Porsche 924 Scheiße - the wonderful* everyday

[Volksy]

I bought the kit to rebuild mine. I haven't dared pull it apart as yet!

I at least have a spare FD if I do decide to have a bash at it. 

I've watched a load of the videos and discussions on various forums, and it seems to be a 50% chance of success/complete borkage. 

They are at least pretty simple to remove, maybe see if you can source a second hand one off a breaker as a back up.

 

 

[Westbay]

"They are at least pretty simple to remove, maybe see if you can source a second hand one off a breaker as a back up."

 

Unless that's why it's in the breakers ! 😂

[N Dentressangle]

1 hour ago, Volksy said:

I bought the kit to rebuild mine. I haven't dared pull it apart as yet!

I at least have a spare FD if I do decide to have a bash at it. 

I've watched a load of the videos and discussions on various forums, and it seems to be a 50% chance of success/complete borkage. 

They are at least pretty simple to remove, maybe see if you can source a second hand one off a breaker as a back up.

 

 

If anyone can do it successfully it'll be my mate.

The kind of person who can just see and understand how things fit together and work.

[juular]

4 hours ago, N Dentressangle said:

Good to hear - thanks.

I just need a direction on what to investigate / fix next really. The fuel distributor is the only part left untouched so far I think, so logically it probably needs a refresh. Which isn't dear if it's a DIY with the kit job.

Plus my far more dextrous and mechanically gifted engineer mate has offered to rebuild the fuel distributor for me, so if it IS that then we should be OK.

If you have someone who has done a FD before successfully then bite their arm off.

I did try to do mine and was really careful about the whole process, but the car never ran right afterwards. I never did find out where I went wrong.

How are the banjos looking? Even a tiny leak from a washer will cause pressure loss and you won't notice the evidence as the petrol just evaporates.

[N Dentressangle]

8 minutes ago, juular said:

If you have someone who has done a FD before successfully then bite their arm off.

I did try to do mine and was really careful about the whole process, but the car never ran right afterwards. I never did find out where I went wrong.

How are the banjos looking? Even a tiny leak from a washer will cause pressure loss and you won't notice the evidence as the petrol just evaporates.

Not got anything apart yet. Stan is coming over this afternoon, so hopefully we'll get closer to a diagnosis and plan of action.

[N Dentressangle]

Stan has been and inspected. Reassuringly (kind of) he's also puzzled by the car's odd behaviour, and can't see anything obviously wrong with it. He's had a play with the mixture and idle screws and it's running a little bit better - conclusion is that it needs properly setting up for mixture before doing anything drastic, so I'll look into that. It's currently idling at 13-1400 revs, and we couldn't get it any lower without it dying.

I'm also going to pull the throttle body (where the idle screw sits) and give that a good clean. Stan also thinks pulling the top of the fuel distributor and making sure the plunger is moving freely and that everything there is clean would be a good plan, so I'll do that. I hadn't spotted this part of one of the PO's videos:

So I'll give it a good clean at the very least. Stan is not in favour of a re-build - 'don't touch it if you don't have to' - which is all good with me.

[juular]

35 minutes ago, N Dentressangle said:

Stan has been and inspected. Reassuringly (kind of) he's also puzzled by the car's odd behaviour, and can't see anything obviously wrong with it. He's had a play with the mixture and idle screws and it's running a little bit better - conclusion is that it needs properly setting up for mixture before doing anything drastic, so I'll look into that. It's currently idling at 13-1400 revs, and we couldn't get it any lower without it dying.

I'm also going to pull the throttle body (where the idle screw sits) and give that a good clean. Stan also thinks pulling the top of the fuel distributor and making sure the plunger is moving freely and that everything there is clean would be a good plan, so I'll do that. I hadn't spotted this part of one of the PO's videos:

So I'll give it a good clean at the very least. Stan is not in favour of a re-build - 'don't touch it if you don't have to' - which is all good with me.

I'd agree with not pulling anything apart until you absolutely know you have to, as it can add another shower of variables to the mix.

Sticky plungers are notorious on these especially if the car has sat any length of time. 

The way I usually check this is to keep everything in place but remove the bellows from the intake metering flap and quickly move the flap up and down.

If you feel the flap tapping against the plunger anywhere then it's dragging on something. It should follow the movement of the flap smoothly.

[N Dentressangle]

Thanks - I'll give that a go first off.

[Zelandeth]

If someone has had it apart partially before, the seal between the metering head and the body is a possible vacuum leak, so hopefully was changed.  It's also absolutely totally completely critical that the metering flap is properly centralised in its bore.  

The fact my first Saab ran pig rich at idle was simply because it wasn't and was juuuuuuust touching one edge as it returned to idle.  That's also why it needs to be kept clean enough to eat your dinner off.

