Loss of boost hd-t

[sandcruiser]

I have removed the entire intake manifold, did not find anything interesting
At the moment I have no intake, no exhaust (and no injectors)

I'm considering spinning the starter a bit to try to blast out any random bits that have remained in the motor, but it seems that I'm as likely to pull in some random leaf or twig and break more vs. fix more

the fins on those impellers are very small. If I assume that they eroded instead of snapping off as 1 large chunk, then they are probably atomized by now or melted to the piston head; either way they should not pose a problem anymore!

if anyone has more thoughts, please do share.

I am certain, by the way, that the cause of this was oily buildup that chunked off of the air intake pipe after years of buildup. Totally due to the crankcase ventilation system.

I don't know if you do or do not need positive ventilation, but I suspect that you really don't.... I mean- if there are gasses building up in there, then the gasses are at higher pressure than atmospheric and will migrate out of the tube regardless of the positive pressure. For now, it'll drip down my frame. Eventually I'll have a catch can. When do have a catch, I'll probably hook it up to the intake again, but only through some sort of filter, to keep bits out of the turbo in the future. I've been thinking that maybe a better solution is to tap into the air filter housing so that the gasses still have to pass through the air filter prior to hitting the turbo.

The more I think about it, the less I like the oily/gassy crankcase air going directly into the turbo housing. If I don't want it in my valve cover, why on earth would I want it in my turbo?

 

[sandcruiser]

also: an intercooler is high on the list too. Safety from turbo bits and better performance? Sounds good to me. Looking for the best way to set it up on top of the motor (like new 4runners and 4tuners)

 

[Adam B]

Any shaft play in that turbo?

 

[Stone]

Erosion? Hmm...I don't know much about metalurgy, but I would expect erosion to leave a smoother edge than the sharp edges on those damaged fins...

Those fins looked like they broke off to me...but again, just guessing.

 

[Dave 2000]

I believe that you need POSITIVE crankcase ventillation to actually extract gasses, not just to relieve the pressure. I've been wrong before, though.

The crankcase should be at atmospheric or negative, positive only comes from blowby. Years ago the crankcase vented to the atmosphere but emissions regs now want it reburnt and sent out the exhaust.

The fitment of a positive crancase ventilation valve that is closed at idle unless of course the engine is very worn in which case the crankcase becomes positive by blowby at idle and makes engine tuning difficult. The valve opens when the engine is being driven i.e. inlet manifold at negative sucking blowby into the combustion process.

TBH if you open the oil filler cap with the engine at idle and you can feel a lot of pressure on your hand then you have a problem with the engine, this is normaly accompanied by oil leaks around crank seals ect.

The process is:

Engine healthy no or very very little blowby.
Engine slightly worn (mid life) a small amount of blowby and perhaps the odd oil leak.
Engine very worn plenty of blowby which also contains oil mist and lots of leaks and oil consumption, also check the exhaust tip for oil residue.

Varies with make/model but all pretty much follow the same rules

regards

Dave

 

[sandcruiser]

I think that the way the factory hd-t is set up, the turbo actually creates a fairly strong vacuum. If the air filter gets at all plugged, then the suction on the valve cover could get pretty strong, which will eventually pull some sort of crud into the turbo.

fin breakage: I don't know anything about the various ways that they could have gone.... for sure they are busted. I am hoping that the bits that came off are somewhere that won't cause trouble, because I'm not planning to pull the head to find them. If they are in there.... I guess they could plug a valve? I'm hoping that they don't!

 

[sandcruiser]

ugh
just found out that a new impeller is $120

total rebuild cost, including balancing the shaft and the new impeller, sandblasting the turbo, painting it (?), new gaskets and seals all the way around and a new oil input line

for the bargain price of $700

which is just about exactly where I had put the mental cutoff vs. buying an Ebay turbo.

But I get it back tomorrow instead of in 2 weeks, which is better.

 

[Stone]

That's about how much I paid initially for my rebuild, minus the oil line. I would make sure that they go over your turbo housing with a fine tooth comb and make sure there are no cracks at all. Not worth rebuilding something that will just be a problem later on.

On a side note, a common area to find a hairline crack is where the wastegate flapper closes. ADP asked me if I wanted to fix this with a sleeve, stating that it's not a critical defect, but that I might be losing a little bit of boost. Since I was rebuilding the turbo and ceramic coating everything, I thought that I might as well fix it. I'm not sure if that was such a good idea...I developed a huge crack in the housing and a piece came off leaving a hole...and that new crack was in the vicinity of the repair. I'm not 100% sure if the repair caused the new larger crack to develop...but I was thinking that the sleeve must put some pressure on the metal surrounding it...and it's a different material with different properties. Who knows...That was the beginning of the end for my 12H-T turbo...ended up with a Supra turbo after that ordeal.

 

[ForealBoreal]

buy the ebay one for half the cost and be done with it!

 

[Tapage]

Steve .. did you found any metal debris in the oil or filter .. ?

 

[sandcruiser]

I would buy the eBay one, but I'm in Costa Rica... so it's $300 to buy, and $35 to ship toCA (plus tax) then I've got to to get it here, which would take various weeks to arrange through someone flying... or I ship it down from the seller for $125 but then have to pay taxes, which would cost at least $200... in the end the savings may be as much as $250, but not having a vehicle for 2 weeks ... I can't rent a car for 2 weeks for $250. Time is money

@ Tapage: I don't know. There might have been some metal in the oil pan, but I dumped and scrubbed it when I did my BEBs, so I wasn't paying attention. The container into which I dumped the oil has the gear oil from when I helped Nicolas Rapp with his diff.... so it is FULL of metal debris from his spider gears.

