the differaces between mack ac and ai engines ?

[Mack Technician]

 

 

[KAYLA]

On 4/18/2012 at 6:18 PM, daveigou said:

The AI / AC designations have to do with EGR. 2004 model year was the first year for the ASET (application specific engine technology)(A) engines, AI for internally cooled, and AC for externally. The AI engine used an additional bump on the camshaft to pull back a portion of exhaust to mix in with the next intake stroke. The AC engine used an external cooler.

The two engines were not interchangable, if you bought a vocational truck, you got an AI, if you bought a highway model, you got an AC. Both had their problems, the AI's were poor low end performers, and accumulated alot more contaminates in the crankcase, but were fairly reliable with "old style simple" turbos. The AC's generally performed fairly well, but were plagued with exhaust manifold leakage, and (VGT) turbo, and cooler problems.

With both engines, maintanence is very critical to follow recommendations.

SO IVE GOT A 2001 MACK WOULD IT BE AC OR AI?

 

[Mackpro]

57 minutes ago, KAYLA said:

SO IVE GOT A 2001 MACK WOULD IT BE AC OR AI?

 

Neither . The ASET AC and AI  Engines did not start till sometime in mid to late 2003 for the 2004 model year.  A 2001 is also a confusing year. As that year you could have a regular Etech engine or a CCRS engine. And some parts between those two engines such as EUP’s, turbo , injectors camshaft won’t enter change with each other

[Joey Mack]

If it has spring loaded exhaust push rods, that would be CCRS... I call it ceramic cam roller sh$t.. It will have ceramic roller pushrod lifters. It may also have pin less intake bridges. The cam has a back cut on the exhaust lobes, I think its to accomadate the spring loaded push rods and act as an internal EGR... Help me out here, Mackpro... Jojo

[Mackpro]

I don’t know exactly when the ceramic roller abs spring loaded push tubes were phased into actual production but they can be found in any ETECH engines out there as they can be used any ETECH out there, the ceramic rollers are quieter and if properly maintained they last longer than steel. But a spring loaded push tube must be used on the exhaust rollers as the .024” valve lash is to much  slack and turns a solid push tube into a jack hammer and shatters the ceramic roller over time. The .016 lash on the intake seems to cause no trouble. That’s why valve adjustment and updating the rocker arm hold down bolts are important. You can sill get the ceramic or steel rollers 

[Joey Mack]

I agree with you... I always push my customers to let me run the valves... I dont care for ceramic, but .. yes proper maintainance will allow them to live longer... and the jack hammer effect, only has to hit once....  at some point they went to pin less bridges on both...  I like pin less bridges. I have seen mechanics ignore the bridge lash, and scratch my head...... anyway... jojo

[Polarhound]

On 4/22/2021 at 9:26 PM, Mackpro said:

I don’t know exactly when the ceramic roller abs spring loaded push tubes were phased into actual production

Ceramic lifters were phased into production in January 2002 beginning with engine s/n 1Y2008.  However, From 07/2002 through 09/2002, ~1100 engines (serial number range 2N, 2O and 2R) were manufactured with steel lifters as well.