4v vs 2v interchangeability

[JoeH]

Engine mount pedestal bolts to front of timing cover instead of the rubber donut style the E6 uses. Then bolts through rubber blocks to the backside of the cross member that spans between front spring hanger.

[Macktruckman]

Joe it’s an old 1978 R685ST. The engine in it is an EM6-285 that I believe is a 1980. At lest the pump shop said the pump is an 80 when they rebuilt and recalibrated it last year. It was tip turbine but I pulled it all off and fitted a air to air charge cooler in front of the radiator from an 88 R model. After pulling the heads I found I have a crack all the way down the side of number 4 liner. So I’m weighing options 

Edited August 31, 2023 by Macktruckman
Misspelled words

[Macktruckman]

To be clear I did the charge cooler and pump rebuild last summer along with injectors and new turbo. Recently it started over pressuring the radiator. Putting compression in the coolant. I figured head gasket after I checked the air compressor and it passed. So I pulled the heads and sure enough number 2 has been leaking to a coolant jacket. Then noticed the crack in 4 liner. I didn’t know how the liners would be to get out but when I barred the engine over some of the liners raised up out of the block when the piston started up. So I assume they will come out easy enough. Going to pull the pan tomorrow and the pistons. I’m pretty afraid I might have a counter bore problem that has caused the crack. Going to check it out. If the block has to come out of the truck I was curious about replacing it with an E7

[Macktruckman]

My 285 has a sorta full circle front mount that bolts together behind the balancer it looks like 

[Macktruckman]

Oh worth mentioning maybe some of you can tell me if it’s an issue or not is the heads have a small crack from an injector over to an intake valve. I was told it’s not an issue but I don’t know. I appreciate everyone very much here

[JoeH]

Generally cracks in heads aren't a good thing? Someone else can chime in.

Cylinder liners are easy to get out, you just weld a bead vertically up the inside of the liner and it'll shrink as it cools. Should pop right out.

[JoeH]

I'd fix that motor or buy a newer truck already set up with an E7. I wouldn't invest that much effort into swapping a different engine in, not worth potential fitment issues. Originally it had an ENDT675 non tip turbine 237hp motor. I assume it's single frame. E6 is just a newer version of the ENDT engine. Sometimes 2v sometimes 4v I believe.

[Vladislav]

1. E6 2V and E6 4V have the same liners. They're of dry style, relatively easy to replave. Pull old ones with a puller (or just by a piston as you saw), than clean the bore through, put new liners in a fridge overnight, apply some oil on the bore wall and just slide new liner in by hand. May be put at a room temperature too but some hitting with a wooden block is needed. So better to freeze up. Worth to point out those liners were produced of standard size and a few stages over for cases you need to bore the block. They have an index in the end of the part# to determine the size so pay attention to what you currently have. Liners could be purchased from PAI parts, good quality and not expensive. Sure attention to the existing bores in the block is needed. Could be cracks, out of rounds etc. 

2. E6 2V and E6 4V cylinder head gasket sets are identical (not E7 though). At least by the part #. If they're for 20 stud heads.

3. E6 and E7 blocks seem identical over the size of their lower portion. The oil pans (and the gaskets) are identical. About the same for the front cover. E6 covers were both stamped steel and cast aluminium. E7's were all alu if I'm not wrong. There were differences on the style of the place the front cranck seal fits (different seal OD's), those mentioned above holes for the pointer and a few others. But as far as I figured basic casting for cast alu front cover for both E6 and E7 was identical. So possibility of swapping front mount setup from one engine to the other seems positive.

This is mostly all I can tell on the subject. I'm not much in rebuild of Mack engines. But have some involvement into so kept my eye for info related.

Vlad

[Macktruckman]

Awesome information thanks so much to all of you. Yes Joe it’s single frame and all budd wheels. 38 camelbacks and I’ve got a bottom leaf broken and all the bushings need replaced too. So I’ve got some decisions to make concerning this old thing. I put a cab and hood on it a few years ago and painted it. Swapped the old 2 stick 6 for an Eaton 9LL and built air ride for the cab. All new interior and insulation. A/C and stereo and the works. Got lots of information here from all these good folks on this site at that time too

[JoeH]

Clean truck! Watch for vertical cracks in the frame where it starts to flare out to go around the transmission. We broke both frame rails on our 79 r686st. We used a donor frame for that repair....

[Macktruckman]

Thank you for the tip Joe! Since it’s in the shop I took that advice and crawled over and under with a light and I don’t see anything suspicious. I’ve been advised a few times to just patch this engine and sell the old thing and buy something later model and already spec’d to my needs. But I’ve had this old thing for many years and I’ve gradually spent lots of time and sweat and dollars on it making it like I want it so I’m not fixing to give up on it as long as the frame and such is solid. My dream truck has always been a super dog with an E9 but I don’t ever see that happening and I like this old thing. Where I live it gets lots of comments as there are not that many R models left and the ones still around are pretty rough and ragged. I’m reading everything I can find. Id like to find or put together an E7-454 and use a mechanical pump. I’m trying to get more power and keep it reliable. I already have a heavier clutch and Eaton 9LL that are fresh. I’ll throw a liner and head gaskets on this 285 for the time being but I’m on the hunt. I would like to get somewhere around 450-500hp. This truck sees mostly lowboy work and some site work and very local hauls. It gets very low mileage per year. Also considering a cut off because I’m ready for locking rears. Does anyone have an opinion about Rockwell 41-160’s on Hendrickson air ride?