I think that the pan did have a little shard of what, in retrospect, might have been shrapnel. The oil pickup also had a few little bits of what could have been metal, stuck in the grill. I didn't put the pan on yet, so I'll take the oil pickup off again and give it a good cleaning, to make sure that there is nothing in there.

Otherwise, I guess I'm just going to hope for the best!

Anyone know if I should use antiseize on the manifold studs?

 

[Adam B]

The crankcase should be at atmospheric or negative, positive only comes from blowby.

Dave, you're misreading what I said.

My point was that the word POSITIVE in the term "Positive Crankcase Ventilation" means that you are actively extracing gasses (hence the use of vacuum), as opposed to just having a passive hose hanging off the side of the valve cover. All that would do it prevent the crankcase from presurizing. I wasn't suggesting "positive pressure" - that wouldn't make any sense.

Cheers

sandcruiser:

When you think about the amount of air being drawn into the turbo, any hose upstream of the turbo will have air drawn from it. In the case of the PCV system I think it's actually a better system than just having it vented to atmosphere.

 

[Dave 2000]

Dave, you're misreading what I said.

My point was that the word POSITIVE in the term "Positive Crankcase Ventilation" means that you are actively extracing gasses (hence the use of vacuum), as opposed to just having a passive hose hanging off the side of the valve cover. All that would do it prevent the crankcase from presurizing. I wasn't suggesting "positive pressure" - that wouldn't make any sense.

Cheers
QUOTE]

Perhaps a different way of wording the sentence? Actively extracting via a vacuum is an easier to understand sentence IMHO.

Different sides of the pond as well ect,

regards

Dave

 

[sandcruiser]

I agree that having the turbo pull from the crankcase is better for the crankcase
but without a catch can/filter on that tube.... you end up with crud in the intake pipe. It may take a year, it may take 20 years, but sooner or later the film of oil will turn into a coating of oily crud, and someday it could break off, which could then break your $120 toyota impeller, necessitating a $700 rebuild of the turbo.

Until I can build/buy a catch can, I'll be venting to the ground. I know it is less environmentally friendly and regret that, but if my turbo goes again and blows oil seals, then dumps nearly two gallons of oil onto the ground, that's going to be worse than a drop here and there.

I think.

Eventually I will get a catch can on there, and then route it to the intake again. But probably not today.

 

[mudgudgeon]

in regards to turning over the engine, I blew a turbo on my 1hd-t, big chunks went into the engine, when I pulled down the engine, I found little burnt beads of impellor material spattered all around the turbine housing, I also found them mashed between valves and valve seats and also had bent valves, damaged piston crowns with little burrs that could become hot spots. I think it warrants some more investigation.

 

[70sguy]

Beware the Chinesium turbo! There are good and bad ways to save money..
A cheap turbo is a big time liability IMO.
VW TDI folks are learning some expensive lessons, $250 ebay VNT-15 replacement Chinese centers dumping oil into intake and causing engine runaways, Compressor wheels shattering and destroying the motors.

 

[rchalmers3]

Steve,

Given the size and quantity of pieces missing off the turbine, I would at the very least put a boroscope into the combustion chambers and back of the intake valves. As we discussed via email, run a feeler on the valves to see if they are off at all, as bits of the turbine may be bedded into the valve seat area. Not too likely, but worth a measure to see if the trash is affecting valve sealing.

If you don't have access to a boroscope and you want to be sure you are in the clear, then you will need to pull the head and inspect the piston tops and combustion chambers on the cylinder head. My guess is the junk passed through, leaving dents and dings. But there may be danger lurking, and if you don't take the time now.......

Needless to say, the entire intake tract needs a complete cleaning, and if pulling the head uncovers ring wear or problematic ring sealing..... como se dice "snowball" en espanol?

Rick

 

[rchalmers3]

Steve, another detail,

I have been using Aerocasillas recently for moving US purchased tools, parts and other goods into CR. They, (along with a hired driver to move the stuff to the bus station) has been averaging 5 days from Miami into my hands here in Nosara, if that helps you at all.

You need not open an account with Aerocasillas, I'll be happy to coordinate any package deliveries you need.

Rick

 

[sandcruiser]

Ok, got the turbo back today. $680 for a complete rebuild with new impeller from Toyota (for the bargain price of $130 for the impeller alone). That price included sandblasting inside and out, and painting the cool side of the turbo. I"m pleased with the work, it looks like they did a good job.

I don't even know where to start looking for a boroscope. If you've got one, Rick, drive it up! I'll trade you a delicious dinner and all the beer you can drink. Heck, I'll trade you delicious lunch, dinner and beer... and we can hit Avellanas for some surf, too.

Barring that, I'll see if some other solution presents itself.
Measuring valve clearances seems like a good step-- if any won't close due to something in the seat, then I suppose that warrants more investigation.

I guess I could also hit each cylinder with compressed air through the injector hole... and turn them so that the valves are open to allow the air to possibly blow out particles... but at this point the fin chunks are either melted to the piston head, or lodged somewhere, I'd guess. I don't think that they will come out.

Hate to tempt fate, but I also hate to tear open the head at this point.

 

[sandcruiser]

well
one more vote for pulling off the head.... not one valve is within spec. The are all really tight... ie: the clearances are lower than they should be.
Bears investigation.

of course, there is nary a head gasket to be found until toyota re-opens next week (April 5th). Which really puts a crimp in my style. And who knows where I'm going to find shims while the whole world is on vacation.

This is frustrating!