Timing Belt - Occasional slapping noise - Toyota Nation Forum : Toyota Car and Truck Forums

Camry84 · 11-07-2011, 02:34 PM

While working on other issues I noticed that every once and a while my timing belt would slap with an increase or perhaps more likely decrease in acceleration. Sounds like it was hitting the plastic upper cover when I'd rev the engine slightly.

Before I dig into the problem (I assume it is a problem), I wanted to get opinions on how common this is and how to fix it.

I hope it's as easy as removing the upper cover, adjusting a tension pulley and putting it back together.
I will, of course, check valve timing while I'm at it and inspect the belt for fraying, missing teeth cracks etc.

I would guess that the belt was changed around 50000 miles or so ago.
Does a belt normally stretch over time and need re-tightening or is something else causing this. I don't drive the car hard except for the occasional Seafoam cleanout where I'll push it toward redline but not off the line, just gradual acceleration.

Any thoughts would be helpful, just want to nip this in the bud and keep it from happening again. I have a hunch that slight valve timing variation may be a part of the puzzle that I've been solving in regards to smooth idle, lack of power etc.

I dread changing the timing belt, hope this is not needed, winter is fast approaching and I don't have a garage here in the Pacific Northwest.

Thanks for any input!

white90dx · 11-07-2011, 03:56 PM

Timing belt change interval is 60k miles - so you are almost there anyway...

That said, hopefully you can just check the belt and its all good. I shouldn't significantly stretch through its lifetime, but maybe something has come loose.

You should easily be able to pull off the top cover (some number of 10mm bolts). I can't remember if you can get the cover completely off without removing the engine mount though... The tensioner is visible and accessible from there and you can see if the belt is loose. For your sake, I hope its the belt and not engine internals...

-Charlie

RolentoGrenades · 11-07-2011, 04:02 PM

Quote:

Originally Posted by Camry84

While working on other issues I noticed that every once and a while my timing belt would slap with an increase or perhaps more likely decrease in acceleration. Sounds like it was hitting the plastic upper cover when I'd rev the engine slightly.

Before I dig into the problem (I assume it is a problem), I wanted to get opinions on how common this is and how to fix it.

I hope it's as easy as removing the upper cover, adjusting a tension pulley and putting it back together.
I will, of course, check valve timing while I'm at it and inspect the belt for fraying, missing teeth cracks etc.

I would guess that the belt was changed around 50000 miles or so ago.
Does a belt normally stretch over time and need re-tightening or is something else causing this. I don't drive the car hard except for the occasional Seafoam cleanout where I'll push it toward redline but not off the line, just gradual acceleration.

Any thoughts would be helpful, just want to nip this in the bud and keep it from happening again. I have a hunch that slight valve timing variation may be a part of the puzzle that I've been solving in regards to smooth idle, lack of power etc.

I dread changing the timing belt, hope this is not needed, winter is fast approaching and I don't have a garage here in the Pacific Northwest.

Thanks for any input!

Since it's been 50k, look into having it replaced anyway in about another 10. Sometimes with no warning these things can pop, even without obvious signs. It won't be very easy to detect whether you're really hearing belt slap, unless you have a way to see it in operation and maybe visually see the belt move. Removing that pesky upper cover would be the only way, but don't rule out slap from the bottom. Take a piece of wood or something, press it up against the top cover and bottom cover and verify if it's louder at the top than the bottom. The wood should amplify the sound quite a bit. And it's less annoying than using a super loud stethoscope or some fancy overpriced automotive tool.

Those old camrys can make lots of weird knocks and sounds you don't even expect, trust me. Especially when the weather gets cold. I've found loose bolts that would make sounds like that, loose pieces of frame, etc. Just give everything and I mean EVERYTHING a good look over before messing with that belt. Could even be a loose spark plug, loose exhaust bolt, loose crank apron. Anything, man.

Don't be afraid of the belt either. Take that sumbitch out if you have to, haha. Sometimes idlers will knock, but check to make sure before replacing it. Good luck!

RolentoGrenades · 11-07-2011, 04:08 PM

Quote:

Originally Posted by white90dx

Timing belt change interval is 60k miles - so you are almost there anyway...

That said, hopefully you can just check the belt and its all good. I shouldn't significantly stretch through its lifetime, but maybe something has come loose.

You should easily be able to pull off the top cover (some number of 10mm bolts). I can't remember if you can get the cover completely off without removing the engine mount though... The tensioner is visible and accessible from there and you can see if the belt is loose. For your sake, I hope its the belt and not engine internals...

-Charlie

Removing the mount is ideal of course, although a bit more work. Sometimes you can pry back the top of the cover after removing only three of the 10mm bolts, but taking off the whole cover would be best.

Camry84 · 11-07-2011, 05:34 PM

Thanks for the feedback!
I'll be checking into it for sure.
Something is still not right (lacking power at lower RPMs) so it could be the valve timing is off due to slipping a cog or something.
I have a manual so at least I've got some guidance in pulling it if needed.
Been over the rest of the engine quite extensively although there could always be something loose where I didn't look before.

Didn't sound like an internal (metal on metal) type of sound.
Sounded like rubber on plastic (an occasional flap type of sound).
If there is the slightest indication of a problem with the belt I'll just replace it and be good for another 60000 miles.

Just have to get my head in the right frame of mind to take it on ... I was hoping I had gotten to the bottom of this and would be cruising in comfort about now ... ah, the joys of cars ... new or old, they can be temperamental and demanding, can't they?

