Rusted hitch attachment bolt holes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by priusrust, Oct 12, 2020.

  1. priusrust

    priusrust Member

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    Went to attach curt hitch to my 2004 Prius....bolt holes (2 on each side) that go into Prius frame on one side rusted beyond use (threads gone, hole is wider than bolt) I've arrested underbody rust damage, but this was done prior to my ownership. Any ideas? Seems like I need to have new metal welded on. Any advice in this regard? Thanks
     
  2. edthefox5

    edthefox5 Senior Member

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    I have a Curt on my 07.

    Those are big bolt holes that's alot of rust. How bad is the front suspension rotted out?

    Btw how old is the hybrid battery because towing hammers that battery hard and I mean HARD.

    If the hybrid battery is so so or original I can almost guarantee you it will push it to failure pretty quick so keep this in mind as you go forward with plans to tow. You need power to haul even a small trailer.

    When mine started to go south I was unable to tow.
    Unable to tow for about 4 years but just installed a new hybrid battery and back towing.

    If you plan on going ahead with welding the curt on i would think about also welding some anti cut anti theft rods to your cat converter so it does not get clipped since your under there welding.

    Go on YouTube search

    Prius theft

    lots of youtubes about cat thefts.
     
    #2 edthefox5, Oct 13, 2020
    Last edited: Oct 13, 2020
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  3. priusrust

    priusrust Member

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    Ya, the bolt holes are ok on one side.... on drivers side- not so. They are slightly bigger than the bolt. Suppose if the steel is still thick enough, I could redrill a slightly larger hole and retap for new threads (?) As far as I know , front suspension is ok. This actually may be connected to roof leak issue prius have. Both sides were rotted out with football size rust holes. Since fixed, but the water path may have passed over the hitch bolt holes (?) So, I don't plan to tow....plan to use it to hold carrier box. I don't think that should affect battery, as it will essentially be like one adult sleeping inside hatch door :) Interesting towing affects battery life. You would ::think:: the system would just lean more heavily on engine and it would not affect battery.... Curious about your new battery......which option did you take? I hear many contrasting opinions of best new battery options....
     
  4. edthefox5

    edthefox5 Senior Member

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    I feel for you with the Curt. Even with pristine chassis holes its a major fight as the Curt really does not line up very well to those holes to begin with there jig when welding up those bolt on ears is terrible. Horrible fitment.
    .
    I had to do alot of drilling to oblong the bolt holes on the curt to mate up properly.
    very common compliant with this mount. It may work out better if you just weld the damn thing on.
    But once its mounted its really good.. About 10 years old now.

    The best deal I could find for new battery in this area is 2K's cylindrical battery retro fit of the existing battery in the battery box. They fit perfectly and the car runs like its new battery wise. Its $1600 out the door but I was able to lay off the old modules and a prolong charger I was using so recouped $ 500.

    Don't have time or energy to whack a mole it. Its mama's car had to get back on the road fast.
     
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  5. priusrust

    priusrust Member

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    Oh, so just yesterday had a catalytic converter shield put on. Got the cheaper knock off version to save $50. (a cookie-cut sheet of metal is a cookie-cut.....)
    I think I will go the welding curt on route.... if they can weld some steel on and add some threaded holes - that would be prefered. I'm a little spooked by having just anyone weld on a prius. Hear things about disconnecting 12 volt, traction b. AND computer (yikes!) ....may head to "Toyota certified" place first. depends on price.
    [​IMG]
     
  6. edthefox5

    edthefox5 Senior Member

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    Oh good your on board with the cat theft they cant get you now with that plate the bastards.

    yeah there was a lot of talk about no welding on the G2 back in the day. Not so much now.

    Easy to protect the just unplug the 2 black wires at the top of the 12 volt assy just press the little lever on the white connectors and pull them out then remove the orange hybrid battery safety plug. Cant hurt you now.

    When you plug the orange safety plug back in just push it in then when you do that the lever automatically flips up then slide that lever straight down till it clicks. There's a little switch in the bottom there that pushing that lever down closes the switch telling the battery ecu the plug is locked and loaded.
     
