timing belt
 

Hey, so I had a mechanic check my timing belt. He said the belt itself is not too bad, but the teeth on the gears (I guess, I don't know too much about cars) are worn down pretty bad and If I was to give it too much gas the torque COULD cause the belt to slip and ruin my engine. Any thoughts on this? He said it'd be about $700 to replace the belt and the gear. Does this sound about right?

Hmm, considering the new style (round tooth) gears are nearly 400 each , and you will probably need a crank and or oil pump gear, I think his price is suspiciously too low.

Considering you have a 16 valve car (and I would never tell someone to drive it til it breaks) , if it is a US 16V car it most likely will *NOT* have an interference issue if the belt breaks (this is a good thing).

If you can follow instructions (like how to bake a cake) and have some hand tools (and a few specialty tools you can borrow or purchase) you can do this yourself, however if the gears are messed up (and if you have the old style gears) you are going to be replacing all the gears (2 cam gears, oil pump gear, crank gear) and a new style belt. I would be suspicious of any mechanic offering to do any timing belt job on a 928 for 700 bucks (unless he is saying the gears are great and the tensioner can be rebuilt)..

yup, very low, It cost close to that in parts, belt, rollers, H2O pump WITHOUT the gears doing it yourself. I'd ask him exactly what he does for that price. Given that your gears are worn I suspect your tensioner may not be working properly either which will require at the very minimum a disassembly and diagnosis. This may be one of those situations that dcrasta should make some excellent points for an certain aftermarket tensioner too.
btw I heard the most torque applied to the belt is at start up when everything is still and cold, so you may not want to start it either :)

OK thanks guys. I have a estimate in my car, I'll get it and let you guys know what it says.

ok.. so the total is $1,885.62.
timing belt $29.42
timing belt roller $195
timing belt roller $94.28
timing belt roller $81.19
2 camshaft gear $210
water pump $608.30
water pump gasket $2.44 ( didnt know there was any part THIS cheap ) ;)
Prestone coolant $13.99
Parts: $1,234.62
Labor: $640

Ok, so me and my dad both were thinking, If theres nothing wrong with my water pump, why pay 0ver $700 to have it replaced. so i guess it was closer to $1000 for the timing belt. Anyway do i need to have my water pump done too? I havent had any problems with it. Just seems sad to put $1,800 into a car thats barely worth that. lol

but, i mean if it needs done.... I'll start saving!! got....... $12 so far!!!

You should do a new pump, chances are if your gears are worn the bearing is tired too. both have the some pressure on them. You have the entire labor bill if it fails.

I see nothing on here about addressing the tensioner or your crank and oil pump pulleys, which are almost certain to be worn as well

Hmm.. approximately how much does that cost? Well.. I've been wanting to get a second job anyway...

timing belt roller $195 [Thats probably the big idler Roller]

timing belt roller $94.28 [PKtensioner eliminates this one]

timing belt roller $81.19 [PkTensioner eliminates this one]

If you were doing your own work I would recommend the PK tensioner, however the gear replacement is tricky and requires additional precision work to align the cams properly.

I suggest doing a forum search on Pktensioner , you mechanic may not want to install non porsche items on a car because of the risk of 'There is a problem .fix it' liability. In any case you are going to be fixing a lot of deferred repairs but this is one of the most expensive repairs that you have to have done (gear/timing belt replacements).

As far as the water pump the replacement of one requires removal of the Timing belt components, so its usually a good idea to replace when you do a timing belt. You can source a good new water pump for less than the price quoted by your mechanic.

Shops often mark-up parts cost as part of their profit margin (not saying its wrong, ..its their business model). You may save some $$ by getting the parts from another source (like Pelican) and having the shop just do the labor.

As always, I recommend the PKtensioner as a nice replacement to the factory tensioner, however some people do not think replacing the factory tensioner, which is very capable of doing the job, with something that is not made by Porsche.

