Grench
SILVER Star
Not stranded. I have other wheels and the truck is in a safe place. So, I called this near RTH as I need to get a plan together before the weekend.
I wish I had a picture of the valve meltdown carnage, but the truck is 60 miles away from me right this minute. I will try to get some pictures of the valve this weekend.
Background:
1996 FZJ80 130,000 miles
Fresh head gasket
Fresh TRD Supercharger Install
Brand new EGR valve
Brand new EGR vacuum modulator valve
Hose routes right according to the SC install book
Stock exhaust
Symptom:
Blew a hole the size of a quarter through the side of my new vacuum modulator valve. The valve body/plastic got hot enough to melt/blow with bubbled plastic and holes through the side & top. The gas flowing from it was hot enough to melt the plastic wire loom around the harness extension 4" away.
Analysis so far:
The EGR valve has a side stem that provides exhaust pressure over and up to the bottom of the EGR vacuum modulator. It pushes quite a bit of pressure and if the modulator valve fails, it moves quite a bit of exhaust out under the hood.
There was enough pressure coming through the lower hose on the modulator valve to cause it to fail. Once it had failed, the exhaust continued to flow into/through the valve to heat it up to the melting point. It then failed catastrophically with curling bits of molten plastic wrapping up in lava-rock formations all over the valve. The hot gas continued to shoot out of the EGR stem acting like an ultra high temp heat gun melting the wiring looms. The wires appear to be fine (lucky me).
The first sign of failure was when the cruise control stopped working on the highway due to the vacuum loss.
So, I'm trying to understand how the EGR modulator is supposed to work. From what I can tell it balances the pressure of the exhaust vs the vacuum flow from ports on the throttle and one port that connects through the T on the EGR back to the (now) high pressure intake port. This is how the SC install guide shows it anyway so that is what we did.
I have two theories, but am interested in hearing more.
My theory 1. The stock exhaust is providing more back pressure than the EGR modulator valve was able to handle under the SC conditions.
My theory 2. The SC install book wasn't right or I interpreted it wrong. Should the EGR actually be fed off of the DS port into the tiny port on the intake (per the SC guide) OR should we reroute it back to the vacuum side of the SC? Having vacuum on one side and pressure on the other seems a bit self defeating as any vacuum fed to it through the pre-SC side would just be defeated by the pressure coming to it from the post-SC side.
What else do you guys have? I searched, but found no reference to someone actually melting/blowing holes in an EGR modulator valve.
I'll try to get some pictures Saturday when I can get back to where my truck is at. That valve looks cool. Good thing I still have the one we took off.
Grench
I wish I had a picture of the valve meltdown carnage, but the truck is 60 miles away from me right this minute. I will try to get some pictures of the valve this weekend.
Background:
1996 FZJ80 130,000 miles
Fresh head gasket
Fresh TRD Supercharger Install
Brand new EGR valve
Brand new EGR vacuum modulator valve
Hose routes right according to the SC install book
Stock exhaust
Symptom:
Blew a hole the size of a quarter through the side of my new vacuum modulator valve. The valve body/plastic got hot enough to melt/blow with bubbled plastic and holes through the side & top. The gas flowing from it was hot enough to melt the plastic wire loom around the harness extension 4" away.
Analysis so far:
The EGR valve has a side stem that provides exhaust pressure over and up to the bottom of the EGR vacuum modulator. It pushes quite a bit of pressure and if the modulator valve fails, it moves quite a bit of exhaust out under the hood.
There was enough pressure coming through the lower hose on the modulator valve to cause it to fail. Once it had failed, the exhaust continued to flow into/through the valve to heat it up to the melting point. It then failed catastrophically with curling bits of molten plastic wrapping up in lava-rock formations all over the valve. The hot gas continued to shoot out of the EGR stem acting like an ultra high temp heat gun melting the wiring looms. The wires appear to be fine (lucky me).
The first sign of failure was when the cruise control stopped working on the highway due to the vacuum loss.
So, I'm trying to understand how the EGR modulator is supposed to work. From what I can tell it balances the pressure of the exhaust vs the vacuum flow from ports on the throttle and one port that connects through the T on the EGR back to the (now) high pressure intake port. This is how the SC install guide shows it anyway so that is what we did.
I have two theories, but am interested in hearing more.
My theory 1. The stock exhaust is providing more back pressure than the EGR modulator valve was able to handle under the SC conditions.
My theory 2. The SC install book wasn't right or I interpreted it wrong. Should the EGR actually be fed off of the DS port into the tiny port on the intake (per the SC guide) OR should we reroute it back to the vacuum side of the SC? Having vacuum on one side and pressure on the other seems a bit self defeating as any vacuum fed to it through the pre-SC side would just be defeated by the pressure coming to it from the post-SC side.
What else do you guys have? I searched, but found no reference to someone actually melting/blowing holes in an EGR modulator valve.
I'll try to get some pictures Saturday when I can get back to where my truck is at. That valve looks cool. Good thing I still have the one we took off.
Grench