I have a problem with my 99 F-800 which has a 5.9 cummins 24 valve in it with an Allison 545 auto. Anytime the motor has to come under more of a load than cruising on flat roads, like driving in the wind or up a grade, I get this awful whistling, whirring, squealing type of sound, and one time the temp gauge rose up and my chk eng light came on. If I back off the throttle a little it quiets down and then quits. I first thought it might be a slipping belt, So I replaced those but that didn't help. After doing some research on here I thought I hit the nail on the head when I found the threads about the restrictor in the heater core nipple from the block causing this sound, but It looks like that has already been taken care of with a new fitting. Could a sticking wastegate actuator be causing this? I also have a tach that jumps around. Does the crankshaft position sensor cause this? It runs great other than that annoying noise, and the tach not functioning. Any help would be greatly appreciated.

 

O.K. Here is what happened this afternoon. Took off up the grade, tach was working fine. Had the accelerator matted, got up to about 45-50mph, then the whirring whistling started. No, its not the normal turbo whine. I said the hell with it and kept it matted. Did about 60 up the grade until it got steeper. Temp gauge was rising (unfortunately this truck only has the crappy gauge that goes from C to H instead of actual temp readings). Got to about the middle of the "normal" range and the Engine Warning light came on. I don't know what it was warning me of? Was going 45 by now after the downshift. Tach wacked out and then read around 1000 (not even close to actual rpm). Peaked out of the grade, upshifted, picked up speed and oddly enough the noise stopped, and engine warning light went off. Even though the wind was blowing head on into me, and I had my foot heavy into the throttle, the noise didn't come back?? Temp still read about middle in the normal range. I turned on my lights and my tach jumped up to about 1500 and held there for the rest of the trip. I haven't gotten a clue as to where in the hell to even start troubleshooting. I could live with the noise, but when the temp rises and warning lights come on I dont like it. Sorry for the long, rambling post. I just want to give as much info and detail I can for anyone interested in tackling this odd situation. If you guys are already tired of me, you can just tell me to shut the hell up and take it to a shop. Thanks. Oh, one more last piece of info. The tach seems to read accurate in the morning until the motor warms up.

 

Just guessing here. Idont know about the tach but could the squealing and overheating have somethig to do with a bad waterpump? Like I said just a guess.

 

Could it be a bad ground? Is the engine grounded to the frame with the batteries and the body grounded to the frame too?
just my .02c

 

Fan clutch?

 

How easily should the fan clutch turn when the motor is cool? It is pretty stiff to turn by hand, but doesnt seem that bad.

 

I dont like the fact that the temp goes through the roof on a stock engine on a probably normal pull up a grade.

I would tend to think the fan clutch just because of the crazy noises that are coming from under the hood. The fan clutch usually has resistance but I can not say for sure if that proves if its good or not, I would think it proves very little but thats just MHO.

Jason

 

If it were the fan clutch, would it only make a belt squealing sound from slippage? The more I listen to it, it sounds more like a whistling type of noise rather than a squeal. I've checked for air leaks around the intake and exhaust but cant find any. Could an air leak even make it overheat?

 

Is the belt squealing from slippage or is the clutch in the fan making all that racket?

The belt has a tensioner on it so it should be nice and tight on its own.

I would think an air leak would show up as a power loss so that doesn't seem to make much sense.

Before this started did you have a certain sound from the fan when pulling hard up hills etc?

The fact that the noise shows up when the temps start rising still points to the clutch fan in my eyes.

The tach certainly sounds like a CPS but I dont like the fact that is shows up when all this other stuff is going on.

 

The tach problem is related to the crankshaft position sensor, and not to the overheating and noise issue. The sensor may be in one of two locations, either mounted on the block like the Dodge version, or mounted on the bellhousing. If it is a block mounted sensor, it is likely just dirty and cleaning will usually bring them around. If it is a bellhousing mounted version it likely has been stepped on by someone working around the engine, standing on the bellhosing, and will need replaced.

