2010 Hyundai Elantra automatic - bad trans or bad fluid?

Egg_Head said:
Which motor does your vehicle have? Valve bodies in 6cyl.'s of that year were notorious for sticking and causing the drivability issues you have described. All the LubeGard in the world will not fix that problem.
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Its the 4cyl, think its like a 1.6 or 2.0L. I have read about valve bodies in these trans in general sticking.

I am wondering how much a replacement VB would be, if it's even possible to find a new/reman for one at this point if that's the route I have to go. I'm not sure how long ago Hyundai stopped using this trans.
 
I agree with the others who said to do a pan-drop and filter. Use Maxlife or whatever SP-III compatible fluid you're comfortable with. If there's any improvement then do a few more drain & fills in short order. (No need to change the filter again) Clean fresh fluid is ALWAYS better than old roagy fluid.
 
At these prices, I'd stick with the OE SP-III fluid, maybe a bottle of LGR for fun 🤷‍♂️

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andrew_j said:
Buy the cheapest transmission fluid that meets spec. Sounds like transmission is on its way out.
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That's what I initially thought when I first got it, but I've put almost 12k on it. It hasn't gotten really any worse in terms of symptom severity or occurrence, just a couple more little oddball things started happening.

The 4r75 in the Crown Victoria blew up within 1500 miles or so of it first starting to show issues, otherwise I've never had a car with a trans issue that led to failure. It's funny because the 4r70 in my Grand Marquis when I junked that car had milkshake fluid but still drove perfectly fine 100% of the time.
 
Try out a bottle of seafoam transtune before you change the current fluid. It will help clean out stuck valve bodies and does not contain any seal swelling additives. You can see if things get better and then change out the fluid to new fluid.
 
Have you scanned the transmission control module? That may show that there's something else wrong.
 
Are you sure it has a filter?
I thought this model just had a rock catcher and you had to split the case to replace it.

IT does have a handy drain plug. Super easy to do a drain and fill drive it for a day and repeat a couple more times.

I wouldnt worry about SP III fluid but it can be found relatively inexpensive if you call around a few dealers.
The mitsubishi and kia fluids are also the same exact thing in a different bottle.

IIRC on the 2010 accent 2 different hyundai dealers one cost 2x the other.
 
Marcozi said:
Have you scanned the transmission control module? That may show that there's something else wrong.
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The only thing it shows is that a P0734 occurs when the car slips too many times in quick succession.


According to Rockauto this does have a removable sump filter, it looks like it goes up into the valve body the same way the filter on a 4r70 does. I'm planning on replacing the filter and fluid, then probably giving it 1000 miles or so and doing another D&F thru the drain plug.

After looking around I'm pretty sure I'm going to end up going with Valvoline MaxLife Import MV. It has a higher viscosity than regular MV MaxLife, which I think would be better suited for this trans.
 
HPL wouldn't be my first choice in a neglected crusty transmission that is possibly failing.
 
I had a 2008 Elantra in the family that I bought used with 28K in 2012 (it was used to drive back and forth to the train station which accounted for the low mileage). I changed the ATF when I bought it using Valvoline Maxlife. Since less than 2 quarts drained out I changed it again 1K later and again 1K after that and added 10 oz. LG Red (3 D&Rs of approx 1.3/4 quarts in 2K miles.)

I then went 30K before changing it again adding LG Red once more. I D&R'd it approx, every 30K until we sold it at 148K (still running great but my daughter wanted a new car after getting her first well paying job (she bought a new 2021 Mazda CX-30.)

The last 2 D&Rs were done with Valvoline Import ATF in the blue container and only 1/2 bottle of LG Red was added each time.

That 2008 Elantra was a tank and I'm sure it's still running 3 years after selling it. Also, the Valvoline ATFs ran great in that transmission.

PS: I did read that Hyundai made some changes to the 2010 A/T in the Elantra that made them a little less reliable...something about making the change to increase fuel efficiency but I can't recall exactly what it was.
 
joegreen said:
Try out a bottle of seafoam transtune before you change the current fluid. It will help clean out stuck valve bodies and does not contain any seal swelling additives. You can see if things get better and then change out the fluid to new fluid.
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Crawled under the car tonight to do an oil change on it myself for the first time (took it to my mechanic a couple weeks after I got it for it's first oil change under my ownership because I didn't feel like crawling on the ground in the cold.)

Also put this (SF Trans Tune) in tonight as well. Following the instructions to evacuate 16oz of ATF and replace with the full 16oz can. Got a little $0.97 plastic 4 cup pitcher with markings on the side every 2oz from Walmart specifically to make sure I pulled 16oz exactly and pulled it thru the dipstick tube with my crappy siphon bulb.

Gave it a short 10 mile drive, getting up to 55-60mph, shifts seemed a little smoother immediately but not much effect other than that which I wasn't really expecting in such a short time.

