1991 DT360 high pitch noise while driving up hill?

[sundancer]

Hi guys! My small family and I have been traveling cross-country since June in our 1991 International DT360. It recently started making a mid to high pitch noise that only happens when we are driving up hill. The noise is non-existent at all other times. Describing the noise is tough. It's not a squeak or screech really. It's just higher pitch and slightly louder than the normal engine noise. Any idea what it could be? We're not really losing power anymore than usual when it happens.

TIA!

[crazycal]

Is it happening when the temp climbs? It could be your fan belt slipping when the fan clutch engages.

[claydbal]

you hear the turbo. its spins faster as exhaust temps rise.

[rvingoffgrid]

the turbo is controlled by fuel rate, (not exhaust temp. higher exhaust temp does result from increase fuel rate) this fuel rate is highest at full load, such as pulling a hill at wide open throttle. it could be that this noise was always there but until the interior was quiet you didn't hear it. the fan will make a noise any time the fan cuts on, which can be anytime the temp is at set cut on temp.

[tincaneasybakeoven]

whats your exhaust gas temperature do when pulling a hill? what about boost pressure?

[cadillackid]

Originally Posted by sundancer

Hi guys! My small family and I have been traveling cross-country since June in our 1991 International DT360. It recently started making a mid to high pitch noise that only happens when we are driving up hill. The noise is non-existent at all other times. Describing the noise is tough. It's not a squeak or screech really. It's just higher pitch and slightly louder than the normal engine noise. Any idea what it could be? We're not really losing power anymore than usual when it happens.

TIA!

if its a squeal it could be the fan or water pump as some state... however the DT360 has 3 belts driving the fan so you wouldve likely seen issues with your aire brakes or alternator charging... the fan clutch itself could be going bad..

does this sound gradually come on as you start up a hill? or is it pretty much right away when you punch the accelerator to the floor. (within say 5 seconds or so?)

the turbo will make a high pitched "whistle" when you are on the throttle hard, however it happens fairly quickly once you punch it and you get your RPM up a bit...

if you have an automatic transmission (AT545) and you pull a hill hard enough and slow enough that it downshifts 2 gears it definitely makes a whine at full load in 2nd gear..


since this just started it could also be an air leak somewhere.. perhaps an exhaust leak around the turbo or a pinhole leak in the intercooler?

-Christopher

P.S. I just bought a 1991 Carpenter wit ha DT360. what kind of bus is yours?

[tincaneasybakeoven]

Originally Posted by rvingoffgrid

the turbo is controlled by fuel rate, (not exhaust temp. higher exhaust temp does result from increase fuel rate) this fuel rate is highest at full load, such as pulling a hill at wide open throttle. it could be that this noise was always there but until the interior was quiet you didn't hear it. the fan will make a noise any time the fan cuts on, which can be anytime the temp is at set cut on temp.

"such as pulling a hill at wide open throttle." does the diesel engine have a throttle? doesn't a diesel throttle itself by fuel increase and or decrease? i haven't found a throttle on a diesel engine yet and i have looked plenty of times. where is it on your engine?

[johnbloem1974]

by "wide open throttle" or WOT, they simply mean that the accelerator pedal is floored...you can interchange throttle with accelerator pedal

John

[cadillackid]

Originally Posted by tincaneasybakeoven

"such as pulling a hill at wide open throttle." does the diesel engine have a throttle? doesn't a diesel throttle itself by fuel increase and or decrease? i haven't found a throttle on a diesel engine yet and i have looked plenty of times. where is it on your engine?

the throttle would be anything that limits air, fuel, or compression(heat) ion a diesel engine... on a mechanical diesel you are most generally limioting the air.

-Christopher

[Robin97396]

"limioting"? Is that Italian?

[Roadrunner]

I had a truck do that once. It was so long ago I don't remember the cause but it was an intake gasket leaking or something. When the engine was working hard it would suck air and whistle. Check all your gaskets. It could be the air cleaner system. Check the air cleaner and ducting to make sure everything is air tight. Is the air cleaner dirty causing it to suck air through a tiny leak? Check the intercooler system and ducting if you have one. Maybe a turbo gasket? Just check anything that sucks air or builds pressure. Just guessing but I think it is air intake system related somehow. Good luck.

[tincaneasybakeoven]

a diesel fuel pump is a carburetor equivalent. diesel engines are just complicated air pumps. after achieving less restriction on the airflow in and out extra fuel takes advantage of the extra air, and gives extra performance. at least that's what the instructors taught back in 80.

[EastCoastCB]

Originally Posted by Robin97396

"limioting"? Is that Italian?

sounds more french to me

[Robin97396]

We we, monseur!

[jazty]

Originally Posted by cadillackid

since this just started it could also be an air leak somewhere.. perhaps an exhaust leak around the turbo or a pinhole leak in the intercooler?

That would be my first guess. Check all the rubber air pipes running past the turbo on the intake side. Follow through the intercooler. You could try spritzing the pipes and intercooler with a solution of soap and water in a squirt bottle to locate leaks.

Have you noticed a slight drop in power as well?