In part two, I presented some tools and equipment which, for the most part, were just off the beaten path in terms of common tools for the DIY automotive enthusiast/mechanic these days. I'd like to continue in that general direction by showing you some of the tools I've built for myself.
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Other Special Purpose Tools
I've owned many different types of cars over the years, and a couple of them have been the kind of cars that you end up with a couple of oddball tools for, like a specially ground screwdriver, or a shortened wrench. But Gretchen is in a class of her own in this regard - I've never had, let alone made, such an assortment of specific-function tools for a single car before. Here are some of them...
Timing Chain Tensioner Service Retainer
Completely endorsed by Porsche in the 16 valve service manual, you take a piece of coat hanger wire and bend it into a "U" to keep the tensioner in compression so you can take it out from under the chain. I'm surprised Hazet hasn't come up with something costing upwards of $300.00 for this...
Timing Chain Tensioner Compressor
If you've ever seen Jürgen's (irina25661) YouTube video on changing the 944S cam chain tensioner pads, or if you've ever done the job yourself, you'll understand why I made this tool. I don't have a picture of it in action, so you'll have to use some imagination: The round hook goes under the intake camshaft. As you pull back on the handle (the long part), the short little leg presses down on the tensioner right beside the chain. It's narrow enough to allow the coat hanger U tool to pass on either side of it, over the upper pad and into the holes in the tensioner body. This tool makes compressing the tensioner a snap.
Fuel Injector Inlet Screen Tool
I didn't make this one, but I wanted to include it because it's a great tool. I got this handy little number from Partworks DE in Germany. It works like a corkscrew to pull the injector screen out. You use the other end to press the new screen in.
Intake Tract Leakage Tester
I made this to track down an intake leak that I couldn't find, and it worked great. The leak turned out to be from a hidden plug on the side of the AFM. This leak tester is really most of the parts of a cylinder leakdown tester: an air line fitting, regulator, a 5-15 psi gauge, 1/4 x 4" NPT nipple, and a 4" PVC plumbing cap. You have to be careful to turn the air right down before connecting it to prevent damage to the pressure gauge, and only use 3-5 psi to pressurize your intake to avoid damaging any rubber parts or seals. On the 944S you also will have to hold the crankcase pressure relief valves on the cam cover shut, or all you will hear is air escaping through them. Adding smoke to this setup will be the ultimate in leak detection - this will be a future post.
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| A closer shot of the intake leak tester. Since this photo was taken, the gauge has been changed to a 15 psi unit, making it a lot easier to read and adjust. |
Cylinder Leakdown Tester
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| Leakdown testers are pretty simple - the inlet chamber is fed by the outlet of an air regulator and the outlet chamber connects to the cylinder you're testing via a hose screwed into the spark plug hole, just like a compression tester. With a gauge on each chamber, you instantly see how much pressure is leaking out of the outlet (cylinder) side. |
Leakdown testers seem like they should be very complicated, and at first glance you would think there's a lot more going on than there really is. They connect to your shop air supply, but even so they still have an air regulator at the inlet. The regulator is needed to calibrate the tester; usually by setting the inlet regulator to 100 psi. There is a front, or inlet chamber, and a rear, or outlet chamber. Between these is a passage divided by a 0.40" orifice. The orifice is there so that even if the tester is connected to a badly leaking cylinder the inlet air pressure can remain at 100 psi, thereby ensuring accuracy.
The principle of operation is this: if you have 100 psi on the inlet side, and no air is escaping (leaking out of) the outlet side, then you will also have 100 psi at the outlet, and therefore a 0% leakdown rate. If instead there's a small leak, say you have 90 psi at the outlet, this amounts to a 10 percent pressure loss; this is 10% leakdown (90/100 x 100 = 90%). If you have only 60 psi at the outlet, then you're losing 40 percent of the air pressure, which of course is 40% leakdown (40/100 X 100 = 40%). Most gauges are meant to work at 100 psi and use 100 psi gauges because of this simple direct relation, but if you do the math you can use any pressure and any gauges you want, it's just a percent ratio of outlet pressure to inlet pressure. The tester doesn't even need to have pressure scales at all; you could have an inlet gauge with only one mark corresponding to the calibration pressure, and an outlet gauge scale showing percentage or even just green, yellow, and red zones to indicate cylinder condition.
