C/K Man

New bulletin from ACDelco on oil filters: https://gmserviceinsights.com/new-acdelco-oil-filters-deliver-enhanced-performance/ Looks like the 'E-Core' filters are being replaced, new filters retain the nylon center tube but go back to bonded metal end caps. No word if the bypass valve psi rating has changed.

The new Big Block rumor was or is supposed to be for medium duty commercial trucks anyway. It is being reported that the 2023 HD refresh will include powertrain upgrades, but my guess is 10 speed for the gas engine and an output boost for the Duramax. Maybe the frame coating will be changed then?

I think the wax on the newer trucks is about as messy as it's ever been, but it seems that it's applied a little thicker. Seems after a couple of years it hardens up a bit. I still think it does a better job overall of protecting the frame than paint, and it is easy to touch it up if it rubs off in places. There were rumors that GM was going to start E-coating the frames of the HD's.

Great, hope it works out for you! I liked those old TopKicks, we had a brand new '93 4 yard dump with the 3116 Cat in it.

You best bet might be to have a dealer look the pump up. It's probably not available anymore but you could search for it by part number and have a better chance of getting the right one. There were many different pumps for those trucks, some were steering only and some were for steering and Hydro-boost brakes. I don't remember if the pumps changed in 1991, but I do remember they sold 2 different types of TopKick in 1990, the new generation and the old Caterpillar 3208 powered version..

And I take it the Stabilitrack light does not come on when this is happening, right? Only other thing I can think of is the weight of the trailer pushing on the truck while braking is causing the suspension to move to a toe out position. Alignment is good?

Do you experience the problem only when braking? This may be an antilock brake system issue.

You have fuel pressure? Spark?

Trying to figure out why GM included Gen IV 6.0L's in bulletin 17-NA-157.

I think GM probably released this bulletin because the bypass valves of the aftermarket filters were all over the board, some as low as 9 psi. Also, I think some aftermarket filter suppliers had one filter crossing over for both the PF48 and the PF64. As far as using the PF63 or PF64 on a Gen VI 6.0L, I wonder if there would be an issue except for a potential problem if the engine failed under warranty and the dealer was looking for an excuse to deny coverage. I have cut open and compared a UPF48R and a UPF63R and the only different other than height is the bypass valve spring tension is slightly higher in the UPF63R. I would not think that would be an issue as long as the can and element of the filter can withstand the pressure of a higher rated bypass valve if the filter was sufficiently plugged or the oil was thick enough (cold start) to cause the valve to open. In addition, I would think if you used the longer PF63/UPF63 the increase in element area would be less restrictive making the bypass valve less likely to open in any situation. Ultimately, you want as much oil as possible going though the filter without restricting flow.

Yes, but bulletin 17-NA-157 was revised on July 13, 2018 and one of the changes was that engine RPO's L96 and LC8 were added. Both NAPA and Wix still list the 7060/57060 as the correct filter for these engines, which appears to be wrong.

If you look at bulletin 17-NA-157, it covers 2012 and newer L96 and LC8 engines, which are Gen. IV iron block heavy duty 6.0L's. Bulletin seems to be pretty clear about not using oil filters with a 15 psi or lower bypass valve. PF48, PF48E, and UPF48R all have a 15 psi bypass valve, the PF63, PF64, and UPF63R all have a 22psi bypass valve. Not sure if it means anything, but the bypass valve in the 48 oil filters is orange, in the 63 and 64 oil filters it's yellow.

According to Donlen Fleet, 2022 initial order acceptance for the GM HD's is 05/06/2021, with production starting 07/21/2021. Looks like the 2022MY will start a bit early, I would imagine that the 2022's will start showing up on the lots by the end of August if the chip situation improves. I hear there are very few changes to the 2022 HD's, the MCE will be the 2023's. I have not heard of any EPA issues with the L8T 6.6L gas, I think it's just supply problems (chips?).

