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Old 04-26-2015, 08:25 AM   #1
Mini-Skoolie
 
Join Date: Mar 2015
Posts: 26
Year: 1991
Coachwork: Thomas
Chassis: Saf-T-Liner
Engine: RE Cummins 5.9
Radiator cap Cummins 5.9

Hey all, driving home we found out the radiator cap was not included on my 1991 Thomas saf-t-liner. Anyone know a comparable cap? The guys at the auto store are no help. Waiting on you!

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Old 04-26-2015, 08:44 AM   #2
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Year: 1992
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Rated Cap: 72
Oh god, here we go again.

Nat
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Old 04-26-2015, 09:45 AM   #3
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Location: Dowdy Lakes, Colorado
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Year: 1989
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Rated Cap: 87
Probably a 10 pound cap. I'll look tomorrow and see if there's a part number on the caps at the lot......
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Old 04-26-2015, 10:26 AM   #4
Mini-Skoolie
 
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Quote:
Originally Posted by M1031A1 View Post
Probably a 10 pound cap. I'll look tomorrow and see if there's a part number on the caps at the lot......
A fella from Napa found the part... Now to figure the next hurdle
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Old 04-26-2015, 12:33 PM   #5
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Year: 1991
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So I am trying to diagnose the overheating issue, it seems to me that the radiator fan isn't running. When I turn on the vehicle it spins for a moment and then turns off. Any ideas?
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Old 04-27-2015, 01:06 PM   #6
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Usually the fan is controlled by an in-line sensor that trips when the temperature gets warm enough and the thermostat opens up. So either the sensor is going bad, the thermostat is not opening up, or the water pump impellers are rotting out and a new pump is needed. Those are the three options. Take your pick.
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Old 04-27-2015, 01:34 PM   #7
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Quote:
Originally Posted by M1031A1 View Post
Usually the fan is controlled by an in-line sensor that trips when the temperature gets warm enough and the thermostat opens up. So either the sensor is going bad, the thermostat is not opening up, or the water pump impellers are rotting out and a new pump is needed. Those are the three options. Take your pick.
Thank you I will try to locate and check these things.
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Old 04-27-2015, 01:36 PM   #8
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is it a hydraulic fan?maybe fluid is low or bypass is bypassing?
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Old 04-27-2015, 01:44 PM   #9
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Originally Posted by bansil View Post
is it a hydraulic fan?maybe fluid is low or bypass is bypassing?
I'm not really sure how to tell. When I go to work on it tonight I'll take pictures and a video of what it does.
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Old 04-27-2015, 04:58 PM   #10
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Bansil,

Do you mean a thermal clutch fan?
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Old 04-27-2015, 05:50 PM   #11
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I am going to make some assumptions here.

First, you have a Saf-T-Liner RE with the engine in back.

Second, if you do have a rear engine bus the radiator is mounted 90* to the engine in the side of the bus.

If those assumptions are correct the fan is operated in one of three ways.
  1. Fan belts turning a jack shaft that turns the fan
  2. Fan belts directly turning a fan
  3. Fan is hydrostatically driven by oil pressure from the power steering pump or automatic transmission.
In all three cases the fan is thermostatically controlled to only turn on when it reaches a set temperature, the exact temp I don't recall.

Some of those are pretty basic and easy to find Horton units.

The hydostatically driven fans were Thomas OEM units and not quite as easy to find.

On most rear engine buses the health of the water pump will have little to do with the operation of the radiator fan.

You can override the fan's thermostat by welding together the inner and outer rings of the fan drive. The down side is the fan will be operating 100% of the time. And it is critical to make sure the welds are balanced or the bearings in the fan shaft will be ruined fairly quickly.

I have seen quick fixes that have worked to get someone home. Two or more automotive electric fans were installed to move air throught the radiator. Depending upon where you will be driving and how fast and hard you drive will determine if the quick fix can become a permanent fix or not.

Good luck and I hope you keep your cool.
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Old 04-27-2015, 06:59 PM   #12
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Quote:
Originally Posted by M1031A1 View Post
Bansil,

Do you mean a thermal clutch fan?
Nope, #3 of Cowlitz mentioned it



If you watch temps 3 or 4 electric fans might work if you can mount them the right way, if she can hit a lick at ambient temperature then being too cool for the ride home will be okay, just change oil if it looks like moisture will be an issue

Just remember you will be pulling a lot of amps so keep bus running and use appropriate wire for the load
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Old 04-27-2015, 07:38 PM   #13
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Ok heres some pictures











and a video of starting the engine, the only time the fan spins.

http://youtu.be/axIRxDnvQ4Q
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Old 04-27-2015, 09:57 PM   #14
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Like already mentioned, that is a hydraulic motor run off the power steering pump. The power steering pump is really a hydraulic pump.

