Porsche Enthusiasts Club Forum

Some people may have seen the battle I had with my conscience after buying this particularly ratty 924.

Well, since then, I've stripped the front of the engine, replaced any damaged hoses, radiator, water pump, belts, painted brackets, brake parts, replaced all the fluids.

Today, I finished reassembling everything, picked up a reasonable second hand battery, as much petrol as I could squeeze into a plastic tank, and then did this:

YouTube - 924 first start

However, it seems rather lumpy!

Also, I noticed visible sparking on the top of the coil. Is that right?

Sounds like you have HT leakage if its sparking.
This could obviously make it run a bit rough.
Try another coil/ HT king lead.

You shouldn't have any sparking anywhere apart from the spark plug electrodes. Watched the vid..I thought I could hear an electrical ticking or cracking as you went round the engine bay. The top of the coil may be damp or have some deposit on it that is causing the HT voltage to track down to ground. I suggest you take off the king EHT lead and give the coil top (the Bakelite bit) a good clean and make sure it is dry. Check all the leads too, as if you have a loose lead or a bad connection then the spark cannot go where it needs to. Check the dist cap and rotor arm as well as the spark plugs, they all need to be clean and dry.

But hey, you are almost there!

Thanks guys! I notice on this engine that the HT leads on the plug ends don't make a very firm connection.

Hi Alex, the plug leads should have a nice tight fit as it has to be a really good mechanical and electrical connection. Otherwise the EHT will arc across and start to burn the lead contact and the spark plug tip. If the lead is very loose, the plug will hardly spark at all, as too much energy is lost jumping the gap.

Are you using the right spark plugs for the engine, and are they the original EHT leads or a set of after-market ones?

I haven't changed or checked any of the ignition system on this car yet! Obviously I need to.

I once had a car serviced and the jobs worths at the Vw dealer had pulled on the ht leads so hard they had split the insulation on one of the spark plug leads so it was sparking from the lead onto the engine rocker cover. The engine ran lumpy as only three of four cylinders were igniting. Went back to the garage and complained and got a nice new set of leads gratis. Ran fine after that. Could be a similar issue. Check your ht leads for cracks/splitting.

The car at the time was a Vw polo 16v. 100hp from a 1.4litre engine. A great little engine. Loved to rev. Miss that little car.

It sounds like you have already self diagnosed Al. As the car has sat unused for so long and it has been so wet recently. You are already seeing/hearing tracking from the coil area, I would suggest that you wait until after dark and then run the engine. You should be able more clearly see any tracking from the leads.

It sounds like a new set of leads/distributor cap and rotor will be your best friends along wuh a can of WD40!

Regards

Jon

Once you have it running on all 4, just take it for an MOT. I'm sure it will pass!!!

David

I think I'll put some brakes back on it first!

Update: ran on all 4 today after simply pushing all the HT leads firmly in place. However, it idles very low (3 - 500rpm), and often not at all. I have increased the idle screw for the time being so it can run unattended. I shall have a better look at the coil and dizzy another day and see if this improves.

On another note, after running it up to temperature, it decided to spew the contents of the coolant tank out of the overflow. Now I'm left with less than the minimum. I understand that this could be an airlock, but any further advice is welcome. I didn't get time to bleed it with the engine running warm today, but yesterday I belched as much air as possible out of the bleed screw and filled it to the top of the bleed screw pipe (with a funnel).

They are a bit of a PIA to bleed. Book says to fill to the max line, start engine, run for a couple of minutes and whilst engine is still running, open bleed valve until just water comes out. The stop engine, let it cool and then top up.

I tend to put front of car up on ramps, then fill, squeeze all hoses, leave a few minutes and then repeat.

Always involves a lot of swearing.

You will get there eventually.

When the brakes are done, take it for an MOT (I am sure that it will pass).

David

One bit of advice I would give any new 924 tinkerer is that a completely sealed intake is king with CIS injection systems.

That means having a good breather hose, injector seals, no cracked or split boots, a good vacuum advance pipe and a working vacuum advance canister on the distributor... All of this makes a massive difference to a 924.

The next thing would be read up on how to make a CIS injection pressure tester or buy one on ebay, if the system and control pressures do not seem right, convert your warm up regulator to an adjustable one (DIY) and get it spot on, replace the check valve on the fuel pump (cheap)

Lastly, when all this is as it should be, set the ignition timing to 8 degrees and the fueling to 2.5% CO.. The original workshop manuals are 10 degrees for the timing and a lower CO figure, but these spec's were for 80's fuels, not the 95 RON you will probably use today.

That's amazingly useful Jon. I've already replaced any damaged boots and pipes, and the airbox is making a tight seal. I don't know quite what to do with all the other suggestions, but I plan on taking the car to a nearby friend for a tune-up once it has all it's faculties bolted on!