Oh deary me, cam belt?

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Oh deary me, cam belt?

dave

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OOOh, Easy Start, https://www.halfords.com/motoring/e...additives/bradex-easy-start-300ml-793737.html a very mixed blessing? especially where diesels are concerned. Yes it will often start a reluctant one but, especially with older engines, as you probably know, they can become "addicted" and refuse to start without a "fix" from then on so you need to use it very sparingly.

they don't really get addicted what happens is the problem that prevents it starting gets worse and worse, giving the impression its addicted,

this seems to start them better and is cheaper, smells the same so no idea why https://www.halfords.com/motoring/e...-additives/holts-cold-start-400ml-130658.html
 
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Pugglt Auld Jock
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they don't really get addicted what happens is the problem that prevents it starting gets worse and worse, giving the impression its addicted,

this seems to start them better and is cheaper, smells the same so no idea why https://www.halfords.com/motoring/e...-additives/holts-cold-start-400ml-130658.html

Absolutely dave, I was just trying to keep things simple, but, just in case someone is sitting here thinking "what's he talking about with this talk of addiction"? I'll attempt to inform. Then you can all jump in with "well yes, but"

The big problem, particularly with diesels where compression is so critical, is the way that the spray product actually works. If we think specifically about the combustion taking place. Under normal operating conditions a diesel fills it's cylinder with air as the piston goes down it's stroke and compresses this air into a very very small volume when the piston returns to the top of it's stroke (a petrol engine may have a compression ratio of perhaps 10:1 but a diesel may be 20:1 or more - and a turbo can "cram" in so much extra air that the compression becomes "formidable" - The result of this compression is that the air becomes very hot indeed. Then, just before TDC, the injector starts to spray a small amount of highly atomized fuel into this extremely hot air. The fuel burns because the temperature of the air far exceeds the ignition point of the fuel. - There are a lot of "niceties" concerning injection we could discuss, but that's probably not appropriate here.

So it can be seen that compression is almost everything to a diesel engine. Modern diesels now have, and have had for many years, glow plugs which are just a metal rod, basically, protruding into the combustion chamber which is electrically heated to red hot and helps the fuel to burn when the engine is cold. However good compression is still necessary to get the bulk of the air hot enough to cause the fuel to burn. Glow plugs serve other functions, like emission reduction when running cold, too but that's not for here.

If you've understood that then we can look at why we might need one of these spray in products. Usually it's because either the glow plugs have failed (and boy can it be "good fun" getting the old ones out without snapping them off) or the engine is old, with worn bores and piston rings, maybe a wee bit leak from a valve seat, so it's ability to compress the air is substantially reduced. This may be exacerbated by a "tired" starter motor and/or battery which is past it's best which will cause the engine to turn over more slowly than a good starter and battery. - All engines suffer "pumping losses", in fact it's sometimes helpful to consider an engine to be just an air pump, so mechanical problems, especially worn or broken piston rings, will let air leak past the piston whilst it's trying to compress the air but also, very importantly, a slow cranking engine will allow some air extra time to leak past the rings so there will be less air and consequently less temperature in the air by the time the piston is approaching TDC. Combine the two, wear and slow cranking, and you often have an engine which will refuse to start "on the key". Worth mentioning though that if it's not too badly worn it can often be started with a tow. However I wouldn't particularly advise this if you've never done it before because tow starting a diesel is a bit different to tow starting a petrol and often involves "barreling" down the road at considerable speed!

Now lets consider what's going on if you decide to resort to a spray start product. I think most are based on ether which is a highly volatile substance so has an ignition point far below diesel or petrol. You use it by spraying it into the air intake whilst the engine is cranking and I can confirm it's often very effective indeed. BUT, the problem with it is the way it burns. Normally with your diesel, the piston, now nearing TDC, has compressed the air charge to a very high temperature and the glow plug is sitting there, red hot in the chamber, heating things up even more. Then the fuel starts to spray out of the end of the injector. The important thing to appreciate is that the fuel burns progressively, over a very short period of time admittedly - and some fueling systems don't inject in one constant flow but "stutter" to give a better burn - but it's a progressive burn, taking place as the fuel is sprayed out of the end of the injector NOT AN EXPLOSION! But if you spray one of these starting sprays into the air intake then this highly volatile fuel is drawn in with the air and it disperses very well into that air charge. Now the piston starts to compress and heat up the air but because the fuel is so volatile it catches fire at a much lower temperature than the intended fuel which the engine is designed to run on so Hurrah! the engine fires up and runs! It will now continue to run, unless the engine is absolutely knackered or there is a fuel system fault, BUT, did you hear the terrible rattly knocking noise it made as it fired for the first few revs? This is because of the volatility of the spray product which you sprayed into the air as it was being drawn in - remember normally the diesel only draws in air and compresses only air up to the point where the fuel is injected. So you can compare start of injection to the spark incident in a petrol engine. - now though you have a highly volatile fuel mixed with the air which is being heated up a lot by the rising piston compressing the air and the result is that this homogeneous mix of air and fuel EXPLODES! long before the piston reaches the top of it's stroke.