Gears seem cheap and the Water pump high,

Water Pump 78 to 86 Laso New - w/gasket - Detailed item view - 928's R Us Porsche Parts Store

or

Alright, ill check on that when I have time. Would it cost about the same to have the pktensioner put in? As far as the labor prices I listed, is that pretty competitive? Or should I keep looking? The guy is a european car mechanic, so I imagine he is cheaper than a porsche mechanic but more knowlwdgable than a regular mechanic.

So, I've been talking to my dad and were thinking about getting the parts and doing it ourselves. Anyone know where I can get some instructions or something for doing this job? Also any tools besides just average hand tools needed for it?

yeah, a couple people have quoted that $200 roller. I have never paid more than $87 for one. I be interested to see the diagram on that.

If anyone is changing the little safety idler next to the crank gear.. that's a normal 6203 (don't quote me on #) $7.50 bearing pressed into a steel sleeve.

On the 2 valve the gear replacement is easy. They just keywayed. I think it's the 4v that needs the special tools.

Normal tools are all that's needed. You'll need to tension the belt with either a Porsche gauge or an aftermarket if you use the stock tensioner, I think the pk is self tensioning.

Camo,
We all started somewhere with these cars. You've got a real good and easy one to work on to start with. Timing belt failure is not catastrophic in your model year. Use the search function here and on the other forums. Read as much as you can BEFORE you order parts or began the timing belt job (Hint: it can save lots and lots of money) If you do not use a Porkensioner, you will need at least a Kempf tool to correctly tension your new timing belt. You can probably borrow one from someone close to you since you'll need it for less than a hour total.

When you finish, you will wonder why you even thought of paying someone else to do this job.

Good Luck.

Exactly

Ok thanks guys. One concern my dad had is with a pktensioner he said there's always a risk of it slipping if you accelerate fast. He just wanted me to ask you about that. He said something about if you give it alot of gas it slacks up and can potentially slip.

I think there is a theory about that but I think it's mostly bs. I'm sure to some extent it may be true but these belts are very stiff, they aren't stretchy like a rubber band. A properly tensioned belt with good gears will not slip. If the belt is loose yes, they have been know to slip, but not on the cam gears. They will generally jump a tooth or so on the small crank gear way before it's loose enought to jump the cam gears. There is too much wrap to jump the cams gears. An option for you then may be the PK tensioner, from what I understand you don't need to tension the belt, it does it for you via a spring and keeps the tension. Other know more about it.

Ok thanks. Also where can I find a pktensioner, what are the benefits versus just replacing the gears, and is it harder to install? :)

Go to Liftbars for info on the PKtensioner.

The factory tensioner is adjusted cold and releases tension due to the bi-metal washer stack when it gets hot. This is to compensate for the aluminum block/head growth after it gets up to Operating temp. Overly tight adjustment or a factory tensioner that is not working correctly (bi-metal washers not collapsing as designed, etc) can cause accelerated wear on the gears, and water pump bearing.

The Pk-Tensioner uses parts from the Audi V8 (the tensioner) and a custom bracket to replace the factory device. The Pk-Tensioner relys on a constant tension that is self-adjusting. This design is intended to maintain a constant and consistent tension (cold or hot). It also has less parts and requires less maintenance.

I have had my Pk-Tensioner for 2 years and about 40k miles. Not a problem . Many other people have used them as low cost replacements for the factory parts.

On a 32 Valve car breaking a timing belt is a much more expensive problem, however for most (US) 16 valve cars breaking a timing belt is more of an inconvenience than a expensive valve replacing nightmare.

You may be able to rebuild your factory parts. The bearing in the idler rollers are fairly common place if you can get the proper ones pressed in. That can save you some $$. The gears will be the most expensive part of it all. Confirm your gears are round tooth (new style) and not the 'square' tooth (old style and I believe no longer available).

Gear replacement should include both cam gears, the oil pump gear, and the crank gear.

In any case, I believe the only 'special' tool you need would be a flywheel locking tool. You probably can borrow one however a new one is about 40 bucks and a good addition to your '928 ' toolbox.