Was anyone able to clarify if the PF63/PF64 are the recommended oil filters for 2012 and newer Gen IV 6.0L's? Bulletin 17-NA-157 is a little ambiguous (in typical GM fashion) in that it includes L96 and LC8 (CNG/propane L96) and warns against the use of an oil filter with a 15 psi or lower bypass valve, like the PF48E. Then it turns around and says use EPC recommended oil filter, which still appears to be the PF48E for these engines. Now I have heard, but have been unable to verify as of yet, that the bypass valve in the high performance UPF48R is 21 psi. ACDelco also recommends the UPF48R for Gen. IV 6.0L's, so that might be the 'safest' oil filter to use if someone is concerned about voiding their truck's warranty. See this thread on another forum: https://www.cadillacforums.com/threads/oil-filter-choice.1090978/page-2 For clarification, the oil filter bypass valve opens when the pressure differential between oil coming into the filter and oil going out of the filter is over the psi rating of the valve. Even with a 15psi bypass valve, the valve should stay closed even with 50 psi oil pressure going into it, as long as the filter is not overly restricting the flow and the oil is of the proper viscosity.

There has been some controversy over what is the correct oil filter for Gen. IV LS engines like the L96 and LC8 6.0L's. There was a service bulletin issued a few years ago that stressed the importance of using an oil filter with a bypass valve setting of over 15 psi for various GM gasoline engines, including the Gen. V 5.3L and 6.2L. A subsequent revision to that bulletin dated 07/13/2018 (#17-NA-157) added the 2012 and newer Gen. IV L96 and LC8 to the list of engines requiring an oil filter with a bypass valve of over 15 psi.. The recommended AC Delco oil filter for the Gen. IV's was the PF48 (15 psi bypass), but the bulletin calls for either the PF63 or PF64, both of which have a 22 psi bypass valve. The PF63 is taller than the PF64, which is the same size as the PF48. What is funny is that if this bulletin is true, most all of the aftermarket oil filter manufacturers still call for a PF48 equivalent for these engines like the NAPA 7060 or WIX 57060. It appears that these aftermarket oil filters all have bypass valves less than 15 psi.. I am thinking about using the AC Delco PF63E or UPF63R for these engines. What are you using?

Should try scanning the BCM to make sure the ambient air temp. sensor is reading correctly, but it sounds like you might need a new HVAC controller.

I agree, rail dust. Careful use of a clay bar takes it right off. It's actually on just about every vehicle delivered by rail, but usually only visible on white and silver paint.

Exhaust brakes are not really needed with gasoline engines, they provide engine braking with a closed throttle on downshift unlike a diesel. I think the 6.6L L8T will be fine it this application.

Update, it might have the Cummins ISB as an option. When was the last time a Chevy came with a Cummins diesel? 1980?

This article talks about the L8T block. Appears that it is quite some hunk of iron, stronger than the iron 6.0L block. Seems like overkill even in an HD pickup, I suspect the L8T was designed for heavier commercial vehicles: https://www.enginebuildermag.com/2021/01/gms-6-6l-lt-iron-block/

Not sure if this is the light duty 10 speed or the Allison HD 10 speed: https://www.13abc.com/2021/02/04/gm-to-invest-75m-in-toledo-transmission/

GM specifically says 100% of passenger vehicles and light trucks will be BEV's by 2035, but that sounds to me that large pickups and commercial truck will be exceptions. That having been said, I expect that eventually battery or hydrogen fuel cells will power those vehicles but it's probably further in the future. BTW, I hope you mean 'investing', not 'investigating'!

It's just because the GM ECM's are now encrypted, Ford's are not. L8T 6.6L components like that beautiful forged crank are already in the performance parts catalog and I expect 6.6L crate engines will be available soon. That doesn't mean much to the 6.6L silverado/Sierra owners that wants to do something to his truck though.

From what I understand regular cab HD's are constrained for the balance of the model year. HD crew cab production is being prioritized. Demand is off the charts and Covid is causing production delays. 2022 ordering will start early, probably won't see many regular cabs until after 2022 production begins. Oshawa coming on line will help.

Is the new hose hanging up on the internal O ring? Sometimes it is hard to get those type of connections to seat. At the very least you should wet the O ring with antifreeze or use a little silicone grease on it. Usually you can leave the clip in the new hose and push it on the radiator until you hear it snap.