The fan that this hydraulic motor runs moves some serious air. I would try to repair the system back to working order without trying to alter it.

Any time you start building custom, it takes time and $$.

Now I have the same bus. I'm going to look it over and see where the sending unit is to trigger the fan to come on. Also make sure the big power steering reservoir is full. That thing needs oil to turn, and I see a massive leak coming from some where in your pictures.

To use electric fans you would need to wire a second alternator to a complete separate DC system. This would make the power needed at the duty cycle needed to keep up to the massive electrical draw.

It's not uncommon to see each 15 inch fan draw up to 30 amps. 4 x 30 amps = 120 continuous. Most alternators are only rated for a small duty cycle. In short, if they spend to long at full output, they burn up in a short time.

Nat
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Old 04-28-2015, 09:42 AM   #15
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Quote:
Originally Posted by nat_ster View Post
Like already mentioned, that is a hydraulic motor run off the power steering pump. The power steering pump is really a hydraulic pump.Nat
The power steering is not working. or at least doesn't feel like it is

Quote:
That thing needs oil to turn, and I see a massive leak coming from some where in your pictures.
Does the power steering need to be under pressure? because the dipstick in the power steering reservoir does not latch properly (it appears to be where you load fluid as well, but has a dipstick on the end). It was on my to replace list but perhaps this is the issue. This may also explain the oil leak (it says to use w10-30 for power steering fluid).

When its not raining all day long ill go out there and take pictures of the power steering apparatus. Given what I've seen in these post it seems likely its at least involved in what going on. The power steering setup is pretty grimy right now.

On an unrelated note when the tow truck driver was disconnecting the drive train to tow the bus he told me the "u-joint" was damaged and the bearings were scoring whatever the u-joint connects into. He said I should replace this part. Given I'm a noob where does one acquire this? My google searches have proved fruitless.
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Old 04-28-2015, 10:42 AM   #16
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If the power steering AND the hydraulic fan motor aren't working then there's a good chance your power steering pump isn't working. Does it squeal or make any other awful noises when spinning?

The reservoir for the power steering fluid isn't under pressure. The cap is there to keep dirt out, not keep pressurized fluid in. In fact, I think it needs to breath since the fluid will expand when warm.

How was the fluid level, anyway?
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Old 04-28-2015, 10:45 AM   #17
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Year: 1991
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Quote:
Originally Posted by jazty View Post
If the power steering AND the hydraulic fan motor aren't working then there's a good chance your power steering pump isn't working. Does it squeal or make any other awful noises when spinning?
I cannot turn the wheel while stationary, at least not much, and I hear no noises when turning the wheel.

Quote:
How was the fluid level, anyway?
When I got it, empty, it has a quart which is all I put in being ignorant of how important power steering is on a bus...
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Old 04-28-2015, 10:51 AM   #18
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Quote:
Originally Posted by Kathos7 View Post
I cannot turn the wheel while stationary, at least not much, and I hear no noises when turning the wheel.



When I got it, empty, it has a quart which is all I put in being ignorant of how important power steering is on a bus...
ouch.. a hydraulic pump that has been running dry is usually a dead hydraulic pump.
The initial problem was that the system was leaking. Letting it run dry has likely made the problem considerably worse.
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Old 04-28-2015, 11:35 AM   #19
Mini-Skoolie
 
Join Date: Mar 2015
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Year: 1991
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Chassis: Saf-T-Liner
Engine: RE Cummins 5.9
Quote:
Originally Posted by jazty View Post
ouch.. a hydraulic pump that has been running dry is usually a dead hydraulic pump.
The initial problem was that the system was leaking. Letting it run dry has likely made the problem considerably worse.
I take it the pump is part of the large power steering reservoir? so i'd be replacing the whole thing?
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Old 04-28-2015, 12:13 PM   #20
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Rated Cap: 36
C'mon man.. Follow the hydraulic lines! It's a loop. I would guess that the reservoir is separate from the pump. The reservoir will have a line leaving from (probably) the bottom of it to the pump, which is driven by the belt on the engine. The pressurized line from the pump probably goes to the steering system first, or the brake boost if your bus has hydraulic brakes, then to any other auxiliary systems like the fan motor, then back to the reservoir.

Poke around. Follow lines. Read up on power steering systems and hydraulic systems in general. Become very well acquainted with this system as it sounds like you have some work ahead of you. Or pay someone to fix it
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