Removal of Sonata under shield ... and maybe leave it off.

I am going to change the transmission oil in my 2006 Sonata with manual
transmission. The car has 70,000 miles and I had it changed at the
dealership at 60,000 miles as I don't believe in the "lifetime fluid"
approach for "normal" service that many now recommend. Anyway, I went
to the dealership just a few weeks before they shut their doors. I
thought things looked a little sparse on the lot and in the shop given
that it was May. Anyway, since then the car is hard to shift into
second gear, especially when cold. I am hoping that they hadn't run out
of the correct 75W85 GL-4 and put in a heavier GL-5 fluid and possibly
caused damage to the yellow metal parts.

I am going to put in Amsoil synthetic GL-4 as I couldn't find a GL-4 at
the local auto parts stores. Apparently, almost nobody uses it anymore.

Anyway, it appears that the only easy way to access the fill plug is to
remove the under shield. I thought this only had 4 bolts that held it,
but a quick look under makes it appear that there are more than 4 bolts
and I was seeing Phillips head screws as well. Can anyone tell me if
all of these fasteners are for just the shield or do they hold other
parts above the shield that may come loose? Also, leaving the shield
off would certainly ease future oil changes and such. Has anyone left
their under shield off? Any side effects such as additional air noise
or overheating? I can't imagine it has significant functionality other
than to smooth the air flow under the car for better mileage and less
noise, but if the cooling system depends on it that would be a different
story.

Matt

 

I've driven a number of cars over 150k without ever
changing manual transmission fluid. I don't think
it's necessary.

 

I am not sure it is necessary either, but I always find a fair bit of
metal on the drain plug magnet even after 50K or so and I'd rather not
have that stuff circulating through the gears and synchros. And I tend
to keep my cars well past 150K unless they get wrecked (which has
happened to my last two high mileage vehicles), so I figure it is cheap
insurance even if not absolutely necessary.

I got the undershield off and mine had 9 10 mm bolts and two plastic
Phillips head screws that got into expandable plug nuts. Of course, one
of them was stripped (probably when the dealer changed the tranny oil
10,000 miles ago) and would not come out. I had to break the head off
with pliers. And this appears to be a special fastener that I can't
find locally. I have an email into Hyundai Parts Online to see if they
can get these.

I drove the car for 30 miles today with the shield off and noticed no
unusual air noise nor any difference in operating temp, but I will
probably put it back on as it does keep things much cleaner up under the
front of the engine.

Matt

 

I don't know what these thingamabobs are called, but they're pretty
standard fasteners. I'd imagine that just about any local dealer (any
brand) would have some spare ones lying about (or some in the parts
department they could sell you) or some Christmas-tree type fasteners
that you could just push in. Realistically, I think these plastic
fasteners were simply for assembly at the factory. Considering their
position, if you leave them out, I doubt the cover will hang down. Or
you could just leave the cover off altogether. Aside from dirt, I
think the worst potential side effect is that there's a greater
probability for something to come up and damage the engine or
transmission.

 

You may well be right about the purpose. I was just afraid the front
might flap in the breeze, but I left the one out and so far haven't
noticed any unusual noise.

I decided to put the cover back on for the reasons you mention.

A question for you if you have another minute: Are you aware of any
problem with synchros on the Hyundai manual transmission in the 06
Sonata? I had the local dealership change the tranny oil at about the
60K mark and shortly after that the tranny got very hard to shift into
second gear, particularly when cold. Now, I own two standard shift
vehicles at present and have driven them all my life so I know they all
shift harder in the cold, but this is unusually hard and affects only
2nd gear. Shifting into the other gears is still fine.

The dealer went out of business less than a month after I had the work
done. My fear is that they were using up supplies at that point and may
have used whatever gear oil they had on hand. I know this transmission
calls for GL-4 which generally means the tranny has
"yellow metal" (brass or bronze) parts, typically the synchro cones.
And I know that most GL-5 oils will eat at these yellow metal parts.

The reason I had the cover off was to change the tranny oil. I put in
Amsoil Gl-4 synthetic gear oil in 75W-90 viscosity which is close to
what Hyundai calls for. It shifts better, but second is still hard to
engage when cold and not completely normal even when warm.

Any thoughts as to what might cause this? Do you think it could be oil
related? Is this a known failure mode for this transmission? I will
probably try to get it back to the dealer (the new one though is nearly
40 miles away) and have them take a look as I at least want to lodge a
complaint before the 100K warranty expires. I also saved the oil I
removed so that I can have it analyzed should the tranny have to be
replaced at some point.

Matt

 

I haven't seen enough of these transmissions to know of any common
failures. Changing the oil again was my immediate instinct, but
you've already done that, so I think it's time to plan a dealer visit.

I hadn't realized I'd been away for so long.