Timing belt change questions.
07-30-2012, 11:07 PM
#1
Track Day
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Timing belt change questions.
This weekend I plan to embark on my first timing belt change on my 1988 Turbo S. I have read/watched several guides and I feel pretty confident. There are a couple of things I have questions about.
1. At 58,000 miles, should I change the spring belt tensioner? If so, what tensioner should I get? I would just go ahead and change it, but tensioners for this car appear to be pretty pricey.
2. I am planning on changing the water pump while I'm in there so I will need to remove the crank pulley. I hear a lot of talk about using flywheel locks, which I do not have, to break the bolt free. On every other car I have done this with I have achieved it by having one person stand on the brakes with the car in gear while I break the bolt loose. Is there a reason this will not work on the 944?
3. I got an oil seal kit from pelican parts. My plan is to only replace seals if I see signs of them leaking. In my past experience with seals of this nature is that if it isn't leaking, then don't mess with it. I've in a few cases ended causing a leak by replacing a seal. What do others feel about this?
That's all I can think of right now. Thanks in advanced for the help.
1. At 58,000 miles, should I change the spring belt tensioner? If so, what tensioner should I get? I would just go ahead and change it, but tensioners for this car appear to be pretty pricey.
2. I am planning on changing the water pump while I'm in there so I will need to remove the crank pulley. I hear a lot of talk about using flywheel locks, which I do not have, to break the bolt free. On every other car I have done this with I have achieved it by having one person stand on the brakes with the car in gear while I break the bolt loose. Is there a reason this will not work on the 944?
3. I got an oil seal kit from pelican parts. My plan is to only replace seals if I see signs of them leaking. In my past experience with seals of this nature is that if it isn't leaking, then don't mess with it. I've in a few cases ended causing a leak by replacing a seal. What do others feel about this?
That's all I can think of right now. Thanks in advanced for the help.
07-30-2012, 11:24 PM
#2
Rainman
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Don't trust the spring tensioner as the end-all - when installing the new belt, adjust the position of the tensioner with it loose and set the belt to the right tension, then tighten down the tensioner. It is not as useful or accurate as you'd think. Kind of a PITA sometimes.
That will work on a 944, I have done it on a 968 before when my 944 flywheel lock would not reach the deeper bellhousing. We recommend the lock just because it is available and cheap. Where are you located? Someone may have one to loan you.
That will work on a 944, I have done it on a 968 before when my 944 flywheel lock would not reach the deeper bellhousing. We recommend the lock just because it is available and cheap. Where are you located? Someone may have one to loan you.
07-30-2012, 11:27 PM
#3
Nordschleife Master
I replace the tensioner, seals, rollers and water pump every other belt change. It's just good insurance. You have the later self adjusting tensioner so use the same one. I've never had a problem with leaks from new seals but I suppose of they are not fitted correctly they will leak. Flywheel locks are cheap, $50 or less, check fleebay. You can probably do it another way but if it doesn't work for you will have wasted a weekend.
07-31-2012, 12:01 AM
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Track Day
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I think the kit I got (pelican parts timing belt kit) has a new pulley for the tentioner. I just noticed that a replacement tentioner assembly costs some real money. It sounds to me like all the assembly does is help set the proper tention initially and once it is all tightened down doesn't do anything. In that case, I just won't rely on it and will set the tention manually.
07-31-2012, 11:36 AM
#5
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My opinions:
1. I wouldn't replace it. As V2 notes, the tensioner cannot be completely trusted. Porsche introduced it because dealer techs were not using the factory tool, were not setting belt tension except by "feel," and they were getting a bunch of broken belts they had to eat. Despite the automatic tensioner, I always check with the belt gauge tool. On the tensioner, I would remove it, clean it, make sure it moves properly (for example the spring isn't broken or bound by debris), and reuse.
2. If you're doing your own work, replacing the water pump on spec is an utter waste of money. I got around 66K miles on my first one, and at 160K miles the second one is fine. When it comes to r&r the crank pulley, just buy the flywheel lock. I've seen techs jam a large screwdriver or pry bar against the timing wheel to lock things, not my preferred technique.
3. I generally agree with you, if you're doing your own work.
In addition, I recommend checking all the idlers, rollers, pulleys for bearing condition. They can whirr a bit but need to be checked and replaced if they make bad noises, do not turn smoothly, exhibit a lot of play, etc. Consider buying a complete set of them, replacing what's needed, putting the others on a shelf against the date you'll eventually need them.
