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Old 12-01-2008, 08:54 PM
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Default sonata engine cradle rust

I'm going to look at a 2001 Sonata tomorrow. I did a "search" on the rusting engine cradle problem. Most of the complaints came from GLS owners with the V6 engine. The car I'm going to look at is a 4 cyl. model. Does the 4 cyl model have the same problem with the engine cradle rust?
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Old 12-01-2008, 09:02 PM
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Default RE: sonata engine cradle rust

I'm not sure what you mean by the engine "cradle".

Last edited by NovaResource; 09-20-2011 at 03:07 PM.
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Old 12-01-2008, 11:55 PM
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Default RE: sonata engine cradle rust

I'm going to look at a 2001 Sonata tomorrow. I did a "search" on the rusting engine cradle problem. Most of the complaints came from GLS owners with the V6 engine. The car I'm going to look at is a 4 cyl. model. Does the 4 cyl model have the same problem with the engine cradle rust?
From what I understand, this is a problem inherent to all early genration "EF" Sonatas. The K member on these cars apparently have a "drainage" holes along the front edge that actual help accumulate moisture and salts inside the structure which is not well protected against corrosion. The problem seems to be worse on cars in the northeast and upper midwest where there is lots of precipitation (especially as snow and ice) and heavy use of salt on winter roads. I would run a Carfax on the vehicle to look at its history and then pay a few dollars to an independent mechanic to put the car on a hoist then probe around the cradle with a screwdriver or ice pick. If the car has spent its life in Arizona or Southern California, for example, I would think the cradle rust potential is minimal.
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Old 04-21-2009, 01:41 PM
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HUGE Hyundai recall for rust and brake lights:
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Old 02-13-2010, 08:20 AM
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More info to support your thought about the engine cradle in the "rust belt"...
I have become the happy owner of a 2000 Sonata 4 cylinder that spent its life in North Dakota, where they don't salt the roads.

About 6 months ago I drilled two holes in the back of the engine cradle for viewing the condition and for drainage. The metal was solid and didn't appear to be rusted at all. I sprayed the entire outside with rust conversion/protectant spray, which seems to have held up perfect. So I think that where the car spends its time matters a lot.

Just this last week, I hot glued some plastic deflectors on all the holes in the engine cradle, so they can drain, but cannot scoop up water. I made them out of the five little bumps on the bottom of a 2-litre soda bottle. It took 10 of them to do the job, but I don't remember if I used them all. I remember one hole I found on the top of the engine cradle, over by the right front wheel, and I just closed it off so stuff won't drip in. There were a few seams that faced forward that I sealed with hot glue too. I had it in a heated garage for two days before attempting this with the hot glue gun. (It needed an alternator)

Now that salt season is here in S.E. Mich, where we drive over piles of salt, I will spray inside the engine cradle, and lower A-frames with Corrosion-X. I have two 16 oz pump spray bottles on order, and I intend to fashion some kind of spray nozzle on an extension tube to spray it inside.

I haven't seen the Corrosion-X liquid, so I don't know the viscosity, but I think it is more like oil than paint. Some of the RC airplane and boat people dip their electronics in it to protect from water, so it can't be too thick, I think.

This stuff claims to repel water, so I think this is better than paint or undercoating, which may not cover a surface with moisture or who-knows-what on it.

So has anybody ever made up a hose extension that would insert in a 1/2" hole and spray all around inside a confined space like a frame rail? I am wondering if there is a clever way to do this, and this forum appeals to all the clever people out there, so if you can share any ideas, I would be grateful.

Last edited by dbacon; 02-13-2010 at 08:28 AM.
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Old 02-13-2010, 05:52 PM
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Well, it's done, I tried many things, most of which covered me in Corrosion-X (I hope its not toxic) and the best method was to put two small fittings into the cap of an empty 2 litre bottle, one for air in (At, I guess about 20 psi), be sure to use a pressure regulator, as the bottle will blow up with too much air. I don't know what the limit is, but the smaller plastic Coke bottles will take 150 PSI.

Anyway one gets the air in, the other, for spray out, has a tube that goes to within 3" of the bottom. Then pour in less than 3" of Corrosion-X, and hook a long hose to the output fitting. Usually the air just blows in and out again, but splash the liquid around and some will go in the tube, followed by more air and it comes splattering out the end. Of course you have the end in one of the drain holes in the engine cradle.