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  7. priusrust

    priusrust Member

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    So I took the car to a Toyota certified body shop. The guy crawled under the car and said that I merely had to drill slightly larger holes-then rethread- with larger bolts and possibly drilling holes in hitch larger - which I knew. Then I heard him say, "oh-oh" from under the car. Apparently rust had eaten a hole in the square tubing (frame) further up on the tube that the bolts attach to. He said- bad news because no way to know how thick the remaining metal is and the hitch could fail. I told him I merely want to put 100lb carrier box on the hitch......he said it was my call. I've long since arrested any rust with 'Blaster' corrosion preventer.....but damage is done. Not sure what to do. Ideally, I'd like to inject some sort of steel epoxy into the hollow frame square tubing to strengthen it. Looks like creative welder is the only answer. No chance in hell I'm putting a container on the roof and watch my mpg plummet to '68 Cadillac gas mileage.
     
  8. edthefox5

    edthefox5 Senior Member

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    Wow lots of rust. Seen a few broken springs in the rear from rust too.

    I would take pictures of everything under there. Post some here.

    I use Blaster on my cars too love it. If you start with a new car it will never have any rust.
     
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  9. priusrust

    priusrust Member

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    [QUOTE=" If you start with a new car it will never have any rust.[/QUOTE]

    ya but those 2nd generation prius.....hard to beat
     
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  10. priusrust

    priusrust Member

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    ok, three pics of the carnage. Pic#1, seems ok, surface rust, bolt holes have depth- drill them out- rethread -use next size bolt- no problem.
    pic#2: Oh-oh.....You can see one of the bolt holes, then the gaping rust hole (after the square tubing frame rises up a bit) towards the front of the car (from the bolt hole) pic#3: aforementioned gaping rust hole. What is interesting is that looking in the hole- you can see the top of the square frame tube and it is pristine- no rust at all. This is giving me the idea to weld in a support piece of flat bar over the bottom of the rusted out section and butt it up against the part of the frame that dips down and has the two screw holes. I say this because looking in, looks like just the bottom rusted.
    [by the way- ignore the foam on the side of the pictures- that was used to cover (with hardware cloth & sheet metal screws) a HUGE rust hole caused by classic leak above rear hatch.]

    IMG_20201017_174705.jpg IMG_20201017_175423.jpg IMG_20201017_175408.jpg
     
  11. priusrust

    priusrust Member

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    question: at 2:27 into this video, the installers left hand knuckles are almost touching a small black cube attached to the frame....any idea what that is?
     
  12. edthefox5

    edthefox5 Senior Member

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    That frame rust looks pretty bad I agree with the guy. Whats with al the foam?

    Not sure what that little box is I would bet its emissions related. Been lucky it hasn't failed knock wood.
     
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  13. priusrust

    priusrust Member

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    1) Foam: so, I had that notorious slight hairline fracture up near where both sides of hatch meet roof- . For years water pooled in both the 12 v battery well and also in the area directly opposite. (I wasn't car owner then). When I looked, there was literally a football sized rust hole. (along with battery dangling over road on other side with battery pan totally GONE. ) Anyway, I was pleased with solution. Treated rust: grind away, ospho, paint....then tacked in some 'hardware cloth'. Then merely sprayed some insulation foam that fills cracks and hardens. This oozed between hardware cloth and made a very solid solution. Rodents no problem, they may chew through foam, but would hit hardware cloth barrier.

    2) rust issue at hand. I agree it does look bad......but not quite as bad as first glance. For one- rust is outside in. (you can see pristine paint inside hole) So not like a rusted quarter panel where it is worse than it looks.....in this case it looks worse than it is. So....I picture a cut to size piece of 3/16 plate steel butting up against part that dips lower with bolt holes.....it will actually go under that bolt hole with square box attached (evap canister?) so I'll make a matching hole in plate steel and just use a new longer bolt.

    3) my problem: welding. I've read so many opinions I'd love a knowledgeable straight answer. MIG welding a prius one must be careful. Disconnect 12 V. and hybrid battery. However, I also read that you must disconnect computer??? Some say yes, some say no. So my plan of action is to make a little cardboard template and have a patch tacked in. I'd LOVE to hear an authoritative answer on prius welding and what you must disconnect exactly.
     

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  14. edthefox5

    edthefox5 Senior Member

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    Oh lordy that rust damage.

    Back in the day heard you cant weld on a G2 many times but there sure is alot of welding going on with all the cat theft. So I do not know.

    Unclick the 12 and pull the orange safety plug?
     
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