1.4T cracked at wastegate - what's your story / symptoms

[steelmesh]

This post is to bring up the common 1.4T cracked turbo's relationship with max power tuning with the stock turbo. What are your experiences with this?

Working on optimizing my LUV again recently, I got meth installed and was trying to get boost above 20 across the rpm range. Boost is inconsistent and most often see about 21 psi peak, which falls to 16 psi by redline, but swear I have seen it hold more than this (same week, same road, similar conditions). I worked all the tables related to boost and parameters that would police the boost...but the telltale was the inconsistent DC % solenoid vs. boost/rpm.

I broke out the inspection camera, squeezed it in the down pipe O2 bung and found the infamous crack at the wastegate flapper.

Image on Google, not mine but basically it:
165714d1443495380-turbo-boost-problems-img_20150928_224119824_hdr.jpg

Before all this, I picked up a used JY 1.4 for cheap, the turbo is also cracked in same spot, some listings in car-part.com are upfront about the crack in addition I saw one cracked at 10k miles, ebay has plenty of cracked used turbos too. Internet searching makes it out to be a common thing.

The jist I got is, the crack does not effect stock performance (as far as maintaining desired boost), probably why no one is really warrantying them unless they get P-codes related to it. I've gotten the code last summer, but it never came back so I didn't think it was the issue. I still don't have the code.

I have visions of weld repairing the crack, unless there have been improvements to the design, I just haven't come across info on this yet.

[cobaltssoverbooster]

gm housings are well known for cracking in this location. research the lnf turbocharger exhaust housing cracking issue from gm. they released a tech bulletin that tells technicians to not replace the unit due to this issue. if the turbocharger boost still regulates properly then the crack isnt having a severe enough effect to warrant unit replacement. lots of lnf turbochargers cracked in the bypass flange as you mentioned and in the turbine inlet division flange. neither of which gm warrants as replaceable per the tech bulletins tests resulting in proper boost management.
to be fair the 1.4 turbo is not a very good unit in my opinion. the unit is very small and takes a substantial amount of heat which is not dissipated properly through the cooling system when used in applications that we all try to use them in. This is due to the size of the center section (there is a reason other than shaft load that the housings go up in size with the size of the compressor/turbine increases). As far as factory application performance in the 1.4 Turbo; it does provide decent spool and power in the factory application which helps drive a smaller displacement engine to perform better while achieving that mischievous mpg rating everyone is after. Unfortunately, it quickly leaves the efficiency range of the unit when used in performance applications. The 1.4 Turbo also has a large factory track record for blowing the journal bearing and leaking coolant into the exhaust housing at a slow rate. Very common for 1.4t sonic, cruze applications to loose coolant over a period of a week due to this issue.

Per Lincoln Electric, most cast iron assemblies are prone to cracking at temperatures around 1450*F which is pretty close to the 1100-1200*F i saw in my lnf KO4 egt i placed in the turbine housing. This is why cracking is a common issue for all mfg turbochargers being beaten upon by us modifiers.
Welding doesn't necessarily work on these units as the turbine housing has to be removed, disassembled, and preheated to roughly 600-700 degrees (welders rule of thumb. some only go to 450 because thats usually the household oven max temp). If you do not pre-heat the housing then you have to use silicon bronze filler which melts around 1780*F and is not recommended for turbine repairs as you only have roughly 600*F grace temp before the fill looses shape. Most people that tig fill cast iron use Nickel Copper Monel-alloy as a filler because it melts slightly higher around 2031-2254*F. Unless you live in an area that deals with a lot of agricultural repairs it will be hard to find a welder who understands the welding process for these fillers. I've asked locals about it before and usually the local welders supply is the only place i find people who even know what the material is. It could be i haven't talked to enough "welders" but here in Reno, its a limited knowledge item.

if you can adapt, i would run the stock KO4 on the 1.4 in a performance application. The efficiency map is better suited on that engine at performance pressures. here is the LNF KO4 compressor map so you can see for yourself.
KO4 compressor map.jpg

[KLUG'S SS]

Haven't checked into it yet with an inspection camera but I am pretty sure my Cruze I am driving has a crack just like this. Turd just cannot and will not build boost like it used to.

