2017 Malibu Hybrid questions...

[Blue Bowtie]

There is a heat exchanger in the cast exhaust manifold intended to rapidly warm the coolant. The intent for this is unclear, whether to rapidly provide cabin heat or to rapidly get the little 109" engine up to an efficient operating temperature, or both. In either case, what are the options when this begins to leak internally? We all know that coolant contamination of the oxygen sensors will dull them down to a non-reactive state, and coolant in the calalytic converter will killl it fairly quickly. I see that GM already offers replacement manifolds, after only 3 years of production, so this may be more common an issue than anyone is letting on.

I've thought about bypassing, but thatprobably isn't the best option in the long term. At just over 50,000 miles, the local dealer isn't helping at all with the GM powertrain warranty.

[maxwedge]

Ok, based on the emissions warranty, any thing from the cat forward, including manifolds is covered for at least 7/70. Not sure if that falls into that coverage.

[Blue Bowtie]

The GM warranty center refused to consider this as an emissions issue, and was of little help. A twenety-pack of Benjis later and the car was out of there. The design is not impressive. Then again, electric/hybrid engineering is not at all mature, and is still working out this kind of issue. Toyota has a similar issue with its welded manifolds and exchangers on their hybrids, and there are plenty of those cases out ther going back to 2011. I expect to see this become a larger problem over time.

[ctesla]

Blue,
GM's "EGHR" is a WAY over-engineered/for the masses 'heat exchanger' as you call it, for a quick warm-up, and higher (not by much) mileage feature;--
much like in 80s and 90s (and 2000s w/Toyota) with Cadillac running small radiator/coolant lines through carb, AND even installing electric heater/grille spacers so when fuel dumped into carbs, hitting grill and diffusing and pre-heating fuel/air mix for better burn and mpg..
from corporate website- "...The exhaust gas heat recovery (EGHR) unit recycles waste exhaust heat that exits the engine and uses it to warm the engine coolant, improving engine efficiency, and also increasing the heat available for warming the passenger cabin.

The EGHR improves the overall vehicle efficiency under cold ambient conditions by recapturing about a third of the wasted exhaust power and using it to warm the engine coolant. The system allows the engine to warm up more quickly and enables a higher coolant temperature during cold operation..."
i own an 06 GMC Sierra Hybrid w142k, and i have a customer with a 16 Mali Hybrid w77k. i will be happy to look into GMs internal memos and TSBs (if you are not in the industry), as my brother and i have access; and even write corporate, to attempt to get you a manifold (if it has leaking currently; and can get pics for proof); however, this might be a long-winded process, with them knowing that national driving averages, you might surpass the 70k within the next year..
SO, with you having your location posted as rural, i do not know your temps.. i am at 9400ft elevation, and even in may, our temps are 73 and 22 prior to wind chill; so my rig has never had the problem of OVERLY high underhood temps; however, since my client was worried about hers, so i removed the scrap tin heat shield from front of eng/exhaust, bypassed her internal one, and used a roll of copper (water/ice maker kit from hardware store) and VW fuel injection compression worm drives (holds against high heat and psi) and coiled the copper on the outside of exhaust, and put heat shield back on.. IF she ever needs warranty, i can pull the copper re-connect OEM, and she rolls into stealership no harm/no foul.
my rig has not formed any leaks; but if so, i would bypass; and if it caused driveability issues, i'd just run through gates high temp heater hose over the intake and valve covers--but i am more function, over fashion; EXCEPT, with customer's cars..
if this is yours, i would do the bypass; but if wanting to fight city hall, i'll get you any info about any MRTBF (planned obsolesce/mean run time before failure) 'pre-failure' issues on these.. hope this helps..

[Blue Bowtie]

The GM part number has changed, likely due to revision. It's installed and running, possibly for another 30 months (MTBF). It's not my vehicle. I'm only at 900' AMSL, and the temperature ranges from -30 to 105°F here along the Illinois/Wisconsin border.

GM Warranty didn't help much, insisting it was an "exhaust" issue and not an emissions / powertrain issue. I believe they did drop their markup on the parts a little, but despite an extended warranty (purchased at the dealership) they begged off responsibility.

I also advised the owner that it could (should?) be bypassed but not knowing whether the PCM monitors the CTS over a start-up timer, I couldn't assure the owner that there would be no DTCs popping up. Many of the even older PCMs and ECMs had such time/feedback monitors for O²s and other inputs, but the hybrids are a different mule.