After about 1/2 hour of using this, I had Corrosion-X dripping out of all the seams, so I think I did it!

Ten years will tell, so stay tuned...
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Old 02-24-2010, 07:53 PM
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hello, my name is Tyler, and im new to this site.

I am currently a Tech a Hyundai dealer in upstate NY, and i do on average 3 subframe corrosion recalls per day on sonatas, santa fe's, tiburons, XG's. and elantras. (im not sure if this has been posted in detail here yet)

our recall basically starts out as you did dbacon, but most 2000 sonatas, especially with 130K+ miles, never make it that far. up here in Upstate NY, they are lucky to make it too 100K, and if not, we replace the subframes.

we have to drill 4 - 40mm(1 5/8") holes, and debur. then measure the thickness. if they are more than 1.5mm (2.5mm for santa fe trailing arms), then we spray provective wax inside, and undercoat the outside. if it is too thin, we have to replace the subframe. about 85% of the recalls that we do, we have to replace the subframe, control arms or trailing arms. i would much rather replace the part(s) than drill and wax them. it pays more, drilling large holes over head sucks, and the wax smells, and it gets everywhere.

again, sorry if this has been posted before, but im new to the site, and havent had much time to look around. but if you feel you have any rust on the subframe, take it to your local dealership ASAP. i mean, come on, its free!
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Old 02-25-2010, 06:30 AM
Join Date: Jun 2009
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Thank you, Hyundai-Tech17, this is valuable information.

I will measure my engine cradle where I drilled two 1/2" holes, but I am sure it is 1.5 mm minimum. I am very familiar with measuring sheet metal on cars, I setup resistance welders for a living, and that is the first step. I did coat the outside, 6 mionths ago, with rust reformer spray, and it was looking very good after 6 months. Now with the Corrosion-X, which I think is better than wax, I am very satisfied that we are in good shape.

Those are large holes, where did you drill them? Also I would shove my drill motot through a cardboard "shield" if I had to do that, it would suck-major!

Replacing the subframe is a better job? Holy crap that sounds serious, how do you accomplish this?, special engine cradle fixtures, and things to hold the front suspension?, these are major items to play with!!!

It would be interesting to hear the details, man I respect you for the guts to do this.

Thanks for the valuable input!

Last edited by dbacon; 02-26-2010 at 01:12 AM.
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Old 02-27-2010, 02:01 PM
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yeah, they are pretty large holes, and its not fun!

i will have to try that cardboard sheild idea. i wear my long sleeve shop shirt, Ingersoll Rand mechanics gloves, a face shield, safety glasses, my baseball cap, and ear plugs. the ear plugs are more to keep hot metal shavings out of my ears!

We only have to drill holes if we cant put a hole in it with a hammer first

the first hole that we all drill is on the right rear corner if looking at it from underneath. right where the subframe angles up towards the rear mount/control are pivot bolt. on that angle, there is another piece of steel lap welded on the outside edge. we drill just inside that lap weld. same for the other side

the front to holes are right where the subframe flattens out after the angle from the front mounting bolts. the passenger side has a hole from the factory, about 1/2"-5/8" in diameter. we drill right next to that.

Hyundai supplies a cheapo guage made out of 16 guage steel, with 2 slots cut into it to measure the thickness. very accurate

they also supply us with a 1 quart siphon feed spray gun with a hose attatched for spraying the wax inside the holes, after we blow all the loose rust out.

And yes, it is a much better job to replace them, at least i feel it is. its very simple after you have done a few. here is a list that i can think of off the top of my head. remember, if its getting replaced, that means its rusty!!! and, air tools are a must!

first, take off the airbox lid/intake tube assembly, removing the one hose near the throttle body. its not necessary to disconnect the MAF sensor, but it will give you more room. then with aleast 18-24 inches of 3/8" drive extensions, and a 14mm universal joint socket, remove the three rear motor mount (roll stopper) bolts.

next move to the pass front corner, and remove the 2 10mm power steering line bolts. one is in the very front corner, and the other is under the pass side motor mount.

raise vehicle up as high a possible, preferably on a lift. remove wheels. tie a large zip tie around the inner tie rod, and around the brake line bracket on the body. this will stop the rack and pinion from falling out at a later time.

remove 2 17mm bolts on for each ball joint, and remove 17mm nut and through bolt on strut "wishbone".