[N Dentressangle]

Very interesting - thanks. It doesn't look very clean in that video!

[N Dentressangle]

OK, I've bitten the bullet and taken the fuel distributor off. Looks filthy:

Here's the underside of the distributor body:

The pin is definitely not free-moving.

And shouldn't there be a gasket of some kind between these two?

 

[Zelandeth]

I can't remember if it's a gasket or a large O-ring around the central bit, but there definitely should be some form of seal unless I'm remembering totally wrong.  Otherwise that's an obvious route for a small air leak.

[Volksy]

Yes, there will/should be an 'O' ring that goes round the plunger housing. 

To be honest that looks minging. I'd certainly get it as clean as you can. 

 

[N Dentressangle]

Yes, it's a large O ring.

Looks pretty flattened and also filthy. As does the base. Plan is now to remove the base and give that all a really good clean. It can't hurt anything.

[juular]

A gentle wipe over the plunger with with some petrol, and some carb cleaner generously blasted into the port should get that nice and clean.

Goes without saying but don't drop or scratch the plunger! One little nick and it's all over.

While you have the metering unit off, have a look into the ports that feed the injectors.

There are 4 little filter baskets in there that can fill with shit. Some carb cleaner and a soft brush should clear them out.

If they are missing or damaged: 99p each.

https://www.deloreango.com/uk/fuel-distributor-injector-line-filter.html

 

[Noel Tidybeard]

this is a little suboptimal!

[Volksy]

53 minutes ago, juular said:

A gentle wipe over the plunger with with some petrol, and some carb cleaner generously blasted into the port should get that nice and clean.

Goes without saying but don't drop or scratch the plunger! One little nick and it's all over.

While you have the metering unit off, have a look into the ports that feed the injectors.

There are 4 little filter baskets in there that can fill with shit. Some carb cleaner and a soft brush should clear them out.

If they are missing or damaged: 99p each.

https://www.deloreango.com/uk/fuel-distributor-injector-line-filter.html

 

I read somewhere to avoid using carb/brake cleaner as it can degrade the rubber seals in the metering unit. 

Rebuild instructions

[N Dentressangle]

4 minutes ago, Volksy said:

I read somewhere to avoid using carb/brake cleaner as it can degrade the rubber seals in the metering unit. 

Rebuild instructions

Having googled it, I think brake cleaner is more aggressive in terms of rubber parts and shouldn't be used, whereas carb cleaner is OK 🤷‍♂️

Gotta be cleaned somehow, I guess.

[rusty_vw_man]

Woo hoo - you’re back at it! Your walk away lasted much less time than mine would have done - fair play! 

I agree, minging, needs a clean and new o ring. Carb cleaner is fine, brake cleaner is less fine on rubber, but not necessarily an issue anyway if you are replacing the rubbery bits…..

[Peter C]

@N Dentressangle

Any good to you?

[N Dentressangle]

I did see that. Unfortunately (or maybe fortunately) about 300 miles away 🤣

[N Dentressangle]

OK, back on this. 

Quick interlude for a holiday, and I got on with the bits that Stan (the 924 OC guy) and I agreed.

Fuel distributor removed and plunger shaft cleaned thoroughly with carb cleaner, including plenty of movement up and down the bore to get rid of any sticky deposits. When I removed it the plunger shaft was definitely sticking, sometimes having to be pulled down from the 'fully up' position. After cleaning it dropped freely, certainly on the 10mm or so section that does all the work. I blasted the air flap housing clean with more carb cleaner and made sure everything moved freely and was correctly aligned. With everything as clean as possible I put it back together and re-fitted the fuel lines with new copper washers.

I then looked at the WUR again. I wanted to re-fit the original type WUR that came with the car. Although the PO had taken it apart, the thin silver diaphragm and rubber seal looked dubious to me so I had ordered a kit from Missingparts and rebuilt the WUR carefully, making sure everything was clean and assembled exactly correctly.

I also replaced the breather hose from the bottom of the crankcase to the intake. It's NLA, but a Jaguar XF of some kind in Harry Bucklands was happy to surrender something that fitted nicely and made sure I had no leaks from there.

Put everything back together, tried the starter and... it ran like a dog. Worse than before, if anything. Balls.

Several cups of tea and some thinking later, my suspicion was confirmed by the sopping wet spark plugs that the mixture was now miles out, and probably far too rich. Removed and cleaned all the plugs to get it running again, started it up and kept it running on the throttle whilst I graaaaadually moved the mixture Allen key to get a smooth, sustainable idle. I reckon I had to go at least 1-2 turns leaner before it would idle smoothly on its own, but finally after trial and error I got to a happy spot. I was now able to adjust the idle properly on the screw on the intake and bring it down to about 900rpm warm, which seemed about right for now. Hot start also seems OK, albeit with about 5-10 sec cranking with foot to the floor sometimes.

