Mack RL question

[Ditchdiggerjcf]

Hey guys, I am new here and needing some info on my old Mack.

What is the difference between a 600, 685, and a 700? I am having an engine mount issue.

 

[j hancock]

600 and 700 are chassis series.  A 685 is a 600 chassis with a 237 engine.

On your door tag, what follows the RL?  What engine do you have have?  Is it original to the truck?

Pictures of RLs always appreciated.

[Ditchdiggerjcf]

It is a 685 with the original 237. What are the differences in the chassis?

I am having a strange engine mount issue. It has been like this since I bought it, and I am finally getting around to fixing it.

The snout on the front cover does not go all the way through the front engine mount. The rear isolators were worn out and allowed the engine to slide back a little. When I replaced the rear bushings, I also did the front. I put a portapower on the trans to push the engine/trans as far forward as the rear mounts would let it go. It is not far enough. The balancer is still right against the engine mount. I believe there is a difference in the distance from the rear mounts to the front mount on an RL vs a standard R.

I have no way of knowing for sure.

[j hancock]

There are some dimensional frame differences depending on the spec of the truck.  The RL/RS trucks have a straight frame at the engine and an eastern R has splayed rails so the mounts are different. 

Do the mount holes look wallowed out?

 

[Ditchdiggerjcf]

 Nope, everything looks good. The trans has been replaced by the previous owner. I am wondering if the bellhousing, trans case, or rear mounts are different.

[Vladislav]

RL/RS originally were West R-models, produced in California. 600 and 700 series differed by the length of hood, 700 were longer to accomodate V8 engines.  After closing Hayward plant in Cali in 1978 or so RS/RL700 were cancelled and RS600 (and RL600?) production moved to Macungie plant on East Coast. But those trucks continued having their original style of the chassis - straight frame rails all the way front to rear. R-models which were originally produced on East Coast (Eastern R600 or R700 but not RS or RL) had almost different chassis with rails spreading at the front end and lowering down and narowing there either. Those chassis had absolutely different front crossmembers and front engine mounts. And probably rear mounts also. Telling further Eastern R's had different front mount on series 600 (shorter hood) and 700 (loger hood). Western RS/RL seemed also having different style of the front crossmembers but as an early and later styles. Unfortunately I don't have particular images or drawings of all crossmembers or front engine mounts used on all R-models of all modifications and all years of production. But what I'm sure of the thing you should start with is determining what exactly model and production year your truck is.

Vlad

[Pepe]

2 hours ago, Ditchdiggerjcf said:

Hey guys, I am new here and needing some info on my old Mack.

What is the difference between a 600, 685, and a 700? I am having an engine mount issue.

 

Hello guys, I really need help, I have a 2013 Mack cxu613 pinnacle, is a nice truck but going uphill doesn’t have any power even just the truck without any hauling, I just realized this truck is not using def at all( is not working, not even on the dashboard) I think the prior owner messed up( exhaust blue bottom on dashboard doesn’t work either) how can I fix this mess, other than that drive really smooth 

[Ditchdiggerjcf]

The truck is a 79 west coast mack.

I am familiar with the history of the different R models. The RL did have an early/late style front mount. One is steel the other is aluminum according to my local dealer. The mounting location is the same. I have seen both.

I keep coming back to the trans mounts and the bellhousing. Either one of those would change the location of the engine. 

 

[Ditchdiggerjcf]

6 minutes ago, Pepe said:

Hello guys, I really need help, I have a 2013 Mack cxu613 pinnacle, is a nice truck but going uphill doesn’t have any power even just the truck without any hauling, I just realized this truck is not using def at all( is not working, not even on the dashboard) I think the prior owner messed up( exhaust blue bottom on dashboard doesn’t work either) how can I fix this mess, other than that drive really smooth 

Particulate filter problem? It's like having a stopped up catalytic converter on a gasser.

[Pepe]

54 minutes ago, Ditchdiggerjcf said:

Particulate filter problem? It's like having a stopped up catalytic converter on a gasser.

