future

I've decided to take on the task of changing the belts myself which were last done at a dealers about 28k miles ago on my 951.

I intend to send the Cam housing away to be painted and have allready shot blasted the intake manfold which looks like new now but have encounted various problems along the way.

After stripping all the top of the engine away i.e. Injector rail, Intake manifold and all of the pipework including coolant pipes I was amazed at the amount of corroded pipes and vacum hoses. I intend to replace these with silicon items.

I then removed the radiator fan assembly to gain better access to the belt cover - making hard work for myself I know but I my as well clean everything whilst I'm doing the job.

I then removed the plastic belt cover after removing the alternator and powersteering belts and after close inspection of the tensioner belt I noticed that there were rows of teeth missing from the belt

QU. 1 - The teeth were only mising from the inside of the belt. Has anybody experienced this before and what has caused this to happen, the cam belt looked OK???

QU. 2 - Can somebody post pictures of how to remove both the belt. I have turned the engine to TDC???

QU. 3 - After inspecting the green Bosch injectors I noticed that number 2 and 3 had cracks on the injector caps - What causes this to happen. I replace the caps and O-rings with the replacement Bosch parts???

QU. 4 - Before I remove the Cam Housing for painting, will anything fall out when I lift it off and is it simple to put back on???

I am a novice when it comes to mechanics but you have to start somewhere and this is turning into a much bigger job than I orriginally expected - But I guess all jobs are like that.

thanks in advance for your help

Charlotte944

A1: Rubber belts age and if not properly tensioned the teeth will break. You got REAL lucky.

A2: You need to slack off the tensioners. Go here: Clark's Garage, click on Garage Shop Manual and start reading. NOTE: The balance shaft belt will come off easily, but the cam timing belt will be a little more difficult. Most folks remove the crank shaft pulleys and gears, but that is not really necessary. To get the cam timing belt off and on you need to work is past the rear timing belt cover. To do this, get the belt off of the cam gear and other pulleys/rollers. Twist the belt so that it is "edge on" and then slip the belt between the crank timing gear and the rear blet cover. To install the timing belt, start at the timing gear with the belt edge on and then work it onto the timing gear. This takes a little practice, but I use this method all of the time.

A3: Plastic cracks. Install new seals and caps. "Kits" are available at your local dealer. Coat the O-Rings with some ATF when you install the injectors. ATF will lube the O-Rings for installation and help them seal.

A4: Yes, and sort of. Since this is an over head cam engine, the "lifters" or cam followers will fall out of the cam tower. Make sure you put each follower back where it came from. When you start to put the cam tower back on, coat each lifter with some grease. This will help keep the followers in place while you install the cam tower.

When you get the belts on and properly tensioned, turn the enigne over by hand for at least one complete revolution to verify that the timing marks stay in alignment. Also make sure that the balance shaft belt does not get loose. I recently did a water pump job, and when I started the engine I got some wicked belt slap. I didn't check properly and there was a good deal of slack in the balance belt. Dodged a major bullet!

Final hints: Take the spark plugs out. This will make it a whole lot easier to turn the engine over by hand. Also, leave the injectors disconnected and leave the spark plugs out, and then fill the crankcase with oil, and put about 2 gallons of water in the cooling system (Don't add anti-freeze just yet!). Use the starter to turn the engine over until you get oil pressure. DO NOT START THE ENGINE WITHOUT DOING THIS!

When you have oil pressure, install the plugs, plug the injectors in, and start the enigne. Verify that you have oil pressure! If you do not have oil pressure, remove the plugs, disconnect the injectors and try again. If you do not get pressure check the sender wires.

At this point you can run the engine and get it up to temperature so you can check for water leaks. If you have no leaks, let the engine cool down, drain the water and add 1 gallon of anti freeze and i gallon of water to the cooling system. Bleed the system and top off with water as necessary. The proper coolant level is between the MAX and MIN marks on the expansion tank when the engine is HOT.

future

WOW... Thanks Charlotte944 - I'll give it a go tonight

I guess I decided to do the job just in time. What would have happened if the balance shaft belt had snapped? I will post some pictures of the belt later so everyone can see. It really is in a poor state. At one point there are over 7 teeth missing in a row!

Charlotte944

If the balance shaft belt breaks it also breaks or severly damages the cam timing belt. Since these are interference engines, breaking a cam belt causes bent valves. CHA-CHING!

