RS Disposal

Ok, I got the injection pump gear off and the cam out. Cam and lifter re install is a no brainer. My question is on the injection pump gear. I don't believe there will be enough of the threads beyond the gear to be able to use the nut to push it back onto the shaft. Don't really want to do any tapping of the gear to get it down. Don't want to screw up my pump. Any thoughts or words of wisdom? Was hoping the shaft had a threaded hole, but in my initial inspection last nite I didn't see one, but then I was tired and it was dark and at that point my day was 20 hrs long.

Any words of wisdom on getting the injection pump gear off. Does the cam just slide out once the lifters have all been captured?

When it comes to the VIN on my older Mack, 1979, if I go anywhere other than the dealer they tell me that it isn't a good VIN. The one parts guy is old school and he can usually find what I need, if not he gives me the Mack number which helps in researching after market.

I have now know that the E7 lifter is compatible with my E6 engine. I have noticed in my researching that the E7 lifter doesn't have the hole that the E6 lifter does. I can only assume that it is for oil flow and lubrication of the lifter in the bore and or for oil flow up the pushrod. I know the E7 lifter is suppose to have a redesigned and better face than the E6, but is the "no hole" going to be an issue in the longer run for the engine?

My regular parts guy who knows these older Mack trucks was out the day I went in. The younger guy did give me an updated part number to the 72GC347A of 25101042. Either his book didn't give the 72GC357A as a replacement or he just didn't research it. As with the intake push rods of having to order six rather than just the one I needed, I can see the lifters having to be ordered as a set of 12 and at about $350-$400 per lifter that is definitely way out of my budget. Quick question also, I have done a quick search only, but does anyone have a source for a timing cover gasket. Dealer tells me I would have to order 10

Interesting being my Mack dealer here in Salt Lake said that they were no longer available In looking at the pricing per lifter being in the range of $350 - $400 that is more than a little out of my budget. I am just the little guy with one truck where it only really makes money during the ski season (5 months) the rest of the year it just pays the enough to keep truck going. I'm 70 yrs old and been doing this for 62 yrs starting to help my dad when he started the business and not really wanting to put truck to work full time year around.

As far as the broken push rod, it is the same cylinder where the exhaust valve dropped and hit piston. My thinking is that the force of the impact traveled thru the valve train and damaged the lifter or cam lobe. as that damaged progressed it affected the intake lifter or cam lobe. There was a pretty serious tinny, tapping noise just before the engine started missing. I'm thinking for whatever reason the tolerances went south and the pushrod was just sorta banging around which caused it to break. If it would stop raining/snowing I can finish tearing down and see what I might see

AG kits and a few of the other vendors I have used are saying out of stock and the ones that did have in stock the lifter is $225 each. I did find a supplier, Premium Trucks Parts, on ebay that has a few for $155 each, Right now my budget for truck repair took a serious hit last fall when the exhaust valve dropped and hit piston.

it is a standard and I thought of that also, but for me it just seemed easier to count teeth LOL

this is the "B" engine. Not exactly sure if the two had different cams or not. threads I have read on other forums have mentioned that it was their belief that both versions of the engine had the same cam. I will definitely be checking closely and comparing the two once I get the old cam out (if the stinking weather would cooperate, I have to work outside) Have been able to actually find any specs, etc. as to what the differences would be

When I have adjusted the valves it was definitely one cylinder at a time in the firing order. I would double check the marks on the vibration dampener to make sure I was at TDC. Once I found TDC on #1, I would rotate the engine one tooth at a time via the ring gear. It has 119 teeth so that divided by 3 is just under 40 teeth. I would count 39 1/2 teeth and then check my marks in the front of the engine and adjust it accordingly. kinda a pain in the rear to crawl under 6 times, but I wanted to make sure I as at the TDC. Bumping the engine with the starter I could never even get close.

I do have some "high performance assembly lube" (not sure of brand name, but I like Lucas stuff so I ordered a bottle anyway. I did see that that lifter was also compatible, but was told by two suppliers that those were also unavailable new

I got the cam shaft off of ebay from a truck parts surplus place. He stated it was for the 673, 675 & 676

I picked up a new cam that was listed as being for my engine last January just on a gut feeling I might need it. Hopefully the description was correct. It didn't state whether it was an engine brake or non engine brake cam. From what I read somewhere during my learning journey with this engine is that the 675 cams were the same either way.

I can get the rear side cover off, but the front one would require the injection pump be removed

Apparently my camshaft was also damaged in the major engine breakdown I had last fall. I did inspect the best I could the cam lobes in # 4 where a valve spring keeper broke and dropped the exhaust valve.. The lobes appeared and felt ok, but a real good visual inspection of lobes or lifter I wasn't able to do, but the engine was only run for a matter of seconds after the incident occurred. Over the course of the last several months I was beginning to notice a tappet noise and wasn't able to keep the valve lash in spec on #4. Half way thru my day last week the noise got real bad and the suddenly the engine had what felt like a serious miss. Took the inspection cover off the side for the rear head and noticed that the intake push rod had broken and I virtually all but had no valve lift on the exhaust. Currently in the process of tearing the engine down to pull camshaft. Had to replace radiator anyway and fabricate mounting being direct replacement no longer available, so that part of the job wasn't actually extra work LOL. My questions are, is there anything I really need to pay attention to when tearing down outside of the timing marks on the gears for when I reassemble? What in particular should I be paying close attention to when it comes to putting back together other than the timing marks? I know they (whoever they is) say that a new cam needs new lifters also. The new lifters for this engine are no longer available and when they were, were incredibly expensive. Actually going to relace all intake push rods being the dealer says they cant' order just one, but have to all six. I plan on using a high quality engine assembly lube at the time of reassembly. Again, I appreciate this forum immensely and everyone's help and insight over the last 10 months of me being thrust into being a heavy truck engine mechanic.

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.