Uh Oh! TB about to go?

morriss · 07-25-2009, 06:57 PM

I just got back from taking the 928 for a spin (it's cooler at night!). As I was turning into the neighborhood, the whole car shut off (probably unrelated). I cranked her back up and then heard this god-awful sound. It was a mix between a screeching and a grinding, more of a grinding than a screeching. It is something I have never heard before. I pulled into the garage, popped the hood, and hunted for its origin. From what I can tell, it was coming from the front of the engine, behind the fan, kind of under where the the distributor is located. It definitely was not coming from the AC compressor, alternator, etc. - it was behind all of that. Sooo... is it the fan clutch, tb tensioner, water pump (no leaks so far), or what?
Dangler- I think I read in a post long ago that you heard a very distinctive sound from under your hood just before your belt broke. What did it sound like?
I sure hope I am just overreacting and it's something really minor because I am not ready to do a tb change just yet - I just passed inspection got her on the road
!

MPDano · MPDano's Garage

On top of the TB Covers should be a hole that connects to the underside of your Air Tubes. Take a peak in there and see if you can see the condition of your TB. Report back.

morriss · 07-25-2009, 07:29 PM

Okay Leo. It will have to wait until the morning, it's now 10:30 p.m. here. I'll let you know first thing, probably even before you guys out in Cali even wake up.

Mrmerlin · 07-25-2009, 08:14 PM

dont start the car until you have pulled off the PS timing cover and inspected the belt , if the smooth side looks shiny then the water pump has probably seized and could also be grinding away at the block.
If there are lots of shredded hairs then the tensioner pivot bolt is bent or the bushings are worn( this makes the tensioer roller tilt the belt forward and it then runs into the back of the harmonic damper.

Warning dont start the car till this has been figured out..
Dis connect the battery first

vdubr928 · 07-25-2009, 08:39 PM

Quote:

Originally Posted by morriss

I sure hope I am just overreacting and it's something really minor because I am not ready to do a tb change just yet - I just passed inspection got her on the road
!

Sounds that sound bad are very rarely minor. Listen to these huys and don't ru nit again till you found the issue.

rhjames · rhjames's Garage

yours will be non-interference, however, if Stan is correct about the H2O pump....do not run it.

better to be cautious than not in this case.

if you have no history or have not done the TB/H2O pump in a while, get with it.

--Russ

m21sniper · 07-25-2009, 09:48 PM

Probably the water pump.

Everything you'll need for the TB job costa about $500.00

morriss · 07-26-2009, 06:37 AM

Okay, I pulled the plastic covers back a bit and then spent the past 30 minutes trying to find the camera, only to find out that my wife has it and won't be home until around 4:00 p.m.
Belt looks fine, no shredded hairs, not sure about the "shininess" of it. I don't know what a tb is supposed to look like after it has been on for a while. It's a tad shiny, but definitely not high gloss shiny (I know this sounds stupid, but I don't know how else to describe it). It is also good and tight, teeth look nice, etc.

MPDano · MPDano's Garage

Ok, this is what I would do since it's a non-interference motor. Start it up and now that you have the top covers off, see if you can better pinpoint the noise. If it's centered right on the Water Pump, then m21sniper is right on. Replace WP and TB.

Here is where others will differ from me with the TB. Since there is no history on the TB change "AND" you have all those covers and crank pulley off, it's peace of mind to just do the $30 TB Belt at the same time as doing a Water Pump.

Report back after pinpointing noise.

Mrmerlin · 07-26-2009, 08:13 AM

dont start it turn the engine over by hand and see how the belt run is.
IE if its hard to turn over then there is a good chance the WP is seized you may have caught things in time, BUT if you dont know what your doing then you cause more damage, best to get a second set of eyes on your project

MPDano · MPDano's Garage

Quote:

Originally Posted by Mrmerlin

dont start it turn the engine over by hand and see how the belt run is.
IE if its hard to turn over then there is a good chance the WP is seized you may have caught things in time, BUT if you dont know what your doing then you cause more damage, best to get a second set of eyes on your project

Well, if your gonna do it Merlins way, then remove the Spark Plugs or it "Will" be hard to turn regardless.

morriss · 07-26-2009, 09:16 AM

Are we sure it is a non-interference? I know for a fact that I read somewhere on this forum that '82 US 16v are non, but that that the '82 Euro S 16v IS an interference.

MPDano · MPDano's Garage

I all honestly, I am not 100% sure. And yes, come to think about it, I do remember hearing that some later 16V motors are Interference.

Any 16V experts know the answer to this?

vdubr928 · 07-26-2009, 10:04 AM

Cams are different part number from us to euro.

MPDano · MPDano's Garage

Ok, found this in an earlier thread:

Quote:

The Euro in 80 to 83 had two flavors, plain and S, from 84 to 86 only S. My 85 Euro S had a timing belt fail and valve damage, your 84 shouldn't be any different. The Euro non S were pretty much the same as the US and non interference.

Safest way to discuss anything specific on a 928 is to talk about the VIN, other bits can be confusing related to model year.

Checking the TB is actually checking everything "related" to the TB, the TB itself rarely fails on its own, the water pump seizes or a guide is damaged. Maybe 20 minutes to look around, take the covers off etc. Nasty noises though need immediate attention.

If the TB skips a few teeth you should still be OK, the valves do have a LOT of clearance, just not 100% of a rotation.

Quote:

Non interference update.

Subject was recently thrashed around again on rennlist with more detail surfacing. Generally only the Euro S 16v motors have a risk of valve to piston contact. Early Euro S motors were 10.0:1 compression, with deeper valve reliefs and should have no risk unless carbon has built up in the pockets. The switch to 10.4:1 pistons occurred after the start of the 84 model year, and these have shallow valve reliefs, good enough for slipping a few teeth or installing a belt, but damage assured if the belt breaks.

Cut off for use of the older pistons is by motor serial number;
0597 for manual cars
6114 for automatics

Thread on rennlist I pulled this info from.
http://forums.rennlist.com/rennforum...d.php?t=431524

928SROCK · 03:09 PM

I sure would like to see some pics. of what your tb looks like do you think u might put some up here? Whats everyone think about waterpump conditioner? thanks

Mrmerlin · 07-26-2009, 05:21 PM

the WP conditioner sounds like the stuff you put into a chevy or ford. if your thinking of using on the P car, I wouldnt

vdubr928 · 07-26-2009, 05:47 PM

If you want tyo put something in your water system that is sure to shred every seal that it can find... Including the water pump seal then you can buy some of that spooge and put it in your finely crafted aluminum performance engine and watch the water start to pour from holes you didn't even know existed.

Sorry, am I being too frank?

morriss · 07-27-2009, 04:15 AM

I will try to get pics up today after I change the oil on our Vue. I still need to pull the plastic covers all the way off so the belt will be fully exposed too.

morriss · 07-27-2009, 04:53 AM

Here's the pic I took last night; I will take more once the covers are all the way off. I