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Hopefully some one may have a few answers for me for which I will be very gratefull for to speed up my learning curve with my recent acquisition of a 1972/3 412 Variant fitted with a 1.7 W code fuel injected engine.

I say it 1972/3 Variant because although it was registered in 1972 it appears that some, if not all the parts are the later version. I have discovered this one by trying to find some replacement front disc for it. The front left one is badly scored from what appears to have been a siezed caliper (found in the box of spares in the car) at some point in its past. The disc that I need to find (I have a supplier looking for them for me) have a 60mm offset and 14mm pads instead of the the earlier 10mm pads with the 50mm offset disc.

Anyway on with the snag list though as I am top of the brakes, hopefully.

Firstly is the rough running at low revs. In a queue of traffic the car seems to stutter its way forward a quick increase in revs sorts it, but it is not a good idea to prolong it. It has been mentioned this might me down to the timing being too far advanced so shall have to dig my timing light out of the back of my shed and check this. I've already checked the points and plugs etc and they all appear to be in good order. However some of the airlines are a bit perished at the ends so is it possible it could be an air leak?

Secondly, there has been a worrying scraping/grinding kind of noise coming from the front left corner when negotiating speed bumps develope over the last week or so. Cursory examinations seem to point to the anti roll bar bushes being knackered as it is possible to move the anti roll bar backwards and forwards by hand and produce a quieter version of the noise. Fingers crossed that is this one sorted.

Thirdly, the gear selection is bit of an art as there is a lot of play in the gear stick so you need to feel and line it up as you select gears, if this is the same as the beetles I suspect it is down to a worn selector bush which should be straight forward to replace, but I can live with it as it is if needed.

Finally the one that has me really stumped (and cold) at the moment is the good ol' Eberspacher not working properly.

When I first got the car it would not work at all so I checked to see if it was all there and as far as I can see it is complete. I have replaced the fuel line (skinning my knuckles in the process) and checked the fuses and the safety cut out on the relay under the back seat. Checked and cleaned the spark/glow plug and then tried it out.

It worked spewing out loads of smoke in the process. But eventually running clear. I ran it through the complete cycle of warm up and run down a couple of times.

Great, I thought it was fixed...alas not

I can get the thing to run when the car is not running and cold but as soon as I start the car it will not run. Likewise if the car is warm and not running it will not run. It blows one of the 8 amp fuses and I am now at a loss to understand why. Anyone have an idea where to check first, could it be a defective connection somewhere or a duff sensor or something else equally obscure? This one has me beat at the moment.

Sorry for a long first post asking for help but I thought it might be easier than lots of little ones

Which 8 amp fuse does it blow? If it is one of the inline fuses with olive green wires coming to it near the reset black box, it is the high limit temp switch. That sensor is located directly on top of the eberspacher with a rubber cover/lug. It has a hot and cold wire to it. It is a bi-metallic element. If it has been smashed or crimped it can cause a problem. If the rubber boot is loose and the positive side contacts the body it can blow a fuse. You need to see where the power wire goes to on the main silver relay with all the pins. A some point it joins a heavy 8 gauge wire on teh right side of the engine compartment in a T-2 connector ( "Y" connector wth two outs and one in. The in side goes to the alternator, one out to the starter/battery and one to the heater relay.)

You need to get a diagram and make absolutely sure that all of the wires go to the correct places. It is very common that owners and shops....not able to make relays open and close properly.....simply route power around....very bad.

Also uncrimp the silver top from the main double relay.....and carefully check that all of the contacts are not carbonized. If they are....clean then carefully with a file. Do no tdamage this relay. I have no idea where you would get a new one configured like it. I have a bucket of them. I have never actually had one go bad...only crabonized contacts.

On your back underneath the car....you will see nect to the blower motor assembly....a flat, rectangular metal protrusion with a rubber cover. This is the thermoprobe/pyrometer. It is identical to one that you find in a home gas furnace. It is preset to a range. It has a compression flange to keep it in the chamber gas tight...and as it gets red hot...it cuts a simple switch or pair of switches off and on. Its an interupter for the main fuel pump circuit. Its what throttle the heater up and down.
Carefully remove the rubber boot....and make sure that no wires have pulled loose. There are four I think. This is common.

The fact that the heater runs when the car is off....but not when its running...is greatly familiar. It makes me think that one or more wires are reversed in polarity on the main power feed. Also check the glowplug tro make sure that the wires of the correct color are applied to the right connections.

Your car...if made after August of 72....is a 1973. The rotors should not be too hard to find. They fit all Porsche 914 as of August 72 as well.

It is a much better rotor and caliper than the earlier ones. You can't use the ealier ones unless you change the steering knuckle with spindle as well. I have done this....but its inadvisable as teh later brakes are superior and the later steering knuckle and control arm combination had a better static castor angle for steering.

The noise can also be several things. First and most dangerous......is a rusty ball joint. Do a search on some of my posts concerning the ball joints. They are very rare and hard to find. They fit no other vehicle ever built.
You can take the three bolts loose from teh bottom of the strut....drill a small hole in the inside of the dome of the ball joint......and install a grease fitting in the drain hole on the inboard side of the ball joint. Then seal the flange of teh ball joint with a hard curing sealer and rebolt the strut. The ball joint can then be greased.

If you joints are not rusted or sloppy loose, you can procure a new boot from a late model bus ball joint, install the grease fitting...and they will last forever.

The other things that go out and make noise are the radius arm donuts, and centerlink (do a search...you can rebuild the centerlink, and make the donuts too).....and the most common noise maker....is control arm bushings crapping out and letting the control arm slide forward and rub against the mounting flange. You can have solid ones made for very cheap at a machine shop from Delrin....thin fit the original steel center tube for teh bolt to pass through back in and they will last forever.

The sway bar bushings generally make no noise. But...spray some oil on the outer ones....drive over a speed bump.....and if the noise disapears....you are right. If it does not....it is the ball joints. Fix them quick. Ray