Hot day driving, feels sluggish, oil pressure dancing around, and the temperature alarm starts to go off! My response was to slow down, manage revs in reasonable range, go easy on rises, and talk nice to the wee beasty since we only had about 5 miles to go.
First check today was to remove radiator cap and add water ( just in case it was low) and it took very little. Started it up and idled it for about half an hour until temperature got to about 180. As this was happening I was checking the components to see what got hot. Hoses into fill box beside radiator eventually got warm. The large pipe from top aft end of engine started getting warm/hot. Radiator fans were turning. The largest pipe from the bottom of the radiator remained cool (as in no fluid passing through) throughout. I then replaced the radiator cap and headed to the Forum.
Among the possibilities are; an airlock in the circulation system, a need for a replacement water pump, an need for a replacement 'internal by-pass plug', or a need for a new thermostat. Any others??
First thing I need is a way to diagnose the problem rather than throwing parts at it. Recommendations?
Found this on Beamalarm.com
Coolant Temperature Troubleshooting Flowchart (http://beamalarm.com/Documents/coolant_temperature_troubleshooting_flowchart.html)
Probably not very useful, now that I look at it...
Random ideas:
Is the water pump pulley turning?
Any water leaking from the water pump "weep hole"?
Any weird sound coming from the water pump?
Is the oil level OK in your hydraulic fan pump oil reservoir?
How long since you changed the filters in the pump reservoir?
Any coolant leaks evident below the radiator?
T stat not opening. Use the heat gun and see how far the heat travels into the radiator. Just the top hose hot, without warming the bottom hose, means that the Stat is closed.
If it where me I would wash the radiator and change air cooler out carefully with a water hose from the motor side if you ca get to it . If the thermostat has not been replaced recently I would replace it with the proper one from Cummins based on your engine number. Thermostats are wear items. Then go from there. You will need to drain a bit of coolant to change it. Likely you will need to drive the coach to get the thermostat to open.
Try blowing the radiator out with air,may be dirty,do you not have a overflo tank,if you do you should see alevel in it,no need to remove cap.Is engine oil level good,is the valve by the coolant filter open?,is the air filter clean and not plugged.How many miles on the engine oil?Could you possibly need a valve adjustment?Take the intake hoses off the turbo and see if it spins freely.
Is this something new? Has your temp gauge been normal or any unusual readings on hills, flat, etc? What is "oil pressure dancing around"? When did you last check the engine oil level? Oil pressure may be low at idle but should be stable at anything above idle. Are you sure you don't have a dash gauge problem? Possible bad ground. Fan not going to the high speed position?
Yes, shoot the piping/radiator with an IR gun to make sure you really do have a overheating problem. What altitude did this happen? What kind of driving, hills, long grade, flat, etc. Did it cool when you slowed down?
Best to included numbers with your posts for temp, oil pressure, anything that might seem out of the normal.
Pierce
That engine has 2 thermostats. Easy to replace, you don't have to drain too much coolant. I would start there. When you add the coolant back in leave the filter loose and when the coolant starts to flow out the filter tighten it and complete the fill. This eliminates air pockets.
At 203 degrees the thermostats completely open and the fans run on high. The temp should immediately start to come down.
If you added coolant to radiator, why don't you have an over flow chamber? That's where the coolant should be added.
Some of the 8.3 only use one thermostat,go by your serial number.
Best to use your engine serial number and the Cummins Quick Serve.
Ours only has one thermostat. ('94 - 8.3 )
Doesn't really matter. I would replace the thermostat(s). Once the housing is off, you'll know. Mine has 2.
woody- you might pull the water pump and make sure that the hose behind the water pump is not collapsing from the suction. The hose should have a support wire coil in it. My hose was replaced but the mechanic did not put the wire coil back in it over time the hose separated blocking the coolant flow. I had this issue and it caused total engine failure. Steve
So far I have replaced the coolant filter (and only after I had scrambled to screw the new one in did I discover the stop-cock tab on the fitting just in-board of the filter, that would have saved bit of coolant.! I am going to be really smart after I am done with fixing one system or another on this wee beastie!).
Hydraulic tanks are full. Water pump pulley turns nicely .
Next step is t-stat(s).
Along the way I also checked the air filter and was concerned with the dust and debris bits I found inside. The outside of the filter seemed clean - so it has been doing its job! Next week I will replace that (has been in place for 3 years).
Saw a sign in a shop the other day - "If you don't schedule time for maintenance... your equipment will do it for you". Seems pretty wise.
Reseach your air filter on the forum and make sure which one you have,some of us have the one that filters from the inside so the
outside will look clean,check your housing for a part number,should be a Donaldson housing.
Put your serial number into cummins quick serve and it will have a drawing with part numbers for thermostat, seal, and housing gasket. When I went to local Cummins parts counter he did not order the seal or gaskets. I called after discovering no gaskets and was told they don't use seal or gasket. Not true. The seal was stuck inside the housing on mine. My late 1997 6TA C8.3 325 hp had a single thermostat. I needed two gaskets. Thermostat change improved my cooling. Also did a coolant flush, washed down radiator and charge air cooler. Recently replaced hydraulic filters. Just crossed the continental divide and max temp was 200/205 but held 190 for most grades. I did drop down a gear to spin water pump a little faster on the longest grade. Really enjoying an operational retarder going down. I was running dash AC since generator is leaking coolant.