So that's where we are now. Took it out for the first time today and it drives beautifully - petrol station shot to prove!

I really hope it's going to stop fighting me now and I can get some miles on it. My friendly MoT tester will adjust the mixture properly on his gas analyser when I take it to be tested in the next couple of weeks. Couldn't resist swinging by to show it off to him:

Thanks to everyone who's helped - much obliged! This car's been a right bastard.

[Verysleepyboy]

Awesome!!! Sounds like you have finally got to one of the primary causes of the poor running! 

[N Dentressangle]

5 minutes ago, Verysleepyboy said:

Awesome!!! Sounds like you have finally got to one of the primary causes of the poor running! 

This still from the PO's video should have told me everything:

That plunger isn't dropping down.

And it should be!

[juular]

Tremendous work.

Regarding the hot start problem.

A while ago I fitted an under dash switch to the 240 that runs the main pump on demand. I did this mainly because I know that when the fuel pump relay dies, hotwiring the pump can get you home.

Anyway, I also found that if I was having hot (or cold) starting issues that giving the pump a buzz for a couple of seconds resulted in a near instant start on key turn.

Might be a low effort solution for your  problem.

I've been considering wiring the pump up to a glow plug relay so that you can just turn the key to ignition, hold for a couple of seconds and then start.

Maybe even wire it up to the door sensor switch so that it primes as you get in.

[N Dentressangle]

5 minutes ago, juular said:

Tremendous work.

Regarding the hot start problem.

A while ago I fitted an under dash switch to the 240 that runs the main pump on demand. I did this mainly because I know that when the fuel pump relay dies, hotwiring the pump can get you home.

Anyway, I also found that if I was having hot (or cold) starting issues that giving the pump a buzz for a couple of seconds resulted in a near instant start on key turn.

Might be a low effort solution for your  problem.

I've been considering wiring the pump up to a glow plug relay so that you can just turn the key to ignition, hold for a couple of seconds and then start.

Maybe even wire it up to the door sensor switch so that it primes as you get in.

Yes, I agree - might well end up doing that. I've just put an extra non-return valve into the fuel hose between tank and pump, just in case that makes any difference.

We'll see how it goes, I guess.

[Verysleepyboy]

57 minutes ago, N Dentressangle said:

This still from the PO's video should have told me everything:

That plunger isn't dropping down.

And it should be!

It's obvious now you point it out!!!

Air/Vacuum leaks are also commonplace on these as well due to age and the complexity of some of the hose routings - can cause erratic running conditions that are often "tuned" out instead of fixing the issue. Running a smoke machine through the intake may be a valuable exercise to do?

[MrBig]

Great news. Kudos for persevering with it. I know sent mine off to be baked bean cans after months of similar issues.

My heart sank for you every time I opened this thread and saw that it had kicked you in the plums again.

[N Dentressangle]

2 hours ago, MrBig said:

Great news. Kudos for persevering with it. I know sent mine off to be baked bean cans after months of similar issues.

My heart sank for you every time I opened this thread and saw that it had kicked you in the plums again.

Thanks.

This has been one of the most challenging cars I've ever fixed. An absolute bastard at times. When it still ran like a bag of shit the other day after everything I'd done, I nearly just put it up for sale for buttons. Had to really force myself to think calmly and logically what to do next.

Anyhow, now this is viable transport I can get back to the Mini - still got the NS sill to weld up!

[N Dentressangle]

OK, it's now raining. Need to sort the wipers properly if more driving's going to happen.

Here's where they live, which also seems to have been home to many, many spiders over the car's time in storage. It's filthy, full of cobwebs and leaves:

So not really a surprise that the wiper linkage was partially seized, and would only work slowly and a bit jerkily. To get the linkage out you have to remove the cowling from the heater fan - the black plastic daleky bit in the middle of the scuttle. This was OK, as the fan was also sluggish and prone to shrieking, so I'd have the chance to lube its bushes up properly and give it half a chance. Here's the manky wiper linkage:

All really stiff and in need of lube. Underneath was filthy but responded to a good clean:

I also wanted to find out whether I could get intermittent wipe back on the wiper motor. The problem I had was that the wipers wouldn't switch off - they just stayed on intermittent. The other two speeds worked fine. I changed the relay but that made no difference, so I removed it and bridged two pins, giving me wipers that would switch off, self-park, and work on two speeds but not intermittent.

The motor was predictably filthy so got a good dousing with brake cleaner before I opened it up. This wasn't entirely a suprise:

Drive wheel removed, all cleaned up and re-greased:

Now time to start putting everything back together and see if I've made any difference...