Loss of boost hd-t

[sandcruiser]

hey all
while driving the other day I noticed that my hd-t is not putting out as much boost as normal.

If I gun it to pass, for example, the boost goes up to 7psi, then falls to 5 or 6. "Normal" would be more like 12 in the same situation.

If I accelerate slowly up a hill, boost climbs to 6, then holds there. It would normally go up higher.

EGTs look about normal, in either scenario they climb, but not perilously and not above about 1,000*F or maybe 1,100*F. Safe.

I did recently change out the oil drain hose as it was seeping pretty badly. But the new hose was a factory hose, I don't think that is the problem. There may be a leak in the oil inlet, can't really tell, there is definitely an oil leak somewhere, that is for sure.... plenty of oil in the vicinity.

I plan to take the turbo out tomorrow to see what's up, but thought I'd enquire first to see if anyone has had experience with the wastegate opening too early or something like that?

Based on the FSM, the problem is either a bad wastegate, some sort of obstruction, or a problem with exhaust restriction.

or the turbo is just plain pooched and I need a rebuild/new one.

obviously the high $$ option is the new/rebuilt turbo. I'm hoping that is not the problem here.

Since I do not have a fancy SST to test pressure on the wastegate actuator... does anyone have a shadetree approach to doing that?

I only have the 1 vehicle, so taking the turbo in to a specialist is not particularly easy.

Thanks in advance!

more info: there is always some oil in the intake from the valve cover. I understand that to be pretty normal. It doesn't seem any worse that what I've normally seen.

 

[simonliew]

Disconnect the hose to the actuator and see how many lbs of boost you get,if you get higher boost then your turbo is ok.
Simon

 

[sandcruiser]

simon- thanks!
good advice
I just realized that by reading the fsm some more
will try it out in the morning

 

[ForealBoreal]

keep us posted
if you need a new one buy one of the ct26s for the 1hd-t off of ebay that is ready to go.
I was so thankful i didn't need a turbo rebuild.

 

[Adam B]

Probably obvious but check your hose clamps on all the boost tubes. I would imagine that it would take a fairly large boost leak to give the results you're experiencing but I would always rule out the little things before you get too serious about it.

 

[Radd Cruisers]

Check your intake ducting and the waste gate tubing along with the waste gate actuator.

Run the engine up and listen for pressurized air coming out of a leaking gasket or duct in the intake side of things.

Check for a leaking exhaust gasket before the turbo or where the turbo mounts to the manifold.

~John

 

[sandcruiser]

good call, but they are all okay

Probably obvious but check your hose clamps on all the boost tubes. I would imagine that it would take a fairly large boost leak to give the results you're experiencing but I would always rule out the little things before you get too serious about it.

 

[sandcruiser]

no obvious noises

I pulled the intake manifold off completely to try to fix a pretty heavy leak near the 5 and 6 intakes, so when I put it back together I'll be checking everything all over again

will keep everyone posted, but unlikely to rev it up until after I get the fuel lines hooked up again
which may be after I get the injectors rebuilt
maybe
still deciding

not that any of this is related to the turbo. just doing other stuff at the same time.
keeping it complicated, you know?

 

[Tapage]

disconect the wastegate ( plug the hose so you don't loose boost there ) and see what happen .. 99% on the wastegate .. or boost leak between turbo and intake ..

 

[sandcruiser]

so, if it is the wastegate... do i need to replace it? fix it?

I should have tested it this morning before I started pulling stuff apart

 

[cruiser_guy]

Look and see if the wastegate is moving freely. I have had times where the wastegate gets "sticky" and won't open or close all the way. If the wastegate isn't closing you're loosing boost.

 

[Tapage]

so, if it is the wastegate... do i need to replace it? fix it?

test it first .. ( actuall the wastegate pressure line it's in a fu** tight place to access it ! ) then you can shime it or shorten the rod, run a boost controller etc .. there are many other options ..

Actuall you can apply pressure with a low PSI compresor and see under which pressure it open .. ( wastegate spring allow movement )

 

[sandcruiser]

good ideas, Tapage
I'll test it w/ air to see where it opens
after I clean it, that is, it is very dirty right now

 

[Stone]

so, if it is the wastegate... do i need to replace it? fix it?

I should have tested it this morning before I started pulling stuff apart

If the wastegate is stuck open and you're losing boost I would be tempted to just install a manual boost controller and use that instead. Of course I guess you run the risk of a faulty wastegate becoming stuck shut also...

 

[sandcruiser]

doesn't a manual boost controller still operate the wastegate?

 

[Adam B]

Yes but it will isolate the wastegate actuator and door until you reach the level the manual boost controller is set to - assuming it is able to close and isn't stuck open. If your actuator is opening the door too easily, an MBC will "fix" that. Mind you, it can still be tested by disconnecting the actuator hose and plugging both ends. You'll find out real fast whether the door is closed and whether you're able to generate normal boost...and then some...

This is one advantage of an MBC, assuming your wastegate system works properly. It keeps the door 100% closed at boost levels below the MBC setting. With a normal system you get "wastegate creep" and it will start opening before you're at your desired boost level. Whether or not you can actually detect the difference is debatable. I can think of at least 1 person who will take each side of that argument.....

 

[sandcruiser]

hey! "Good" news: the wastegate is probably fine!

Bad news: the vanes aren't fine at all

that's the intake side
it is at the rebuild shop now, I await an estimate
obviously need a new impeller
going to rebuild bearings/seals while they have it

I'm trying real hard to see the bright side here- at least it broke down while I'm at home vs. having done so while I'm in the mountains of Guatemala or something like that. That's "good", right?

I'll be running my valve cover hose to the ground until I build a catch-can. I am confident that the damage happened from bits and chunks of goo building up in the lines from the blow-by collector.

I think that if Mr.T is going to vent crankcase gas back into the turbo, there should be *some* sort of filter or catch can on it. Otherwise what is to keep a bit of oil-based crud from flying off and taking out the impeller? 30,000 rpm and very hot makes for a pretty easy-to-break part. Even just a large droplet of liquid oil would be enough to cause damage, I think.

Ah, well, live and learn.

 

[Tapage]

the good news dude it's those pieces didn't break your engine ..

 

[sandcruiser]

yes
lots of good news here!

it gives me a chance to fix some other stuff
the motor is going to be so happy when I'm finished!

 

[Adam B]

Wow.

Assuming you don't have an intercooler, where did the missing material end up?

If it was my engine I'd be pulling off the whole intake side and trying to find as many pieces as possible. They have to have gone somewhere and there's really only 1 direction to go...

That said, I'd also use a catch can as a first choice, a longer hose as a second choice, and the original factory routing as a third choice. I wouldn't consider having it open to atmosphere or through a breather filter. I believe that you need POSITIVE crankcase ventillation to actually extract gasses, not just to relieve the pressure. I've been wrong before, though.