BTW: How about adding your location and car modle to either your profile or signature. That way "we" can give you the straight skinny.

Crazy Eddie

Check out http://clarks-garage.com/
He has a good write up on the cam housing
Regards
Ed
Edit opps I just saw that that was recommended already

future

Yes I went to the Clarks Garage website last night.

I must have printed off every PDF page from his website. This guy must have spent loads of time doing his site - GREAT WEBSITE - VERY HELPFUL - BETTER THAN THE HAYNES MANUAL!!!

Charlotte944: Just to confirm, does 'Interference Engine' mean that if the cam belt snaps, then the valves will have an 'up close and personal relationship' with the pistons?

P.S. I've added a picture of my car to the aviator. I have just had the car fully re-sprayed, new kkk turbo fitted, Just added 968 door handles and mirrors, Carbon Fibre GT Wing to be fitted next week, currently stripping the interior out to install full welded in MSA approved roll cage, just fitted 18 inch 993 Turbo wheels (getting painted black this week), Recaro Profi SPG seats about to go in when they arrive. Next I'm going to start on the engine after fitting my new Bilstein Cup coilovers which are to currently being held by Customs awaiting me to pay the Duty, Vat and clearance fee and removed rear torson bar (550 springs on the rear and 350 on the front). Need to purchase Carbon front splitter and I have currently commisioned a designer to design and produce a new headlight kit comprising of 2 Hella road lights to be fitted under each pop-up light and the lift motor arms will be shorterned so the light only pop-up half way for better look and improve nighttime aerodynamics!

Once the job is finished I will post loads of pictures. I originally purchased my car as a light damaged project with the intension of using it mainly for track day use with light road use.

I am to have everything listed finished in the next 2 weeks so

future

OK... I need to purchase a belt tension tool but the Porsche item looks expensive to say the least for a tool that will get little use.

I have seen that other Rennlisters have used the 'Kriket I' tool as an alternative.

My question is: Where can I purchase the tool from in the UK or an alternative tool or does somebody want to rent the tool to me?

I have seen this tool forsale on www.9xauto.com but I need access to one ASAP as I would like to complete the job this weekend.

Anyone have any ideas!!!

future

OK... Another question. After reading the Clarks Garage website there was reference to each of the balance shaft sprokets - the one at the top and the one at the bottom. It goes on to talk about the 'Woodruff Key' what is this and what sould I be looking for or at?

Maybe I'm missing the point, but 'Woodruff Key' sounds like a tool *HELP*

jurg

Here maybe this help

Charlotte944

Furute:

Yep, "Interference Engine" means that if the cam belt breaks while the engine is running, one or more valves will be bent.

For the belt tension tool, I did a Google search for "Optbelt". (Same tool as the KriKit)


Optibelt GmbH
Corveyer Allee 15
D-37671 Höxter/Germany

Telephone +49 (0) 52 71 - 6 21
Fax +49 (0) 52 71 - 97 62 00
info@optibelt.com
www.optibelt.com

For the balance shaft alignment:

First, the timing marks are moulded into the rear belt cover. The upper shaft mark is a small 'V' shaped notch at about the 12 o'clock position where the shaft comes through the cover. The upper shaft has a corresponding notch. The upper shaft sprocket also has the letter 'O' stamped on the front of the sprocket. With the 'V' notches aligned, the stamped 'O' will be at about the 11 oclock position.

The lower mark is a tab at about the 7 o'clock position, and the lower shaft sprocket has a 'V' notch just like the upper shaft sprocket. Align the lower sprocket's 'V' notch with the tab.

BTW: You won't see any Woodruff Keys unless you disassemble the balance shaft sprockets. The end of the shaft has a curved groove, and the sprocket has a slot. With the key inserted into the shaft, the sprocket slips over the shaft so that the key locks the sprocket to the shaft.

future

Jurg: Thanks for the image, that clears things up

Charlotte944: You must spend more time in the engine bay than driving the car!!! Your help is much appreciated. I’ll do a search for the Optbelt tool with google as recommended.

Below is a picture of the balance belt I have just removed – it is the poorest thing I have ever seen, what do you guy think?



