I am having a company seal the undercarriage of my 2002 TJ. There is very little visible rust. In doing the inside of the frame the company is saying that they will only use the existing factory holes in the frame. That pressure is good enough to seal the complete inside. I have seen, posted elsewhere, that you should drill a hole at the lowest part of the frame to fully coat the inside. Is this necessary and if so what size hole? Thank you in advance
Sealing undercarriage and inside frame
- Thread starter Mike H.
- Start date
Can you help me understand why? Seems like all that matters is how long their application wands are. If long enough, you only need the factory holes, right?
The hole isn't needed to coat it. One us needed to drain water that will get back in there from normal use. My post should have been more specific to the OP.
LONGJP2
TJ Expert
The holes that are often added to the bottom of the frame are for better drainage.
Allows the water that gets in the factory holes to get out.
I just Fluid Filmed my rails. There are plenty of holes in the frame rails to get full coverage inside. I did rill 1/2” holes in front of and behind the CA mounting brackets but that’s for water drainage.
If you haven’t done it already, be sure to thoroughly clean the inside of the rails of any debris, rust chunks and flakes. I made a dozen trips to the self-serve car wash to power wash the inside of the rails before applying the Fluid Film.
I should tell you, applying the fluid film is a really easy DIY job. I think I paid $50 for three cans of FF Black. It was the perfect amount to treat both rails front to rear as well as inside the torque boxes, with about half a can left over. Took about half an hour to do
If you haven’t done it already, be sure to thoroughly clean the inside of the rails of any debris, rust chunks and flakes. I made a dozen trips to the self-serve car wash to power wash the inside of the rails before applying the Fluid Film.
I should tell you, applying the fluid film is a really easy DIY job. I think I paid $50 for three cans of FF Black. It was the perfect amount to treat both rails front to rear as well as inside the torque boxes, with about half a can left over. Took about half an hour to do
For the cleaning last year I used a combination of compressed air and the power washer at the self-service car wash to purge all the debris from inside the rails. I cut a three foot piece of garden hose that slid over the end of the pressure washer head so I could get in deep to the middle of the rails with the pressurized water. Dirt and small debris came out the 1/2" drain holes I created, but larger flakes will clog the drain holes so I used a magnet wand to grab the larger chunks out through the large holes in the sides of the rails. Rinse & Repeat. Literally. When I was done there was nothing in the rails. Let it dry really well.
I did it last year for the first time and did the thorough interior cleaning I described above so this year all I did was flush the rails out with water and air about a week before I did the FF treatment. I was surprised and pleased with how little debris had collected.
The items I needed for the FF were:
I was going to cover all but a few key frame holes using the masking tape to control blowout & overspray, but it wasn't necessary. And there were no drips to deal with so the drop cloth was something to lay on since I did the procedure in the woods rather than my driveway. The FF is all natural, lanolin based and candidly.. it smells like the monkey house at the zoo on a hot summer day and it did so for a few days after the application.
It took one can per side and the third can did the torque boxes and a few key spots (like the hollow on the tops of the spring perches) with some left over.
The outside of the rails, axels, TC skid, upper and lower spring perches, CA's, gas tank skid and some other bits were done with POR 15 last year and are still in good order.
Hope this helps. Questions are welcomed and encouraged!
I did it last year for the first time and did the thorough interior cleaning I described above so this year all I did was flush the rails out with water and air about a week before I did the FF treatment. I was surprised and pleased with how little debris had collected.
The items I needed for the FF were:
- three cans of Fluid Film Black,
- a pair of nitrile gloves,
- shop towels
- wire hanger,
- drop cloth (which I didn't use)
- Roll of wide masking tape (which also went largely unused)
I was going to cover all but a few key frame holes using the masking tape to control blowout & overspray, but it wasn't necessary. And there were no drips to deal with so the drop cloth was something to lay on since I did the procedure in the woods rather than my driveway. The FF is all natural, lanolin based and candidly.. it smells like the monkey house at the zoo on a hot summer day and it did so for a few days after the application.
It took one can per side and the third can did the torque boxes and a few key spots (like the hollow on the tops of the spring perches) with some left over.
The outside of the rails, axels, TC skid, upper and lower spring perches, CA's, gas tank skid and some other bits were done with POR 15 last year and are still in good order.
Hope this helps. Questions are welcomed and encouraged!
Kenneth G Zinis
TJ Enthusiast
Kenneth G Zinis
TJ Enthusiast
MikekiM,
I've been hesitant about drilling the frame drain holes but you kind of convinced me.
Do you just put them at the visual low points in frame rails, front and rear?
Do you think larger than 1/2" would be best, maybe 3/4"?
I read about a guy that put 3/4" holes in the rear frame rail vertical end caps, behind bumper, so he could feed his extended pressure washer flexible hose all the way to front of frame. He used a sewer jet nozzle type nozzle that I think sprayed 360 deg and it aims backwards. To me this sounds like a sound and thorough approach for cleaning frame and then FF application but seems drain holes are needed regardless.
What are your thoughts on the rear holes and this pressure washing approach,
hesitate no longer my Pennsylvania brother as your rig aint gett'n any younger. Half inch is plenty.
As for the rear cross member, yes, pop the bumper off & drill out the bottom holes lower than what's already there. The engineers in their infinite wisdom put the holes above the level of the bottom of the frame rail guaranteeing that water would be trapped inside.
These holes will also allow you to fish in whatever you want more easily be it a fluid film or Eastwood wand, or other...
Great questions..
I put the drain holes right in front of rear and behind the front CA mounting brackets. I've seen them done inside the mounting bracket, but where I put them doesn't require removing the CA's.
