mechohaulic

another quick option to crank cover would be one or two welding gloves placed in bottom of cyl. high tech would be piece of asbestos cover; for most welding gloves work. one wraps the journal another for added coverage lays on top of first in liner. easier to move cyl to cyl. also stick rod makes more sparks (does better on heat distribution?) wire feed not as messy challenge to get in cyl at times. lest we NOT forget how /where the ground is attached !

bad or broken engine mount should show a gear shift moving erratic . cruising 45-50 would be a "no strain "condition for drive train. engine mount/ rubbers wouldn't be under load to twist UNLESS the cruising condition involved torque. change the front tires with another set if possible or have those balanced to confirm they aren't the problem. had a brand new truck with vibration at 40-50 mph = turns out the balance weight fell of the rim == think I'm showing my age again. tires were bias not tubeless . also how is the word "bounce " used in reference to problem . truck bouncing up/ down or is it shimming at 45-50/ wandering ?? I agree with all above comments terms of 5th wheel set wrong etc. was the low bed empty or hauling a D-10!! (i know it can't just point of issue).

title shows B-67 ST indicating a concave cab twin screw. freight hauler operation ?? general over view of rear section is a positive ?? ; brakes / suspension decent indicating good Maintenace ?? as always on BMT pictures help a great deal

It's a machine there is NO way to ensure it keeps running. hoping you have received an honest history of the unit terms of servicing/ repairs made etc is a start. go with the basic same as a used car. change the fluids possibly take sample to sent out for analysis , send the masterminds on BMT a few more stats of the vehicle such as mileage/ hours ; do you know it's principle use before you purchased ??? job giving it more hrs then mileage ( road truck/ local delivery operation?? why "clean engine internally an issue?? blow by out breather when running ??? have a spare set of valve cover gaskets then remove valve covers check sludge under covers.

not hearing it spin(by hand) my main concern would be the lower shaft bearings. the gears are Mack tough=a little/lot of cleaning they will run a long time providing no pieces missing. the bearings and races being in water may be a different story. transmission on the ground and open would be the opportune time for covers off ; bearings/ races inspected or replaced. wining going down the road not good. you want wining then take my wife with you.

the "beads of weld" were a common practice back then; personally I've never done it . possibly due to Mack having a super HD sleeve puller . off site I have resorted to a 20 ton bottle jack under the engine with custom made plate having exact dia of sleeve and pressed liner up and out from bottom. the "skill was the honing of block to fit new sleeves. don't tell anyone but yes I did over hone and need a P2 sleeve on (rare)occasion. then the challenge of new installs; clean cloth with clean 2x4, if the fit was correct =standing on the 2x4 body weight sent the liner in ;;;NOT forgetting the shims under the liner for proper ridge height. new liners were called dry = still sprayed them on install for lube. after all was said and done the sound of the new rebuilt on start up was = yep the old dog got a bone(r). proud to be part of all the sick puppies here .LMAO close call on hearing the engine start or having "helper take down Christmas tree -" other post. hear that engine = I built it.

all it needs now is a set of pneumatic tires for those rough terrain projects. 😄 tubeless and fill with some green stuff.

one fine looking shop also.

to quote the phrase ;"a pictures worth a thousand words "::: You sure said a lot of words in those EXCELLENT pictures. a person can read some lines , go ok that's cool. but to see in pictures the process ,it becomes = OH I remember doing that or oh yea . another fine example (NOT LIMITING TO JUST ONE persons post -too many on here ) of pictures saying a million plus words; watching the amazing build from start to finish of a B-73

small clear "parking lights" next to headlights another give away of '60's Mack. don't remember yr the clear lights were eliminated from head light panel.

'66 it's an early Dog. that's why the nose/ radiator side extensions.

old school rules must be obsolete by todays standards ;;; but cleaning studs and block holes a major importance. also threads were lubricated on install making sure NOT to over lube studs to where oil went into holes. studs threaded in till tight THEN backed off 1/4-1/2 ? turn. one reason a retorque was always needed. oil in bottom of stud hole with studs tighten reportedly build excessive pressure when engine up to temp. backing off allowed for expansion.

never seize on the attaching screws for sure , I would also recommend caulk or silicone on the nutsert going in to roof panel. easier to seal hole on install of nutsert then to have a drip/leak . thin roof panel if being drilled out for nutsert may have a tendency to distort

back to original post; I'd say roof lights are held in with nutserts looking at pictures. question would be whether or not nutserts spin in cab sheet metal.

see : like I stated Jojo has my back all the time. didn't want to be first to say it's bedtime''' ; that makes me sound old ::: oh that's 🤣right Jojo works early am== I'm retired LMAO. 😂

don't remember specifics; yet remember lifter faces separating ; cam removal (with finger tip scalping). rare occasion of cam bushing replacement. clothes pins holding new lifters in place while cam reinstalled. ceramics never a part of process. but also never dreamed of oil velocity being 0-5. times change.

not speaking of """off topic ""I hope !!!

I'm a senior ; I can make up my own words and get a way with it, LMAO.. I'm nutserted according to the wife. ... so yes it is a word. can't print the other words I heard ..

NOW You are NOT putting a F-250 in same category as a Mack !!! 😂🤣🤣. couldn't help myself. try a hold down screw see what happens.