I would also use the covers-off time to do a good job cleaning under the covers: any oil or belt dust. Cleaning will help you be more sure of the occurrence and degree of future seepage. Consider replacing hardware -- nuts and washers -- if what you have is old, corroded, or has been torqued a bunch of times.
Kevin
Catellus Engineering
1. I wouldn't replace it. As V2 notes, the tensioner cannot be completely trusted. Porsche introduced it because dealer techs were not using the factory tool, were not setting belt tension except by "feel," and they were getting a bunch of broken belts they had to eat. Despite the automatic tensioner, I always check with the belt gauge tool. On the tensioner, I would remove it, clean it, make sure it moves properly (for example the spring isn't broken or bound by debris), and reuse.
2. If you're doing your own work, replacing the water pump on spec is an utter waste of money. I got around 66K miles on my first one, and at 160K miles the second one is fine. When it comes to r&r the crank pulley, just buy the flywheel lock. I've seen techs jam a large screwdriver or pry bar against the timing wheel to lock things, not my preferred technique.
3. I generally agree with you, if you're doing your own work.
In addition, I recommend checking all the idlers, rollers, pulleys for bearing condition. They can whirr a bit but need to be checked and replaced if they make bad noises, do not turn smoothly, exhibit a lot of play, etc. Consider buying a complete set of them, replacing what's needed, putting the others on a shelf against the date you'll eventually need them.
I would also use the covers-off time to do a good job cleaning under the covers: any oil or belt dust. Cleaning will help you be more sure of the occurrence and degree of future seepage. Consider replacing hardware -- nuts and washers -- if what you have is old, corroded, or has been torqued a bunch of times.
Kevin
Catellus Engineering
07-31-2012, 12:16 PM
#6
Proprietoristicly Refined
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I agree with Kevin, Why are you replacing the WP?
The main reason the WP will fail is due to an over tensioned cam belt causing the WP seal or bearing to fail.
I might not have the miles on my WPs but both were changed with rebuilds when I bought the cars--in 1996 & 1998. I have one on the shelf collecting dust.
Get a flywheel lock. If you go "redneck" and stick a tool in the flywheel gear you may break off a couple of teeth. Now that is a big problem. You will need one to replace the front camshaft seal and oil pump sleeve.
You mentioned you "read" about cam belt tension. What method do you plan to use? What tension tool do you have?
I change my cam belt every 2-3 years and re-tension at 1000 miles and 3000 to 5000 miles intervals thereafter.
I also agree with V2Rocket, the spring tensioner is only a poor substitute for a real tension tool or a few years of experience to get the "feel"
Porsche has put out a couple modifications to the spring tensioner tension method.
This is only one. Do not put all your trust in the spring tensioner.
GL
John
The main reason the WP will fail is due to an over tensioned cam belt causing the WP seal or bearing to fail.
I might not have the miles on my WPs but both were changed with rebuilds when I bought the cars--in 1996 & 1998. I have one on the shelf collecting dust.
Get a flywheel lock. If you go "redneck" and stick a tool in the flywheel gear you may break off a couple of teeth. Now that is a big problem. You will need one to replace the front camshaft seal and oil pump sleeve.
You mentioned you "read" about cam belt tension. What method do you plan to use? What tension tool do you have?
I change my cam belt every 2-3 years and re-tension at 1000 miles and 3000 to 5000 miles intervals thereafter.
I also agree with V2Rocket, the spring tensioner is only a poor substitute for a real tension tool or a few years of experience to get the "feel"
Porsche has put out a couple modifications to the spring tensioner tension method.
This is only one. Do not put all your trust in the spring tensioner.
GL
John
07-31-2012, 01:45 PM
#7
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I just replaced my water pump after 80k miles, and the bearing was just starting to have some play in it. I doubt it would have gone another 10k before starting to leak, or maybe seize and take out my valves.
I agree with the flywheel lock. I don't like the put in gear and have a friend stand on the brakes method. The spring in the clutch takes away from the force you might need to snap it loose. I suppose if you had a powerful enough impact wrench, that would work too.
Also don't forget about the o-ring that goes on in front of the oil pump drive sleeve. Mine was getting hard. I replaced the crank seal also because it was just starting to weep.
