| Author |
Message |
Ray Johnson (Rayj) (209.50.10.47)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 10, 2001 - 4:10 pm: | |
I have a couple of questions reguarding our 4905GMC with an 8V71 and would like some inputs. 1. steering-this coach has steering assist(long hydralic cyl) warn parts have been replaced and steering seems tight but when correcting it oversteers. Its not too bad on concrete but grooved blacktop roads make it a real chore to drive. will sheppard steering solve this? 2.Engine temp-when weather is cool temp runs in normal range.When outside temp is 90 or more engine temp runs in bottom of red on guage. Have seen no steam or boiling but it bothers me. Buzzer has been disconected for this reason. Air scoop has been added but did not seem to help much. |
Geoff (206.173.202.212)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 10, 2001 - 8:09 pm: | |
You need to check your toe-in: too much toe-in makes your bus "dart" when you turn. 1/16th" is stock, some go 1/8th", but you may wear your tires out funny if you go too far. I just had my bus aligned after replacing the king pins and bushings and it drives great!
"Bottom of red" is not telling us much (or if it is right)-- do you have a regular temperature gauge in the engine compartment that gives you a number like 100-240 to check it against? Personaly, I would put a regular marked gauge in the dash that gives temperature readings instead of a red area so you know what you are dealing with. If it is overheating it could be any number of things, but I don't want to scare you before you know how hot it is actually getting, so get an accurate temperature reading first! |
James Stacy (Jimstacy) (166.72.161.27)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 10, 2001 - 8:30 pm: | |
Ray,
The hydraulic assist(and to a greater extent the air assist) require an initial movement of the wheel to operate the control valve before the steering can take place. Play anywhere from the steering wheel to the tire can aggravate the situation. The steering column, miter box and shaft drive to the steering box can be problems. The support bearing for the shaft through the bulkhead can be a problem, as well as toe-in. The Shepard box will only correct the valve play problem. When it is all done right the coach will drive like a new car.
Temp problems can be caused by a lot of factors, but the GM is not a chronic problem. Has someone removed the fan shroud, for example. We need more info.
Jim Stacy |
Buswarrior (Buswarrior) (64.12.105.53)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 10, 2001 - 10:10 pm: | |
2 things:
I'll echo the toe-in issue. Easiest and cheapest one to start with.
On the overheating:
AARRGGHH!!!!
Disconnecting the alarmstat (the overtemp sensor) isn't one of the brighter things to do. How will you know when you have a critical meltdown happening? Thermostat stuck? Rad hose burst?
I guess when it seizes.
The usual configuration that one finds on many, many coaches is: an alarmstat in each cylinder bank wired to the light and buzzer, a sensor leading to a dash mounted temp gauge(and some folks have added another one so they have one per bank), and a mechanical temp gauge in the engine compartment(when all else fails, the mechanical one usually tells the truth, and lets you know what "normal" is on the electric gauges on the dash).
The idea behind the redundancy is that, as long as you keep the three systems maintained, you will always be able to know if it is overheating. Overheating is BAD and should be avoided, unless you have money to burn on unneccessary engine rebuilds.
Now, with the temp outside over 90 degrees, you will see a lot of coaches running their temp gauges a little higher than "normal", especially if they are trying to top gun a hill, but should not overheat, unless there is some deficiency in the cooling system ie: plugged rad, low water, missing fan shroud, failure in the fan system, mismatched cooling parts after an engine swap, and so on.
I do not recall that the GM coach in this case has any design deficiencies that would cause an overtemp when in proper condition.
Please take note that "misters" are sometimes added to compensate for cooling system deficiencies instead of fixing the system. If the rads and the rest of the cooling system are in proper condition, and properly sized, they are not necessary.
(No flaming folks! I'll acknowledge that misters will get you by after stuffing that high heat 500HP 8V92 with automatic transmission into your older MCI, etc when there isn't space for the above noted properly sized cooling system!!!)
I wouldn't want to have any newbies "figuring out" what not to do!
happy coaching!
buswarrior-MC8-ON |
Steve Fessenden (63.27.88.181)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 10, 2001 - 11:59 pm: | |
BAB Steering Hydraulics in California told me that if the servo (ram) for the power steering system is rebuilt with seals that are too tight the steering will be squirrelly. It is supposed to have a small leak across a cheap looking plastic seal from Vickers. They said if someone looks at it and decides they can make a better seal and makes it perfect the steering becomes squirrelly. Unless you had the ram rebuilt, though, that's probably not the problem. If it is fixed right, a 4905 steers beautifully with the original system.
Steve Fessenden |
RayJ (209.50.10.52)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 11, 2001 - 2:18 pm: | |
I want to thank everyone for their prompt replys.This gives me some ideas to think about.Here is additional info. Front tires were replaced new and was alligned. After roadtrip bus was alligned again by truck shop that I have faith in. This was done according to manual and was an improvment but is not the answer. As I stated before mechanical parts seem tight but if steering needs to be corrected wheel has to be turned to far to get action and then goes to far the other way. I do need to find actual engine temp when guage shows in the edge of hot.This wont be until June when outside temps warm up. Bus is now sitting low to the ground in A snowdrift..Thanks RayJ |
FAST FRED (209.26.87.66)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 12, 2001 - 5:34 am: | |
I'M not sure how different the dash of a 4905 is from a 4106 but I purchased VDO gages from Summit Racing and the temp gage is right on.
The VDO is a tiny bit too small for the GM mounting hole so I used a single black insulated wire , bent and crazy glued behind the VDO bezel to make the bezel larger.
Not noticable at all, might even shock mount the gage a tiny bit.
The VDO oil pressure matches , and although not near as accurate as the temp gage does its job.
Purchase the senders with the gage , oil can use the 0-80 sender setup.
FAST FRED |
Chuck Harris PD4104 (207.172.52.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 12, 2001 - 8:28 am: | |
As a veteran of driving vehicles with lots
of play in the steering, All I can say is you
have to drive with a little "finesse".
You don't just point the steering wheel where you
want to go, like you can with a tight new
sports car, you kind of nudge and return to
center, nudge and return to center...
Hold the wheel loosely, and make minor corrections
and return to center, and the bus will drive as
smooth straight and stable as can be.
-Chuck |
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