Yes, “Capcom, we have a problem…”. The history of a problem like this is important to try and make the best decision short and long term. let me let you in on this issue. So we have a “money maker”, a commercial built GMC motorhome. Being that, it must be relied upon to make money for it’s existence. Like a race horse…. the animal needs to win to stay on the track…. Tell me your thoughts when I finish:
So 2 years ago the coach blew it’s motor…. Needs to be fixed to use the truck…. not being near Orlando, a local builder built up a motor with the local repair center installing and warranting the motor and install. 9 months the motor dropped, the powers to be came together and another motor was installed. Shortly after it blew and the service center was understandably upset…. even more labor has been invested. Everyone was there pointing fingers. The owner wanting to just have a running money maker bought a core motorhome… running with a recent (20,000) mile Jasper motor. The service center did the swap and sheer disaster was overted….. life is again pretty good.
Then… and this is where we get in the mix…. the motor developed the dreaded intake manifold crack. Now remember, this is a production built Jasper motor. A good, quality company for sure but it was built in a “production” fassion. Things were done well but details were not checked. Probably no line bore and balance of the rotating assembly and all that. The intake wasn’t blocked off… that’s a GMC Motorhome community known thing… non-stock. There were other things like a high volume oil pump, restrictors and all that but remember…. this was a stock built motor….. So we fixed the cracked intake… you saw that last week Motor is now running great. Pulling away the coach ran @ 35 miles and the tranny lost reverse. Now remember the coach came down from Atlanta one hours trip at a time. Having the cracked intake… as soo as the block heated up and expanded the coach had to stop. Man.. what a long trip! And what stress on that production Jasper motor and no good on the tranny. Now the motor had to limp the money maker BACK to the safety of our shop for even more surgery!
Installing the rebuilt Manny trans was easy but then on the test run….. bad JuJu… a low end knock at cruising RPM. That’s rod knock brother. A run to Gatorland and back Now understand, everyone and all the decisions made on this coach were right when they were made and done. The broken production well built motors happens. Guys, you are pulling 12,000 pounds. Every take off from a light is like whipping that motor like doing a burnout… on every stop!
So yesterday my Marine vet mechanic ate his Wheaties or whatever turns his crank and dropped that puppy tranny & motor out the bottom for a looksee at this ailing motor Whatever he learned during 8 years of military service has served him well and we are the benefactors! So flipping the puppy over wow, there are some disturbing sights… Yeah, Phillip did the deed with a soft cast on his wrist! A can’t stop him!!! But anyway, this front motor mount is crying to be replaced Obviously not replaced when the last 3 motors were installed it’s about to let go. There are only 3 mount point on the entire drive train…. We need a gold watch for this front motor mount. But see it’s understandable, that motor mount cannot be found at your local NAPA store… so they reused it.
Pulling the pan, we have shiny stuff in the oil pan… not good…. Pulling main and rod caps we could see where that metal in the pan came from GONE… the mains didn’t spin.. we didn’t loose any oil pressure when the motor was running but the rods chewed things up.
SO… here we are. A well built production motor with a chewed up crank. 20,000 miles on the Jasper build…… this is the 3rd motor the money maker has gotten in a short period of time… big bucks has been put into this machine to keep it making that income… but now what do we do? Do I do a “crank kit” alone? Any deeper and the motor would need to be disassembled. The motor ran good… just had that knock and we can see where it’s from…… valve train sounded perfect AND now with the repaired intake all is good up there. It lost it’s butt… it’s bottom end is gone.
So there is the question… what to do? I’m off to the machinist right now….. I’ll let you know the decision. Of course if $ and time was no object we know what to do but is there anything we can not do… anywhere we can save cash but still come up with a reliable motor for this moneymaker? Think about it….
Think about this too… I’ll be doing another video over on Patreon that I hope will straighten it out and it’s all more understandable. Let me just say this…. it’s all free. A smart man once said….. “Give it away, if it comes back it’s yours”. That’s what “Motorhome Rehab Ranch” is all about. See ya later today there…..
<<<<<< Updated decision >>>>>
That’s right Johnny… all production built motors have to cut corners…. it’s a simple matter of physics…. more work, more investigation, more performance means more time (time= money) and there’s just no way around it.
Post mortem from the machinist…. motor had not been overheated, the bearings were not blue and the heat tab Jasper put on the motor was in tact. Mains wearing different means the block was never actually line bored, spinning of the rods could be from no balance. The knock happening when the motor gets into it’s torque curve means the motor wore out. Yeah only 20,000 mile but that was hard 20K miles in a food truck loaded to the gills and drive hard to make money…. Basically the bottom of the motor is toasted from the torque.
What are we going to do? The machinistis going to attempt a lower in rebuild or a “short block” rebuild. We will rebuild the rotating assembly, clean up the block.. resize piston rods, if there is little fidge on the bores we hope to reuse the pistons.. maybe new rings. The crank will hopefully clean up at .020 over, new rod & main bearing, do the machine work and we put it back together. The valve train including the cam looks good.. the intake is fresh so if the motor Gods smile on us it will be back. It will not be a roller valve train.. it will still need hi ZDDP oils but at 20K miles with no valve train noise we hope with some investigation all will be well there. I’ll do pics to stay tuned for more…. .