Need Help!

[Full Bull]

Went and had my cats gutted this afternoon....noticed some increase in acceleration....and a little improvement over the sound coming out the back end. Unfortunately, I've also noticed that my car is now running much hotter than before. For example, while cruising at 30 mph the temp eventually maxes out.... Seeing that the only thing different is the cats being gutted, what in the world could doing that have done to my car to make the temps soar? What's the fix?? All of a sudden I'm feeling like that my "good deal" is going to cost me some bucks!!! Any help appreciated.....

 

[cntrhub]

Let me get this straight? You "gutted" the cats, and now that same day, the temp needle is pinned? I would think the cat "was" the heat sink. Now where will the heat travel? It might be traveling right back to the engine, via the exhaust headers. The engine is now the "heat sink." The engine is constantly being cooled and the heat will travel to a cooler location. If you did nothing else to the car, and it was running (temp wise) fine before the cat work, this would be my guess?
I could have saved you a whole bunch of money if you wanted to have a faster car........don't hit the brakes as soon!

 

[Full Bull]

cntr...seen several postings from folks who have had their cats gutted, with no comments regarding any increase in engine operatiion. So, why's mine doing it? Understand your "heat sink" theory...but question it's accuracy. The catalyst material heats up as the hot exhaust passes through it....but, with the material gone, the exhaust now passes through unabated...so, why would that make the engine now the "heat sink?" What would you advise as the fix?

 

[cntrhub]

I would agree with your theory also. But again, if this was your only modification to the car, and now it's overly hot, what are the odds? Now I'm thinking that the thermostat is going south? A way to check that, is to touch both radiator hoses. If one is hot and the other is cold, there's your problem. Just let the car idle from a cold start and wait. Don't wait for the temp gauge to pin, or the fan to go on. Keep checking the top hose to see if it stays cold? If it is, the stat is stuck closed. Check coolant level first before starting the car. This way, you'll know if the coolant is lower than normal.

 

[Full Bull]

thanks for the advice...certainly hope that it's just coincidental, and that the thermostat's gone bad....keep them fingers and toes crossed!

 

[JonM]

Did you stick a pipe through the cat or just gut it. Turbulance inside the cat if you didn't pipe it could cause back pressure and overheating.

 

[WhalePirot]

RU sure the whole thing was reassembled properly?

The O2 sensor(s) back and connected?

If so, I would wonder if the back pressure somehow kept the sensors operating better, such that the ECM got different information. Maybe it is leaning out the engine too much.

I noticed no difference w/o my cat. Perhaps yours were partially clogged. Also, perhaps resetting the ECM might help it relearn better values and not run hot.

Lots of shots; mostly in the dark.



U do know it is a Fed. offense to do that, right? I'm no cop, but folks should weigh their options based on facts.

 

[vette-dude]

Well what a mess!! I will put in my .02 also. If the ECM leans out the mixture due to less back pressure or the O2 sensor giving bad readings, it will make the engine run hot. They make an O2 simulator harness for the C-5 models but not ours and I don't think the ECM really needs it. Maybe someone in the know can research this and answer if one is needed with gutted cats??Second thing to check is on the pass. side of the radiator shroud there is an opening where the ac lines go through. Take a flashlight and look in the cavity between the rad. and the condensor and see how much trash, leaves and road kill is in there. Mine was really plugged up on my 94 and it did a similiar heat up thing. Take off the upper shroud (not an easy chore) and clean out both the rad. fins and the condensor fins and remove the leaves and gunk. Third, make sure your fans come on. If you turn on the ac they should be operating. If not you probably have a bad relay or motor.

 

[Full Bull]

thanks to all for the feedback....took the car out today and it ran fine...no overheating??? Perhaps just some of the "gunk" left over in the cat was causing some blockage?? But would that cause an overheat situation? No, I didn't know it was a federal offense...looks like I didn't do my homework before undertaking this.. Oh, well.....not the first time that doing so will cost me some bucks to make it right! Live and learn...........