it is slipping a bit from 1st to 2nd gear. All other gears it shifts very smooth.

I don't have the owner's manual but I wanted to make sure that I was checking the fluid correctly. I had a Buick and a Caprice some years ago that had instructed to check fluid with engine running and recommended doing it when the engine was warm (they had TH 350 trannys), it even said after driving it for like 15 or 20 miles, but it said that it could be checked when it was cold as well.

Also what type of fluid would the truck take if it was low?

Thanks for any help or suggestions!

[bd]

Check the fluid level with the engine running, park brake set, and trans in Park or Neutral.  When the trans is at operating temperature, the fluid level should be at the "FULL" mark.  When cold, the fluid level should be between "ADD" and "FULL."  Use Dexron II.

[LTZ C20]

Welcome from California. Your ideas are correct. You want to check the fluid while it's running and parked on a flat, level surface. Based on your year, your truck should have a 700R4 transmission, the dipstick had a cold and hot level on it.

To check fluid cold:
-park on flat surface
-idle engine
-remove dipstick and wipe clean
-reinstall and then remove dipstick
-reading should be on the cold mark

To check fluid hot:
-park on flat surface
-idle engine
-remove dipstick and wipe clean
-reinstall and then remove dipstick
-reading should be on the hot mark

If checked cold and reading is over cold mark, it may be over filled.

If checked hot and reading is under hot mark, it's either not full or not up to operating temp so the reading will be incorrect.

If it's not on the stick at all, it's low on fluid.
Add 1 quart and recheck. If on the stick, add 1/2 quart until it gets close and then add 1/4 quart until your on the correct mark depending on checked hot or cold.

I usually check it cold first, then if it's at the proper level, drive it awhile and get it hot, then recheck to verify it's on the hot mark.

The best fluid to use is GM Dexron VI Automatic transmission fluid. (VI is 6) also referred to as Dex 6.

If your not sure or have an issue, take it to your nearest GM dealer and ask if someone can show you how to check it and make sure it's properly filled. Dex 6 is not expensive and they should be able to show you in just a few minutes. I work at a dealer and show people stuff like that all the time. The fluid should be bright red with now metallic, shiny, rough or foreign particles and should not smell burnt, if it's burnt you will know because it really stinks when you take a whiff.

If the level is proper and the fluid is clean and the trans still doesn't feel right, there could be an internal problem with it OR the throttle valve (TV) cable requires readjustment. That can be addressed if needed at the proper time.

Best to start with fluid level and condition and proper cable setting before condemning a transmission as broken.

[lumartin1989]

Thank you guys for the reply I will check it this evening when I get home from work, hopefully its not a bigger issue, figure start small before getting all worried.

[LTZ C20]

No problem, sometimes that's all it is. You have the right attitude. You can always take pictures of the stick when you take the reading and then post them on here and we can tell you how it looks.

[lumartin1989]

So I ended up checking the fluid with truck running, I had been driving for about an hour sitting in traffic so the truck was definitely warm. The fluid was only showing on one side of the dipstick and it was reading well over the full line. The other thing somewhat concerning to me was that there were bubbles on the stick. The fluid was red and did not smell burnt or anything. I attached a pic of the dipstick let me know if you can see it, if you look closely you can see the bubbles on the stick.

[nosurrnder]

It is possible to have to much fluid which would cause problems. Also you may want to drop your tranny pan to see if you have any metal shavings in the bottom of the pan

[LTZ C20]

Assuming that it was at operating temp, the fluid looks to be over filled. May now be a good time do a transmission service. Gives you a change too do a few things:
-look in the pan and examine the fluid
-drain some fluid so it can be filled properly
-change the filter
-look for metal flakes, chunks or foreign debris
-introduce new fluid when you fill it back up

If anything weird is found in the pan, you can then choose a plan of action from there.

[lumartin1989]

I used to hear that changing the fluid on transmission that hasn't been serviced regularly can cause more harm than good. Not too sure what the service history is on this tranny, do you think a drain and a flush would be ok with the age and mileage, it's got 115k on it?

[LTZ C20]

I understand the confusion. Flush no, drain and fill yes. It would be better to only replace the fluid that was emptied when the pan is removed. I think it's usually about 4-5 quarts. Some people prefer to use a pan with a drain plug, when they do an oil change, they drain the pan, then refill what was lost. So every oil change you get a few quarts of new trans fluid also. This is not a requirement though.

[lumartin1989]

Ok that does make sense thanks for the clarification, that is good to know and I feel comfortable doing that on my own.

Thanks for the help!

[LTZ C20]

WELCOME!

[Irish_Alley]

ive heard all sorts of arguments both saying its ok to change and its not ok. some say a transmission needs the clutch material in it to work right. some say if the trans fluid was supposed to be changed they all would have a drain plug on it. gm even says not to flush and the only tool they recommend is a flusher thats used to clean the cooler in the event of a trans that has failed.

ill tell you this in my moms 99 e150 the trans was slipping so i changed it and added Lucas fluid to it and it fixed the slipping and the trans is still going strong 15 or so years later without changing the fluid again since. my 04 impala ive changed the fluid and it help its problem has it fixed it, no but its a servo problem and fluid wont fix that. ive changed the fluid in multiple transmissions never have done a flush and never had a problem after changing the fluid. my mentality is when you change the fluid youre only changing a small portion of the fluid thats in the trans so your just pretty much doing a filter change.

problem is a flush is just a gimmick to get more money and it does do harm cause it puts chemicals in the trans and it runs backwards in the system so if you dont change the filter first you will be pushing the trash right back into the trans and you will break loose trash thats just sitting in the trans. a fluid exchanger uses the transmission pump to pump out the old fluid and put new fluid back in much like someone who doing dialysis. you will replace much is not all of the old fluid with new fresh fluid. seams like a better alternative but gm doesnt recommend this practice either.

i think its bmw who warranties their trans for the lifetime* of the trans, and says the fluid never has to be changed. the part behind the "*" is the lifetime if the trans is something like 100,000 miles, after that its surpassed its lifetime. the thing thats guaranteed to kill a trans is heat. heat kills the fluid and the fluid is what keeps a trans going.

some transmissions are "sealed" from the factory meaning no dipstick and youre not supposed to touch them. their filter isnt even paper like the conventional one its  metal.

[jg1977c20]

So I ended up checking the fluid with truck running, I had been driving for about an hour sitting in traffic so the truck was definitely warm. The fluid was only showing on one side of the dipstick and it was reading well over the full line. The other thing somewhat concerning to me was that there were bubbles on the stick. The fluid was red and did not smell burnt or anything. I attached a pic of the dipstick let me know if you can see it, if you look closely you can see the bubbles on the stick.

sounds like its overfilled and or needs changing -peronally i like to use b&m trick shift just because its a little higher in viscosity than dex 3

[LTZ C20]

Sounds like you should just do a transmission service.