Sudden loss of power and fan-like whine

[James4]

I need some help on this issue:

Background: About 3 to 4 weeks ago I was doing some highway driving to test out different tire pressures, and I think I got some bad diesel fuel at that time, because the water in fuel light came on, but it went off after a few minutes and has not been on since. I did not worry about this as I just had it serviced by the Ford dealer a few months previous.

Situation: There is a short, but steep hill on one of the approaches to my house. The other roads leading to the top of this hill (ridge) are at most 6 to 7 percent grades of about a mile or so in distance, but this one is steeper and about a quarter mile long, if that. When pulling this hill from a standstill at a red light at the bottom of it, or approaching it going the 35 mph posted speed, the van pulls it easily without lugging, and all is well. However, once the steep part has been pulled, whenever I let off of the accelerator to come to a stop, or slow down to turn into my subdivision, and then press on the accelerator to resume speed, there is a sudden loss of power and a fan-like whine, this fan-like whine becomes much, much louder and much higher in pitch when applying more pressure to the peddle. That said, it does not last very long once the whine has died down, maybe thirty seconds or so, when things go back to normal.

What might cause this to happen? Is it bad gas? Is it a sensor trying to adjust from a stopped position up a steeper than normal, short hill, to having to let off the gas near or after cresting it? What could be causing this?

Hopefully, some of you folks might be able to help me figure this out.

James

[rallypanam]

6.0 experts to the white courtesy phone.

[lugee]

What make and model do you have?

My Dodge does this. It engages the clutch fan when the engine temps get over a certain temperature. Especially apparent at elevation, steep hill climbs, and hot hot days.

[James4]

Thanks rallypanam!

lugee:

Thanks for the post. I have the 2008 Ford E-350 Super Duty 6.0 diesel.

The oil and coolant temp on this run from the time starting up the hill, crest it, go through the problem increases about 10 to 12 degrees above normal operating temps.

James

Added: Lugee, how serious has this problem been for you? I drove this vehicle to Cody, Wyoming from the Seattle area last year with not a problem one.

James

[lugee]

James - Not a diesel guy so I don't know if my response addresses your issue.

It hasn't been a problem for me and I have climbed some steep grades in California. The fan does kick in when climbing up a steep hill or when slowing down (on a hill or flat). For my case, I assume not enough air is getting through the radiator when slowing down or at a stand still. It does the same when sitting in stop and go traffic in 100+ degree days.

I monitor my temps with a Ultragauge and just keep an eye on it when I climb hills.

[JoeH]

Got anything that can read codes? The loss of power could be sticking vanes on the turbo. Not sure about the whine. Do you know for certain it's the cooling fan?

How are you monitoring vitals like EOT and ECT?

[boywonder]

Does the whine sound like the turbo whine?

Radiator fan noise wouldn't cause noticeable loss of power......my (uneducated) guess is that it's turbo related....

[Flux]

That's normal. What is going on is that your turbo is getting hot and at high RPM it cools itself. You let off and the fan kicks in to cool the turbo. It will also do this on extended climbs etc. It can go from a lower pitched sound to very high. No worries, just gun it.

Not exactly sure what you mean by loss of power, if it's momentary that's just the good old 6.0l turbo lag. Not sure if you have a boost gauge in your van, but if you do, look at your boost psi when this loss of power occurs and then watch the turbo spool up and the power kicks in.

I own a 6.0l F250 and the first time the fan kicked in I thought it was all over. The fan will kick in at funny times like after I spool up good and then let off. It kicks on to cool the turbo.

[daveb]

Has it thrown any codes? Sounds like its jumping into limp mode for some reason.

[James4]

lugee: Thanks again!

JoeH: I use the scan gauge and from what I can tell, all of them are okay.

boywonder: I' don't know much about how the turbo whine might sound, but according to Flux, you're right about it being turbo related.

Flux: Thanks, man! What you said makes perfectly good sense. Next time it happens I will not wait so long before giving it the gas! I'll be checking the boost next time I take that hill.

daveb: No codes have shown up at all.

Have a good evening, everyone!

James