So– my coach all works– what could POSSIBLY go wrong?
The GMC was a well designed, well built vehicle and that is a true statement. The problem with a GMC though is its age. No matter how well something was built, time has a way of stealing any man made machines integrity. Parts break, parts deteriorate and even though they may be operating properly will fail in short order because their integrity has been undermined.
Undermined in that heat, humidity, corrosion, oxidation, dust, insects and even hungry animals attack components, wiring harnesses and just about everything else. What you end up with is either a system that will not do its job, one that will barely operate or one that may check out well but will fail shortly after you start to use it again. These are the major issues in renovating, relying upon and maintaining a GMC.
In understanding this, you must now also understand that until a system has been totally renovated, you will not be able to totally rely upon it. This may sound impossible and you may say to yourself “why would I want a vehicle that has every part a suspect for failure”. Hey, and this is a good question and the answer to it is you MUST go through especially all important systems to say they are in reliable condition. Your mission then in your mechanical work on your GMC must take on a serious goal. Take your blinders off, do not search for a problem and fix it alone, suspect every component in a system and if in doubt at all— replace it. This way, when you finish the repair, you will have your best chance that the system you worked on will work and continue to give you something to rely upon.
Let me give you some great examples of what I mean. I tell new owners to bring a coach to me for check out, “It’s easy for us to stand here and list things you want us to do, the hard part is trying to figure out where to stop”. This is probably the truest statement of fact you can make about renovating a GMC.
Greg D. purchased a coach after months of searching, Greg got with us about what to look for, what to check and what to expect. Greg was not a novice at this, after 30 years working at an auto sales dealership, he has seen his share of vehicles and then some. He knows what to look for, what to expect and how to bring a vehicle to a reliable condition but having a GMC was new to him. Greg brought the coach in and we went through a list of issues to look into. Greg wanted to invest what it took to make the coach reliable but as many was not looking to completely renovate the coach at this point. I tell new owners to drive the coach right away, be sure it is something that fits your lifestyle before you make costly renovation decisions, owning and maintaining a GMC is not for everyone. You must be able to identify issues as they come up, have contingency plans for many problems and have backup assistance if needed.
So Greg left the coach and his check out list with us, our work load is extremely high and he understood this so he left it with us and gave us the time to do the work. This past Sunday, we scheduled his pickup, we had looked into the brakes, front & rear suspension, engine & generator operation and an overall check out of needed systems. You know, a once around. Anything we found we were to repair or replace. Brake, as an example, are very important to me– I mean stopping a 12,000 pound projectile seems to me to be an important thing so we jacked the coach up and checked pads, shoes, wheel cylinders, calipers, flushed the system and test drove it to prove our work had taken. This happened literally weeks before delivery, then other less important systems were checked out and attended to. OK, delivery came and in the test drive with Greg to the gas station I noticed some fade in the pedal. Checking the fluid levels in the master cylinder (a part we had not replaced) I found the rear well (controls the front wheel system) was low in fluid. The master cylinder was not the style we use but it bleed down well and seemed to operate properly in the initial check out. I’ve seen many different master cylinders used, most seem to do their job and since performance is what we are interested in, the master cylinder was checked out and left in place.
Looking over the front brake system, I saw no leaks or even wet spots so I topped off the rear well of the master cylinder and sent it out. Not far from the shop, Greg went for the brakes and they hit the floor– being an the car business for years, he instinctively pumped on them and got a pedal– this was not a good situation, the worst in my book. He called me on the cell phone and I met him back at the shop. We had performed what I would call a complete brake renew on the rear shoe system but in flushing the system and checking operation had found the front brakes and master cylinder operational so we left them alone looking to keep Gregs repair expense as low as we realistically could.
There were still no leaks in the system and the front well supplying the rear shoe brakes was full but the rear well supplying fluid to the front brakes was again low. How could this be if there were no apparent system leaks? We have seen some retrofit master cylinders have a different piston throw and in the bleeding process have their rear seal tear when the pedal gets bottomed out. This torn seal between the back of the master cylinder may allow vacuum from the booster to suck fluid from the rear well of the master cylinder– this is what we think has happened. Gregs comment was probably true, The master cylinder had been replaced recently”. I had never seen one in that configuration though & I betcha dollars to donuts, the rear seal was torn by the bleeding process.
Point made– yes we went through the brakes and found the wheel cylinders & rubber hoses needed replacing but we found the rest of the system operational and in that the master had recently been replaced, we left it—- and there in rested our error. We assumed that different styled master cylinder would service us well– it did not and the brakes failed. We will now replace the master cylinder, inspect carefully the front brake system and rebleed the system. The brakes are not a weak component of the GMC and when operating properly will flat spot all 6 tires— but it has to be to spec and again without going through the system entirely there is not guaranty. WE are committing to our customers that we WILL create a reliable system which means we MUST go through that system entirely— there is no option.
And if that weren’t enough, while Greg was talking to me on the cell phone about the brake pedal kissing the floor, his alternator light came on— you guessed it, the alternator was checked out and was putting out just fine but it failed while Greg was looking at it. Nothing was done to it and maybe that is the point we need to listen to— if a system is not renewed, expect problems. The alternator will be replaced with a Delco totally remanufactured unit and that should take care of that but I am prepared to totally check out the charging system before I give it a clean bill of health. This is what MUST be done on every system before you can rely upon it. So this is what I say to you, “If you only fix a system to work for today— it will fail tomorrow— fix it to work for tomorrow and it will also work today”. Renew all components in a system and you will have the best chance of having it service you well.
I tell you this and give you just one example to drive home this point. More frustration on repairs on a GMC is caused not because the repair was not done well but because other components not touched in the system also failed shortly after the repair. Spike that gun, do a total job of renovating a system and the fruit will always taste better. Greg and Tika left the coach with us for another week and even though the frustration level was elevated by coming to get the coach and find this issue– Greg understood probably more than most about what happened. Kicking the tire makes you feel better but replacing the master cylinder and checking out the front brakes will probably go further to fix the brakes. So whoever works on your coach, it may even be you, must look at every components and when you find something different expect unexpected results. I know now that I will not let a coach out especially with brakes unless I can personally vouch for every component— what can I say, its just the way it has to be!
Another point, when bringing his coach to us, Andy had his brakes lock up. After they cooled down, he brought the coach on in carefully. So now, do you think we’ll inspect everything on his brakes? He has center wheel discs — well had had them 
until his pad melted– and that’s not all– the rotors took a hit 
, they got so hot that metal is flaking off– then there is the bearings 
that got so hot that they cooked the grease. All of this has to be replaced and I’m talking about all the wheels AND a new master cylinder will go in. Can’t help what it will cost to be able to vouch for the brakes but it will all have to be renewed. Please learn from these examples of brakes and look at every system in your coach in this way. Brakes, to me, are the most important but does that mean that the motor is of less importance? Does it mean that steering and wheel bearings can go unchecked? Of course not and they too must be totally renewed before they can be relied upon. This should be your drive and your goal when working on your GMC.
OK,ok, I’ll shut up now but its a fine line, what we want to do and what we must do to make these classic coaches road worthy. Good luck with your coach, remember, when in doubt— replace it!