High pitch whine

fatboy1 · Nov 22, 2009

We have a 06 columbia, when pulling a hill with decent load or a long grade, when truck downshifts, we hear a whine that sounds like coming from turbo area any suggesrions or has someone had this prob. Before, fuel economy has decreased since this started last week.

davekc · Nov 22, 2009

Hard to tell. Could be a bad pulley or tensioner on the belts? If you are convinced that it is the turbo, I would have it pressure tested. You could have a leak on the air charger causing a drop in pressure to the turbo.

Kurn · Nov 24, 2009

Check your fan clutch,as well.

smokn72ss · Nov 25, 2009

sounds like loose clamp .. torn flex hose ..... I had a turbo replaced on a western star .. dam mechanic didn't tighten **** on it .. check the clamp on the turbo itself ..

fatboy1 · Nov 25, 2009

ok i'll check again on all clamps if down this weekend will pull of flexs

nightcreacher · Nov 26, 2009

could also be bearing in transmission,or could be the best thing,,nothing

smokn72ss · Nov 26, 2009

is this truck stick or automatic ? if automatic maybe a restriction in the cooler lines to the trans cooler or vibration from fluid pressure raising in the lines as you put more strain pulling the hill that is transmitting to the frame .. is there transmission filters mounted over on that side maybe one is getting some restriction just trying to think or the posiblities

piper1 · Nov 26, 2009

The noise gets worse when the truck downshifts under a pull,
Fuel economy has gotten worse,

2 things there point to either a turbo or a leak in the air intake piping or charge air cooler. Under load the boost is higher, after a downshift it rises considerably. That event will expose any weakness your turbo or piping etc will have.

Does the noise happen in any gear after a downshift or only when you drop out of top gear? If it only happens in 1 gear you may need to look else where.

fatboy1 · Dec 1, 2009

took truck to freightliner in raleigh,nc, it coded,they checked and said egr temp sensor was bad replaced(still under warrenty)
so far havent heard the high pitch whine like before. so thanks for all the sugguestions,knew i could get some here.will check fuel in a couple days and see if that helped. be safe and have a merry christmas

smokn72ss · Dec 1, 2009

I forgot about the egr system down there .... on the new ones ... I hope that helps maybe its a restriction in the egr system too .. on top of the sensor ..... good luck