Sullair compressor wont stay cool??

[79lance]

I have what is probably a mid 80's model Sullair 185 compressor hooked to a John Deere diesel. It is mounted on my sandblast trailer, but still has its original box on it. Lately it has been running hot it shows. so heres how it goes:
temp guage shows 245! so check rad cap, but not boiling over??? get a laser gun and point in there, and get a 215 reading. guage is bad? so replace it with a new guage, but still shows 245. so i dont know what the deal is???
So next i get to thinking about how the oil cooler is mounted (stock) right against the radiator. but then again, it was made this way, so why would this be a problem all of a sudden??
Next, i notice the fan is pulling air into the box, and not pushing out.. maybe the blades are supposed to be reversed and it is supposed to push out instead?? not sure which way is the proper way for the fan to run since i took it apart once and could have switched it accidently.
my next idea is to order a massive 18" electric fan and mount on the other side of the cooler/radiator to help move a ton of air. would this help? i considered moving the very hot oil cooler but i keep reminding myself that it was made this way, so that couldnt be the problem! any ideas or experiance with this?? thanks!

 

[d9gdon]

The one I was around was in a feed mill and it pushed air instead of pulling it across the coolers.

 

[Delmer]

The stock answer with any overheating is to clean the gunk off the radiator, especially if there's another "radiator" in front of it. One or both have to be removed to clean them effectively.

You may have reversed the fan when you had it apart and that could cause it to overheat because it moves more air the way it is designed. Reversing the fan won't cause it to pull instead of push, but pull less effectively than it would pull the right way. Just look at any curved blade fan to see the way the curve is supposed to be.

How suddenly did the overheating start? Did the air output change any? Can you post the temps of the top and bottom/inlet and outlet of the radiator?

 

[FSERVICE]

lets go back just a bit... was it working perfect & just started running hot? or have you just set it up & its running hot after you took it apart?? it makes a bit of difference

 

[79lance]

The one I was around was in a feed mill and it pushed air instead of pulling it across the coolers.

was it inside a box? mine has a metal case around it, and it seemed wierd to be pushing hot air from inside the box onto the rad and coolers. but that may just be the way it runs. i think i will swap it back, so that it pushes like your saying and see what happens, but i think i may still go with he 18" fan to help it out. thanks for the response!

 

[willie59]

Well, you don't want to point the lazer gun at the radiator cap, you need to point it on the engine where the temp sensor is, you could have a faulty temp sensor. Also, are you certain the radiator isn't covered with dirt/debris restricting air flow?

 

[ttazzman]

diagnostics arent that difficult...

#1 is it actually overheating.......i personally like to take temp at radiator inlet....laser gages are notorious for being OFF i always shoot a known temp first to make sure its reading right ...

#2 if it is actually overheating......first stop is air flow(fan,debris etc)......second stop is water flow (themostat, pump, etc).....3rd step is engine/work/mechanical heat (engine generating excessive heat, excessive load from compressor, bearings etc)

 

[lantraxco]

To restate what Delmer said, putting a fan on backward will not reverse the direction of the air, it will only cause it to be inefficient as hell. Fans that are designed to reverse from push to pull and back again are built so the individual blades will rotate thus changinng the angle of each blade by about 90 degrees and reversing the air flow.

Ran into a CAT dozer once that was heating badly.... inspection revealed that some joker had reversed every other fan blade, poor fan couldn't make up it's mind. Turned it into a push-me-pull-u.

 

[79lance]

diagnostics arent that difficult...

#1 is it actually overheating.......i personally like to take temp at radiator inlet....laser gages are notorious for being OFF i always shoot a known temp first to make sure its reading right ...

#2 if it is actually overheating......first stop is air flow(fan,debris etc)......second stop is water flow (themostat, pump, etc).....3rd step is engine/work/mechanical heat (engine generating excessive heat, excessive load from compressor, bearings etc)

Thank y'all for the responses. I'll check my laser and see if it is correct. Still may not be very accurate tho. It has always got hot in the summer, but just after a few hours of run time. However, after taking it apart it gets hot in about 45 minutes. I did just wash the radiator out, it looked decently clean, but a good flush may be necessary. I think I will turn the fan around and see what kind of difference I get, but it still was overheating gradually before the work I did on it. Maybe a good flush of the rad and a big electric fan after swapping the fan back?

 

[Nige]

If you have an oil cooler mounted across the front of the radiator I would bet money that if you remove the cooler you will find the radiator behind it (where you can't see) totally clogged with debris. That's where I'd start.

 

[79lance]

I'll definitely check behind the cooler for debris. I also forgot to mention that I did a test the other day. Waited till it was up to about 200 and began spraying the rad with a water hose and it stayed cool. So that probably my eleminates the circulation problem possibility

 

[kshansen]

Ran into a CAT dozer once that was heating badly.... inspection revealed that some joker had reversed every other fan blade, poor fan couldn't make up it's mind. Turned it into a push-me-pull-u.

Do not have to reverse everyother one, just one will cause an overheat, had that problem on a
Cat loader many years back.

To get to the real question here as others have said be sure you actuallu have a problem before trying to fix it!
If you can confirm there is a problem as Nige says very good chance there is dirt build up between the rad. and cooler. Not too hard to believe a sand blast out fit would be getting dirty!

 

[icestationzebra]

LOL. A friend of mine calls them random number generators because people get so many bad readings!

First, infrared temperature 'guns' will not accurately read any chromed, plated, metallic painted, liquid metal, or other highly reflective surface unless you change the emissivity setting, but to do that you have to know what the correct value is. ( essentially a large portion of the IR energy is reflected back inside the part) Fortunately the emissivity value for most other materials is about the same, so the the default setting will be very close.

if you have to measure a shiny part there is a workaround. Either paint it or put some tape on it, then you will be measuring the temp of the paint or tape.

Secondly, realize that the farther away from the gun the bigger the measuring area. I often run across people who think they are only measuring where the laser dot is, but that is not true. Most guns have a little diagram on the side or back that tells you how big of an area you are measuring at a given distance. For example, at 2 feet you are probably measuring a 4" circle.

And dont point at an item with the sun in the background.
ISZ