so, a new sputtering noise started on the way to work today, accompanied by very stiff brakes. pretty clearly the vacuum system - probably the pump, but i was poking around a lunch and found that the vacuum line connection to the brake booster felt loose. its a right-angle plastic fitting and i could spin the plastic fitting in the brake booster body. is that normal? i'm thinking perhaps a new or greased up fitting could be my fix. anyone else ever have this problem?

while i was in there, i studied the vacuum pump with the engine running and it wasn't making any different noises and the pulley motion didnt look abnormal. i suppose it'd be the internal diaphram seals that fail, though, not something visible from the outside.

while looking at the vac pump, i did notice that my water pump pully seemed to be wobbling a bit. then, when i went and looked from the other side, i noticed the belt coming off the pulley was vibrating quite a bit and the tensioner was moving up and down consitently about 1/8-1/4". i assume this is not normal. does the wobbling water pump pulley mean i'm due for a new pump very soon? i'd guess so.

if so, i' think i'll just do all three (water pump, vac pump and tensioner) all at once. maybe the idler pulley as well?

any input from experience would be much appreciated.

 

My tensioner jumps the same way and the consensus from some friends is that it is normal. The right angle fitting in the booster - on every other vehicle I have ever messed with - always moves some like that, so I don't think it is your problem. The real question is whether it is your pump or your booster going out. My brakes are terrible so I am doing that hydroboost swap this Saturday. I don't think it is my pump because my air vent mixer works just fine. I think if your pump is bad, then it won't change from floor to vent, etc very well.

 

i was kind of thinking that same thing since i posted my problem. my blower switches from defrost to vent to floor just fine with no hesitation. maybe that requires much less vacuum than the brake booster, though?

i'm kind of afraid to change the vaccum pump only to find it was the booster that was the problem. maybe its worth trying to find/borrow a vacuum gauge to test it...

 

Maybe just pull the vacuum line off the booster to start and see what you're getting. A guage would be best - maybe autozone would have one if you pulled in the parking lot they would let you use it?

 

Yeah, the HVAC requires very little vacuum energy. Is the sputtering sound pretty constant? If so, try this - remove the hose at the booster (that right-angle fitting is actually a check valve) and plug it with something, and start the truck. If the noise persists, the pump is suspect. If it goes away, then it's more likely the booster or perhaps just that check valve. You should be able to find that check valve in the Dorman/Motormite HELP section of your FLAPS.

Water pump pulley - look to see if it's just the pulley, or the shaft as well, that's wobbling. If the pulley is loose relative to the shaft, then it just might need to be tightened. If the whole shaft is wobbling, then the pump is probably on its way out.

And no, the tensioner should not move that much with just hand pressure on the belt. The spring is probably shot. Replacement tensioners have a longer arm. There's also the option of employing a SD tensioner, which also replaces the idler that's next to it. Requires a slight mod to the bracket. There's a Ford TSB about it floating around.

 

When you get the belt off to do the vac pump, grab ahold of the fan and wiggle and move the fan around to see if there is play in the water pump pulley.

Mine likes to walk off the back of the pulley as well, never could figure out what makes it do this, but it destroys belts all the time.

 

Here you go: http://www.thedieselstop.com/faq/949...les/982314.pdf

Its a pretty good mod, my belt was walking all over and getting chewed up, this mod stoped it.

 

thanks for the info guys - ran the tests on the booster and pump from the service manual last night, and its definitely the pump and not the booster that's my problem. my pep boys has the vacuum pump in stock as well as the stock tensioner, so i can do the work this weekend. after researching the SD tensioner mod, though, i'll see if i can pick that up instead. ...and see if they'll take my spare stock belt back and swap me for a new longer one for the mod.

in related news, Talyn's post confused me for a few minutes, before i realized i had mixed up the crank pulley and water pump pulley in my head. my water pump pulley is fine. its my crank pulley that is wobbling. hopefully its just a loose pulley and not shot main bearings... i guess we'll find out this weekend.

 

A crank pulley wobble doesn't sound good.

 

You can say that again... not words I ever want to hear.

