Macktech20

Just now, MACKS said:

Went to Mack today,no good..

I think Pai Makes a kit also.

The only place you'll find that oring is from Mack, and it comes in a kit. I might be wrong because it's been along time, but the kit number is 207SH32 I think this is the correct oring kit for a 12 speed.

For the most part yes they were very reliable engines. They had their issues with camshafts and other stuff like the later E-Tech engines but for the most part the AI engine is a good engine. The biggest downside of them is the lack of power but you can change a few things on the engine to make more power.

On 7/29/2021 at 7:01 PM, Durango Bill said:

My Mack started running high oil temperature 145-150 degrees, but the coolant was never above 220.

I was pulling a grade loaded, but I’ve pulled those hills in the past without issue.

any ideas why the oil temperature would run high with normal coolant temperatures??

Is there a check engine light or a vmac light on. Your oil temp seems a little cold it should be near coolant temp. What this could possibly be caused by is a bad oil thermostat on the oil filter housing on the right side of the engine. But most of the time if the thermostat is bad there will be a active DTC.

I would check fuel pressure off of the fuel pump, I've had a couple of those engines that did the exact same thing you're describing and it was caused by low fuel pressure. Are you having multiple unit pumps code at the same time?

Do you have oil Blowing out of the vent on the top left of the trans?

On 6/26/2021 at 5:07 PM, Pipelayer said:

The transmission will not shift gears when in low side. No matter which gear you have it in, when you let up to shift it goes to neutral. I put a gauge in the air line that goes to the valve that shifts it. The pressure stays the same even when the transmission goes to neutral. What am I looking at to get it fixed? 

Sadly 99% of the time if a Mack trans does not complete the range shift it has something to do with the syncro and not air pressure. A few things you can do to check is remove the rear cover and remove the range cylinder and fork. Look for any Galding on the cylinder shaft and the fork should have a good amount of wear on the side closest to the rear of the trans. This would indicate that the syncro is not locking in and it was being held for in the low range position by the cylinder and range fork before the syncro went out. Another thing to look at is when the cover is off check the spacing of the steel and fiber disks in the syncro make sure they're not broke its easiest to use a flat head screw driver and push the disks side to side. Also make sure the intermediate plate that sits against the high range gear (small gear) is relatively tight. Its not going to be soild but make sure it has. No more than 3/8 of an inch of movement side to side. Another thing to look at is the 311 spigot bearing in the input shaft make sure it hasn't failed that bearing supports the front of the main shaft and can cause difficult shifting. Another thing I have came across is a broken counter shaft in the back box. Is usually caused by the 538 bearing in the high range gear when it fails it causes one of the 3 to break. But it causes difficult shifting in any range and no coumpound shifts. You can check it by pushing up on the yoke on the trans and see if it the main shaft clunks around.

Is there any ABS or or V-Mac(Lightning bolt) lights on if there is an ABS fault one of those lights will be on, most likely the ABS light. Another trick to try is if the truck is a manual, unplug the transmission output speedo sensor from the harness on top of the trans. An electrical malfunction light(V-Mac) will come on. Then drive the truck when it's cold and see if it continues to have issues.

The spec is 6 3/4 to 7 inches but make sure the petal can still push the lever for the engine brake when the pedal is all the way up.

The metal tab is bent. It happens all the time, take a pair of vice grips and bend it back to the correct pedal height.

It depends if you need a clutch usually what I would do if the truck doesn't need a clutch I would just unbolt the back box and just do synchros without having to pull the transmission. It is way easier to do synchros on a Mack compared to a fuller if you're doing it in frame. Fuller's run helical cut gears and makes it a little bit more of a pain in the ass to get the gears to mesh back together when you're going back together. If you do plan on doing the synchros in the truck you shouldn't have to worry about the countershafts falling on you like with a Mack transmission if you dont have the retaining plate in. Because everything comes out with the back box on a fuller.

It depends on the type of engine you're looking for if you are looking for just a mechanical P-pump engine the 1994 E7-400 is your best bet but if you're looking for something newer any E-Tec engine in between 99 and 02 would also be a really good choice. Personally I have a 1995 CH with the E7-400 with a V-MAC pump on it and it's coming up on a million miles and hasn't had a major overhaul done on it. The problem with the 93 to 97 E7's is that they had weak oil pumps and ran low oil pressure so if you bought a truck within that year range I would recommend replacing the oil pump and doing rods and mains if it hasn't been done yet.

On 6/17/2020 at 5:20 PM, Nobody454 said:

i found the mack version much tighter and harder to drive, just took some getting used to i guess. I'm back to an Eaton now in the KW

Mack made a few different models of Transmissions their TM 309 Transmissions were very difficult to shift just because of how close the gears were but just a standard 2180 transmission in my opinion shifts almost as good as a Fuller but that's just my opinion.

Have you thought about switching the exhaust manifold, Mack also put a very restrictive exhaust manifold on the AI engines to be able to pass the 2004 EPA restrictions. It might be a little bit cheaper then replacing the cam, if you're looking still looking for power after the dealer turns it up a little bit.

I just worked on a 99 CH613 that had a bad transfer pump causing a misfire

On 7/23/2020 at 7:21 PM, fjh said:

E7 no egr  E7 aset and AI are both egr engine’s 

AI Engines are not EGR they run a overlapping cam and a restrictive exhaust manifold to pass emissions. They do not pump egr back into the intake manifold.

Unplug the speedo sensor on the back of the trans