RS Disposal

Thanks, It was worth a try. Maybe I can locate a blown donor engine. Really weird being the rocker arm itself is readily available. Not sure if they can be rebuiilt/repaired. I believe I have one that is damaged when a valve spring keeper broke and the exhaust valve stuck a piston. This one just wont stay in adjustment

I know this is a really old thread, but did you have any luck in finding a lash adjuster. My dealer says both Mack and PAI show no longer available.

I do agree it seems that the newer manuals are more one topic rather than multiple topics. I would of thought the factory manual purchased at the same time as the truck, 1979, would of been more inclusive. Thankfully I found this web forum. It has been a very valuable resource. Sometimes real world experience, particularly on older vehicles, is better and more helpful than the manual. I feel alot of manuals are not written by real world experience mechanics

That is what I was thinking on the steel washer and "O" ring. Really disappointed in the "factory" service manual as to alot of things dealing with my truck and engine

WOW thanks I will definitely be going thru that. My search on the site for dynatard engine brake kept coming back "error" try again later. LOL

Question #1 Last year when I had to rebuild a head on my 1979 Mack 675 ENTDB engine I notice that the dynatard solenoid wire was all but broken. Ordered a new solenoid. When I removed the old solenoid from the rocker arm I don't remember seeing the steel collar or the "O" ring pictured. Not saying the weren't there, just don't remember The small steel collar I believe is a no brainer as to where it goes on the new solenoid. Question is does the "O" ring just go onto the bottom of the solenoid or the grove that the pencil is pointing to. My thinking is the bottom of the solenoid. Question #2 I am thinking the hydraulic valve lash adjuster on the #4 exhaust valve was damaged, #4 exhaust valve hit the piston. Valve spec won't stay in adjustment. In getting with the dealer, Mack is saying the las adjuster is no longer available even though the rocker arm itself is. Anybody have a suggestion as to where I might be able to get one either new or somewhere somebody might have a blown engine for a used one. Googling hasn't given me any hope. I do have a machine shop. Is this something that can be repaired? Question #3 Being I am really new to heavy truck engines, how does this dynatard actually work? What happens when the solenoid is energized?

Yea, thats the way mine works. Not sure which of the two things (tilt cab specific pump & Mil H-5606 hydraulic fluid) I did at the same time was the actual problem. Ordinarily I would of only done one at a time, but I was getting frustrated, so I did both. The way my brain works I like to know for sure what works and what doesn't when doing repairs that required trouble shooting. But, it's working now. So onto my next item on my list Just want to thank everybody, again, for all the help and insight. This site and everybody has been invaluable.

My lines actually go up the side of the ram and over the frame rail and along side the inner frame rail where they come out behind the front quarter fender to the pump

the truck is parked outside. The problem first appeared before it got cold enough for water to freeze. The plumbing was reinstalled the same way the original cylinder was plumbed.

Im the type of personality that I prefer to do one repair at a time when trouble shooting a problem.. I like to know what works and what didn't. This problem was starting to get me really frustrated so I actually did two things at once. Not sure what the end problem was, but I got the tilt cab system working. I put on a new "tilt cab " specific pump (rather than the generic 2 way pump I had on it) and I flushed and filled the system with the Mil H-5606 aviation fluid. This fluid is definitely much thinner viscosity that regular jack fluid. Pretty expensive also. $55 a gallon of Amazon. nobody here in my town had a clue what I was talking about. LOL. Maybe the newer check valves in the ram are really picky.

In the process of doing rear brakes and this truck the drive hub has to come off so it is a little more time intensive. Hopefully will get back to my cab tilt problem. I do have the 5606 spec hydraulic fluid and a new specific cab tilt pump, also power packer. I normally like to do just one thing at a time until I actually determine what worked, but I think I am just going to put the new pump on and use the fluid. Just getting frustrated.

The cylinders would lock up even during the first half of travel raising the cab. If I remember right my problems started about the time is started getting cold over nite. I agree that I didn't think viscosity was the problem. I also didn't think that a generic 2 way pump might be the problem. The fluid and the generic pump are the only 2 wild cards in the system right now. The hydraulic cab locks function flawlessly. The ram is new from the dealer (power packer- brand). The new "tilt cab" specific pump (also power packer brand) I will be installing hopefully this week. As far as oil, all I can think of is that the safety check valves are really picky about viscosity. Starting to get really frustrated as to what I thought was a simple system repair.

The hydraulics kinda got put on hold for a bit while doing rear brakes. I did get a new "cab tilt" pump. Just haven't had a chance to install it though. Just about everybody I have talked with has said that the two way pump I was using should work. It does work the ram both directions when just hooked up but not dealing with the weight of the cab when the cab goes over center and and finishes its travel with just the weight of the cab. I did notice in reading the spec sheet that came with the pump that a certain hydraulic fluid MUST be used or issues with the system could arise. MIL H-5606 What I used was a hydraulic jack oil. In researching what this specific oil to be used was and why it might be different it appears that it is a bit thinner than regular jack oil being what is used in aircraft due to the colder temps that those hydraulics encounter. As we all know, hydraulics don't like the cold as I am reminded every morning I run the packer on my truck up canyon all winter. in my thinking of trying to remember when my issue became an issue it was early winter here and even though it wasn't the bitter cold I get up canyon, it was colder than back when I can recall the system was working with the old ram before I thought that ram had just worn out. So I did pickup some aviation MIL H-5606 spec fluid to refill system after I flush it out of the old. My thinking, if that is the case, the fluids being thicker may of been causing the safety valves in the ram to close. My weekends are tuesday-wednesday so next week I guess I will find out if my new plan of attack is going to work.

This was grey gasket maker and I used very little being it was a metal to metal seal. Like I mentioned earlier, I will watch to see if it leaks and if necessary pull back off and and make a gasket.

I was pretty much just going on the previous axle removal and replace where there was just evidence of silicone and no gasket. I did make sure that the cones were clean. I do know that the last time the axle was pulled was 30+ years ago due to a pinion gear break. This truck sees ALOT of salt in the winter being it works up canyon at the local ski resorts. I had no problem getting axle out. Two quick hits with a hammer and the axle popped right out. If the axle ends up showing signs of leaking I will just op it back out and make a gasket. Previous heavy work was all done by my dad who is no longer with us. I have been keeping up on the lighter pm maintenance work. But as far as the more intense work I am pretty much a newbie to heavy trucks, as those of you that followed me on my engine breakdown last summer will attest to. I asked ALOT of questions. I am a light truck/automotive mechanic so I do understand the basics of mechanic work. Shop manuals are great for alot of things, but I highly value real world experience. Particularly on older trucks