 

agreed. i've got my fingers crossed its a loose pulley, or even better that it was my imagination when watching it idle... maybe just the bad tensioner causing the belt to slap around excessively.

i would think that busted front main bearings would have all sort of other symtoms like terrible noises, leaking oil, etc...

does the pulley hold the oil seals in place on these trucks? if so, i should probably pull the pulley and inspect everythign behind it rather than just re-tightening.

i had a late 90's subaru that the main pulley actually fell off - had some work done at a shop and i think they forgot to tighten it. or didnt torque it correctly. once the pulley fell off, the oil seal followed immediately, and shot all the oil right out the front of the motor. ...just as i was pulling out of the tolls on the Atlantic City Expressway. i fogged the expressway for about a half mile behind me before i wondered what the haze on my rear window was.

 

ok, afraid that i had much more serious problems than a bad vacuum pump, i just went outside from work and pushed and pulled up and down on the crank pulley and couldnt get it to budge at all. i went from bench pressing the truck with my back on the ground to hanging my ~200lb weight from the pulley and it didnt move. even with belt tension, i'd think i'd feel some movement there.

so, hopefully its just that bad tensioner causing the belt to flap that was playing tricks on my eyes...

now i can feel better about spending my time and money doing the SD idler mod.

 

Reckon you can confirm by running the motor _briefly_ with the belt off, see if the crank pulley appears to move then.

 

I'm guessing it was your eyes because if it was that loose you would have heard something - I mean it is spinning pretty fast so it wouldn't take long for all hell to break loose if it was coming off or something.

 

post-work update: new vacuum pump and SD tensioner were installed over the weekend without issue. brakes are better than they've ever been and the brake warning light has stopped coming on completely - even if i sit and pump them like 20 times in a row. And, as usual, all the help from different posts and threads on this forum were a huge help.

and in the spirit of giving back, i'll summarize the tricks and tips i used for this work here in case it helps someone down the road:

vacuum pump:
- i bought the cheapo reman version from pep-boys (the only in-stock option in my area last weekend). it didnt come with a new pulley on it, but from reading other threads about vacuum pumps, i new that hammering my old pulley onto the new pump was not an option. i removed the pulley off of my old pump by partially inserting a 3/8-16 hex bolt into threads of the pump shaft and supporting the edges of the pulley on the jaws of my vice so that the pump body hung below. 6 or 7 whacks with a hammer on the head of the bolt and the pulley was freed from the old pump body. then, using a new 3/8-16 bolt, a bunch of washers and a wrench, the old pully was on the new pump. HOWEVER - again, from this forum, i knew to insert the 3 screws that would hold the new pump to the engine BEFORE putting the pulley on. otherwise, it would have to come off again to get the screws in. then, the pump was on the engine as fast as you can say 'pick the wrench up off the floor 5 times.'

SD tensioner:
- at pep boys i asked for a belt tensioner and belt for a 99 F250 Powerstroke. they gave me the correct tensioner and a Dayco 1223 serpentine belt (or was it a 1233 belt). whatever the case, i had read on here that some guys could not get anything but a motorcraft belt to work (which is actually a 1227 belt, or 4/8 = 1/2" longer than the dayco), so i asked if they carried the motorcraft belt. they did not and their next larger size in stock was 4 inches longer... so i drove over to the ford dealer (always a last resort) and found that they didnt have the belt in stock. so i went home to start the work and figured if i couldnt get the dayco to fit, i'd just order one online and be without the truck for a few days.
- following the TSB procedure in OldBird's post above, i removed the alternator and tensioner/idler bracket and hacked and ground as instructed. everything went back together smoothly, but in order to give myself the most play in getting the belt back on, i followed Jim Rosewood's advice (from another thread) and left the alternator bolts loose until the belt was properly routed over all the pulleys and idlers. the square hole in the boss between the two pulleys on the tensioner is there to insert a 1/2" breaker bar when installing the belt - made it very easy. then i pushed the alternator as far to the driver's side as it would go and tightened it down. in the end the tensioner was about 1/4" off of its full-tight stop, which seemed perfect to me. moral of the story - in my case the dayco belt for a 99 SD F250 worked just fine. i'll keep an eye out for abnormal wear or anything in the near future, but hopefully all is OK.

...finally, as for my possible crank pulley wobble. ...its still moving, but i think/hope its just my harmonic balancer starting to go. i started a separate thread for this...

thanks again for all the input guys.