Holset HX40 failure

[KWIKKURT]

After only a few weeks and 3,000 miles my Bombed HX40 blew up.



It was a HX40 Center Section and Wheels with machined 12cm housings. The Turbo work was done at a reputable and established Turbo shop.



It performed exactly as I was told. Lower EGT's, Less Smoke, More Boost and still be Fast Spooling up. I was very happy with it and was getting ready to swap it back and forth with my stock HX35 while Towing and running empty for some real numbers on the Benefits/ improvements. My EGT's were Lower at all boost levels and no problem with lag.



The turbo failed during Fairly heavy acceleration and at around 2300-2500 rpm. Right before shift to 5th gear. We are not sure what failed the shaft, Turbine wheel, Bearings or maybe FOD. It has been sent to Holset for their analysis. The Turbine side was trashed and the Compressor side looked good.



To be fair I had run the turbo at estimated 45+psi boost during my R&D testing looking for the lowest EGT with that Turbo setup.

The best boost setting according to my EGT's and at the time of failure the (wastegate) was set for 36 to 38psi. If the wheel threw a blade first it could of been fatigued from overspeed at the higher boost levels.



One other possibility is shaft failure. On a Diesel engine without the stress that a throttle plate can impose what could cause the shaft to fail? Of course the bearings but with little mileage on the turbo this is not likely. .



My fellow Bombers with experience in HX40 Turbo's and / or the recent rash of failures. What is your Thoughts and Opinions. It will benefit us all if we can find out what improvement or weak link change can be made that will keep them alive and happy.

 

[Max340]

What trans do you have? Stick or AT is my question.



Reasoning behind asking is that a turbo has a huge amount of strain put on the shaft during a shift when the turbo is accelerated, then decels, then re-accels due to letting off the fuel between gears. This was a noted problem on the Mopar turboed 4 bangers w/ high boost and performance mods.

 

[Bigsaint]

Max, Kurt has a 6 speed, HO.

Kurt, that really stinks, with all the R+D you put in it especially. I hate to say this, but mine, a BD Power HX40, has been holding it's own since the install in late January(now it will probably explode tomorrow) . All that I've done with mine is to follow the advice of the guys at Auto Wurks, break it in slowly, build a bit more boost with each day and pass. I am anal in regards to shut down, always let my pre-turbo egts get to 250 before I turn her off, I'm sure that you probably do the same so that's not much help. Why some seem to last and others do not is a mystery to me.



Scott W.

 

[work2muchplay2little]

Sorry to hear of the trouble Kurt, hope you get a fair resolution. It seems from reading the forums that modified HX-40's are the ones to fail. This may or may not be accurate. I think I'll start a poll to try and find out. Hate to think my unBOMBed HX-40 is "ticking"

 

[Vaman]

I would tend to suspect what Max suspects. If you were between shifts, the odds are pretty good that you blew the shaft. Let us know...

 

[Marco]

Sorry Kurt

Sorry to hear about your trouble Kurt!



I have the HX-40 with no problems. It has the Majestic vane clipping thing done. Others with the same stuff have failed, mine NOT. I've not even oiled it when I installed it! Once installation was complete, went to the road and floored it all way up to 50+Psi. Believe me, mine has seen any kinda abuse with no problems. Luck?



Max sez:

"Reasoning behind asking is that a turbo has a huge amount of strain put on the shaft during a shift when the turbo is accelerated, then decels, then re-accels due to letting off the fuel between gears. "



A TDR member is working on a solution for that problem!



Marco

 

[Max340]

Big Saint, I suspected he had a stick, just on my limited info, already put forth.



Marco, so whats the solution? A check valve of some sort or an anti reverse clutch bearing? I know some forklifts had a shaft driven cooling fan, driven off the "front" damper (faced rear in the lift truck) and had a clutch bearing so the fan could "overrun" the crankshaft speed if need arose.

 

[HEMI®Dart]

Kurt,



My HX-40 busted at only 90 EASY miles. The main shaft bearings(bushings ) were gone. Majestic replaced the 2 bearings under warranty, but did nothing about the turbine wheel & compressor wheel and housing ( both sides) rub damage. Its junk.



It seems some HX-40's came from Holset with the wrong clearence on the shaft bearings. I don't know if this is true or not.



