CheckEngine Light on EA81 hatchback for awhile, now forward CAT is overheating.

[SnatchedHatch]

I bought my car with this problem:

The CEL appears after 15-20minutes of driving/warming up.

Sooner if rough/hard driving, or 4WD is engaged (more stress on the engine).

Also if left to warm up for more than 5 minutes it appears.

 

Yesterday:

~Popped hood, found a whisp of smoke, the front catalytic converter heated up enough to start to melt the outer edge of the inner CV boot on the passenger side.

 

//From what I've read, an overheated cat can be cause by a failure in the O2 sensor, surprise surprise it looked as if it was the source of the smoke.

 

I just want to get some advice on if I should start by replacing the O2 sensor.

I'm thinking it caused the CEL all this time?

 

BUT does an old car like this depend on the CEL for regulation of gas flow, or is that silly to think for a carb?

I'm not familiar sorry!

 

Could it be a combo of the O2 and a not properly tuned Carb? I would admit it has been on the weak side, but I just have blamed old tech.

 

 

Please, any advice would be appreciated.

My plan is to replace the cat, and at the same time or after confirm if the cat is still usable.

If it's a dud, then time to straight pipe this girl

[czny]

I'm going thru much the same thing. 87 GL 4wd front & rear cats are failing. Last year had P/S intake gasket start leaking both into the intake & on top of the block. Replaced the leaking gaskets & some hoses. Months later now the CEL comes on just before everything is fully warm at cruising speeds on the fwy. Then goes out later. No codes while running. Tried everything else.

If you can borrow an infrared temp gun you could check the cat(s) for failure. Or a vacuum gauge test. Search the old threads here.

Watch this:

 

Read here starting post 21: http://www.ultimatesubaru.org/forum/topic/87359-loyale-lacking-power/?hl=%2Bplugged+%2Bcats&do=findComment&comment=739770

 

Edit: Could be too rich. Like carb float level is too high causing percolation. Or choke stuck on. Excess fuel can cause converter meltdown. Some late 70's domestic vehicles used to catch the interior carpet on fire when running rich.

Edited February 12, 2014 by czny

[SnatchedHatch]

Thanks, unfortunately I'm waiting for my Wireless router to come in. I've been using public/cafe wifis for the last week or so, and I jsut can't spend that much time browsing while here.

I will take a look once my home connection is back up,

 

but to comment on the info:

I believe my rear cat is failing too, that or the guard is rattling as many have said on here that is the more probable case. Thing is, I had my car up on a lift and my mechanic buddy gave it some knocks and said it sounds like the mesh is caking and crumbling if that makes sense.

 

Now the front is overheating. I wasn't aware I could tell if it is still good by temperature alone.

Is there a certain range of temp that defines hot cat and broken?

I can still browse the forum on my phone with ease, I'd appreciate any input on that!

 

 

 

I'm also worried that my carb might be out of tune causing a lean or rich mixture, as this can cause problems in the cats (I know first hand from my last car that any unburned gasoline will destroy the cat over time).

..and I would not be surprised if I'm my sub is not reaching peak efficiency.

 

Anyone have experience with carb tuning?

[El Presidente]

Subaru integrated a system to let you know when to replace the cat right from the factory thats built into the CV boots...its real high-tech..

 

 

When they melt the cat is dead

 

Josh

[czny]

Subaru integrated a system to let you know when to replace the cat right from the factory thats built into the CV boots...its real high-tech..

 

 

When they melt the cat is dead

 

Josh

Rather than replace the front cat I added a galvanized sheet metal heat shield to the cross member on P/S. Just big enough to protect the DOJ boot.

A band aid until I do my EJ swap. But the rear cat failed first.

 

Cat temps should be higher at the rear of the cats. If the cats run hotter at the entrance, they are failing.

Edited February 13, 2014 by czny

[czny]

"but to comment on the info:

I believe my rear cat is failing too, that or the guard is rattling
as many have said on here that is the more probable case. Thing is, I
had my car up on a lift and my mechanic buddy gave it some knocks and
said it sounds like the mesh is caking and crumbling if that makes
sense."

Had a rear cat come apart inside. The biscuit was turning around inside & rattling like h3ll. Never buy Eastern Cat products. Poorly made.

[SnatchedHatch]

Rather than replace the front cat I added a galvanized sheet metal heat shield to the cross member on P/S. Just big enough to protect the DOJ boot.

A band aid until I do my EJ swap. But the rear cat failed first.

 

Cat temps should be higher at the rear of the cats. If the cats run hotter at the entrance, they are failing.

Damnit. It was definitely spewing smoke from the front of the front cat, I would guess that to be dripped rubber though.

 

I'll check it out,

thank you!