Delica Canada | Mitsubishi Van Club

4d56t. intake manifold blow off valve. any idea exactly what this part is called? Part number?

its located on top of intake manifold toward back, near firewall.

seems like the spring is weak? it opens when under load. Didn't used to do this, recent issue. Had exact same sound before but that turned out to be a hole in one of the intercooler hoses.

Confirmed its the valve opening in this case. Don't see what could be causing this other than weakening valve spring. Turbo appears to have no issue.

I looked at the pdf and see the part but its not referenced.

Looks like a plug and play part though.

Any idea what this is called. Hoping one of the suppliers have em in stock.

Thanks for your help.

Artie

Sounds like the pressure relief valve is opening due to the wastegate actuator being stuck. It's a common problem on these. On a diesel there is no "Blow Off Valve" like on a turbocharged gas engine because there is no throttle plate. This valve only works to prevent an overboost condition. If the wastegate is stuck in a maximum boost position the relief valve will open to relieve intake pressure. Usually the wastegate actuator rod gets rusty and sticks inside it's bore. Try spraying some penetrating oil on it (with the engine cool of course) and with pliers try to work it back and forth until it moves freely. You will find that removing the intake snorkels will provide more access to the turbo to make it easier.

Dino wrote:Sounds like the pressure relief valve is opening due to the wastegate actuator being stuck. It's a common problem on these. On a diesel there is no "Blow Off Valve" like on a turbocharged gas engine because there is no throttle plate. This valve only works to prevent an overboost condition. If the wastegate is stuck in a maximum boost position the relief valve will open to relieve intake pressure. Usually the wastegate actuator rod gets rusty and sticks inside it's bore. Try spraying some penetrating oil on it (with the engine cool of course) and with pliers try to work it back and forth until it moves freely. You will find that removing the intake snorkels will provide more access to the turbo to make it easier.

That's a great tip!. Thanks Dino.

Artie.

Dino,

Just to confirm.

This wastegate actuator is on the turbo itself?

If I remove the incoming snorkel its on the face of the turbo? Meaning I don't have to remove the turbo and disassemble it?

Thanks.

There will be a vacuum pod on the side of the turbo with a steel rod going to a pivot arm on the turbine side of the turbo. Make sure all of that moves freely.

I hate being a pedant, but its the way I am...

The wastegate actuator looks like this:



It's bolted to the manifold, it has a pipe connected to the turbo side of things (diesels have no vacuum as such) and it provides a feedback loop to the turbo, when the boost pressure reaches x amount, the diaphragm and spring inside, moves, and hence the rod, and moves a valve in the turbo, venting gasses around the turbo unit. As above, this should all move ok. If it was stuck, the pressure valve will fire off, if the turbo feedback pipe is missing, the same, if the pressure relief device spring is weak, it will go off, er, prematurely, DO NOT ASK ME ABOUT THIS I HAVE NO EXPERIENCE OF THIS I JUST WENT TO THE CLINIC WITH A FRIEND AND HE HAD THIS PROBLEM!


and we're back in the room, what happened?

Thanks man, I was trying to upload a pic.

Ohhhhhhh, that's what that thingy is!! Been wondering....

Thanks a lot yojimbo and Dino. Very helpful indeed.

Artie.

No worries, picture tells a thousand words and all that.

Update:

Problem solved. Wastegate valve itself was fine. Where the rod was attached on side of turbo had a bit if rust and locked up, wasn't seized inside turbo.

Couple squirts of penetrating oil, couple light taps with hammer and metal rod , pressure test waste gate to make sure diaphragm was good, test drive, done.

Hardest part was getting bottom bolt back on heat shield. Bolt dropped 3 times, a little cursing and it's all good.

Thanks Dino and Yojimbo. Right to the heart of the issue!

Artie

Glad to hear you got it sorted. I gotta do mine tomorrow night. Same issue affects the 4M40T as well :P