3406B Running hot?

[Keith Merrell]

I have a 1986 Freightliner 10 wheel dump truck with a Cat 3406B and 13 speed transmission. I pulled my 20 ton tag trailer up a 6% grade today empty, and it was about 90 degrees outside. I was in 8 low doing 900 on the pyro. Towards the top of the hill, I noticed my water temperature was at 208 or so. (It normally runs about 185-190 when idling or on flat ground) so I backed it down some to keep the temperature from rising any more. I do not have an air fan hub on this truck, just a thermal one. First off, is this normal, second what should I look at first? Thanks in advance, this is my first real truck and I don't know much about them.
Keith

 

[Truck Shop]

When was the last time the core was pressure washed? If it has A/C and Air Charge cooler over time
the core will clog with fine dust. Grain trucks I use to work on would need cleaned twice a year
sometimes. That viscus fan may not be pulling enough air also.

 

[mekanik]

A viscous fan hub has a life expectancy. The very small amount of fluid eventually disappears
and the engine starts to run hotter.

 

[skyking1]

if that fan is working properly you should be able to hear a change when it gets that hot.

 

[Keith Merrell]

if that fan is working properly you should be able to hear a change when it gets that hot.

Thanks, sounds like it is the fan clutch then, because I hear no change and the temp seems to just keep climbing with no stopping it even if you drop gears.

 

[Keith Merrell]

When was the last time the core was pressure washed? If it has A/C and Air Charge cooler over time
the core will clog with fine dust. Grain trucks I use to work on would need cleaned twice a year
sometimes. That viscus fan may not be pulling enough air also.

I made sure the outside of the radiator was clean, is that what you mean? I don't know any of the history on the truck.

 

[Delmer]

NO, the outside can look clean, you can't see the whole outside if there's other coolers in the way, and then you'd have to shine a light from the other side and look through to see how dirty the fins are. One way to check, is to rinse with a garden hose, then spray on some detergent, keep rinsing and repeating. It will run clean for a bit, then you'll hit a dirty spot, and you know it's dirty.

Sounds like the clutch though, if it stays cool enough when moving, but overheats going up a grade.

 

[skyking1]

^good stuff Delmer. I ran a 977 raking up roots on a golf course job, very dusty and they blew that out every week or it would climb on up there. I too think it is the fan but a clean rad and CAC would not hurt.

 

[suladas]

That seems like a high temp for it sitting. Unless my gauge is off mine sits at 170 idling and normal driving if it's not working too hard. I do find on the warmer days like above 85 if it's really working the fan can't keep it cool if pulling up a grade with my 210 on but I am at about 90,000lbs and have to take it easy, seen as high as about 205. I just chalked it up to being older and cooling system not as good as newer stuff, below about 85 it will keep it cool no problem.

 

[Truck Shop]

To properly clean a radiator core externally, A/C denser and air charge cooler has to be removed. And
carefully using a pressure washer {not to close} start at front side and doing your best from back side.
Air charge cooler can be washed as well as A/C denser.

Normally on a viscus fan hub if it's leaking fluid-dust/oil will collect on the front side, check with mirror.

 

[Keith Merrell]

Thanks, I will make for sure the rad and CAC is clean. Sounds like I need a fan clutch though.

 

[Mark250]

Hi after you have checked all of the above.check to see if the water pump impeller is not turning on the shaft.the impeller is a taper fit on the shaft and if not fitted correctly can come loose.
Also there were a batch of water pumps that had a plastic type impeller bonded to a steel hub, when hot the impeller would spin on the hub
Mark

 

[Keith Merrell]

Thanks. I cleaned the radiator tonight with my friends home made radiator gun. Will also test fan clutch and inspect water pump.

 

[Keith Merrell]

Removed fan clutch. Should I replace with a Horton air fan clutch? Also I am assuming this flange is part of the clutch itself as there are no fasteners holding it on.

 

[Truck Shop]

The Horton is a complete unit. You will need a fan solenoid, temp sender, cab switch for manual over ride.
Kind of spendy because you will get hit for no core unless you buy new. Personally I would find a
replacement viscus fan hub and leave it be.

 

[Keith Merrell]

Could I set up the Horton just to be on / off manually? With no sending unit, just the new clutch hub and a cab switch and small solenoid and an air line? And make sure the right nut is behind the wheel?

 

[Truck Shop]

You could yes but does this rig have working A/C? I have known a few that have done that and wished
they had not later on. Only takes one time on a hot day.

 

[Keith Merrell]

No AC doesn't work

 

[Truck Shop]

Well no problem there with a A/C pressure switch. I can't tell you what to do but if it was me I would
wire it up for automatic and manual over ride.

 

[Keith Merrell]

Interested in the Horton because I am having a tough time finding the thermal clutch which is what I want to do, no part number...