As far as size, 1/2" was sort of arbitrary. I didn't see need to go larger. I used a step bit.
I didn't do the holes in the rear cross member, but now that I see how @Westtown Willy did it, I will consider it next time I have the rear bumper off. Hit it with some paint afterwards. You can't readily see those hole for rust inspection. I suppose you could over-size those holes but there are so many holes along the rails allowing access all the way to the front, that it might be overkill. Plus, do you really want to remove the rear bumper just to clean the rails? There are oval holes four inches from the back end of the rail (access for the flag nut for the rear tow hook), just stick the hose in there, push all the way to the rear end of the rail and spray. Any debris in the ends of the rails will come out the oval holes.
Mike, keep in mind the primary reason I enlarged those holes was for drainage, easier access was a byproduct. Look at your frame from the side & what you'll see is that the rear of the frame where it meets the crossmember is its own isolated trench so no drilling you'll do elsewhere will drain that small run of frame (unless you do a pair underneath that short run which I didn't see the need for given that there are already two 'pilot holes' from the factory in the back). All I did by widening them is lower the bottom flush with the bottom of the rail, now the water has a place to run out of rather than collecting there.
This occurred to me to be necessary upon inspection with the endoscope, I could see from inside that the holes were above the bottom of the frame rail. Of all the areas of the frame this resulted in those spots at the rear collecting by far the largest amount of debris, leaves, sand, I even pulled some sort of rubber grommet out of there
... Now when I flush the rails through the rear-most holes on the sides of the frame the water flows out really nice. Also keep in mind that the bumper does NOT restrict the flow from those holes whatsoever, the stock bumper anyway, can't speak to the million aftermarket varieties, but looking from the top down there's a few inch gap between those drain holes and the inside of the rear bumper...Here's a couple other shots of the secondary use, I was able to fish in my redneck Eastwood wand contraption rather easily for good coverage:
Edit: by the way none of this is an issue at the front because the front rails are completely open, the cross member is set back and doesn't completely block the rail so there's drainage up there.
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Mike, keep in mind the primary reason I enlarged those holes was for drainage, easier access was a byproduct. Look at your frame from the side & what you'll see is that the rear of the frame where it meets the crossmember is its own isolated trench so no drilling you'll do elsewhere will drain that small run of frame (unless you do a pair underneath that short run which I didn't see the need for given that there are already two 'pilot holes' from the factory in the back). All I did by widening them is lower the bottom flush with the bottom of the rail, now the water has a place to run out of rather than collecting there.
This occurred to me to be necessary upon inspection with the endoscope, I could see from inside that the holes were above the bottom of the frame rail. Of all the areas of the frame this resulted in those spots at the rear collecting by far the largest amount of debris, leaves, sand, I even pulled some sort of rubber grommet out of there
Here's a couple other shots of the secondary use, I was able to fish in my redneck Eastwood wand contraption rather easily for good coverage:
View attachment 369390
View attachment 369391
That’s exactly what I did the the FF spray hose. That front tape strip is a good indicator as to where the wand end is.
I know the stock bumper stands off the ends of the crossmember but a few inches. See below. I was thinking of trying to snake a large hose between the bumper and crossmember. I suppose there is enough room, now that I look at it.
Interested in your comment about the isolated trench. Maybe we have slightly different rail configurations. Here is mine.
With the rear tow hook removed there are two holes in that short section of rail. The oval hole, to the left and 1/2” bolt hole to the ovals right that has the tow hook bolt installed. I’ve been ‘in’ that section of rail with a scope and didn’t see anything obnoxious in there. Are you suggesting the drain holes for drainage of that three inches of frame between the two holes and the cross member?
you're correct, and all of my comments are assuming the hole is sealed by the tow bar mounting bracket. I retract my insult to the engineers (for this 4 inch section of the frame only, they still suck on the overall frame
). My frame has been sealed back there since I bought it which created the trench, with those giant holes you've got back there, there's no need to widen the rear holes as I've done. I'd still widen however on a case by case basis as I'm sure many others have unwittingly plugged that hole up - the prior owner installed the tow bar on mine & it has those bolt plates (?) that you fish in to secure the rail which completely covers over everything.I actually have an endoscopic photo that lit up that entire inside section showing what mine looked like but damn if I can find it; here's the outside though:
This area in red would probably hold a half cup of water. And if you're in the salt-belt make that a half a cup of brine. I've seen more of these sections rotted out than I can count around here.
Just chiming in to say that whereas @MikekiM used a pressure washer with a hose attachment, I used a sewer jetter attachment to "pull" the debris toward my drain holes. I found that my jetter fit through the existing frame holes just fine, so I did not have to make these additional holes you mention here.
My notes, with links to the products I bought, are here.
Kenneth G Zinis
TJ Enthusiast
Thanks SSTJ, very nice write up. is this the sewer jetter you used? What is diameter hole needed to allow tip to fit? https://www.amazon.com/dp/B08K2SJNN7/?tag=wranglerorg-20
That looks like it. I put the link the write-up on my build thread.
As I recall, I used the existing factory holes on the side of the frame. I did drill extra drain holes (about 1/2") on the bottom of the frame, but that's not where I inserted the sewer letter.
Like Westtown Willey did I just slotted the hole a little bit lower to allow for more drainage. I didn't take a picture after I did it, but I did flush the frame in that area and a nice stream of water came out. A few others on here have done the same thing. Just my 2 cents. And this is the crap I'm dealing with PO had a trailer hitch on it and crap just built up under it. Love NE