westgate valve question

[fixitman4710]

hey guys i have a turbo question. i have 98 chevy k3500 with 178,000
miles. my question is does the arm move when you first start the truck.
can someone explain how the westgate works on cold engine. my truck
starts up easy when cold and no smoke. runs good for about 30 mins of
driving. then starts to surge and miss. new fuel lift pump,batteries,
fuel filter, recent oil change, new 195 degree tstats, new ops 60 psi cold
45 at 2000 rpm. im not sure about injectors and pump, they look old.
thanks for any help

steve n.carolina

[phantom309]

vacuum is supposed to draw it closed, so you shouldn't be able to move the arm with the truck running (at least not easily) when it want to it bleeds off vacuum,. and then the wastegate is pushed open by the exhaust,.which inturn bypasses the exhaust side of the turbo which backs down the boost,.

your other problem sounds like a classic pmd problem,. it warms up and then it starts to give you trouble,. do a quick search about moving the pmd onto a heat sink and moving it with a longer cable off its current location which is on the side of the injection pump,.

Nick

[JohnC]

If the wastegate is open when you start the truck, it will pull closed as soon as there is vacuum. It should stay closed until boost exceeds a prescribed limit, then the PCM reduces the vacuum and allows it to open.

It will not generally cause surging.

[fixitman4710]

i have a bad exhaust leak at crossover pipe that needs to be welded
so im going to fix this and then relocate the pmd.
thanks a bunch

steve merry xmas to everybody

[scot5146]

Steve-

I had the exact same symptoms on my 99 k2500 suburban, new exhaust crossover pipe and a new pmd and its running like top, 21 mpgs

The exhaust pipe was huge issue, i kept thinking I was having waste gate problems but it was the leak... Now she really whistles...

Mike

good luck!

[JM99burban]

Check the sending unit "sock" in the tank also, I just recently had a problem with this. I think I got a dirty load of fuel.

[Robyn]

The surging/missing is not related to the turbo or any of the exhaust components.

A problem in these areas can cause poor boost and performance issues.

The missing can certainly be from a bad load of fuel.

Yank the filter and see if you have a load of crap in the thing.

The pickup sock in these rigs has a "safety" valve above them to allow fuel to be pulled in, should the sock get plugged.

These valves do go bad and cause air to get in when the fuel level gets below the valve.

Check thse things (bad fuel, water or?? ) before going too far.

The exhaust system certainly needs to be in good order for the turbo to work right.

The arm on the turbo should move freely back and forth with the engine OFF

With the engine running the arm should be tight and not easy to move.

The ECM will pulse the vacuum to the "Pod" when max boost is reached and thus moderate the boost level.

A leaky cross over will drastically effect the boost levels and overall performance.

Good luck

Missy