OK, next question: Being the impatient person that I am (well so my wife tells me), I turned the engine to TCD loosened the bottom Balance Belt Tensioner Roller and turned it to slacken off the belt and then removed the belt – EASY! Next I loosened the nut that hold the spring tensioner locked and pushed down on it with one hand and re-tightened the nut so that the cam belt was slack, but try as hard as I might, I just could not get the belt off from behind the spring tensioner. It says on Clark’s Garage website that it is possible to get the belt out with the spring tensioner in place but anger got the better of me ‘so out came the knife’ and I just cut it off!!!

It says on the Clark’s website that to remove the spring tensioner that you have to remove 3 bolts, but not the 3 bolts on the cover of the spring tensioner, but three located underneath it. I cann’t I prodded and pocked my finger under the spring tensioner and found loads of them darn bolts so am unsure which ones to undo. Any one got a diagram of even better a picture so I can see what I am doing. I even used one of those dentist mirrors to have a good look – This job is getting very surgical! *SMILES*

Question 2: I have not locked the flywheel yet as I do not have the tool! I can not see the timing marker on the Balance Belt Drive Gear (Cambelt drive gear), do I need to remove the Balance Belt Drive Gear from the front of the Cambelt drive gear to see a mark, I did tipex a mark myself.

So I do not have the flywheel locking key, can I just jam a large screw driver in there to lock it and then remove the Balance Belt Drive Gear?

Charlotte944

Future:

Yeah, I've spent a lot of time under the hood with test gear and such. After having three of these cars (I still have two), and doing 3 head gaskets, 3 water pumps, two radiators, rebuilding brake calipers, rebuilding clutch slave and master cylinders, replacing front and rear wheel bearings (both late and early), rebuilding front control arms, and a host of other stuff, I guess I sorta know my way around.

For question 2: The timing marks are on the main cam gear, at the back of the engine on the flywheel (look through the hole near the speed and reference sensors), and on the balance shaft sprockets. For the cam gear there is a static mark at about the 1 o'clock position on the rear cam timing gear cover. Unless you plan to replace the front engine and oil pump seals, there is NO NEED to remove either the balance or cam drive sprockets from the end of the crank shaft.

MAJOR HINT: Unless you are going to remove the cam tower, DO NOT remove the cam timing belt unless the enigne is at TDC!

With the cam timing belt installed and tensioned you can turn the engiine over by hand to get the timing marks aligned. Once you have that you can remove the auto tensioner, and then remove the cam timing belt. If you have the cam timing belt partially removed, but the engine is not at TDC, then you need to remove the cam tower, turn the engine to TDC, set the cam gear to TDC, reinstall the cam tower, install the belt, install the tensioner, and then tension the belt. Remember, we are dealing with an interference engine, so it is real easy to bugger valves.

When you get the new belts installed and tensioned, turn the engine over by hand and verify that the timing marks come back into alignment. DO NOT turn the engine over backwards (anti-clockwise as viewd from the front)! Turning the engine over backwards will cause the belts to jump timing when you start the engine (Don't ask me how I know!).

future

Yes, I'm removing the Cam Tower as well so I can run it though the parts cleaner and replace the gasket at the same time.

I have come across what may well be the reason for the balance belt stripping notches as pictured previosly, see picture below:



As highlited above, when I turn this lower balance shaft sprocket buy hand now that the belt is off the car, it feels stiff to start with untill you get it turning!

I persum that the amount of friction when turning sould be the same as the Upper Balance Shaft Sprocket which turns easily in my fingers.

Does this sound like a problem and if so what should I do about it?

I will give the thing a good spraying with WD40 or another product.

Also, how do I know when the water pump is on its way out. At the moment it turns freely and there is no play when pupping on the wheel both in an in and out direction and from side to side! Does this sound OK. I have no idea when it was last changed!

To confirm my engine is at TDC, I have the Camshaft sprocket lined up with the grove on the sprocket matching that on the rear off camshaft sprocket cover (aluminium cover). When also looking down the rear of the engine from above in the opening next to the speed sensor cable, the mark on the Flywheel is visibly lined up with the marker in the sensor with a mark on the flywheel?

future

P.S. Does anybody have a photo they can post of what the inside of the cam housing looks like when removed from the car.

Charlotte944

Future:

I think you found the source of your problem. Both balance shafts should turn freely with no binding.

Figuring out when a water pump is getting ready to die is like winning the lottery. However, "When in doubt, rip it out." This adage has saved my butt more than once.

You have the engine at TDC, so you are ready to remove the cam timing belt.