In my leakdown tester pictured above, the brass pipe dividing the two chambers has a quarter inch thick plug made with J-B Weld right in the middle. The orifice was formed by drilling an 0.40" hole in the cured JB Weld.
To do a leakdown test, you should start with a hot engine for the most accurate results. Set piston #1 at TDC (to close the valves), and connect the outlet hose to the cylinder. Connect about 120 psi of shop air to the the tester and set its inlet regulator to read 100 psi on the first gauge. Read the leakage on the second gauge. If your cylinder leaks more than about 5-10%, it's considered excessive, and at that point you listen for the escaping air to determine if your leakage is the head gasket (air & bubbles in coolant), intake valves (hissing in intake heard at the opened throttle body), exhaust valve (hissing in exhaust), or past the rings (hissing from the dipstick or in the AOS/oil fill pipe), or maybe some combination of those. Then do the same to each cylinder in turn (reduce the pressure before connecting to the next hole) , follow the firing order and set each one to TDC (a 180° turn of the crankshaft gets you there) before running the test.
Fuel rail pressure port adapter
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| Bel-Metric has all the fittings, hose, and clamps to make yourself a fuel pressure adapter for your pressure gauge. |
If you have a fuel pressure gauge that isn't able to directly connect to the Porsche fuel rail port, you can easily make an adapter for it. The 944 fuel rail requires a 60° M12x1.5 ball cone fitting, available from Belmetric.com, part numbers CNPL5-6/12X1.5 and CNPL12X1.5NUT. Add a short piece of 5 mm fuel hose, a couple of Oeteker clamps, whatever fitting you need to mate to the fuel pressure gauge hose (a Schrader valve in my case), and you're done. If the hose on your fuel pressure tester is 4-5mm, you could forego the adapter hose altogether, and use part number CNPL4-5/12X1.5 right on the end of the tester's hose, making it Porsche specific, if you wanted to. The bottom line is, there's no need to mess around with incompatible connectors, fittings, or AN fittings, anything like that. The right parts are readily available and not expensive at all.
Quick & Dirty Tap Guide
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| This improvised tap guide came in handy when I had to re-tap threaded holes in the intake manifold for M6 Helicoil screw thread inserts. |
I made this simple tap guide when I was installing a bunch of Helicoil STI's in the intake manifold (read about it in this post). It's just a drilled-out 5/16" coupling nut with the end ground ninety degrees to the sides so it can be held tight against a flat registration surface. The guide hole is just large enough to allow the tap to be turned without catching inside the guide. Once the threads are established, the tap stays straight in the hole without the guide.
Camshaft Pulley puller adapter
I forget where I saw this, it was either a YouTube video or a forum post. But I thought it was a great idea, so I made one for myself. Basically it's three pieces of M5 threaded rod, fender washers, nuts, and a standard harmonic balancer puller. Besides locking the M5 threaded rods into position for the puller, The nuts at the base of the pulley perform the job of the 5 x 20mm cam adjustment locking nuts that holds the cam pulley adjustment while you're working on the pulley/seal/camshafts.
Coolant Drain Channel
I made this radiator drain channel one day last spring after realizing I had to drain coolant yet again, and I had just watched an episode or two of Trev's Blog dealing with hand-shaping aluminum body panels. It bolts to the undertray attaching bolt point nearest to the radiator drain and this positions the notched end right up against and under the drain hole. If you leave the coolant reservoir pressure cap on, the coolant drains neatly into this channel and down into a bucket.
Copper gasket scraper
I saw Jürgen using a copper gasket scraper like this in one of his YouTube videos and immediately made one for myself. It works perfectly, doesn't scratch the aluminum, and when the edge gets dull, it's quickly sharpened on a whetstone. All you need is a vise and a file or a whetstone to make it. There are two grades of copper pipe - try to use the softer grade for this.
That's it for now. Thanks for stopping by and taking the time to read. Stay tuned for more mechanical adventures with Gretchen - to be notified when the next blog post comes out, just click the green button below or enter your email address in the sidebar at the right!
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