[cobaltssoverbooster]

since this is a thread about 1.4 turbocharger unit problems ill post these here:
TSB #PIP5418 VEHICLES WITH A RATTLE NOISE FROM ENGINE AREA WHILE DRIVING. TECHNICIAN WILL NEED TO CHECK THE TORQUE ON TURBOCHARGER MOUNTING BOLTS.
TSB #000601026I INSPECTION/REPLACEMENT OF INTAKE MANIFOLD AFTER SEVERE INTERNAL ENGINE OR TURBOCHARGER DAMAGE.
TSB #090693002 TURBOCHARGER HOUSING INLET FLANGE CRACKS IN PARTITION WALL (STILL APPLIES FOR NEWER MODELS UNTIL SUPERSEDED)
TSB #PI0851 WHEN SERVICING A TURBOCHARGER UNIT: (A) UPDATE ECM CALIBRATION TO CURRENT RELEASE (B) CHECK OIL FEED PIPE FOR BLOCKAGE (C) EDUCATE CUSTOMER ON COOLING FAN CHANGES.
TSB #PI0675A RELATED TO WATER LEAKS FROM TURBOCHARGER SHAFT FAILURE (NTF) NO TROUBLE FOUND. SHAFT FAILURES RELATED TO BLOCKAGE IN OIL FEED LINE. CHECK FOR BLOCKAGE BEFORE RETURNING TO CUSTOMER.


it would seem the coolant leaking turbocharger problems i remember were caused by a severe oil issue. The motors are notorious for trying to sludge up when driven to the extent of their listed oil change service which causes blockage of the feed line. After some reading it is highly recommended to change the oil roughly every 6k miles to prevent the oil from breaking down in the harsh crankcase environments caused by fuel blow-by. This will also reduce the failure rate of the camshaft solenoids which have a pre filter TSB #100604016 REMOVE PRE-FILTERS FROM INTAKE AND EXHAUST CAMSHAFT ACTUATOR SOLENOID VALVES.

[KLUG'S SS]

my turbo.jpg



Well hot off the press, a picture of the snap on inspection camera from my own turbo about ten minutes ago! Don't know why I felt the need to circle it, pretty obvious!! LOL

[cobaltssoverbooster]

lovely

[KLUG'S SS]

lovely

Right! The crazy thing is and now mind you I've got a very aggressive tune setup on meth/water injection but the car still actually pulls pretty well. But from day one when I bought the car last May the turd has never been fully able to hit my targeted boost levels. Been a real struggle. Lol. PID tables, base duty cycle, knock airmass raised to a ridiculous high number, torque management, etc etc etc.. You name it the thing just has never achieved what I was asking for. Tuned another Cruze around the same time I bought mine and that sucker was even overshooting commanded, EASILY hitting commanded boost levels and then some!

[KLUG'S SS]

Going to just throw another stock low mileage newer turbo on it for the time being. Short term of course as my plans are to go bigger. They are a dime a dozen and I can pick up one from like a 2015 Cruze or Sonic in many salvage yards with 15,000 miles and under for 250-300.

[cobaltssoverbooster]

sound plan

[steelmesh]

Going to just throw another stock low mileage newer turbo on it for the time being. Short term of course as my plans are to go bigger. They are a dime a dozen and I can pick up one from like a 2015 Cruze or Sonic in many salvage yards with 15,000 miles and under for 250-300.

Be sure to look for that crack when picking up the used unit. I've seen some for sale already cracked with only 10k miles. I agree with Cobalt the final solution is to upgrade the turbo. I'd like to play with welding the crack, but this is a side project.

Right now I am creating content (how to tune basics) that I need to show results by comparing stock vs. bolt-ons, then tuned and tuned with meth. I am already struggling high IAT2 temps being summer, but then add on this crack, the delta power increase between stock w/ bolts-ons and max tuned was pretty sad, like 20 whp difference...to combat the temps I figured with methanol injection I could squeeze out a lot more, nope she doesn't got it no benefit because boost is falling...the dynamometer is a Passport GT2 performance meter, it is a reference tool and so far pretty precise, but I have no idea about accuracy.