vacuum pumps??
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Elder User
Joined: Dec 2008
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From: Ocala
vacuum pumps??
For the last two months or so my truck has a horribly loud squealing coming from one of the pulleys. It is not the belt, it's new. And the squealing is random, some days its extremely loud and others its not there at all, then others its a real quiet squeal. But it can be so bad someti,es that you cant even hear the engine over the noise. Maybe its just me but I swear when it isnt making this noise it seems to run MUCH better.
Does anyone have any idea to what this might be? Would a bad vacuum pump do this?
Does anyone have any idea to what this might be? Would a bad vacuum pump do this?
Postmaster
Joined: Jun 2007
Posts: 2,795
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From: Rogue River, OR
Relieve the belt tension then carefully feel each pulley for any sign of catching or roughness. I'm going to just make a guess and say "Idler pulley"
If you have a mechanic's stethoscope you can place the pick-up end near each pulley while the engine is running but be extremely careful, if you get it caught in the belt it's very unforgiving.
Rog
If you have a mechanic's stethoscope you can place the pick-up end near each pulley while the engine is running but be extremely careful, if you get it caught in the belt it's very unforgiving.
Rog
Posting Guru
Joined: Nov 2000
Posts: 1,005
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From: Cincinnati, Ohio
I bought one of THESE 15-20 years back and have used it for everything from diagnosing mechanical issues to finding a cat in a basement wall (true deal, this past Tuesday in fact). One of the best diagnostic tools I have, and cheap at that.
If you do not want to do that you can take a large screwdriver and place the tip against what you want to check, cup your hand around the handle and put your ear against it. Old mechanic's trick, actually works decently but the stethoscope is better.
Dave / Believer45
If you do not want to do that you can take a large screwdriver and place the tip against what you want to check, cup your hand around the handle and put your ear against it. Old mechanic's trick, actually works decently but the stethoscope is better.
Dave / Believer45
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From: Ocala
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From: Ocala
Ok, took off belt, spun pulleys, all are normal except the vacuum pump pulley seems a bit off. It turns halfway with no resistance, then the other half is kinda hard to turn. After the hard part it kinda shoots forward then spins easy again.
I know the screwdriver trick works but call me a panzy, I dont want to stick a screwdriver on a moving pulley then put my head that close to the belt lol. I'll probably invest in a stethoscope.
I know the screwdriver trick works but call me a panzy, I dont want to stick a screwdriver on a moving pulley then put my head that close to the belt lol. I'll probably invest in a stethoscope.
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More Turbo
Joined: Dec 2002
Posts: 664
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From: Columbia, MD
Yeah, that should be normal. Vacuum pump is a cam on the pulley shaft driving a spring-loaded piston. Hard spot in rotation is where the cam is driving the piston and compressing the return spring. Once past top of the cam lift, the return spring forces the cam down and ahead. Got to look at the insides of my vacuum pump one day.
Squealing usually is the belt slipping... something is too hard to turn, belt is failing, or the belt doesn't have enough tension. On mine, the tensioner needs a good push on a 24" breaker bar to get the belt off. If yours takes less, the tensioner may be too weak and letting the belt slip, even though everything else is OK.
. Squealing usually is the belt slipping... something is too hard to turn, belt is failing, or the belt doesn't have enough tension. On mine, the tensioner needs a good push on a 24" breaker bar to get the belt off. If yours takes less, the tensioner may be too weak and letting the belt slip, even though everything else is OK.
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From: Ocala
Its driving me nuts too! Especially because I'm ready to drop in stage 1's but I want to fix all the little problems first. It seems like the noise is worse when its cold out. I'll check the tensioner tomorrow. I can always get the belt off with a standard 3/8 ratchet. Paddler, if yours takes a 2ft breaker bar mine might need to be replaced.
Elder User
Joined: Aug 2005
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From: NW Wisc
Heres what I got, about a $100 delivered.... eBay Motors: NEW diesel vacuum pump vacumnFord Powerstroke 7.3L 7.3 (item 270341724003 end time Apr-09-09 07:23:33 PDT)
Slick!!
Slick!!
Post Fiend
Joined: Feb 2009
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From: Texas Coast
If your idler pullies are not showing signs of wobble (bearings raceway wear) then it could be the inner sleeve of the idler pully its self. I dont know if all idler pullies on PSD's are this way; but mine was sleeved and I have yet to find a replacement sleeve that covers the bolt on the inside of the pully. Another posibility is that the water pump is starting to go.