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Discussion Starter #1 (Edited)
Towing hard, when the engine revs up, the fan clutch is acting strangely.

When the truck unlocks in 6th, or even kicks down to 5th:
1) very high pitched squeal (almost inaudible) and
2) the fan RPMs cycle up and down (1 sec at 3k, then 5 sec at 2.5k).

It is similar to this post:
http://www.thedieselgarage.com/forums/19-2003-2007-6-0l-power-stroke/116734-high-frequency-noise-under-load.html

However, I think it is more fan clutch/bearing/belt related than degass cap leaking. It is very repeatable with the engine RPMs and the fan clutch RPMs. As soon as the tranny locks in 6th again, the sounds immediately stop.

I've posted a video of the problem:
fan clutch wierdness

It's really hard to see and hear what's going on. Turn your volume up really loud. I'm pulling a hill that required me to downshift. As soon as the downshift happens, you can hear the high pitched squeal and then the fan speed cycle up and down.

The dominate sound is the fan speed cycling up and down, but the squeal is there, just so high pitched it might be inaudible to some of you grey beards. :)

Thanks for the advice!
 

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Old Fart
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A lot of things are inaudible to this old fart, but locking up in 6th AND the high pitched sound going away tells me that it is not the fan clutch. That cycles on temperature and not the tranny gear. Have you had the truck scanned?
 

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Discussion Starter #3
A lot of things are inaudible to this old fart, but locking up in 6th AND the high pitched sound going away tells me that it is not the fan clutch. That cycles on temperature and not the tranny gear. Have you had the truck scanned?
I have a scanner, no codes related to this. Have you watched/listened to the video? The fan cycles up and down really fast (1s/5s), abnormal it seems? And the high pitched squeal is painfully loud, if you can hear it. My kids complain, "what's that noise Dad?"

It all *seems* to be engine RPM related. There is obviously fan cooling at lower RPMs, but the fan is spinning faster when I downshift.

Thanks!!
 

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Old Fart
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And the rpms increase when you downshift. You stated that the codes you see in your scanner are not related to your problem. What are the code numbers?
 

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I can't tell what temps are you at?

I had my fan points moved with custom tuning so the pulse is around 210 and lock around 215. It spins around 1600rpm when clutch is pulsed and 3000 rpm when locked at 2k RPM engine speed. The only time the lock struggles is when I have my plow on and RPM drops very low it seems to struggle to lock. My hunch is the clutch fro the plow package locks when the fan is barely spinning from air flow being blocked. I'd guess fan clutch but you may have a bearing going in the tensioner or other idlers. I'd have to imagine that fan spinning at 3000 rpm is drawing 5-6 HP
 
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Discussion Starter #6
I can't tell what temps are you at?
ECT was 210-217 F
EOT was 212-218 F

At 2.5k RPM engine speed, fan cycles between ~2500 (5 s) and then ~3000 (1 s). When Torque converter locks and engine RPMs drop, fan locks solid ~ 1500 when it kicks on, otherwise < 1000 RPMs.

Perhaps the abnormal 5s/1s fan RPMs cycle is my custom tune problem in the PCM. The very high pitched squeal I'm guessing is bearing, clutch, or like you said, tensioner pulley.

Thanks.
 

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From your video, it almost sounds like a dry crank seal sound or some type of bearing noise, really hard to tell without actually being there.

(don't know if this applies to you or not)...in cases of an egr delete, trucks when deleted and the egr valve is also disconnected electrically, the fan won't function properly. Even with a delete you want to keep the egr valve plugged in electrically.

Harry
 

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Discussion Starter #8
From your video, it almost sounds like a dry crank seal sound or some type of bearing noise, really hard to tell without actually being there.

(don't know if this applies to you or not)...in cases of an egr delete, trucks when deleted and the egr valve is also disconnected electrically, the fan won't function properly. Even with a delete you want to keep the egr valve plugged in electrically.

Harry
Harry, I'm getting ready to tear into my truck to fix a sudden hot-oil no-start problem (no degradation; started perfectly with hot oil one day, then not at all the next; after a long haul though).

While I'm in there, I'd like to fix the subject of this thread. It's been doing this all these years. I did my own EGR delete, the EGR valve is still plugged in, but is welded shut. Do you think that could be the problem?

Thank you!
 

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Discussion Starter #9

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Sorry for delayed response, just logged in today...

Hot restart issue is usually high pressure oil system related, either an internal leak in the system like hpop fitting or similar. Can also be a faulty icp sensor or ipr valve. If you have a ScanGauge2 or similar, you can monitor icp & ipr as they work hand in hand. If you have high ipr reading while cranking like 75-85% which means the valve is closed trying to build up the high pressure oil, and at the same time your ipr reading is low like 200psi, then that would indicate an internal high pressure oil leak in the system, it takes 500psi just to start the engine. On your 05" yr model the icp sensor is located on top of the passenger side valve cover, try unplugging it when the symptom occurs, this will set it to a default reading and allow it to start if the sensor is the issue, if still won't start, then you likely have a high pressure oil leak as mentioned.

Harry
 

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Ok, I watched the video, and with pause button was able to focus on your hpop which was hitting over 3600psi, which is good as 3700-4000psi is normal under hard accel or pulling hill loaded. But I could not see an ipr reading.

My truck at operating temp fully warmed up on hot day running 5w-40 oil will see 26% ipr at idle in gear at stop light with icp reading 790 psi, but mine has custom tuning also. But typical 6.0L reading can be 21-22% ipr and 580 psi under same circumstance.

When I accel hard and full boost, my ipr will be only 45-55% and icp 3770+ psi

Need ipr reading (Injection Pressure Regulator %) in order to compare with your icp readings, especially during crank no fire hot.

Also, be sure ficm is healthy too....46-49V

Harry
 

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Man, I'm off track here, just re-read your comment about addressing the original posting issue.

I did watch the video and I'm not sure since your egr valve is still plugged in, but hopefully it's not a low pressure main oil pump issue and related to hot start condition too. Custom tuning can be calibrated for fan clutch operation to be custom too. Rpm's range and harmonics of rotating parts of engine can be one of many part causing this issue. I watch it again and let you know if I come up with something.

Harry
 

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Discussion Starter #13
Thanks. I decided *not* to replace the fan clutch or bearing while I had the engine torn apart to fix the hot no start. We'll see how it goes on the next tow trip.

BTW, the hot no start was caused by the one-piece HPOP fitting o-ring that failed. I replaced the quick connect HPOP fitting 10+ years and 102k miles ago. I *almost* didn't remove the HPOP because I had done that modification all those years ago. But while I was waiting for parts to come in the mail, I decided to remove and inspect. Sure glad I did.

I would attach a picture of the failed o-ring, but this stupid website won't accept the *.jpg picture. It's been shrunk, saved multiple times, rotated. Nothing works. Very helpful error message too : "Upload of file failed".
 
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That one would have bitten hard had you not caught the hpop fitting oring. The payoff for being thorough in inspection & repair is priceless, good job pstrang!

Thanks for the update.

I think were the only 2 left on here :happymugs


Harry
 

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That one would have bitten hard had you not caught the hpop fitting oring. The payoff for being thorough in inspection & repair is priceless, good job pstrang!

Thanks for the update.

I think were the only 2 left on here :happymugs


Harry
Yeah, it's been quiet lately :shrugs
 
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