remove 14mm through bolt and 17mm nut on front motor mount (roll stopper) (1999 model year sonatas must have a new roll stopper installed. there is a special part number for it, ending with QQH)

now you will be able to rock the motor back and forth by hand since the 2 side mounts up top are still connected. now, wrap a reliable ratchet strap around the pass side axle at the transmission, and to the front tow loop on the subframe. tighten the strap until the motor stops rocking forward. this will give you plenty of room to reach behind the motor to remove the 4 17mm p/s rack bolts. note that the 2 longer bolts go on the drivers side!

now that the rack is loose, and supported by the zip ties, and column shaft, you can remove the ratchet strap.

now remove the 2 17mm nuts, and 4 14mm bolts that hold on the 2 triangular support brackets on the rear mounts of the subframe.

there is one more p/s line clamp bolt to remove now, and an air ratchet and 10mm swivvel socket work perfect. its on the pass side towards the rear, just behind the axle.

now comes the fun part!

what we have are a couple high lift transmission jacks with 2 4' 2x4s across it. put this under the middle of the subframe, and put a little pressure on it.

only 6 bolts left...

remove the 2 17mm front subframe mounting bolts.

remove the 2 19mm rear mount bolts (with a stud on it, that you previously removed a 17mm nut and support bracket from)

next are the 2 that almost always fight us. behind the strut, there the 2 final subframe mounts. these are 2 17mm nuts, and large washers (one on each side) luckily Hyundai was smart enough to put holes in the lower control arms so that you can put a 17mm socket and extension up through to remove the nuts

now, slowly lower the subframe about 3 inches. At the top rear, there is one more bracket that holds the p/s lines to the subframe. another 10mm bolt there. remove it.

now the subframe, lower control arms, sway bar, and front motor mount can come straight down.

remove 2 14mm bolts on front motor mount.
remove 4 14mm bolts on sway bar bushings.
remove 4 17mm bolt on the control arms, saving the aluminum spacer on the rear of the 2 bolts.
remove the 2 22mm bolts at the control arms rear pivot points

take off control arms and swaybar as an assembly, so that you or your shop dont have to buy new sway bar endlinks!

take off all 6 rubber insulators at the mounting points.

now, installation is the opposite of removal.

a good set or torches and the skills to go along with them will help you out alot, but they can be very dangerous. thats where the miniductor somes in. check it out:

there arent many special tools that you need, but air tools, and swivvel sockets are a must. also everything is metric.

i dont think i forgot anything, but im sorry if i did. i hope this helps at least one person. hell, it took me as long to type this as it takes me to replace a subframe!!!
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Old 02-28-2010, 12:21 PM
Join Date: Jun 2009
Posts: 41

That angled area in the right rear corner is exactly where I drilled a 1/2" hole. It was nice and thick and no rust flakes came out. It was miserable drilling that hole, the big hole would be really nasty to do. And I did both sides too, because it looked like a good drain location.

You know 2 liter pop bottles are made out of a material that resists heat to some extent, and you could make a see through shield/cup to catch the shavings, that would slip over the front of your drill motor.

That "Cheapo" guage is probably the most accurate thing, when you consider it is mistake proof. I have seen people set up resistance welders (my profession) measuring sheet metal with micrometers that don't even zero out!

Boy I wish I would have had that sprayer, mine was a piece of 1/4" tubing stuck in a 2 liter bottle with Corrosion-X splashing around while I pressurized the bottle about 30 PSI. Pretty hokey, but it seemed to work.
When you remove the lower control arms, aren't there some compressed coil springs to deal with?

That MiniDuctor is the coolest thing ever! I used to service induction heaters at Chevy Gear & Axle. They would harden the surface of an axle after heating it by using a water quench. There weren't very portable though, so I am amazed with this hand-held device! Are they expensive? Are they very high frequency? (I would guess about 3000 Hz.)

Thanks for taking the time, I am sure that many of us now appreciate what is done at the dealership much more. I myself am so afraid of the work done by anybody that I try to do everything myself. (NOT based on any Hyundai dealers, based on Pontiac, Chevy, Dodge, Plymouth, Olds) Hearing a professional such as yourself goes a long way toward swaying my opinion.

Do you inspect and/or replace the control arms too?
Are you familiar with Corrosion-X? Maybe have an opinion on it?
I haven't tried to spray inside the control arms, maybe I should...

Thanks for taking the time.
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