Project BX17RD - the further adventures of PBO

[Stinkwheel]

I have maybe something for you to try. Before trying to start the car in the mornings (or whenever you do try) prime the fuel bulb or head (depending if Lucas or Bosch) the see if it starts easier. I think it might.


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[vulgalour]

The only thing priming does is make the car smoke while it's trying to start, it otherwise makes no difference.

[Stinkwheel]

The only thing priming does is make the car smoke while it's trying to start, it otherwise makes no difference.

That’s a shame, I had a BX estate that had a slight air leak - the priming thing showed it up.
Have you checked the glow plug relay and that the plugs are actually drawing current when switched on?


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[mat_the_cat]

I don't have a definitive answer, but the change in behaviour when primed could be a clue. It suggests that if you don't prime (on the occasions when you have the problem) you aren't getting fuel. Although, when you do prime you are obviously getting fuel, but it's not igniting, at least properly. Do you have a video of the symptoms, showing the smoke too?

[vulgalour]

It does behave a lot like a car with a carburettor that has a full float bowl but the pump isn't working at first.  Then, after a couple of attempts to start, it's like the pump starts working fine, if that makes sense?  But as far as we can tell, fuel is being delivered when it should on start up, the glowplugs are doing their thing as they should too, the relay is working as it should, etc. so the problem is a bit of an odd one since it doesn't seem to be manifesting in the usual way.  Unfortunately I have no video of the starting problem because whenever I've tried, the problem simply hasn't been there and there hasn't been anything to record, typically.

Today, it was raining.  The good news is that means the BX was, as usual, much easier to start and it highlighted that the sealing I had done behind the washer bottle had improved water ingress issues quite a lot.  I also learned that the driver's door only drains out of the front drain hole once you open the door and while it does drain very fast since the drainholes are all nice and clear, it does seem a bit weird that it won't drain when the door is shut.  And no, that isn't how the water is getting into the driver's footwell, I did double-check.  So, the thing to do before starting the car was to disconnect what I understand to be the cold start cable.  There wasn't any slack in the cable before doing this, nor when I reconnected it.

Now, the car did start slightly easier than on a dry cold day, but no easier than usual than on a wet day, so the results of this were inconclusive.  There didn't appear to be any external bits to adjust at the pump end of the cable so I assume the adjustment would be done on the arm on the back of the housing at the other end of the cable.  The two adjustment screws are very stuck, but there is a little movement in the arm anyway, which I assume is as it should be, I didn't fiddle about with it for fear of making it worse and due to not having much time spare to faff with this today.

 

Here's a wider shot of where that cable above actually runs.  I took both pictures from opposite sides of the engine for extra confusion.  The accelerator cable doesn't have excessive slack, nor is it excessively tight, and it moves freely.  I can't see anything obviously amiss so I imagine the fault I'm looking for that's causing the cold start problems is a hidden part.

Typically for a rainy day, the car started perfectly happily throughout my errands and ran perfectly fine.  The very first attempt to start the car with the cold start cable disconnected did fail where normally it would succeed on a rainy day like this, the second start was reluctant, but did go eventually from a sluggish chug to normal running within a few seconds.  I'm not sure if any of the above information helps clarify the problem, or just muddies the waters further.

[Stinkwheel]

I've just remembered something. I don't know how it would relate to cold days/damp days/fuel etc but...….  Years ago these had a reputation for being a bit of a pain to start if the valve clearances were a bit tight, what with them being bucket and shim they didn't get checked/adjusted very regularly. Might this have a bearing here?  Ignore me if I am being stupid. 

[mat_the_cat]

I was about to say that wouldn't explain an intermittent problem, but actually it could. If you had a valve that was sticking, rather than badly adjusted.

To check, 'just' pop the valve cover off and check the clearances next time it fails to start quickly! Hmmm...

[Stinkwheel]

I was about to say that wouldn't explain an intermittent problem, but actually it could. If you had a valve that was sticking, rather than badly adjusted.
To check, 'just' pop the valve cover off and check the clearances next time it fails to start quickly! Hmmm...

And therein lies the problem. I suppose you could just check/do the clearances on the off chance as good practice and see if starting improves, but who wants to bother with that nonsense?


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[vulgalour]

Not me!

But if I can't find what else it is causing the issue, I will do it because hey, it's not a bad idea.

[vulgalour]

Today, it's cold enough to be a stubborn start, and dry enough too, so before doing anything I lifted the rear seat base to get to the two plastic grommets that allow access to the stuff in the tank.

The only thing in here that shouldn't be was spider webs and spiders casts. No signs of any damage, leaks, or anything untoward. They're both done up really tightly and while I did have a go at undoing them, it felt a bit futile, they didn't really want to budge at all. Just in case I gave them a knock the other way to ensure they were as tight as could be and then left well alone. The hoses look healthy with no signs of perishing or pinholes, nothing was showing up to the eye, ear, or nose with the car running and my gut feeling was that this was a dead end for fault finding.

