Guy said aftermarket e/x melted bumper?

[zorobyte]

I'm picking up a CB7 tomorrow and the guy said that the exhaust melted the bumper and something about his friend said that it is burning gas into the exhaust? High EGT? Lean? Timing? Anything I should check before driving it 100 miles so I don't blow the eng? Is timing adjustable from the dizzy?

I'm thinking some idiot has the exhaust touching bumper with a test pipe but shouldn't it be cool enough not to melt by the time the exhaust exits?

[ja23merz]

if it has unburnt fuel in the exhaust, it could mean that the O2 sensor isn't functioning properly. adjusting the timing might be able to help and yes, it is adjusted by turning the distributor.

[zorobyte]

Thank you much! I have been trying to answer as many threads as possible for all the knowledge I have been amassing. It won't be long until Im a CB7 guru

[my 9t9d]

Just enjoy everything you learn and never mind the ones that will talk shis but are still here

[TomQuick]

Last summer I drove from NY to Florida for our family vacation. Shortly before the trip, I cut the turn down off the exhaust on our Caravan, in order to relocate the tow hitch, as it was hanging too low. When I finished, I added in a short bit of straight pipe, and the turn down, making it just long enough to clear the cross bar of the trailer hitch. The muffler, and bit of pipe left behind it was kind of rusty, and cruddy, but I was in a rush, and instead of grinding the rust off, I just tack welded the pipe on through the rust and crud.

Somewhere around GA, my scabby weld job popped loose, and the straight piece of pipe, along with the turn down fell off, leaving the short (about 3/4 inch) straight pipe behind the muffler pointing straight back. It was at least 8" from the rear bumper, but the heat coming out of the exhaust system was plenty enough to melt the hell out of the rear bumper cover. We actually smelled it burning inside the van well before I figured out what the stink was. It did a good bit of damage to the bumper cover, and there was absolutely nothing wrong with the van, it was, and still is running perfectly. I would say that there is plenty enough heat in the exhaust to mess up a bumper cover.

[zorobyte]

Exactly what I wanted to know. This accord seems a bit modified and I know of a few people putting a spark plug into the exhaust for flame throwers. Don't want to be driving home and "what does this button do" with a state trooper behind me mahahaha

[deevergote]

I'd be careful... if the exhaust is hot enough to damage the bumper, who knows what sort of damage has been done to the engine!

[batever]

High exhaust temperatures due to unburnt fuel vapors could damage the catalytic converter, but probably won't damage the engine, is my take. But I'm a newbie to engine stuff. Such a problem could be caused by either a decent exhaust leak or by a nonstandard exhaust setup with less backpressure than standard, *if* the engine hasn't been modified (with a different cam setup) to compensate for the reduction in backpressure.

[deevergote]

Compensate for the reduction in backpressure? That makes no sense...


If the exhaust temperatures are that high at the muffler, then the engine is releasing exhaust with eveh higher temperatures. This can do SERIOUS damage to the valves, as well as any seals exposed to that heat. Not to mention underhood components exposed to it.

High EGT is also an indication that the motor is running lean... which can cause all sorts of problems. That motor could be burned to a crisp inside.

[batever]

Compensate for the reduction in backpressure? That makes no sense...


If the exhaust temperatures are that high at the muffler, then the engine is releasing exhaust with eveh higher temperatures. This can do SERIOUS damage to the valves, as well as any seals exposed to that heat. Not to mention underhood components exposed to it.

High EGT is also an indication that the motor is running lean... which can cause all sorts of problems. That motor could be burned to a crisp inside.

What would a good average exhaust temperature at the downpipe be? And at the muffler?

[TomQuick]

I don't know about the OP's Honda, but I know that my Caravan is running 100% properly, has been running fine for the past year since it melted the rear bumper cover.

[deevergote]

What would a good average exhaust temperature at the downpipe be? And at the muffler?

Honestly, I'm not 100% sure. One of the more experienced tuning guys will be able to chime in here. For turbo cars (which this is not) 1300-1400 in the exhaust runner of the leanest cylinder is considered good, from the little research that I've done. NA should be lower, especially stock. At the muffler, I don't know... that is rarely tested. It should not be burning the bumper though!

[deevergote]

hahaaaha lol lMFaO!!!

Let's try this again, shall we? We'll start by reading the "sticky" threads in Beginner Off Topic. I can hold your hand while you venture over there, or you can be a big boy and do it on your own. Your choice.

[TomQuick]

Must be a significant difference between the exhaust operating temp on my V6 van, and the 4 cyl Accords, because the exhaust at the tailpipe on my Accord is warm, but certainly NOT any where near hot enough to melt a bumper cover (I know this because after this thread, I was curious, and had to stick my hand behind the tail pipe with the car running to check it out), even after warming up thoroughly. I wouldn't want to hold my hand near the exhaust pipe on that Caravan though, that exhaust is pretty hot. I wouldn't have thought that 2 cylinders would make that much of a difference. It kind of makes me want to get one of those no touch thermometers, and do some investigating just to see what the temps are.

[deevergote]

It certainly gets hot... but hot enough to melt a bumper cover is too hot.