Mackpro

Looking in my 1989 Mack tune up manual. It list both the EM6-300L and the EM7-300 engines . And yes both show 1425 torque at 1020 rpms

This is probably of no help , But my buddy has 5 GU’s all with the 455 MP8, however all his have Allison transmissions. He’s running 24.5 full size tires and 4.19 Mack rears and runs 87 mph at 1900 rpms . Unsure of the overdrive ratio difference between the two transmissions

For CCRS and ASET style engines the fuel pressure regulator starts opening at 59 psi. Early ETECH engines had an 59 psi and later a 100 psi valve . The 100 psi valve caused some fuel in the oil issues on some trucks . If the valve sticks it causes low power and in most cases hard starting as the fuel in the injection galley flows bank to the tank

According to my AI HP chart , if you have a AMI-300 you will need injectiors and download to go to 400HP. If you have a AI-300 Engine you only need the download To get to 400.

Cam key swaps were only on early ETECH 1998.5 till around 2001. Beginning with the CCRS engine sometime in 2002 , all key ways are straight regardless of HP. But good on reminding us !

All AI engines internals are the same except the for turbo and injectors and download that determine horsepower ratings. I will have to find my AI horsepower charts to see the difference between 300 and 400 , sometimes the turbo has to be changed along with the injectiors .

What’s the T2 ( center of DPF temp sensor) temp running ? We like to see around 880 degrees. High temps in the upper 950-990 can kick out the regen momentarily and resume.

I had my buddy look up the part number and yes it is unavailable and no other dealerships show to have any in stock . The part number did crossover to a new Mack/Volvo part number but the description was listed as “Wiring Schematic “ and had a price of $650.

It is on the intake manifold on the drivers side of engine, between the middle to rear of manifold, it will have a round 3 wire plug

Yea , what happened? I loose my password to this place from time to time and sometimes take me a month or more to find it and log back in . But always like coming back here. Mack Technician did the homework and wasn’t afraid to swap parts around on the ASET engines to try to get them to run like they should.

It was a learning process for sure. I was thinking I could adjust the arm to where I wanted it and put the actuator back on and all would good, but the pressure inside the turbo would overpower the actuator and let the arm move. Also the actuator gear has no internal stop in either direction , so the gear will move in either direction somewhat freely.

I’ve seen lots of bad deletes on Macks , seems very few work out great. The last one was where a delete was done and a export model data file was installed in the engine ECM. This sounds like a great idea but the export models don’t have a VGT turbo, they have a standard turbo. The truck would barely build boost because the VGT turbo was not being command to move abs build . I had to remove the turbo actuator and manually move the arm on the turbo and test drive , if I went to far it would over boost and backfire through the air filter and derate. Once I got it figured out I built a wedge spacer and put it inside the turbo actuator to hold the arm in place . This was years ago and don’t remember the actual position of the arm .

The dealership I used to be at always used United Turbo and Fuel in Birmingham Alabama for any injection pump and injector work on pre-ETECH engines. We had better luck with them than Mack Reman and the local pump shops.

An AI 350 and 400 are the exact same engine. On a factory HP upgrade No hard parts to change, only download is different. Bumping to 427-460 then your talking turbo and injectors. Only the early Etech ( 1998.5 -2001) needed camshaft key way swap to go to bigger HP.

Truck returned tonight for me to install the new parts on . Truck was driven almost 800 miles pulling a loaded dump trailer .with the outlet NOX sensor sending unit unscrewed from the exhaust pipe and just zip tied up handing in fresh air. I plugged up tech tool to check codes and only one fault code . It was inactive and was for the outlet NoX sensor , the FMI was 7 I believe, unidentifiable failure. No derate or other warnings of any kind. Looks like the trick worked . Not sure if it will work on any of the 2013 emissions OBD trucks .

I got a 2011 non-OBD that’s needing a DEF doser and outlet NOX sensor. But I’m unable to do any work on it till Monday . I pulled the outlet NOX sensor out into clean air and cleared codes and did a learned data reset and turned it loose for a couple of short trips till I can get back on it Monday. Hopefully it will make it

Any word on removing the outlet NOX sensor to fresh air as a more permanent fix ?

The Horton HT650 is the ones I’m thinking about.. Only issues we had was not with the fan clutch itself but the air solinoid leaking and wearing out the friction disc in the clutch. We always installed a new air solinoid when replacing a fan clutch. Also , sometimes the fan clutch would not fit flush on the water pump and a shin was needed . If the shim was not used , the clutch would wobble and cause the water pump bearings to go out .

If you have the last 6 of the VIN I can do some digging for ya and see if there were any bulletins on the issue

All the RD’s that I have seen that came factory with a 460 had a Horton air fan, If it has a viscous fan on it might have been originally a lower HP engine then later upgraded to a 460. The RD radiator it barely big enough for the 460 HP

Mack/Volvo makes a gauge that checks the turbo stroke with the actuator removed. 90% of the time the turbo has to be replaced. We have seen actuators go bad or not calibrated but it usually throws a code. We did have a turbo not doing the full stroke and had our DPF cleaning guy come to the shop with some special machine that shot hydrogen ( or something similar) into the intake/air cleaner and cleaned the carbon out of the engine and turbo. I don’t know what this service is called but I saw it work in this case and we didn’t have to change the turbo.

Way to much boost . Probably turbo actuator is stuck in the full boost position. A guy around here has been doing crappy emission deletes. He’s using a “Export” engine file made for a eXport MP with no EGR and a non-VGT turbo. Then locking the actuator in the full boost position. On the MP8 it kinda works OK up to about 42-45 psi of boost . But the MP8 I worked on started back firing through the intake/air filter at about 46-48 psi of boost .

You can try the conical puller but it will probably break the cup off around the nozzle tip area. We have had the stainless cup tips break off in the head several times. We revert back to the old tap/threading tools of the copper cup days. On a couple of extreme cases we drove the tip through in to the cylinder area and pulled the exhaust manifold and dropped one of the exhaust valves down and blew air into injector hole and blew the piece out the exhaust . It worked the 2 times we tried

Clusters go bad a lot on the “Grey engine trucks” ( non-MP engine trucks). When the clusters go bad there should never be a de-rate issue. You can unplug the cluster and drive it with no performance loss. If the speedo sensor fails you can get engine de-rate if that parameter is turned on. I would first un-plug the low coolant sensor in the coolant reservoir and check the harness plug for coolant. If you have coolant in the harness plug then unplug the 2 connectors on the engine ECM. Coolant in this area can cause cluster data issues.

Sorry for the delay, I lost my log on and password info and finally found it to log on . I’ll try to answer your question asap