I agree with the flywheel lock. I don't like the put in gear and have a friend stand on the brakes method. The spring in the clutch takes away from the force you might need to snap it loose. I suppose if you had a powerful enough impact wrench, that would work too.
Also don't forget about the o-ring that goes on in front of the oil pump drive sleeve. Mine was getting hard. I replaced the crank seal also because it was just starting to weep.
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07-31-2012, 02:36 PM
#8
Rainman
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FWIW I replaced my waterpump after 6 years but only about 30,000 miles. Bearing was going bad, likely because I had used 4 sets of belts on that pump (lots of while you're in there work).
The waterpump is so cheap it's hard to justify NOT changing it.
The waterpump is so cheap it's hard to justify NOT changing it.
07-31-2012, 04:10 PM
#9
Addict
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This is just one data point, but . . .
Bought a 1987 924S in March 2011; 52K miles. Changed the timing belts and water pump (did not change any seals) within a month or two.
Fast forward to April 2012, I see oil dripping onto my garage floor. After a couple of weeks I diagnose that it is coming from one of the front engine seals.
June 2012, I get to remove and replace my timing belts again so that I can change the front seals (I changed all of them).
Moral of the story: I wish I had done the front seals when I did the belts and water pump last year.
Bought a 1987 924S in March 2011; 52K miles. Changed the timing belts and water pump (did not change any seals) within a month or two.
Fast forward to April 2012, I see oil dripping onto my garage floor. After a couple of weeks I diagnose that it is coming from one of the front engine seals.
June 2012, I get to remove and replace my timing belts again so that I can change the front seals (I changed all of them).
Moral of the story: I wish I had done the front seals when I did the belts and water pump last year.
07-31-2012, 04:15 PM
#10
Drifting
IMHO, Mark is spot on about fixing things while you have access to them. It's called WYIT (while you're in there). This is especially true of these 20 something old cars, mileage not withstanding. With all the rubber seals in the front of the engine, age makes them hard and if even one is starting to leak, they're all just as hard and will begin to leak also. While you have the front torn down and inner plastic belt shield removed, perfect time to replace all the camshaft front and rear seals, front balance shaft and housing seals, oil pump sleeve (if it's got grooves in it) and all of it's seals (don't forget the little green one) and the front crankshaft seal. You'll feel better about it later. Make sure you get the gears back on with the proper faces in the right direction. You'll read about it being improperly reinstalled on this website occasionally. The spring tensioner for the timing belt gets you close but since it sounds like you got the kit with the belts, idler rollers and cogged rollers you only really need to set the tension such that when you try to turn the water pump pulley by hand it barely turns. if it doesn't....to tight. If it turns easily....too loose. The balance belt should allow you to get a 180 degree twist. After about 1500 miles, do a recheck of the tension. You'll probably see a timing belt stretch slightly because of it's teeth settling into their cogs on the gears. Some people get real specific about using tension gauges and others use this method successfully. It's worked well for me and I have no oil leaks anywhere.
07-31-2012, 11:12 PM
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Track Day
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Thanks for the good info. As far as the flywheel lock goes, I don't have one and I'm not gonna be able to get one to me before this weekend. If I have issues, I will just stop and wait for one to come in the mail. I don't plan on using anything like a screwdriver that could damage the flywheel.
I really don't have the money/feel the need to get a tensioning tool right now. I've watched some video tutorials and done enough timing belt changes on other cars to be able to judge if the tension is around proper. I will probably get a tensioning tool for my first re-tension just to be safe.
Is there a good guide on how to properly remove and replace the front engine seals? Are there any seals that I should be changing that are not in this kit: http://www.pelicanparts.com/cgi-bin/...rbo)Brand: OEM
I am changing the waterpump because for all I know, this car (which i just bought) has the original water pump from 1988 and to my understand 60K is the recommended service time anyways. In my experience from other cars with timing driven water pumps is that water pump failure equals timing failure. Don't feel the need to risk that on 23 year old bearings.
As far as rollers go, I will change all of the ones that I have replacements for in the pelican parts kit. I'm really not that familiar with this car yet to know that I have all of the parts that should be changed. I will deal with anything I don't have on a case by case basis. My main goal is to get the car to the point that I feel comfortable driving it for the rest of the summer without causing damage (via timing belt failure). Anything else can wait until this winter.
Again, Thank you all for your valuable input so far. I am sure I will be back for more as I learn about this car.
