DT466 cooling issue

[alexzckary]

I have a 96 DT 466 mechanical and I was out on a trip this past weekend and the alarm went off saying the engine was too warm. I don’t run this bus a lot, but last year replaced the leaking radiator. I also replaced the old thermostat for good measure. I heard the cooling fan kick in but only if I sat at idle for a couple of minutes.

I have 2 possible culprits.

When I replaced the thermostat, the stock was a 180 degree one. I could only get a 190. So is that why the fan is not kicking in?

Or I am wondering if I can replace the cooling fan with this one and set the temp lower? Here is the link.

https://vanderhaags.com/detailview.php?part=24863513

Let me know what you think is the problem!

[Mountain Gnome]

Originally Posted by alexzckary

When I replaced the thermostat, the stock was a 180 degree one. I could only get a 190. So is that why the fan is not kicking in?

If you are talking about the round coolant thermostat that controls the flow of coolant in the motor, then no, that would not cause the fan to "not kick "in.


Many things can cause you to overheat. We need more info.


If your coolant level low now?

[alexzckary]

Bus has plenty of coolant, but it seems to loose some because every couple of weeks I have to top it off. No leaks, just think the water evaporates?

[bus-bro]

Have you pulled an engine oil sample?

[alexzckary]

I have not... what will that tell me? I had just changed the oil right before this trip.

[rensch26]

If you're topping off the coolant every couple of weeks you either have a leak in your coolant loop or in the heater loops. Or worst case scenario is you have coolant leaking past the cylinder liner o-rings and into your oil pan. If you perform an oil analysis they'll be able to tell you if you have coolant in the oil. If the leak gets bad enough you'll be able to tell yourself by just looking at it.

There could be other possible leaks within the engine but your cooling system would more than likely be pressurized and blowing off the cap on your coolant reservoir tank.

[alexzckary]

So how do I do that oil sample? Also is that super crucial that I do? When I changed the oil, it wasn’t really dirty or gritty, looked normal based on other oil changes I have done. Is this really gonna help me fix my problem listed above? I’ve had the bus 3 years and it’s always have seemed to do the coolant thing, even when I bought the bus. They said it “blows it out” if that helps.

[cadillackid]

im not sure I would ever buy a used fan clutch.. start new withy kit-masters.. you can get the OEM part number from the dealer and kit-masters can cross it over.. you can adjust it down.. the 190 engine thermostat shouldnt hurt.. if you trigger the "im too hot" alarm you hit 225-230 (dangerous) so your fan shouldve been blazin..



now that said with a viscous clutch.. your fan wont engage if the coolant is too low as the fan clutch measures the radiator air temp.. if that air temp is not hot enough (due to low coolant, stuck thermostat, clogged radiator fins with debris, broken fan shroud) then the fan wont turn on regardless of the clutch...


make sure your cooling system is tight, kept full, no air bubbles, and the radiator fins are clear..



if the thermostat is sticking partially you'll have your temperature going up very quickly to overheat condition.. bad fan clutch or clogged radiator fins results in a slow rise till it over-heats

[bus-bro]

If you have changed the oil and you have put some miles on your bus since the oil change an oil analysis could tell you if you have even a slight amount of coolant in your oil, and it will tell you a lot more than that about the health of your engine. You can also do a combustion gas leak test on the coolant to see if you have that issue.

[Drew Bru]

Originally Posted by alexzckary

So how do I do that oil sample? Also is that super crucial that I do? When I changed the oil, it wasn’t really dirty or gritty, looked normal based on other oil changes I have done. Is this really gonna help me fix my problem listed above? I’ve had the bus 3 years and it’s always have seemed to do the coolant thing, even when I bought the bus. They said it “blows it out” if that helps.

We sent ours to Blackstone Labs, it cost like 30 bucks. IIRC, they'll send a bottle in the mail with a prepaid mailing label, and a pump if you want to buy one. Send the oil sample in and in a week or so they'll email you an analysis with their recommendations, if any. This can help tell you the health of the engine and whether there's bearing wear, coolant in the oil and whatnot. There's other labs too, this is just the one that we used.