I hope someone has seen this before I can't figure it out. I installed a new EGR valve and after a few days the truck started running badly again. I removed the engine cover and the plastic vacuum booster( I think thats what it is) was melted on one side and the bottom and it looked like it had blown outward from the inside out. I replaced it with another one(just the plastic part) and the first time I drove it the same thing happened.

Could this be too much exhaust pressure building up. Maybe the Cat. is clogged or obstructed? Help !

Timming is right on the factory spec. done with the temp sensor disconnected.

I hope someone has seen this before. Any help would be greatly appreciated.

 

what year is the truck and what engine does it have?

 

oops sorry it's a 1990 B350 Van with the 360.

 

did the egr port look carboned up? the part you are talking about should not be blowing up or melting. all it does is control the egr valve.

 

It looks like the metal tube from the EGR valve to the plastic part is where it is coming from. Like hot gases are coming in thru that tube and melting the plastic. And it looks like it has some pressure as the melted plastic is pushed from the inside out.

The ports were black but there didn't appear to be any real build up of carbon just a thin layer.

I guess it could be a defective EGR valve from the factory? I just hope someone has seen this before.

 

you can test a egr valve. you just apply vacuum to it and the valve should move. i don't think the heat coming off the egr valve should be hot enough to melt anything unless the engine is running hotter than it should be. does it seem to be running hotter than normal?

 

No the temp. seems normal.

 

to be honest i removed the egr valve thousands of miles ago because it became clogged. It was simple i removed the valve plugged the hole in the exhaust header and plugged the vacuum line. But this may not be practical for you due to emissions testing in your area because removeing the valve will increase your NOX emissions but where i am that is not a problem

 

No problem with emissions here in Fla. But I have always heard that if you remove the EGR it will cause your combustion to burn hotter. Have you noticed this or any other adjustments you had to make?

I think I may have solved the problem. After melting 2 transducers(finally looked up the name) I became suspicious of the Catalytic Conv.
Well, turns out when I cut it out I saw that the honeycomb inside had broken loose and was moving around inside the Cat. Seems it would get blown around by the exhaust and would turn so that the solid sideswould be turned twoards the front and back and the honeycomb would be up and down. Then it would be pushed back against the exhaust pipe causing an obstruction reducing the exhaust flow and causing a lot of back pressure. This caused much hotter than normal exhaust gas to be forced into the Transducer at much higher pressure than normal. And it seems this was what caused it to melt. I gutted the Cat. and re-installrd it and it is running great. Engine temp. has dropped. And the Transducer is not melting. So I think that was the issue. So if you ever hear of this symptom again! Thx for responding guys!

 

no all I did was remove the egr and plug the hole in the exaust header and plug the vaccume line going to it i did not makke any other adjustmens and the truck seems to be running normally the onley difference i notice is that once it is fully warmed up if you accelerate quickley then let off the gas you will get a popping throught the exaust but from whet i understand that is the excess NOX burning off in the exaust system.