Rust In Frame Rail

[polarbear123]

I knew there was a reason the former owner had undercoated the car. I was scraping off the crap to install sub frame connectors and found a tiny pin hole. I than started to look further back and found this.

[tommyg29]

 
Dont you hate that.
Looks like someone covered it with bondo too.
I'm sure that structurally held everything together!
Im not a body man but Im guessing you have to replace that section.

[burdar]

That would ruin my week.  You'd better start poking around the rest of the underside.  Get it all fixed at the same time.

[polarbear123]

New winter project scrape the rest of the frame rails and see what I have. Can this be patched if  I don't find anymore?

[anlauto]

Yes it can be patched....a little bondo and undercoating 

[BIGSHCLUNK]

Naw, first you take some of that spray foam insulation. File it sand it, then bondo and undercoating.

Seriously tho just heat it up a little , it scrapes off much easier.

[polarbear123]

Naw, first you take some of that spray foam insulation. File it sand it, then bondo and undercoating.

 

You left out the most important part. When your done, sell it. 

[Topcat]

I used one of these to remove all my under coating.

Be careful! These things can throw a ball of flame out.

http://www.harborfreight.com/propane-torch-with-push-button-igniter-91037.html

[burdar]

Would a heat gun be better for that job?  Less toxic smoke maybe? 

[polarbear123]

I have a heat gun and I will try it this weekend.

[Topcat]

Would a heat gun be better for that job?  Less toxic smoke maybe? 

I tried the heat gun when I strippped my inner wheel wells.
Took way too long.   

[BIGSHCLUNK]

My car has the 3M body schutz underneath... just take a small bottle torch. A heat gun will never go quick enuff from my experience. 

[Topcat]

With the HF torch, you'll strip a wheel well in about an hour or 2.
Anything smaller in flame output will take way longer.

a small torch is O.K. if you're just doing small areas.
If you want to do alot, get the torch I recommended and a 5 gallon propane tank.
These really can put out alot of flame about a 4" area so turn it way down.

Wear a mask or have a fan going to reduce inhaling any smoke.

[jimynick]

With the HF torch, you'll strip a wheel well in about an hour or 2.
Anything smaller in flame output will take way longer.

a small torch is O.K. if you're just doing small areas.
If you want to do alot, get the torch I recommended and a 5 gallon propane tank.
These really can put out alot of flame about a 4" area so turn it way down.

Wear a mask or have a fan going to reduce inhaling any smoke.

  AND, have a good sized extinguisher and water squirt bottle close to hand! The undercoat is petroleum based and flammable if you heat it enough. Many of us have done it, just take your time and watch the heat, as mentioned. did I mention that ice cold beer takes the smoke out of your throat effectively? 

[jimynick]

Take a 2lb ball peen and tap, not clobber, the rail all over. A good rail will not dent with a gentle blow and a rotten one will. Good advice given to look further; these cars are brutal for rust.