i have a 1975 F250 Highboy and i think the previous owner had after market exhaust pipes installed. But there is a terrible rattle coming from the catalytic converter its not the mounts i have shaken and knocked. But the pipes and the catalytic converter seem to be one piece. there are no bolts just welds. Is this how it should be. Or did the previous owner just put me it a S**t hole

 

sounds like the innards of the cat are breaking down or broken down already and rattling within the case.

Have an exhaust shop cut the cat out & look and do it soon.

I've had cats break down before & have had pieces of them come free & lodge themselves in the exit pipe of the cat. No exhaust being able to pass through the system = no good.
I've had it happen while driving on the freeway & it was a big surprising. Lost power all of a sudden on a hill!

 

Thanks for the help

 

And after it clogs, the pipe in front of the clog will get cherry red, and cause a fire if you keep pushing on.

 

Had that happen too (well, no fire but the red pipe) on a different truck years ago!

Coming home from the mountains on valentines day at about 10 PM or later. Stopped at every gas station I found and used the water there to cool the thing down so I could drive to the next one. That drive SUCKED! What is normally a 2 hr. drive took over 4 if I remember right. Gotta love things that go wrong when no shop is open & when you have no tools! Truck didn't catch fire though luckily!

 

Yep, also a very common way to misdiagnose very retarded timing (red hot exhaust pipes leading into the cat).

but in your case, Id agree with chase, the innards are gone, rattling around, and will pack themselves into the case outlet and your muffler if you have a normal one. Time for a new cat if you live in smog country or care about air quality, or time for a straight pipe if not.

 

A 75 F250 with cats? Not quite normal.......

 

+1, you wont find that here in Pa either. My 77 is non catalytic which I love. The OP is listed as living in Greenville SC so I don't know what their restrictions are there.

 

I don't think the F100's got cats until 1977, and the F150/250 until '79 ('78 in california, I think). But he says it has a cat, so... idk.

 

My son's first car was a 86 Crown Victoria, when the cats started rattling I had him remove them and we opened them up to clean them out, afterward I got out the welding torch and set him up so he could teach himself to gas weld. He never forgot that. Kenny Nunez

 

Consider what catalytic converters are worth in the scrap market, its probably wiser just to cut them off and sell them if thats your bent.

 

are the chunked up ones still worthwhile to the scrappers? I know the stuff in the internals is what brings the $$, but I didn't know if it started breaking down if it was still worth $.

Either way - I second what the guys are saying - if you don't have an inspection requiring them in your state just cut them off & enjoy the nice exhaust tone that comes when they're gone

 

I just cut mine off my 78 and added a glasspack and WOW sounds AMAZING! If you don't have smog where you're at I would ditch it all together.

 

1975 f250 + cat =odd. so it's unleaded only?

quote from "NumberDummy"


Quote:
<TABLE border=0 cellSpacing=0 cellPadding=6 width="100%"><TBODY><TR><TD style="BORDER-BOTTOM: 1px inset; BORDER-LEFT: 1px inset; BORDER-TOP: 1px inset; BORDER-RIGHT: 1px inset" class=alt2>Originally Posted by bmuhlbach
cars started cats in 75. trucks in 79 except heavy duty

</TD></TR></TBODY></TABLE>
First year for catalytic converters in F100's: 1975 w/300/302/360/390's.

First year for catalytic converters in F150's: 1977 w/351M/400's.

First year for catalytic converters in F250's: 1977 w/351M/400 Regular/Super Cabs only.

First year for catalytic converters in F350's: 1977 w/351M/400's.

Info source; 1973/79 Ford Light Truck Parts Catalog / Exhaust System Application Charts / Section 52.1; Pages 2 thru 7.
<!-- / message --><!-- sig -->__________________
Bill // Retired Ford Parts Manager // SoCal Chapter member // Part Number Research: 1928/2001 FoMoCo vehicles.

 

Wow this post blew up quick hahahahaha thanks for all the input. Like i said i know the exhaust tips are after market so my best guess is that the pipes are too. but i will take a picture some time and ya'll can see for yourselves. The previous owner lived in Alabama anybody know if they have emissions test there. In Greenville SC we dont have emissions tests.