Whats Holset going to say when they see your HX-40 has been modified? Was it only the housings that were modified?



Was your shaft broken? Could you spin both wheels from one side?

 

[Bad340fish]

The Solution is Easy... . DON'T LET OFF WHEN YOU SHIFT



IMO a blowoff valve is not practical(sp) on our application due to the amount of boost we see. Plus most of them operate off of a change in Vacuum... . which we never have since we have to get vacuum from a pump.



Another TDR member had a 12V truck that was cranking 50+psi(a guess... automter35psi guage stuck between the OOs on bOOst). You talk about some nasty sounds when you let off quick. You could hear his air box try to come apart sometimes. We figured out it doesn't make that noise as often if you stay in the smoke pedal!! That truck had over 130K on it when he sold it. It had been bombed like that most of its life.



Have any STOCK turbos failed in a similiar way as the HX-40 has been failing?? It seems stock turbo failure is very very rare on here.



And for any of you that try and STOMP shift for the first time. Clean off your dash and any cubbyholes. Because if your BOMBed at all its all gonna come out onto the floor.

Happy Shifting

Clark

 

[HeberRam]

Kurt. . Keep us posted on this. I have a Hybred HX-35 with 14cm exhaust, wastegate diabled on my 2001 HO 6-sp. I went that route instead of HX-40, as many here at higher elevations, 5000+ using the HX-40 turbo lags to much, even after heavy bombing. I can get 38 psi max. boost WOT. What I'm trying to get at, is there a safe or max. boost for the HX-40 or Hx-35 we should be concerned about? It appears according to the various posts of those that have problems, they were pushing their turbos at very high boost when things blew? I know for a fact, when I drive down to Las Vegas, I can pick-up 3-4 more psi boost, in my opinion because of the lower elevation ( more air). I hope, that someone out in TDR land can help with the Max. boost safe operation question.

 

[HEMI®Dart]

When my HX-40 blew, I was at about 35 lbs boost @ 1900 rpm's. I was nowhere near shifting. If Kurt broke a main shaft, then it could be caused by letting off before a shift, at high boost and the pressure has nowhere to go, then it wants to spins the turbo backwards. If the bearings burned up, like mine did, it shouldn't really be boost or shifting related.

 

[Marco]

Max 340,

It's a kinda pop off valve with an electronic controller. Since there's no vacuum in the CTD the electronics will open and close the valve. Kinda neat!



Marco

 

[KWIKKURT]

Sorry for the delay I am on the road towing a RV trailer to Phx and I will be back at my store in the morn (sat). I am late for a meeting so I will not Proof read or spell check until later



MAX 340, I added my sig to this post.



BigSaint,



I think it was shaft failure - It shouldn't be a bearing problem with only a few thousand miles on it. Unless a bad one had slipped past Holsets Quality control. From my experience Holsets are like the "Cummins" when it comes to quality. They last and last. With the higher than normal failure rate we are experiencing I want to believe that Holset had recieved a batch of below "par" materials that the HX40 shaft is made out of. The shaft must withstand Tremendous stress at speeds that they are turning. (130,000+rpm). I think the 40's wheels are the largest used with that shaft. So if the shaft size is already close to max stress level then with the "Little" extra fuel we add, Mix in a few 1/4' miles, a Mustang or two and maybe A few dozen Smoke Fests and whamo!



If that is it (Weak Shafts) than we need to have a HX40 shaft assembly Bombed in some manner so it is not the weak link. Then it would be the perfect setup for Street HP and Towing. Mean while their are Thousands of HX35's (Mine Included) and HX40's making High horse power with no problems at all.





Work2much & Vaman, I think their has been a few Stock of the shelf units that have failed. It would make sense that the modified ones would fail at a higher rate if it is from weak or undersized shafts. Most of the Bombed ones have smaller housings so I would think they would be more stress on the shaft. Not from the other Modifications as in Balancing because most of the Turbo Shops Balance the turbo's to or better than Holset. They know the turbos will be reving higher than norm and are more able to give each turbo a personal Tweaking.



Marco, Do you have a Auto??



I will put together a poll tomorrow for the HX40's and lets see if we can use the power of TDR and the Net to Find a pattern.



