| Author |
Message |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1772
Registered: 2-2001
| | Posted on Tuesday, August 13, 2002 - 3:38 pm: | |
I have two factory bearings and belts that I used for the R&D on my timing belt system. They are like brand new. $75.00 for all. |
Paul Newman (Newman)
Member
Username: Newman
Post Number: 326
Registered: 12-2001
| | Posted on Tuesday, August 13, 2002 - 3:07 pm: | |
Obviously the belt got hot. I would bet on a tensioner bearing because of it being the back side that is burned. Its really hard to pinpoint it over the internet but If the drive bearings are ok, then what else could it be? A bad drive bearing wont burn the back of a cam belt either. There are many variables. Was the belt too tight and it overheated the tensioner bearing causing it to sieze while hot? Maybe. Replace the front tensioner bearing only if funds are the issue and reassemble it. I wouldnt dig deeper without eliminating the tensioner bearing first. And replace the belt as well. Observe it with the covers off but water pump belt on. You can rely on the lower alternator bolt to hold the fan belt tight for this in garage test. Good luck. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 809
Registered: 12-2001
| | Posted on Tuesday, August 13, 2002 - 1:03 pm: | |
Drive bearings have no play at all. I have a few spots on my tensioners of rubber, not just dust. The belt has slight little boils on the back of it. |
Tom Treue (Treue)
New member
Username: Treue
Post Number: 23
Registered: 4-2002
| | Posted on Tuesday, August 13, 2002 - 8:54 am: | |
Rich:
Some belt residue (fine black powder) is expected. Look at the tension rollers. Do the bearing seals touch the inner race or are they pulling away from it? Are there radial streaks of grease coming from the bearings? If there are no leaks, the seals look OK, and the bearings are not loose-or dry-feeling, then the roller is probably OK. Could be replaced for $70-120 each.
BTW, How are your drive pulley bearing's? Should be no leaks and no play. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 808
Registered: 12-2001
| | Posted on Monday, August 12, 2002 - 9:49 am: | |
I removed both tensioner bearings and t-belts. Both bearings feel fine and rotate smoothly. The front bearing has belt residue on it. This is where the squealing was coming from. I am not sure exactly what this means. Does this mean that the bearing is going bad and it feels ok when spun by hand but at idle it is having problems. Any info would be appreciated. |
Verell Boaen (Verell)
Junior Member
Username: Verell
Post Number: 243
Registered: 5-2001
| | Posted on Thursday, August 08, 2002 - 2:18 pm: | |
BINDER CLIPS ARE GREAT FOR KEEPING BELT ON PULLEYS
I use 1-1/2" binder clips to keep the belts in place. With care, you can fit 2 on a cam drive pulley & 2 or 3 on the cam pulley. They're much better than clothespins as they grip with a lot more force. (Got this trick from the Dodge Stealth web site's cam belt change procedure. It saved me a lot of time when I was doing my timing bearing job earlier this year.)
The binder clips make it very hard to accidently slip the belt over a tooth.(Not impossible tho, ask me how I know.)
Once you've marked your belts, & put the binder clips on then very carefully loosen the belt tensioners, back them off slightly to get a little bit more slack & lock them down again.
Then rotate the crank backwards a couple of degrees in order to get enough slack on both sides of the drive pulley to see if you can wiggle it.
NOTE: Make sure that the binder clips aren't jamming against the crank pulley & missleading you.
TAKE OUT SOME INSURANCE:
Before you start any of this, it's cheap insurance to plan for the worst. (ie a belt slipping on you.)
- Align the flywheel on the PM1-4 mark.
- Looking thru the oil filler hole, the cam marks must be aligned. If not, rotate the engine again & they will be.
Now you know you can recover in case the worst happens & a belt slips off & the markings get obliterated in the process.
|
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1733
Registered: 2-2001
| | Posted on Thursday, August 08, 2002 - 1:48 pm: | |
Get you a bottle of "White Out" correction fluid, the same stuff that Blondes use on their computer screens, and use it to mark the cam and belt reference points. |
Tom Treue (Treue)
New member
Username: Treue
Post Number: 21
Registered: 4-2002
| | Posted on Thursday, August 08, 2002 - 8:43 am: | |
Rich:
Bill has a good idea. Be careful that the belt does not slip a tooth on one of the pulleys.
The bearing seals and the lip seal on my car were hard, cracked and distorted. I think they were doomed from the start. If you follow the factory tensioning procedure, the belt cannot be over tensioned. It seems to me that there was a string, some months ago, where they were talking about a much better quality bearing available for this application. Look it up. From my experience and anecdotal information, I get the impression that failure of this bearing and seal is not uncommon and might even suggest regular inspection and replacement.
Paul had a good point: the torque requirements of the two camshafts is anything but constant and this fact is probably a major cause of bearing and belt degradation and ultimate failure. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 302
Registered: 5-2001
| | Posted on Thursday, August 08, 2002 - 8:39 am: | |
Richelson, I think Paul is referring to the belt tension. As a valve spring is compressed there is a corresponding tension on the drive side segment of the belt. As the the cam lobe continues to slowly rotate, the spring tension will transfer to the back side of the cam lobe and will tend to autorotate the cam shaft, loading the trailing side of the belt. This will be a minor problem only when turning the engine over by hand. During engine running, things happen fast enough that the belt is always tensioned in the running direction.