Today, I was expecting it to be a bit awkward to start, it's cold enough, dry enough(even though it rained a lot last night) and the car has been sat idle long enough that I expected it to be one of those many attempts start. I decided to use no throttle, a single warm up of the glow plugs (waiting for the relay to click off, as usual) and turned the key. It fired up first time, no hesitation. That flies in the face of everything I've learned so far about what causes this problem, it should have been incredibly difficult to start today.

I did turn the car off, have a poke around things, and try again and it started perfectly. Oh well. I had a look at what was going on with things in the engine room anyway, might as well. I noticed a blue spade connector hanging loose, I didn't check in the book but I assume this is for the oil pressure sender since the thing it plugs onto goes into the block, rather than a temperature sender.

This made absolutely no difference to anything. The other thing I checked was the fuel lines. When I turned the engine off some bubbles came back down the line heading towards the back of the car, as they usually do. Bear in mind, the car started and ran like there was nothing wrong with it, so I wasn't expecting to see any air in these lines at all.

That's quite a large section of air. I'm lost on this starting issue now. Shouldn't that much air in the lines make it an absolute bear to start? I am very confused.

[richardmorris]

Have you replaced the fuel primer? That was the cause of air getting drawn in to my CX fuel lines.

[vulgalour]

I haven't, but I'm not sold on that being the problem anyway because today it's been running impeccably on my errands, starting willingly, and generally just being An Car.  I'm not convinced that the problem really is air in the fuel and until I am, I'm not willing to start throwing darts blindly in the form of new parts.

[chodweaver]

The tank only has a level sensor in it, right? No in-tank pump? If there is the latter, I'd be looking at the wiring connector shown in the pic of the second grommet hole. It's probably brown plastic on the plug, but it don't half look like something well rusty that would struggle to make a good electrical connection...

(Prolly barking up a tree that doesn't exist)

[chodweaver]

PS that IS a lot of air

[vulgalour]

Since the fuel gauge works perfectly fine, and always has while I've had it, I can't imagine that connector being any sort of problem. As you assume, pump is up at the front on the engine rather than at the back in the tank, so I doubt that connector would affect it in any way, even if it were super crusty.

[vulgalour]

Today, big progress was made on a job that needs to be done before the Princess arrives.  We're fortunate enough to have a double-width driveway with a full dropped curb.  We're also unfortunate enough to have a fairly well established mixed hedge planted across half of it.

It means getting in and out requires some planning ahead which hasn't been a problem so far, but will be once the Princess is delivered.  So today's attempt to trim the hedge back a bit to give us less work on Wednesday, when we'll be stump pulling in earnest, got a little bit out of hand and now we almost have proper access.

There's a couple of stumps to pull which, thanks to the very nice loose soil, is actually surprisingly easy.  There's also big run of concrete footing for the original wall which was demolished at some point in the past, its nearly a three man lift if we can't break it up into at least two pieces.  Then we can flatten the gap between the existing drive and the path, steal a dozen paving slabs from the back garden in an area we want to return to lawn anyway, and we'll have better access and space for two cars down the side of the garage.  Eventually, we'll be re-paving this whole area to make it a nice uniform work and parking space and adding a car port on the BX side of the garage, and even later we'll be demolishing or extending the existing garage to turn it into a reasonable sized double garage.  A lot of work ahead of us, for now it's a case of making things as practical as we can with what we've got.

We met a good number of our new neighbours just doing this job, which was a nice added bonus.  The house to the left of the photo has the most awkward driveway to access on the street, it's just as well they have a small car because otherwise it would be a real struggle.  Our plans for improvement on this area has actually been of benefit to this neighbour since she can now not only see for getting in and out of her driveway much easier, she also has more space to maneouvre.  Visibility is the biggest bonus of all too, because of the jetty/gennel/walkthrough/alley/[insert local variation here] that runs down the side of the house there's quite often pedestrians to look out for when you're backing on or off the drive, usually with kids or small dogs or the like, so it's good for safety for all concerned.

[Asimo]

FWD cars in reverse are really good for pulling hedge stumps out.........

[Dick Cheeseburger]

Is the issue purely that it's a thirtysomething gallic wannabe diva? It's done infinitely better than its counterparts to reach this milestone to be fair. 

On a side note, are you giving up the unit which you shared with MikeKnight? It was interesting seeing the various projects going on within. 

[vulgalour]

Given that I'm 300 miles away from said unit yes, that is a sacrifice I have been forced to make.  Mike is stopping on with it, obviously, since it's his unit.  He's not so good at doing the updates though.

