12/07/2010

How to repair sunroof on a Porsche 944 (Square Dash model)

THE WHY

Before I bought my 944 I did a fair amount of research on the net to find out about the things to look out for when purchasing a car of such an age. Amongst some of its well know weaknesses the sunroof lifting mechanism happens to be one of them. There also happens to be TWO versions of the 944 sunroof lifting mechanism, one for the earlier Square Dash model and one for the later Oval Dash model. A lot of the forums and tutorials on the web will often cover the Oval Dash model only which has a habit of stripping the white plastic gears (two gears, one in each lifting arm), and a simple fix for it can be found here. The Square Dash model does NOT have these gears and uses a different method to lift the roof. A good tutorial for fixing both versions exists in the official Porsche Workshop manual (contained in this tutorial) and here at Clarks Garage. I used both of these sources to help understand and fix the sunroof on my Square Dash 944 and have therefore provided more detailed pictures to supplement these existing guides.

THE TASK

You'll need the following:

Philips cross-head screwdriver
Flat-head screwdriver
Cleaning wipes/cloth
Degreaser

THE HOW TO

(Amateur mechanic job time: Approx. 1-3 hours)


Having taken the complete mechanism apart I discovered several faults on mine, these were as follows:

1. Broken drive dog (Shown further down post)
2. White transfer box mounting holes disintegrating


3. Both black lifting arm boxes mounting holes disintegrating


4. Main drive coil and left lifting arm coil missing several coils where it engages white transfer box



Luckily I managed to source items 2-3 in one 2nd-hand lot on ebay, and item 1. I was easily able to get from Porsche.


Tips for reassembly:

Once all the new parts arrived I cleaned out all 3 drive tubes using pipe cleaners and degreaser, then degreased all the coils themselves. I also cleaned all the accumulated dirt from the drive motor and slide rail too.

I then re-greased the drive tubes and coils as well as the lifting arms themselves.

The next step involved attaching the the new drive dog (white plastic square in photo below) to the new main coil I'd received. Luckily the new coil I received had the modified screw-in connection (upper picture) for the drive dog as opposed the old crimp style version (lower picture) on the broken coil.


Once the drive dog was attached I then threaded the coil into the drive tube in the boot (shown by right-hand orange arrow) so that went all the way back into the car. Left-hand arrow is the power connection for sunroof motor.


The drive dog was then slid into the rail on the motor assembly with the correct length of coil (305mm).


The motor assembly was then mounted back in position


Next I moved back inside the car to assemble the lifting arms and attach them to the transfer box. I made a slight modification the lifting arm boxes by securing them with zip ties after they had been secured together. I did this because the fixing holes on the previous pair had disintegrated where the screws had either been over tightened or the pressure of the arms had made the boxes explode. The zip ties therefore help spread the strain the screws come under.


Now finally, the transfer box is quite a tricky part to piece together with one pair of hands especially as all 3 drive tubes and their coils have to be lined up correctly. To make up for the lack of an extra pair of hands I used a 3 zip ties to hold the two drive tubes (that are attached to the lifting arms) in place in the transfer box before I inserted the drive gear and then finally the main drive tube (in the space shown by the orange arrows).





Once the whole mechanism was assembled and secured it took a bit of trial an error lining the lifting arm boxes up with the insertion point in the roof. This was achieved by packing them out with a few large shilling washers (shown by orange arrow).


The last piece in the jigsaw involved setting the limiter on the microswitches back on the motor assembly (shown by orange arrow).

09/07/2010

How to change water pump, camshaft / balance / timing belts on a Porsche 944 Turbo

THE WHY?

Having had my belts done when I first got my car a year and half ago I shouldn't really need to touch them for another 25,000 miles and having looked extensively around the net everyone has their own methods. The trouble is nobody seems to have posted a complete tutorial until I came across these excellent videos by VSVENSON on youtube. He takes you clearly through the steps and it doesn't appear to be as daunting as I had originally imagined.

THE TASK

There are a couple of special tools you may need to do this job and they can be quite rare and expensive. Luckily I found this site where a fella makes his own versions for a lot less.

THE HOW TO

Well here are the videos. Please make an effort to visit VSVENSON's YouTube channel and leave him some words of encouragement and praise for all his hard work.

Part 1 - Water pump



Part 2 - Water Pump



Part 3 - Water Pump and Camshaft / Balance / Timing Belt Change



If you need a written walkthrough try these at Clarks Garage

Camshaft (Timing) Belt General Information
Camshaft (Timing) Belt Installation
Camshaft (Timing) Belt Removal
Camshaft (Timing) Belt and Balance Shaft Belt Tensioning
Camshaft Chain Tensioner Replacement (16V)

And now there is now also an excellent thread on the whole procedure at the Pelican Parts forum (more specific to the non-turbo 944) to which most of the credit should go to forum member John_AZ.

How to remove and replace OPRV (Oil Pressure Relief Valve) on a Porsche 944

THE WHY

Since purchasing my 944 I'd always been aware of a slight fluid leak, but since none of the fluids (engine oil, power steering, water, brake fluid) seemed to be disappearing at any great rate and there were other more pressing issues I decided to put investigating it on the back burner.