There’s not any checking light on but I do know for sure the DEF and DPF are not working, but is weird, runs great but as soon as I get to the smaller uphill , it stop automatically and goes really slow ( not power)

[Ditchdiggerjcf]

Try the late model truck forum. You will have more luck there.

[Lmackattack]

what does the truck vin start with?  RL685?  if so that calls for a 237hp maxidyne and should have a mack maxitorque transmission.

if the truck was built with a off breed trans that may be the reason the mounts are off.

[Ditchdiggerjcf]

Truck is factory, gold bulldog and all.

[Ditchdiggerjcf]

I was hoping there were a few old heads around here that could impart some of their vast knowledge on me in regards to my problem. Anybody have any idea where else to look?

[j hancock]

My next step would be to contact the Mack Museum and see if they have the drill dimension layout for the frame rails.  It may be a born with defect.  If the fellow in the frame shop was having a bad day in 1979, he may have indexed the transmission mount holes (for example) a 1/4" or 3/8" rearward from where they should be?

https://www.macktruckshistoricalmuseum.org/

[terry]

wonder if could be the wrong front mount or front cross member?   terry

[Ditchdiggerjcf]

I've seen several of these mounts and they all look the same. I think it's the rear mounts. I wish I knew if there was more than one part # for the rear mounts.

[Vladislav]

Just a thought, not a particular advice. Once i looked at rear engine mounting brackets of my R-model and a pair of such ones off a RD chassis. They looked almost similar to me until I noted RD's had less "meat" in the attachment area. Figured those were made to be used with a double frame so had 1/4" ground off to be set into the same position as R-model ones put to single rails.

[AZB755V8]

I would have to say that since the trans was out the issue is the trans mounts. I do not have an R or RL but in the B's the trans mounts do have an offset. If they are not put on the proper side of the trans there is probably about a 2 inch change in moving the engine and trans. Check to see if the driveshaft slip connector is "fully in" and not in the proper mid position. This will confirm if the mounts are on the wrong side of the trans and have the engine/trans moved back or forward.

Edited February 10, 2020 by AZB755V8

[JoeH]

I have a 1980 dm686 that has a 1976 motor in it that was pieced together from misc. Other engines.  Long story short, it had the wrong timing cover. Didn't sit well in the front engine mount.  Don't assume the engine has never been out or had parts replaced with other parts laying around.  There should be a rubber bushing in the front engine mount.  Replace it, could be worn and sliding the engine backwards.

Engine blocks are pretty much the same on **685 and **686 trucks, just peripheral changes for different HP ratings. 

[Ditchdiggerjcf]

6 hours ago, AZB755V8 said:

I would have to say that since the trans was out the issue is the trans mounts. I do not have an R or RL but in the B's the trans mounts do have an offset. If they are not put on the proper side of the trans there is probably about a 2 inch change in moving the engine and trans. Check to see if the driveshaft slip connector is "fully in" and not in the proper mid position. This will confirm if the mounts are on the wrong side of the trans and have the engine/trans moved back.

This could be true. It puts me back in the same place I am with the mounts. Are there different part #'s for front covers, if so, what are the differences.

[Vladislav]

At least there were stamped steel and cast alu covers. I tell about E6 and EM6 engines but earlier engines could have them either.

[Lmackattack]

Here are pics of the steel timing cover for a eastern R model not sure if that would be the same parts as a Western RL as they used aluminum front crossmembers /engine mounts

[Ditchdiggerjcf]

2 hours ago, Lmackattack said:

Here are pics of the steel timing cover for a eastern R model not sure if that would be the same parts as a Western RL as they used aluminum front crossmembers /engine mounts

I have seen that before but it is not the same on the west coast trucks. 

[Ditchdiggerjcf]

Fought my battle again today. Replaced the front isolator bushing that isn't 3 months old. I really, really need to figure out what is going on with this truck.