I have an 85, I changed the waterpump last year, had it into the garage for a tuneup, plugs, wires, rotor, cap, timing etc. Picked it up and it had no power till it got to 2K then still sluggish. Got home after 7-8 miles parked it and noted temp to be 241. 15 minutes later I came out and heard the radiator gurgling into the overflow.

Well, my guess was the cat so I ordered a replacement (had the original with no mods to my knowledge, had care for 9 years). When I drove home car began to sound louder than usual. I have dynamax ultraflo mufflers which typically have a nice sound but this was different.

I figured I had a clogged cat so I ordered a new one and today I put it on the jack stands and pulled out the old cat. Found it not clugged but totally empty, could see from one end to other, nothing but two twisted pieces of metal on either side. Obviously not clogged as I thought!!! Could the guts to the cat have blown into my mufflers and blocked them or am I way off base and should be looking at something else? if they did go into mufflers, what do I do?? can I take them off and shake them out or blow out any residue?? I'm stuck and it's the end of the drive season and want to get the few few weeks out on the road!! Any help??

 

So it was running OK before the tuneup?

 

If no one has gutted the CC before you, then it is very likely that the CC guts went into your mufflers and it would be worthwhile to take the mufflers off and see if you can detect CC stuff inside them and get it out.

 

Check timing. If they adjusted it during tune up without disconnecting the est wire, then timing could be way off. This would cause lack of power and also generate more heat than usual.

I would guess that previous gutted the cat. You would have heard rattle from broken parts for a long time before all was clear out.

 

Just drop off portions of the exhaust and go for a drive......but I think the tune-up may have gone wrong......not a disaster, just have them readjust it.

 

Flush the coolant system and make sure you dont have crap stuck on the radiator i knoe i had bags and **** stuck to mine, i had same problem flushed it out cleaned the radiator and put a 160 thermostat on and it hasent got over 205 and i live in houston and this was in the summer... As for the other not to sure about it i had a leak that was dripping on my distributer but i have the lt1 so not to sure hope this helped

 

About 7 years ago half the cat on my car was gone. I noticed one muffler was hardly blowing any exhuast. Dropped the rear Y pipe. Big chunk of cat honeycomb was blocking on fork of the Y pipe. Look inside the cat with flashlight. Only 1st half was totally intact. Amazing it still passed emissions with flying colors. Yes, you might be able to fish out the chunk. But someone told me not the run the gutted cat because it could get too hot. I never gave it too much thought because it was louder and I didn't want to fail emissions anyway.

SO yeah, the cat can blow out the back.

Is the cooling fan coming on when it's supposed to? What kind of prom are you running? I'm running the Hypertech Thermomaster and my fans come on at 180. For diagnostic purposes I swapped the original prom in last week and it was horribly warm - 224. I swapped the Hypertech back.

If you have any doubt as to the condition of the radiator, replace it with new. You can feel around on it for cold spots. It should feel equally hot everywhere on it. Unplug the cooling fans before doing this.

Also, it is possible there is combustion gases going into the cooling system causing a hot running condition. Is the overflow bottle level rising?

 

I would pull the rad and clean in between the Ac cond. you will find a bunch of trash in there if you have not cleaned it before.this will help,plus a means of turning on the cooling fans at 205-210* off @ 190* with a 180* stat.