The noise and overheating is from the transmission failing to properly pressurize the clutches. There are two types of actuators used by the Allison 545, and you will need to check which one you have. The newest style is fully electronic and dependent on the Allison programming module that talks to the Cummins ECM. If that is the problem, you will need to visit an Allison shop for a diagnostic and fix. The older type of control system is a series of levers and cables mounted to the side of the fuel pump and connected to the transmission. If you have that one, one of the cables is the throttle valve cable and my bet is that is has popped loose or the bellcrank on the engine is loose.

If your truck has the later style, the fully electronic control system, it will be fully drive by wire and will not have a throttle cable from the cab throttle lever either. If it is the mechanical version, you will also have a throttle cable running to the bellcrank for the transmission throttle valve control. If you have the older style, also check the plastic ends of the throttle cable to the bellcrank from the foot feed.

One other thing to check is your shift control unit itself. If you have a retarder, make sure it is releasing properly.

 

The noise isn't really coming from down around the transmission. It actually sounds more up towards the dash on the passenger side. Today I was trying to think about when it actually started making this noise. When I first got the truck in January, it seemed very noisy in the cab from the engine growl. It didn't sound bad, just like a motor working, and the fact that there is no insulation lining the fiberglass hood, or any soundproofing in the cab. Then after probably 2 weeks or so of driving it, one day it seemed to be running quieter. I thought maybe I was just getting used to the sound, but I could defenitely tell a difference when sometimes it ran quieter, and sometimes it would be louder. Well, this is when the annoying whistling sound started every now and then. Now it seems to run quieter all the time, and the whistling happens everytime it has to pull. When the noise started at first it never heated up either. It just started doing that in the last couple of days. Is there any possibility I could have some sort of exhaust restriction? I don't know how to check that other than maybe take the muffler off and run it up the hill to see if it was restricting it or something. How exactly does the wastegate actuator work, and could this be causing the problem maybe?

 

Mine sounds like a jet taking off when i'm in a heavy pull. but no squelling.

overheating could be several things. clogged radiator, sticking t-stat, bad fan clutch, low coolant,dirty radiator on back side, condenser dirty in front blocking air,water pump.

 

For the whistle, if you have a Toys R Us or Wally World nearby, pick up a full case of kid's bubble blowing soap. Then slather the stuff on all the hoses and connections for the turbo, also do both end caps on the intercooler and the top of the intake plenum and the air horn. Start it up and look for bubbles. Once you rule out loose connectors, loose bolts, broken hoses, or a failed intercooler as any air leak candidate then pull the hose from the intake side of the turbo and reach down there with the engine OFF and try and work the turbo shaft, if it moves from side to side or up and down much at all get the turbo serviced.

If you eliminate the turbo and the pressure system, then focus on a compression test. The 800 has a pretty healthy GVW for the 5.9, and when you really work a 5.9 hard and do not follow a careful cool down sequence after a hard pull you will crack the exhaust valve seats.

The other thing to check is the diverter valve on the Allison. The way they manage their hydraulic pressure requires that valve to dump excess line pressure on full torque shifts, and those are done all the time on a rig that heavy. When that valve starts going south it will squeal like a pig when the truck is pulled hard, and drop the line pressure so low that the clutches will start slipping or you get air in the converter. Either of those conditions makes a ton of heat that can cause engine overheating.

Checking your radiator, the intercooler, the hydraulic cooler, and the transmission cooler are also a good idea. Dirt builds up between them and will work like a winterfront and cause overheating. The best way to check is to drop a sheet of newspaper ten inches in front of the cooling assemblies with the front end tipped off, and the engine up to operating temperature. If the fan air flow grabs the paper and pulls it against the radiator you are likely clean.

Also, check your air actuated winterfront shutter controls. If the airmotor conks out it can squeal and fail to open the shutters when it should.

 

Where exactly is the diverter valve and how do I test it?

Thanks