Doctor J · 11-08-2011, 08:41 AM

Remove engine drive belts (easy said then done) and re-check for the noise
If noise is surely coming form the T-belt case, then
most likely the bolt for the tenson roller work itself loose, so the tension spring cuses the belt deflection and slapping

Camry84 · 11-08-2011, 01:53 PM

Could belt deflection alone (assuming the belt has not slipped one tooth) cause problems such as difficult to start, lack of power on hills and poor gas mileage?

Sounds like a good time to replace all belts if I'm going to remove them, they don't look particularly bad, no cracks but they look rather gray and weathered.

Thanks Doc.

Camry84 · 11-08-2011, 04:24 PM

Well, I decided to just bite the bullet and have a local shop put in a complete timing kit. (Belt, Idler, Tensioner & Spring)
I figure I'm close enough to 60000 miles on the current belt that it only makes sense to just get it taken care of and be good to go. Parts & Labor are $300, not sure if that's a good deal or not but I doubt I can get it done much cheaper around here and I do trust the shop since they have done great work on my rigs before.

I could put the kit in myself but don't have a garage and the weather is starting to get a bit nasty.

RolentoGrenades · 11-08-2011, 09:35 PM

Quote:

Originally Posted by Camry84

Well, I decided to just bite the bullet and have a local shop put in a complete timing kit. (Belt, Idler, Tensioner & Spring)
I figure I'm close enough to 60000 miles on the current belt that it only makes sense to just get it taken care of and be good to go. Parts & Labor are $300, not sure if that's a good deal or not but I doubt I can get it done much cheaper around here and I do trust the shop since they have done great work on my rigs before.

I could put the kit in myself but don't have a garage and the weather is starting to get a bit nasty.

$300 isn't bad at all for the job. While they're in there, you might want to also change out the water pump and gaskets, and perhaps cam/crank seals and oil pump o rings/spaghetti gasket. Sounds like they aren't ripping you off on the price, so it wouldn't be that much more and less to think/worry about down the road.

Camry84 · 11-09-2011, 06:02 PM

That's a good point Rolento, if I weren't really pushing the budget as is I would definitely consider doing just that.

I think the car will really be a happy camper after doing this. I was under the hood today and just revving the engine slightly several times via the throttle butterfly valve produced the flapping sound of the timing belt, each time I revved it. I placed my fingers on the plastic timing belt cover and could feel the direct vibration from the belt hitting the cover when I did this. Engine itself sounds nice, hydraulic lifters don't make much noise and there is no other rattling or metallic sounds coming from the block.

I really hope this helps my difficult starting, pulsing (surging) throttle during lower rpms and lack of power on hills ... not to mention gas mileage (which has been terrible lately for this car).

If it fixes that, it will be $300 well spent.
I have roughly $400 into the car lately with all other repairs/ replacement parts so I'll have a total of $700 into getting the car back in shape.
Brakes next spring and she'll be lasting a good while longer.

To be honest, I'd rather have this car running good than many newer cars.
The mileage can be as high as 42 mpg in this Camry and the driving comfort is nothing to complain about.

RolentoGrenades · 11-09-2011, 08:54 PM

Quote:

Originally Posted by Camry84

That's a good point Rolento, if I weren't really pushing the budget as is I would definitely consider doing just that.

Yeah, I know how it is. The new belt and idler/tensioner alone should be a huge improvement if these symptoms were being caused by the old ones.

Also agreed on the Camry mileage rating. That is what has me fixing mine again and again, haha. I may even have my entire engine/transmission rebuilt one day.

Camry84 · 11-10-2011, 08:10 PM

Timing Belt and Tensioner was the problem alright.
The old belt had 3/8" of all teeth missing along one side of the belt.
Tensioner was loose and the belt was flapping loose.
Belt, Tensioner, Idler Pulley and tensioner spring were replaced.
While it was apart the shop replaced all other belts and readjusted idle, reset ignition timing and even swept my floormat ... not bad for $337 IMO (extra was for the additional belts).
Nice to have a good shop two blocks from the house.

Talk about a MAJOR difference!
Car starts easy, idles nice and has all kinds of power.
Can't believe how much power this car has now, I dropped it into 5th gear while going about 25 mph, gave it slight throttle and was going over the speed limit in seconds. I don't think hills will be a problem any more.
Now if this equates to MPG that will be icing on the cake.

Car and driver are very happy campers now!
I'll do my brakes next week ...

It's amazing that this care would even run with that much damage to the timing belt, constant valve timing fluctuation etc.

dem2757 · 11-10-2011, 08:37 PM

how much power? my timing belt is old....like at least 100000 miles old. tensioner and timing pump too.

my v6 cant stay speed at 2k rpm going up a 30-35 degree slope

RolentoGrenades · 11-10-2011, 08:55 PM

Quote:

Originally Posted by Camry84

Timing Belt and Tensioner was the problem alright.
The old belt had 3/8" of all teeth missing along one side of the belt.
Tensioner was loose and the belt was flapping loose.
Belt, Tensioner, Idler Pulley and tensioner spring were replaced.
While it was apart the shop replaced all other belts and readjusted idle, reset ignition timing and even swept my floormat ... not bad for $357 IMO (extra was for the additional belts).
Nice to have a good shop two blocks from the house.

Glad you got it sorted out, man. It's definitely refreshing to have one of your rides back on the road.

dem27,

Your best interest is changing out that old belt if it has that much mileage on it. You may have lost a tooth or something and maybe the ignition timing is off. Check it with a light, but don't get stranded out there man.

dem2757 · 11-10-2011, 09:04 PM

that could explain why the car sounds better after it runs on the highway for a bit.

sometimes the car sounds "off" and then after driving for a bit (randomly) it sounds more like a v engine.

more fun work =]

edit: it definitively seems like timing issues because the car really doesnt seem to have 160 lbs of torque, or 160 hp