Hemidart, Max340,



My shaft was broken and I think the center section (shafts and Wheels) were Holset factory stock. The housings were machined and installed.



The diesel does not stress the Turbo's near as much as a Throttle boddied Gasser. When you lift to shift the motor keeps it self open to as much air it can get you just cut the fuel which should lighten the load.



IMVHO, I think the shaft size / strenth is just the weak link --- If we or (holset) can address that it will be good for all!



Off To MEXICO... Thx all . . Kurt

 

[Max340]

Kwik, two points:



The throttle plates are part of the cause, I wondered if the boost being 2-3 times as much and a sudden let up would be the same. I doubt any real comparison can be made.



I must not have been thinking real clearly, the ETH only has one transmission option. So used to seeing trannies listed I failed to extrapolate the ETH to its full meaning.

 

[Bad340fish]

Hmmmm I wonder

When you let off of the throttle you lose the turbo drive pressure. When you let off you drop the amount of fueling which means you drop the amount of exhaust. At that time your Boost becomes greater than the pressure driving your turbo and you get a "kickback" or sneeze as some people call it... bark, chirp whatever. That is JMHO I have nothing to back that up. A pressure guage on the exhaust manifold compared to your boost guage might get you an idea though.



Just for sh*ts and giggles I put the boost guage in front of the throttle blade on my old conquest. WOW wierd things go on there. WOT the boost read the same as it did WOT in the manifold but all other times it was way off. I noticed when I ran WOT then let off quick it would spike the boost about 10psi then kick it back though the turbo and make the "angry squirell noise" as my friends called it lol. Its not quite so drastic with the CTD but its close when your running high PSI

Clark

 

[csutton7]

KK--sorry to hear about the breakage-hope you get it worked out fast and to your benefit--



I think most guys will say that the HX40 wastegate should be set at 45 lbs of boost to avoid breakage-I've run mine up to 45 and it's still working good--

 

[KWIKKURT]

That's what was in my Turbine housing! SQUIRELL FUR !



I should hear something in about five more days. I think they are sending the failed unit on to Nasa for further testing.

 

[Alan Reagan]

Marco and I have been discussing the pop off valve solution for a while now. I have been working on a solution that does not use a pop off that could be set up to use the CTD electronics but there are drawbacks with that approach. The goal is to bleed the air pressure off after the intercooler if the pressure on the intake manifold exceeds the pressure on the output of the turbo. This will stop the backspin effect of sudden deceleration and as a side benefit probably reduce turbo lag when you get back on the throttle.



Of course, there are losses that have to be considered and temperature extremes that make this a little more than a game of trivial pursuit. However, I do have a solution and am currently talking to several manufacturer's about the parts. If there is real interest about this, I'll proceed with development. At this point, the R&D phase continues. Interested?

 

[Bad340fish]

When you let off to shift all the valve would bypass the air out of the motor and back into the atmosphere. Would that leave an airless "hole" between the intake and the valve when you stomp back down on it??



You might have to go off of a miscroswitch on the throttle, or clutch. But I think that would need some kind of override to avoid idling with the valve open.



Would the pressure switch method of opening the valve cause problems for some of the guys that need bigger turbos but don't have them?? If the boost exceeds exhaust manifold pressure(the way I understood your system) the valve would open when you didn't want it to.



A shift doesn't take very long(or shouldn't) when drag racing or just fogging a honda. So this thing would have to be quick and have a pretty good size opening to bleed off the massive amount of air this motor can run.



Just my thoughts

Clark

 

[Alan Reagan]

No, when you let off to shift, you would not bleed the system. A microswitch would cause the system to bleed when you didn't want it to. As far as the "hole" , with this system, there would not be one. The trigger is differential pressure and as soon as the pressure equalizes (relatively speaking because of losses in the system) the valve closes maintaining pressure. If it were electronically driven, one could come off the ECM like the Ebrake. That has a two second delay, tho and two possibilities come into play: 1) the system activates too late to save the turbo 2) it activates every time you let off thus bleeding your pressure when you don't want that to happen. This system doesn't do that. It's real time looking at pressure only with a very fast activation when the threshold is crossed requiring the trigger to occur.



Starting a thread on product and accessories to check for interest.



https://www.turbodieselregister.com/forums/showthread.php?s=&postid=189092#post189092