Melted EGR modulator (1 Viewer)

[ncduckman]

After a day of wheeling at The Badlands with the Hoosier Cruisers crew, my 1996 FZJ80 was running poorly on the way home. It had poor power and difficulty holding speed. Eventually a hissing sound came from under the hood. I pulled over thinking exhaust failure or vacuum leak.

An under hood inspection found the vacuum hose (bottom) came off the EGR modulator. It appeared a bit melted on the underside. We reattached the very hot hose and carried on, as we were only 10 miles from home.

I popped the hood the next morning and found this. The modulator was looking pretty bad. I figure the diaphragm on the EGR valve had failed, allowing exhaust to enter the modulator, hence the meltage. My plan is to replace the EGR valve and modulator and call it good.

My question is though, would there be an underlying issue that could cause the EGR valve to fail? I had my exhaust replaced from the y-pipe back with an up-and-over the frame, new (larger) single cat, and new O2 sensors. I have a slight leak that I have not addressed (no time) and have been throwing cat deficiency codes (P0420).

Would the O2 sensor code mess with the fuel mixture to cause a lean condition, hence higher EGTs, and cause EGR valve failure?

If the EGR valve diaphragm failed, could bits of it enter the intake/engine and cause damage?

P.S. I do not plan on bypassing/disabling the EGR system.

Thanks,
Robert

 

[Tools R Us]

Your theory is likely what happened. Once the diaphragm on the modulator fails, there can be a constant exhaust flow, overheating/melting it. I would replace the modulator, but the EGR should be good, maybe test it with a vacuum tester?

 

[ncduckman]

I figure the diaphragm on the EGR valve had failed, allowing exhaust to enter the modulator, hence the meltage

Your theory is likely what happened. Once the diaphragm on the modulator fails, there can be a constant exhaust flow, overheating/melting it. I would replace the modulator, but the EGR should be good, maybe test it with a vacuum tester?

Kevin,
Thanks for your ideas. Correct me if I am wrong, but isn't the modulator isolated from the exhaust and just serves as the controller for the EGR valve, which is exposed to exhaust gasses? I cannot picture how exhaust gas would come in contact with the modulator unless the valve had failed.