If you elect to slaken the belt to provide wiggle room for the drive pulley, make sure the belt does not slip teeth an any of the pulleys. It might be helpful to mark the belt and pulley teeth to ensure you know the correct belt to pulley correspondence. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 800
Registered: 12-2001
| | Posted on Thursday, August 08, 2002 - 6:13 am: | |
Thanks Paul and Bill. By adjusting are you referring the the cam timing? When I had previously set the belt tension I rotated the engine over once and it still wasn't as tight as I had thought so I rotated it again until I could turn the belt 90 deg. with some force. Thanks and please keep me posted. |
Paul Newman (Newman)
Member
Username: Newman
Post Number: 305
Registered: 12-2001
| | Posted on Wednesday, August 07, 2002 - 8:55 pm: | |
Richelson, depending on the cam position when the engine is off, the belt if improperly adjusted will be loose and tight at times. This is because the cams will either be pulling on the belt depending on lobe position or pushing on the belt creating slack at times. The belt is definately not adjusted correctly whether its the drive pulley or and idler. With the cover off, you should run the engine and listen at the drive cover as well as see if there is movement like Bill suggested. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 300
Registered: 5-2001
| | Posted on Wednesday, August 07, 2002 - 7:00 pm: | |
Richelson,
You may be able to slaken the tensioner assembly enough, by depressing and temperarily locking it in the fully depressed state, to gain enough slack to wiggle the drive pulley. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 793
Registered: 12-2001
| | Posted on Wednesday, August 07, 2002 - 5:18 pm: | |
Thanks for the info Tom. I will look at it and see if it has any play. The reason why I started to think the drive bearing is a possibility is because I have been chasing a squealing or chriping sound, then I found the front timing belt slightly loose. I will look closely to see if there is any oil present as well. I had just changed the timing belts recently too. Could this have shortened the life of this bearing? Please let me know if there is anything else to check. |
Tom Treue (Treue)
New member
Username: Treue
Post Number: 20
Registered: 4-2002
| | Posted on Wednesday, August 07, 2002 - 4:08 pm: | |
As long as the belt is tensioned, it will pull all the play out of a bad bearing. The only way to truly check the bearing is to take the belt off (You can mark the belt and each of the three pulleys to reinstall the belt when you are ready, but DO NOT move the crank or any of the pulleys without the belt properly in place.) There should be no play in the bearing and no oil leakage coming from behind the pulley. It would be better to remove the pulley and inspect the bearing's ouboard seal but this requires a special socket (about $70 from Baum Tools). If the right end of the block is not clean, observing an oil leak will be difficult. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 792
Registered: 12-2001
| | Posted on Wednesday, August 07, 2002 - 3:33 pm: | |
Thanks for the info. What is the best way to check the condition of the drive pulley bearing? Should I remove the belt and see if it has any play or can I do it with the belt on? Will it shake back and forth when the engine is running if it has play? |
Tom Treue (Treue)
New member
Username: Treue
Post Number: 19
Registered: 4-2002
| | Posted on Wednesday, August 07, 2002 - 3:30 pm: | |
Rich:
Another thing to check is the drive pulley bearing. My aft bearing problems began with a slight leak, then produced a singing noise then the leak became a stream. The pulley had nearly 1/8" play when the belt was removed (it should have none). The bearing was near death and the lip seal inboard of the bearing had come totally free. The play in the pulley brought the belt adjustment near its extreme. This malady is not uncommon in this range of models. |
Ric Rainbolt (Ricrain)
Junior Member
Username: Ricrain
Post Number: 202
Registered: 2-2002
| | Posted on Wednesday, August 07, 2002 - 9:58 am: | |
Lawence is right, The 308, 328, 348, 355, TR, Mondial (and probably most others) have "fixed" tensioners. Once tightened, they only turn, but don't move otherwise. |
Lawrence Coppari (Lawrence)
Junior Member
Username: Lawrence
Post Number: 138
Registered: 4-2002
| | Posted on Wednesday, August 07, 2002 - 9:39 am: | |
If the tensioner is like that of a 328, it should not move once it does its job of tensioning the belt. You lock it down with a bolt to allow absolutely no movement from that point on (other than spinning). If 308's don't have locked down tensioners, that could be the culprit. I was assuming the 308 tensioner setup is like the 328. |
Matthew J. Morgan (Kermit)
New member
Username: Kermit
Post Number: 25
Registered: 8-2001
| | Posted on Wednesday, August 07, 2002 - 9:02 am: | |
You might also consider a stuck tensioner bearing slide. They often "gunk up" until stuck. |
Lawrence Coppari (Lawrence)
Junior Member
Username: Lawrence
Post Number: 137
Registered: 4-2002
| | Posted on Wednesday, August 07, 2002 - 8:14 am: | |
If I were you I'd remove the cover and have a look see. I'd take the plugs out and turn the engine over with a wrench to see what is happening. Don't know about 308 but it's work on a 328 because of AC and gas tank. I suspect it is very similar.
The only way the belt can be loose and tight is one of the following possibilities.
1. The belt is acting like a spring and streaching (highly unlikely).
2. Its fixed points are moving. There are 4 fixed points. One or more of them is moving in a motion other than rotational. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 790
Registered: 12-2001
| | Posted on Wednesday, August 07, 2002 - 7:22 am: | |
I went ahead and started the car and watched the drive pulley. It didn't shake or vibrate at all. Would it have a substantial amount of play if it is going bad? I then felt the belt after running the car for ~5 mins. and the belt was very tight. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 789
Registered: 12-2001
| | Posted on Wednesday, August 07, 2002 - 6:39 am: | |
I felt the timing belt on the front cover and it was quite loose. Does this usually indicate a drive bearing issue? Are there any other things to look for on drive bearing issues? This is where the squeal is coming from I believe because the belt is loose. Any info would be appreciated. |