I really don't have the money/feel the need to get a tensioning tool right now. I've watched some video tutorials and done enough timing belt changes on other cars to be able to judge if the tension is around proper. I will probably get a tensioning tool for my first re-tension just to be safe.
Is there a good guide on how to properly remove and replace the front engine seals? Are there any seals that I should be changing that are not in this kit: http://www.pelicanparts.com/cgi-bin/...rbo)Brand: OEM
I am changing the waterpump because for all I know, this car (which i just bought) has the original water pump from 1988 and to my understand 60K is the recommended service time anyways. In my experience from other cars with timing driven water pumps is that water pump failure equals timing failure. Don't feel the need to risk that on 23 year old bearings.
As far as rollers go, I will change all of the ones that I have replacements for in the pelican parts kit. I'm really not that familiar with this car yet to know that I have all of the parts that should be changed. I will deal with anything I don't have on a case by case basis. My main goal is to get the car to the point that I feel comfortable driving it for the rest of the summer without causing damage (via timing belt failure). Anything else can wait until this winter.
Again, Thank you all for your valuable input so far. I am sure I will be back for more as I learn about this car.
Last edited by jred42; 07-31-2012 at 11:16 PM. Reason: Had the wrong link for the seal kit
08-01-2012, 10:26 AM
#12
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I like this guide for the FOES.
http://arnnworx.com/front_seals.htm
Great info on setting the tension on the belts in one of the other DIY links from Arnnworx.
Michael
http://arnnworx.com/front_seals.htm
Great info on setting the tension on the belts in one of the other DIY links from Arnnworx.
Michael
08-01-2012, 10:40 AM
#13
Chainsaw
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I've just finished my first belt change on my '86 944 NA. They've been changed before but I had more money than time. Now I have more time than money.
I skipped the flywheel lock and after setting the flywheel to TDC I marked it w/ chalk and used two punches to lock the flywheel. (pic one, clutch slave is missing in pic). It worked great.
IMHO do not try to do anything with the crankshaft pulleys w/o a gear puller. It's tight working with the puller because the radiator and fans are right there. Fortunately for me I had the resources of a fully equipped community college auto shop to use their puller.
I skipped the flywheel lock and after setting the flywheel to TDC I marked it w/ chalk and used two punches to lock the flywheel. (pic one, clutch slave is missing in pic). It worked great.
IMHO do not try to do anything with the crankshaft pulleys w/o a gear puller. It's tight working with the puller because the radiator and fans are right there. Fortunately for me I had the resources of a fully equipped community college auto shop to use their puller.
Last edited by NCporsche; 08-01-2012 at 12:54 PM.
08-01-2012, 04:08 PM
#14
Track Day
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I am a little worried about clearance for my puller. I suppose I could always remove the radiator and fans if there is a clearance issue. Is the radiator for this car difficult to remove?
Another thing I've noticed is that a lot of people have been manually marking TDC on their flywheel. Is there not a TDC mark already on the crank sprocket for the timing belt? It just seems like marking this has been completely unnecessary on any other cars I've worked on.
I apologize for my ignorance, I have only owned the car for 8 days and it has been parked in my parent's shop for the majority of that time. I will understand more once I have a chance to spend some time looking at the car.
Another thing I've noticed is that a lot of people have been manually marking TDC on their flywheel. Is there not a TDC mark already on the crank sprocket for the timing belt? It just seems like marking this has been completely unnecessary on any other cars I've worked on.
I apologize for my ignorance, I have only owned the car for 8 days and it has been parked in my parent's shop for the majority of that time. I will understand more once I have a chance to spend some time looking at the car.
08-01-2012, 05:18 PM
#15
Chainsaw
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Clearance on the puller...I had to put in a short bolt and wrap it in electrical tape, used a pair of fchannel locks to turn the puller to pull the crankshaft gear. The bolt head on the puller was in between the fans for the radiator.
There is a slot in the housing and an indentation in the crankshaft (here the arrow is pointing) behind opening. It is a two person job. One to turn the crank and one to look in the slot to tell you when TDC was found.
Turning the crank, you will feel when TDC is found because you will feel the resistance then feel the release of the piston moving away from TDC.
There is a slot in the housing and an indentation in the crankshaft (here the arrow is pointing) behind opening. It is a two person job. One to turn the crank and one to look in the slot to tell you when TDC was found.
Turning the crank, you will feel when TDC is found because you will feel the resistance then feel the release of the piston moving away from TDC.