My plan is to drive it this week with the Trans Tune in it, order a new filter on Tues when I get paid, then pull the pan on Friday (assuming the filter and gasket get here by Fri afternoon.) That's roughly 200 miles with the Trans Tune in it before I pull the pan. I'm going to just pull the pan myself, there's plenty of room with the car jacked up a foot off the ground and the drain plug makes it so I don't get an ATF shower doing it on the ground. Replace fluid with Maxlife Import MV, and most likely add another bottle of Trans Tune. Probably drive it for 2-3 weeks (about 1000 miles) and pull the drain plug and add more Maxlife Import, and see where we're at after 1000 miles on straight MaxLife. If it's still acting up, I'll probably do another D&F and add Lubegard Red to the fill and see if that helps any.

The fluid I evacuated was disgusting looking. It still had a slight reddish tint under the right lighting, but it was otherwise dark brown, not see-thru whatsoever. The good news, though, is that the fluid
a) wasn't straight jet black, just very dark brown, and didn't smell rank like burnt fluid would - just like some well used ATF.
b) wasn't syrupy and didn't have any sandy/grittiness feel to it, and no metal particulates settled to the bottom either.

It was only 16oz of fluid out of almost 7qt total capacity in the trans, but it still gives me hope that I pull the pan and don't see fuzz city all over the pan and magnets, and gives me hope that the trans still has plenty of life to give.
 
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This is how the fluid looks on a paper towel after pulling maybe 1/4oz out with the suction bulb and letting it drip onto the towel. This is after I've put 60 miles or so on it with the Trans Tune in it. It smells quite a bit different than the bottle of Castrol Import MV I have sitting here, but doesn't smell acridly burnt. I'd say it smells like used Mercon V tbh.

Again, it doesn't feel gritty or sandy on the fingers. Slightly oily but that's about it.
 
Update:

Decided I was going to forego the filter change for now, and just pull the drain plug and replace what came out, because the Trans Tune has had about 200 miles to work through the trans by now. I bought a gallon of regular MaxLife - I figured a) I have the Lucas stuff if I really need to thicken the fluid up any and b) the filter (and 2qts or so more fluid) still has to come out eventually. Plus it was $11 cheaper (@ Walmart) vs the Import ML (@ Autozone since my local Walmarts don't stock gallons of Import ML.) and this gallon really was just to get SOMETHING new in it, I am on a budget this week. Upon realizing Hyundai uses gasket maker and not a regular gasket, I don't want to deal with scraping the old gasket off and setting the new gasket (laying on the ground no less), it will go to my mechanic for the filter as I originally was going to do.

Spent about 2 hours trying in vain to get the plug off, just ended up rounding it out. Socket, open ended wrench, box wrench, pipe wrench, vice grips, torched it too, nothing worked. I don't have an extractor socket set. Plug has definitely never been pulled before and the NJ winters didn't do that any good. Settled on just pulling the supply cooler line off and pumped 2qts out of the cooler line. Fluid was again super dark but didn't feel gritty, nothing metallic settled to the bottom of the fluid on the drain pan, etc. Just nasty old fluid.

Replaced with 2qts of MaxLife, let it idle for about 20 minutes while shifting through the gears every couple minutes, then took it on a 14mi round trip drive.

Shifting is noticeably smoother, but it still acts wonky. I was mimicking a pass on the freeway and it was a little less abrasive than before, but still shift flares then jolts into the downshift. It didn't start doing the TC unlock/lock stuff, but time will tell on that.

So now I am thoroughly convinced that there is no major hard parts failure in this trans - it was fairly obvious by the fact that it drives normally a large majority of the time, but about 3qts of old fluid has been exchanged by now (about 1qt for the Lucas in the winter and the Trans Tune a few weeks ago, and 2qts tonight) and it's seemingly improving. I am sure the clutch packs have probably been affected, but they are obviously not toast by any means. Sonnax and Maktrans do make/install several different "valve body kits" ie TCC regulator valve and a couple other ones, so my assumption is that if anything, the valve body bores are worn out.

I am going to throw another bottle of Trans Tune in, drive it another couple hundred miles, and then have my mechanic do the plug extraction and filter change. Doing that would bring me to roughly 50-55% new fluid after the filter change, and I'll see how it feels from there. I am strongly considering doing a full 7-8qt cooler line exchange after I get the filter done, just to get the rest of the nasty old (most likely factory fill) fluid out, then throwing in some Lubegard Red. If that doesn't resolve the issue, I'll most likely look into getting the valve body replaced, or I'll just live with it until the trans blows up (or the subframe rots out, whichever is first.)
 
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IMO you are whistling in the dark and wasting your time & $$. The drivability symptoms you describe point to a valve body issue that needs to be addressed. Time to take your medicine and get it properly diagnosed at the dealer.
 
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