More than 1 reason for running too hot?

Hmmm....it appears you may have several problems going on here.
Your cats come apart indicates they were either hit with a pretty good force which broke them or youre running pretty rich fuel mixtures which is burning the unburnt gas in the cats. Prolonged rich mixtures will burn the cats up causing them to break into pieces.
You mentioned bad gas mileage ans I suspect that your overly rich mixtures took out the cats. Now a rich mixture will make the engine run cooler not hotter but it will make your exhaust system temps soar because the excess fuel is burning in the exhaust system.
All that extra hot exhaust system may be radiating heat into the fuel lines causing your fuel system to heat up and it will heat up the floorboards and anything bolted to them. I've actualy seen cars catch on fire because of this and burn to the ground. I hope you get this fixed before something bad like that happens.:(
 
Ah, sorry about that.

I should have noted, that when the chunks came out the exhaust it was running super lean. That was when # 1 piston got partially melted, two plugs had their electrodes completely burned way, & most of the others weren't much better. This was all before the current rebuild.

You might want to check out my Member Page for the current mods.

I'm currently running a tuner with a Dr. Fred file, so the parameters are fixed with the fan comming on at 190* & 195*, obviously while it stays cooler in town.
I considered pulling the board, but 1. don't want to have the fan holding off to the factory temps and 2. the O2 sensors are probably gonna tell the EEC to lean the heck out of the mixture. I really don't think adding more heat to the situation is a good idea at this time.

This is another point which is confusing; it just passed smog testing last week in one of the toughest counties in CA. :confused:

Additionally, after the rebuild, there was an exhaust leak at the left side header and downtube. A muffler shop fixed that but said there was still a leak at the head/header. Immediately after the rebuild, that was checked, the gasket was evenly compressed and a 2nd one installed. There's also a loud rattle in the rear exhaust which doesn't appear to be any part of the exhaust hitting anything.

So here's what we're wondering; if the CAT's are partially melted/broken with pieces partially blocking the exhaust in the resonnator and/or the mufflers, what would the symptoms be?

There would certainly be a lot of heat build up in the exhaust, which in turn , as you pointed out, would cause most everything under there to heat up. The engine would be fighting the restriction which may be moving back and forth creating the feeling of driving into an inttermitant stiff wind. That's what I meant by it felt like the car was fighting itself.

As far as the rich mixture, Fred said he was going to be conservative in the #'s considering what happen before. So, it may be set on the rich side. I'm not sure why that didn't show up in the smog test, since that is done dymanically under load, although not at hyway speeds.
 
Well that explains the cat pieces! LOL!!
I would'nt think your mixtures were too far off then since you passed emissions. Thats odd, maybe there is cat pieces stuck in a muffler baffle and its just enough restriction to really heat up the exhaust. Thats about the only thing I can think of now.
 
I had a cat break up on me once. It ran ok at normal throttle but when I got into it at all the boost would spike up to much higher levels that it should have been. Also when I was coming over the Grapevine I couldn't go over 60 or I would overheat. Think that may be where you want to look. Either just clear them out completely or get some new ones.
 
Thanks guys.

That was what my plan was for this morning - getting to a good muffler shop and trying to get a pair of hi-flo CATs. I'm not sure what to do about the possible blockage. Hopefully the shop will have some ideas.

It's nice to have a couple more opinions I trust on this. ;)

Lee
 
Before they replace the cats, have the shop do a pressure test on the exhaust. Basically they will drill some little holes at various places and check the back pressure. If it's too much pressure they will be able to tell easily.
 
I'm still in the dark.

There wasn't any "excessive" backpressure at the CAT's and the rattle was the emergency brake cable on the exhaust.

Since I knew the CATs had been damaged, I had them replaced.

I then drove through town to the freeway. The entrance was straight, so I stood on it through 1st and halfway through 2nd ending up cruising at 80 mph, 3,000 rpm for several miles. The temp never went above the "N". Ran smooth without any "fighting" of itself.

Problem is the ambient was only low 80's. :confused:

I'll have to wait til the temps go back up and put it under the heavy stresses again to really see if the problem is resolved.

I still want one of Mike's radiators. ;)

Lee
 
Re: I'm still in the dark.

rivlee said:
There wasn't any "excessive" backpressure at the CAT's and the rattle was the emergency brake cable on the exhaust.

Since I knew the CATs had been damaged, I had them replaced.

I then drove through town to the freeway. The entrance was straight, so I stood on it through 1st and halfway through 2nd ending up cruising at 80 mph, 3,000 rpm for several miles. The temp never went above the "N". Ran smooth without any "fighting" of itself.

Problem is the ambient was only low 80's. :confused:

I'll have to wait til the temps go back up and put it under the heavy stresses again to really see if the problem is resolved.

I still want one of Mike's radiators. ;)

Lee

Maybe the cats were semi plugged, that sure would make your engine run warmer. I understand you withholding the final verdict until you can torture it a little more though. :)

I appreciate your interest in my project Lee. Soon I hope to make an anouncement on the progress. I'm affraid to say too much right now out of fear of jinxing things.;) But soon!!:D :D
 
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