Need quick response on hissing and missing

Need quick response on hissing and missing

Postby Jawon [OP] » August 31st 2020, 2:59pm

After a one hour trip in high temps, engine started hissing like release of air and then steering and braking immediately became stiff. After resting an hour, I tested around a parking lot and it went back to normal

Took it to the mechanic and I got a very fishy diagnosis. They said the cause was the belt tensioner was missing. Bolt was still loosely on but the actual tensioner was gone.

Would I have been able to drive around the parking lot with a missing tensioner? Is it possible a tensioner could disappear leaving the bolt in place? How does that solve my original hissing problem?

I feel like I’m getting duped.
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Re: Need quick response on hissing and missing

Postby M_a_t_t » August 31st 2020, 3:14pm

I don't see how a belt tensioner can "fall off" (or break off?) and leave the bolt there.

One time I had the pulley on the tensioner start to lock up and it pushed the belt off enough that I lost P/S and brakes intermittently. So I suppose it is possible, but the fact the bolt is still there seems fishy.

If you can I would put the tensioner back on yourself, if you have to buy it from a local store even. It might be hard to do without removing the fan shroud though. The details just don't add up.

Is the belt still there, just no tensioner?
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Re: Need quick response on hissing and missing

Postby augidog » August 31st 2020, 3:51pm

if the entire tensioner "fell off" I'd think there'd be a god-awful mess under the hood.

however, I can venture a guess that something's wrong related to the belt drive (unsprung tensioner? tensioner pulley as Matt mentioned? idler pulley?) and it's affecting the hydroboost system, which likely explains the hissing, based on the described symptoms.

a picture will probably save a thousand words.
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Re: Need quick response on hissing and missing

Postby Jawon [OP] » August 31st 2020, 4:04pm

augidog wrote:if the entire tensioner "fell off" I'd think there'd be a god-awful mess under the hood. however, I can venture a guess that something's wrong related to the belt drive (tensioner pulley as Matt mentioned? idler pulley?) and it's affecting the hydroboost system, which likely explains the hissing, based on the described symptoms.


Belt was apparently shredded. Idler pulley was also rough and replacement recommended. They did mention there was a little leaking at Hydroboost but replacement not needed at this point especially with $800 part cost (OEM?)

How does the belt drive affect Hydroboost? What could the hissing rush of air sound been?
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Re: Need quick response on hissing and missing

Postby augidog » August 31st 2020, 4:10pm

better explained in detail by someone more experienced, but the accumulator holds enough pressure for a couple/few brake pumps...and if the system's not fully bled, there's a growl associated with it either discharging or recharging, I'm not sure which.

if it were me, I'd be doing a complete new serpentine kit.

my arms are long and I did it all without removing anything else.
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Re: Need quick response on hissing and missing

Postby MechBob » August 31st 2020, 4:11pm

Belt runs power steering pump.The pump provides pressure to the hydroboost.The hiss could have been a lot of things,even the shredding belt strands.
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Re: Need quick response on hissing and missing

Postby M_a_t_t » August 31st 2020, 4:12pm

Hydroboost is powered by the P/S pump. If the belt is messed up then you loose power steering and power brakes. No idea on the hissing unless it was low on fluid and the pump was just starting to whine.
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Re: Need quick response on hissing and missing

Postby augidog » August 31st 2020, 4:17pm

he mentioned a leak, and a "hissing rush of air" so could this be the accumulator burping?
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Re: Need quick response on hissing and missing

Postby Jawon [OP] » August 31st 2020, 5:16pm

Thanks so much for the quick responses about the tensioner. This might be distracting the real issue so let me go back to the hiss

It was wifey who was driving at the time and described the situation to me. The hissing was definitely air not rubber or metal. Engine was running for an hour when this happened. It happened about three times each time she tried starting the car. It was prolonged and stopped only when she shut the engine off. Brakes and steering stiff.

An hour later, I drove around the parking lot and heard no hissing and the brakes and steering were perfectly fine.

Could there be a loss of vacuum or a deteriorating hose that could have caused this? Tensioner doesn’t solve this. The tensioner diagnosis feels fabricated.
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Re: Need quick response on hissing and missing

Postby MechBob » August 31st 2020, 5:19pm

Get the belt,tensioner and idler stuff fixed,then worry about the noise.One step at a time.
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Re: Need quick response on hissing and missing

Postby Jawon [OP] » August 31st 2020, 6:46pm

Got more clarity from the mechanic. It appears the tensioner arm and pulley somehow broke off and is nowhere to be found. But the spring housing is partly there still. Photo attached.

Mechanic states it could be possible to drive around the parking lot for a short time without steering or braking issues, as I did, even without the belt.

As suggested here and by the mechanic, I’m gonna get a new tensioner, idler pulley and belt installed. Then see if hissing noise persists. I’m tempted to do myself but it’d be a hassle getting the van back and my time is limited and it seems the mechanic may not be duping me after all. And at 160k miles, I’m inclined to let a pro give it a good look over.

Thanks for all the opinions.
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Re: Need quick response on hissing and missing

Postby augidog » August 31st 2020, 7:03pm

wowee! someone here likes to say "pics, or it never happened." well...it happened !

first, I agree you can't know more until you get the new serpentine kit on there.

second, no water pumping could certainly result in some hissing. or...damaged radiator, cooling hose, or unrelated line, from when the tensioner bounced it's way out of there.

I'll keep my fingers crossed for a good outcome.
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Re: Need quick response on hissing and missing

Postby Leeann_93 » August 31st 2020, 10:40pm

Wow. I've never seen that happen.

I guess the tensioner or idler (or both) could have seized and caused that, but I'm a little questionable on that. You should have heard nasty noises for a long time before that happened if that was the case.

I guess we shall see.
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