[Dick Cheeseburger]

14 minutes ago, vulgalour said:

Given that I'm 300 miles away from said unit yes, that is a sacrifice I have been forced to make.  Mike is stopping on with it, obviously, since it's his unit.  He's not so good at doing the updates though.

Ah, I hadn't really clicked it was his. At least you have the potential, level space for car ports now. Exciting times ahead!

[Broadsword]

That is a very strange set of symptoms. The rain thing makes no sense at all to me. Air in the lines is like the problem I had on my Range Rover P38. On that it turned out the in tank fuel pump was faulty. Replacing that solved a whole list of issues and now it runs great. Does the BX have a in tank pump? Even if not I would look inside the tank for a blocked gauze filter or something like that. Other than that the symptoms would suggest injector pump to me.

[vulgalour]

Current theories are filter housing leak (common), valve clearances too tight (not so common), damaged fuel hose (common), or a faulty cold start waxstat (common).  Trouble is, with the weather being that bit milder down here the problem is likely to go away before too much longer because it only manifests when it's quite cold.  Another theory offered was that when it's rained, there's enough moisture sitting on whatever is sucking air in to seal the leak for long enough for the car to start, after which point things are warm enough to seal up the leak to make it air tight again.

[Broadsword]

I like the moisture sealing up the air leak theory. Good luck getting to the bottom of it!

[Noel Tidybeard]

go through fuel system and remove any jubilee clips as not fit for purpose and replace with proper diesel hose clamps

[vulgalour]

It was cold and dry today, just the sort of conditions the BX hates to start in.  Look at all this luscious ice all over everything.

Me: I'm going to diagnose the heck out of this starting problem.
BX: Starts without any issue.

FFFFFFFFFFFFFFFFFFF

[Stinkwheel]

Me: I'm going to diagnose the heck out of this starting problem.
BX: Starts without any issue.
FFFFFFFFFFFFFFFFFFF

I’m going to go ahead and say it’s self healed .....


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[Zelandeth]

We had a not totally dissimilar experience once on a generator (Gardner 6L-somethingorother based) which had a slightly dodgy fuel pump and would *sometimes* leak air in once stopped and drain the fuel aaaaaaaall the way back to the tank.  It would only do it one day out of about 20 but was a pain when it did.

We fitted a one way valve in the fuel line just before the inlet to the fuel filter/primer.  Think it was about £1 from a tractor specialist.  Thing started first touch every time I saw it after we did that, and as far as I know still is.

It just meant that there was no way the fuel could drain back and draw air into the system as the fuel could only travel along the line towards the engine, and the failed seal wasn't bad enough to let fuel out, just air in.

If the problem does reappear it might be worth sticking a check valve in...I can understand not wanting to spend the money changing the filter/primer housing, but a one way valve and a couple of hose clips is a bit cheaper!

[Angrydicky]

Nice gaff!

[vulgalour]

@Zelandeth Would there be any issues with the fuel not being able to return to the tank when a valve is fitted?  The bubbles only appear when the fuel is returning and the problem is intermittent, just like you describe on that generator.  I'm happy to spend the money to fix the problem, I'm just not happy to throw money at parts in the hope it's what's broken, you know how out of control that can get.

[Zelandeth]

Shouldn't be a problem as there's a separate return line.  So any pressure building up (i.e. due to heating due to heat soak when the engine is stopped) should be pushed out the normal return line I'd think.  Fuel doesn't expand much though so it really shouldn't be an issue.

There *shouldn't* be any fuel flowing backwards down the fuel feed line though...the only reason it can in this case is because there's air getting in somewhere.  It takes a much smaller hole for air to get in than it does for fuel to get out.  The valves within the pump itself should serve the same purpose, the additional one we're suggesting is just bolstering that functionality.

I think in our case it was the throttle shaft seal that was to blame, we think it was because the governor meant that the throttle had spent 99% of its life at one setting.  Not helped by the thing having a tendency to hunt by about 250rpm that we never got to the bottom of - though it's apparently done since about a week after the warranty expired...in 1973.

Was astonishing the difference it made.  Went from sounding like death for the first ten seconds to starting on the first compression stroke with barely any unburned fuel smoke.  Still burned oil like a cold Deltic for the first five minutes, but it's a Gardner, they're meant to do that! 

The only worry in my mind potentially is that it could impact the rate of fuel delivery as it will represent a slight restriction in the fuel line - though in the same breath I *really* wouldn't expect the fuelling demands of a 1.7 litre normally aspirated XUD to be heavy enough for that to be an issue.  Potentially more of an issue if you were running it on veg in colder weather, as fuel viscosity will make a restriction in the fuel delivery system a bigger issue...my forgettory is failing to recall whether you've been using veg or not.  Not sure I'd see it as worthwhile in something that's as good on fuel as a diesel BX.