Mack E7

My 98 E7 has 715k and it has blow by. I expect that. What I don't expect is oil dripping out the vent......

Q: Should there be a diffuser or baffle in the vent pipe ?

Q: Will running the overhead help?

Q: What weight oil should I run?

Sure I know, it needs rings....probably been abused and it might be too late but I can't allow it to throw oil on the underside. That will get me shut down.

I considered welding a 1.5" pipe to the exhaust to create a siphon effect but I'm afraid she might suck all the oil out of the heads if I don't do it right ya know?

 

Take a lesson here at my expense.......

I bought a used 613...... air was out among other things......
Started repairs by replacing expansion block valve..... guage readings were funky and the suction line was freezing back to comp. Ended up twisting off the copper lines to the evap., totally unavoidable even with heat..... ok got that done. Put new evap and aftermarket E-valve. Charged it up and guess what, same readings, same problems.

Replaced both hoses, dryer and comp.... guess what, better readings but funky and high side at comp not real hot, only like 85 deg.and evap temp only 60.

Scratched head and called expert. Take truck to him and he hooks up guages and watches.......then asks key question......

DID YOU BUY THAT E-VALVE FROM MACK?? I said no, he said thats your problem, it's wrong or broke. Most of the freon is just circulating in the system and not changing states like it's supposed to.

I also had the e-valve wrapped in tar tape. That had to go so it can sense the outside temp. I would have never thought this. The aftermarket valve plumbed right in and looked identical to the factory one coming out.

Costs so far? Over $600 in parts and the final change will run another $60 plus my labor.