[doubleclutchinweasel]

I think you have a gem there.  As long as you can keep it running, you're probably better off doing so.

[Macktruckman]

I appreciate that. It’s sure no show truck but it works for a living and it lives most of it’s life in the dirt. There are much nicer trucks but I’m sorta attached to this one. Lol

[doubleclutchinweasel]

There used to be a saying that Macks built the roads for the Peterbilts to drive on.

[Macktruckman]

Hahaha love that!

[JoeH]

For dirt stick with camelbacks. You can upgrade the rears to full lockers, but the used ones are rare and hard to find. Nothing will feel like your EM6 pulls. I'd fix the EM6.  Get a parts truck.  Going to 500hp you'll need bigger driveshaft and you'll have an easier time snapping axles. And more frame twist.

[JoeH]

Problem with most air ride is it doesn't compensate well going through bumps. Takes time for air to pass forward/backward, whereas the camelback seesaws instantly and averages out the bumps.

[Joey Mack]

Ive got a short amount of time driving an E-9, but a couple years in an E-6..  personally, I would stick with the E-6..  I am by no means a super trucker or Guru,,  but as a mechanic,  the E-6 can do a good job...  and it is still repairable.  J.M.O.      Jojo

[Macktruckman]

Thank you jojo. I would agree with the camelbacks in the soft ground from what experience I have. I was just thinking about my own back… haha. As far as the EM6, it is impressive at 11 liters I don’t disagree. Just everything I’ve read says the E7 is a much stronger block. I have almost zero experience in a E7. Lots of EM6 with 2 stick 6. Some  3406B and some C12 and a little in some C15’s. My 285 is probably in the neighborhood of 325-350hp and the cats and one lone N14 525 in a KW will lap me every few rounds. Lol. That said mine rolls through the soft ground and pits much easier than those Pete’s and that kw. Lol. I have access to a 88 R parts truck with a 4 valve EM6. That particular engine was a 250 and a mack dealer turned it up years ago and restamped the plate with 300. I never drove it but they all say it was the best running E6 on the place. It has an identical twin one serial number apart that was done by mack at the same time and it never ran as well. I don’t know anything about the 4 valve. Never driven one. Would it be an improvement over my 2 valve or a waste of time?  Again I appreciate the knowledge here. I’m asking and learning. 

[Joey Mack]

of my limited knowledge slows me down, but to me the 4 valve was smoother steady power.  E-6 is 672 c.i.  and E-7 is 728 c.i.  I also drove a few different E-7's when I was a driver for a construction company. looking back, it was pretty impressive the way those Macks pulled 100,000 + out of the pits and down the road.  We were always illegal grossing up 120,000 lbs.  the old '79 R that I drove was pulled over by ''The Man''  he weighed me,  120,000 lbs,  he made me dump the dirt at a local car lot..  anyway,  They are tough. 

[Joey Mack]

I'm not sure if you need this part number, but it is for E-6 2 Valve studs/ 20 bolt heads.   jojo

Edited September 2, 2023 by Joey Mack
More content needed

[Joey Mack]

I worked on an E-6 2 Valve for a customer, today..  Here is some part numbers for you.  I dont know if you need this info, but I will post this and other parts as I work on this 2 Valve.. 

 

P.S.  I can sub-out my helper if you need some help. She (my wife) has helped me build somewhere near 10 engines..  

[Macktruckman]

I appreciate all the information and the part numbers very much. I have decided I’m going to slap a liner and head gaskets on this engine this week on the cheap. It needs out of the shop it’s in and on the job ASAP. I know it won’t last. I suspect the counter bore is off enough the new liner won’t last too long but I am aware of it and I am going to make a decision on what to do long term and start gathering parts for a new engine and get ready to just swap out one weekend. I’m still very much considering an E7 but also considering this 4 valve E6 in the parts wagon. I don’t really HAVE to have more power but man it would be nice. Lol. I was looking at its suspension today. (The parts truck) It’s a mixer truck. 12 yard drum I believe. 2 drop axles ahead of the drivers and a drag behind. I don’t know what the rears are other than Mack and HEAVY. LOL. walking beam and no spring at all. 6 spoke drives and steer.  Thank you again  jojo and vlad and everyone. 

[Macktruckman]

I don’t know for sure how much it weighs here but somewhere in the vicinity of 100k gross I’d guess. 

[Macktruckman]

It wears many hats. Lol