Cooling issues- Help!

[rffffffff]

Dt466e 2002 front engine flat nose.

Engine had inframe rebuild, reman head from international, new water pump, boiled out radiator and new thermostat.

My first cross country trip from ny to nm...

So my bus is getting hot, especially on hills, to the point that the overtemp light turned on to my horror. I immediately pulled over and idled it down, less than 30 seconds with the light on I think but completely unacceptable.

I had to drive based on the temp gauge more than anything else, almost as if I just don’t have enough cooling capacity. Hills were down to 25mph at some points because I could rev over 1900rpm without the gauge starting to climb. I had more than enough power but couldn’t use it at all. It cools off very fast when i coast down a hill at 65mph but I’m wondering if this is normal or if I have a bad fan clutch or how these busses cool.

So, is this normal? I’m thinking of adding an electric fan in front of the radiator for additional air flow for the return trip but I’m pretty diesel clueless and I’m trying to sort out how it should be before I go crazy.

All thoughts are appreciated.

[Gustav]

Check coolant level?

[rffffffff]

It’s full, I checked a couple of times along the way.

[Gustav]

Does fan increase speed along with temp? Bent radiator fins? Too many bugs? Just spitballing here.

[rffffffff]

The radiator looks good to me. I don’t know about the fan speed because it’s hard to see on a front engine bus. I’m gonna take the covers off and see if I can identify a physical problem.

Am I correct in assuming this is not normal behavior?

[Kubla]

Can you hear the engine fan running, if not you have a bad clutch, the fan is pretty loud when running at speed

[Danjo]

Is this the first time out since the work was done?

Air in the system?

Thermostat in backwards?

[rffffffff]

I can see the fan moving and speeding up a bit at idle when it’s cold. I’m assuming if I let it heat up and shut the engine down the fan shouldn’t spin by hand? Any idea how hot the clutch needs to be?


Sorry for duplicate post

[rffffffff]

I’ve run it around a bit but not for hours and hours. I think the thermostat is okay based on it warming up and usually staying at the same place after a while, but I wouldn’t know how to rule that out. It was fine for like 5 hours on flat ground and I think it would be worse if that was the case. After 40 hours of driving I think the air would work itself out? Not sure obviously.

[rffffffff]

I can see the fan moving and speeding up a bit at idle when it’s cold. I’m assuming if I let it heat up and shut the engine down the fan shouldn’t spin by hand? Any idea how hot the clutch needs to be?

[Johnny Mullet]

Sounds like a fan clutch to me. You should be able to hear that fan roar at road speed.

[Danjo]

Originally Posted by rffffffff

I’ve run it around a bit but not for hours and hours. I think the thermostat is okay based on it warming up and usually staying at the same place after a while, but I wouldn’t know how to rule that out. It was fine for like 5 hours on flat ground and I think it would be worse if that was the case. After 40 hours of driving I think the air would work itself out? Not sure obviously.

Thermostat pic. Do t know if it can be installed backwards in that engine, but a backward tstat will make the engine run hotter.

[rffffffff]

Should it be easy to hear the fan engage and disengage? I hear it running but I don’t think I ever heard it really roar. I have a feeling it’s toast too but it feels fine based on googling that.

They’re not cheap and it’s hard to replace I think on the front engine bus so I May try an electric fan to see if it makes it better before spending the $400 that they seem to be.

[rffffffff]

It was done by the international dealer so I kinda doubt that it’s backwards. I’m working on the fan clutch theory first!

[Danjo]

Originally Posted by rffffffff

Should it be easy to hear the fan engage and disengage? I hear it running but I don’t think I ever heard it really roar. I have a feeling it’s toast too but it feels fine based on googling that.

They’re not cheap and it’s hard to replace I think on the front engine bus so I May try an electric fan to see if it makes it better before spending the $400 that they seem to be.

Can clutch test (carefully!)

https://www.bimmerforums.com/forum/s...an-clutch-test

[o1marc]

Originally Posted by rffffffff

Should it be easy to hear the fan engage and disengage? I hear it running but I don’t think I ever heard it really roar. I have a feeling it’s toast too but it feels fine based on googling that.

They’re not cheap and it’s hard to replace I think on the front engine bus so I May try an electric fan to see if it makes it better before spending the $400 that they seem to be.

If you've never heard it properly turn on before, you'll know it when it does, it's quite a bit louder and obvious, you'll think something went wrong. I doubt you'll find an electric fan big enough or strong enough for this application.

[rffffffff]

So strange... I’m isling to get it hot... and it’s not getting hot after 20 minutes still. I revved the engine to warm it up faster and the temp went down and it’s only indicating 165 maybe, like the thermostat was open prematurely. The fan blows a good amount of air into the bus with the engine cover off... it seems like it increases flow with RPM reliably even though it’s cold. I may have to pull the thermostat to check it out... I’ll wait longer to see if i can idle it up to temp and see if I hear a fan change.

[o1marc]

Originally Posted by rffffffff

So strange... I’m isling to get it hot... and it’s not getting hot after 20 minutes still. I revved the engine to warm it up faster and the temp went down and it’s only indicating 165 maybe, like the thermostat was open prematurely. The fan blows a good amount of air into the bus with the engine cover off... it seems like it increases flow with RPM reliably even though it’s cold. I may have to pull the thermostat to check it out... I’ll wait longer to see if i can idle it up to temp and see if I hear a fan change.

I doubt you'll get it hot enough in the driveway to turn that fan on.It comes on before it overheats and you'll never get that hot at idle unless you have other overheating issues. When I was pulling the first hill that got it hot enough to turn the fan on , it was a rude awakening. But doesn't come on till about 225-230*.

[rffffffff]

Okay, that’s great info. I’ll go for a cruise in the hills tomorrow with the engine cover off. Nothing seems amiss here, I think the temp drop was likely the thermostat opening after playing more.

[Danjo]

You could have a thermostat sticking open. If it’s stuck open it will run cool for a while and then get hotter and hotter, the coolant never staying in the radiator long enough to cool down.