Mack Technician

It was a product improvement. The jumper was free. We installed a bunch as they came through. Some slipped through the cracks? Or people changed the tank and didn't understand the purpose? Who knows?

Nice find, disappointing it took money out of your pocket. I wonder how many trucks are running without the capillary protection?

Service bulletin SB273009 coolant level anti-capillary jumper harness.

Be aware RED! Don’t wreck your new ECM. What Fred is talking about is capillary bleeding through the wire. The sensor in your coolant tank ruptures internally and 10 PSI will push coolant down the wire using it as a capillary tube. That’s how coolant gets in past the seals of the J connection. Its not likely coming from outside in, but rather inside out. You can pour coolant over the outside of your ECM all day and the seals will keep it out. The capillary failure is coming straight in via the unsealed wire. Coolant flows down the wire like a pipe. Mack makes a jumper you install in the wire connection leaving the sensor. It’s a few inches long. The jumper has a sealing compound pressed into the wire strands. If the coolant sensor ruptures the coolant will hit the protective jumper and dead-head. Mack was handing out jumpers back in the day. Check to see if you have the jumper. If you don’t, install a new coolant sensor and jumper. If you do, install a new coolant sensor and jumper anyway..... cheap insurance.

That's ugly......R.I.P. ECM For future......I was given a small 5 Oz can of Deoxit D5 by Liehberr. Stuff has been my go to. Hit it with regular No Flash electrical cleaner then Deoxit and reassemble. The machines Liehberr sold have to rotate continuous, so they are running sensitive Serial/CAN lines through a constant rotation brush style electrical connector. That Deoxit is the only stuff that would lubricate/clean/maintain a connection. Regular Dielectric grease lifted the connection stinger off the contact disc and set codes. Get your Coolant Level Sensor Capillary Jumper in there ASAP. I thought all trucks got a free one from Mack? Maybe someone failed to follow up? Your coolant sensor harness wire is also filled with coolant.

This is what your about to buy.... It's just a helluvalotta tubing and jargon.

This is what you would like...….

Hard to work on, but not a bad engine overall. It has the complications you see with the introduction of tier 3. A 2002 would be a better engine.

K&S sells Bosch reman @ $300.

Google “Mack E media”. They sell complete wiring diagrams. $22.00

Welcome to BMT. What chassis is the E-Tech in? What make/model?

If you have no air moving at start up it is not a freeze issue. And you say the fan completely stopped working suddenly.... You need to stop and get your HVAC (heating, ventilation, Air Conditioning) dash blower working. If blower motor fails to work on all three speed levels then check to see if you have a blown fuse. If fuse is blown (or circuit breaker fuse failed) then replace it and retry.

What are you looking for(or at?) under the hood when the A/C stops working?

Blower motor in dash. It works properly and always moves air?

Failed water valve can still leak hot water when fully stroked to off position. Do as Cmac suggested and clamp the hose. You have no working HVAC fan?

I like the heater water control idea more that the stinger, they were notorious for leaking hot flow, but it can't explain zero air flow and then HVAC system working fine next time you run it? Freeze up would cut your air off completely and stop the air flow.

Doesn’t look like you ever accidentally backed over it in the woods during 38 years? Good job!

Be ironic if this thread became the explanation to Rob’s lack of interest? ~Blabberer esq.

You’ll never hear the answer to your question Joe. BMT can be a dark and mysterious place.

Pull air cleaner and inward mount bracket.

Great, now Moxie’s a gateway drug? Suppose you have to look at like this.... when folks committed drunken vehicular homicide, we didn’t stop drinking......when folks committed rape, we didn’t outlaw sex.....when folks shot up malls, we didn’t turn in our guns.....when little Pete ruined himself on Moxie, 41Chevy didn’t empty out his fridge.....

Time to come over to the dark-side and drive a truck that makes Prius drivers swear out loud? The payback is that you won't have to shift that T300 Mack transmission so much. AMI-370 is a good program and candidate.

You failed to properly insert the freeze stinger into the dash evaporator core. It’s too shallow. Your symptom perfectly describes “freeze up”. Get a clothes hanger, straighten it, Jam it into the core where the freeze stinger is planted, once it’s hogged out put the stinger in as deep as you can.

WHAT!!! $100.00??? Hosed! Give me your part number and I’ll try to find a cheaper source.

Your OCD getting rubbed raw on that AI engine? Or liking it?