Having now decided to tackle the problem I firstly discovered I actually had two fluid leaks, one from a power steering hose going from the reservoir to the pump which I dealt with right away by replacing the hose. The second however seemed to be coming from the engine but it was difficult to tell where from due to the oily grime all over the bottom of the engine and aluminium floor tray. So now the rest of the story follows how I went about identifying the cause of the oil leak and how the OPRV (Oil Pressure Relief Valve) fits into the story.

THE TASK

You'll need the following:

Karcher or other brand Water Pressure Washer
Gunk Spray Engine Degreaser
10mm socket
17mm socket (if you have the old style OPRV)
24mm socket (if you have the new style OPRV)
Ratchet socket wrench
Long socket wrench extension bar
2 x Axle Stands
Trolley Jack
Torque Wrench
Plenty of tissue or old rag

THE HOW TO

(Amateur mechanic job time: approx. 30mins - 1 hour)

Start by jacking up the front of the car and support on the first or ideally second stage of the axle stands.


Remove the seven 10mm bolts that secure the aluminium under-tray to the bottom of the car and remove the under-tray.


The picture above was taken after I'd degreased the underside of the car. I tried various methods of scrubbing, wiping and pressure steam cleaning but by far the best was pressure washing.

The best method I found was to let the engine run for 10 mins to warm it up, then spray Gunk Engine Degreaser over all the oily blackness you may have (Do not spray it near the belts or any bearings). Let the degreaser have 5-10 mins to take effect and then simply blast off with the water pressure washer (There's hardly any electrics on the bottom of the car but avoid them at all costs). Spraying the washer in quick bursts is the best method. Repeat as necessary and wipe down anything that looks oily, not forgetting to also clean all the oil of the under-tray too.

Now you have a clean canvas to identify your leak. Unless the leak is bad you probably won't be able to see it straight away, so this is where some patience comes in. Either leave it jacked up over night and see if you can identify a drip in the morning or re-attach the under-tray and do a few miles to put the engine under load which usually force the oil out of the place it is escaping. When you jack the car up again, you'll be able to see the area where the oil is dropping on the under-tray and then just trace it back up into the engine well.

The oil on mine was falling onto the left hand-side of the under-tray so I started to investigate in this area as shown my the orange arrow below.


This is where I found a drip coming off the end of the OPRV (Oil Pressure Relief Valve) nut.

Here's a couple of photos to show you what to look for (The nut has been removed but you can see the port it screws into)



--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

THE OPRV - here's where it gets complicated:

83-86 models will have a 17mm or 24mm nut
87 models onwards will and should always be 24mm.

Picture shows the difference between the 24mm on the left, 17mm on the right.


The 17mm nut may also look like this one below as well (photo taken from another Porsche source)


If you have the 17mm nut then you have the OLD discontinued OPRV, which can look like one of the two versions shown below (Difference is in the style of the nut and and piston). There are 4 pieces to each version, the nut, aluminium washer, spring and piston.



From the 87 model onwards a new OPRV was produced along with a retro-fit upgrade for people with the old style valve.

Here's the NEW retro-fit valve (944 107 035 11) for 83-86 models


And here's the one (944 107 035 02) for 87 models onwards


 And here they are side by side, 83-86 on left, 87 on right. (Main differences in length and taper on thread).


Originally I'm sure I read somewhere that these NEWER valves were not serviceable apart from aluminium sealing ring and the green O-ring at the opposite end. However it seems they are serviceable to a certain degree and a kind fellow has posted the procedure on PelicanParts in 6th post down. The photo below shows what one of the newer OPRV's looks like when you take it apart. Note the aluminium sealing ring far left, damaged black internal O-ring in the middle and what should be a thicker green O-ring at the end (also damaged). If you need to replace the entire valve they aren't cheap either, £250 from Porsche.


--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

OPRV removal

Take a 17mm or 24 mm and socket extension bar that should be long enough to enable you to ratchet it from inside the wheel arch.



Once I had it removed I ended up with this


Notice the small nut that was inside the piston that some previous enterprising owner/mechanic had used as a space packer. I also found the spring to be 3-4 coils shorter than it should be, so who even knows what vehicle it was from. So not only did I have a leak from ORPV, I now had to replace the OPRV and at £250 that's quite a hit.

So here we are the OLD alongside the NEW




Installing the new OPRV is the reverse of removal, making sure you use a new aluminium sealing ring and lightly oil the o-ring and length of the valve to aid it's insertion. You should then use a Torque wrench to tighten to 45Nm.

Finally re-install the under-tray, run the car making sure the oil pressure gauge doesn't exhibit any strange behaviour and you're done...........well almost.

After doing all this I still found I had more oil leak coming from the same area, it now looks likely it's the gaskets for the Oil Cooler that the OPRV screws into. This looks a bit of an ugly job and not having the time to do it I'm going to get a mechanic to sort it out. For anyone that wants a go here's the procedure and here's another.

Finally here's the Porsche bulletin that goes into a few pages of detail on the OPRV. (Click the pictures for larger versions)