This creates two problems the lesser of which is possibly the fact that the exploding hot gasses in the combustion chamber are exerting maximum force on the piston before it goes over TDC so is actually trying to force the engine to turn backwards. Of course the turning flywheel's stored energy and the starter motor keep it rotating - not a good situation though. Of greater concern is that the fuel is not subject to a controlled burn. It has EXPLODED - burnt all at once throughout it's entire volume - no flame front involved! The result in the cylinder is an extremely violent event which will tend to break loose any carbon which has built up around the top lands and piston rings, even, maybe, the top of the bores which will have been making a considerable contribution to the piston's ability to seal against the bore. Result? even less compression than before and an engine which will now only start if fed some "dope" hence why people talk about diesels in particular becoming "addicted"

This Addiction can also occur in petrol engines but is slightly different because of the way a petrol initiates it's burn. The compression in a petrol engine is much lower so, under normal circumstances, the air does not exceed the ignition point of the fuel with the piston at TDC. Until Direct injection petrol engines were introduced, the fuel and air mixing took place outside the cylinder and is drawn into the cylinder as a mixture of fuel and air. This is then compressed but won't ignite until the plug sparks - direct injection is different in that it initially draws only air into it's cylinder and then injects the petrol into the air inside the cylinder, like a diesel does. The air and fuel are still mixed together before ignition is initiated by the spark plug, but the big difference is that the burn is initiated by the spark not, as the diesel does, at the point at which the fuel is injected or the temperature of the air in the cylinder. Then the burn itself will start as a little flame around the spark plug electrode and then travel, as a "flame front" - a bit like a heather fire front - through the combustion chamber (Ok, those of you who really know about this, there's a lot more to it - like the influence of "swirl" and other factors - I know) until it reaches the farthest corners of the combustion chamber. The big thing to realize with both the petrol and diesel engine is that the fuel air mixture in the cylinder never normally explodes. It burns, over a very short period of time admittedly, in a controlled and "relatively gentle" manner which produces a very controlled rise in pressure in the cylinder. Regardless of which type of fueling your engine has - carburetor, port type fuel injectors or direct injectors - If you spray one of these highly volatile starting sprays into your air intake although the flame will initiate around the spark plug electrode the temperature and pressure in the combustion chamber will increase very rapidly to the point where the rest of the unburnt fuel will EXPLODE. The resultant damage will be similar, but could be more severe, when compared to a diesel because a petrol engine's components are less robust. Actually, if you have a heavily carboned up combustion chamber spontaneous ignition of the fuel could occur at almost any time so watch out for backfires from the air intake which could burn you badly!

So there you are. Hope some of you found this interesting? Anyone like to add anything I've missed?
 

StevenRB45

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There is the possibility that the "addiction" would be the ECU committing the values to memory it used for the previous starts.

All ECUs have a learning capability to some degree and are unaware of any outside inducements you may give to the engine to start.

So you add an outside influence it is unaware of, the engine starts. ECU uses same parameters without easy start...it fails to start.
 
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Pugglt Auld Jock
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When I worked at Firestone my department boss was an American and he had a wonderful vocabulary of "strange" American words. If he ran into something he found difficult to understand he used to say "You really got me Hornswoggled there" - Well, the Ibiza is back as I said earlier but what was wrong with it has really got me, and the garage, Hornswoggled!

I just spotted my neighbour defrosting it in the layby out side the flats so I popped over to find out what had transpired at the garage. She tells me they took it down to their wee workshop but as it can only take a couple of cars inside they did a quick look at it whilst still on the flatbed. The cambelt was intact! so they tried to start it but got the same result we did - sounded like an engine with no compression and showing no signs of firing at all, not even a backfire!

Because there wasn't room in the workshop they left it on the flatbed 'till late in the afternoon when they sent the "laddy" out to bring it in. Apparently he ran it off the flatbed by letting it coast but then couldn't push it by himself round to the workshop door so, without a second thought, twisted the key and it fired right up!

They were surprised when he arrived at the workshop door! They stopped and restarted it several times and it performed perfectly. Then they left it until closing time when the boss and his main worker put it back on the flatbed and dropped it off here on their way home. They only charged her for a one way trip on the lorry too! which I thought was more than kind. In fact she's so impressed with them that she's now going to use them for services etc.

They've told her they've no idea what was wrong with it but suspect it was something electrical caused by the cold - it has been very cold up here for several days now. This guess bothers me a little because the engine sounded as if it had absolutely no compression when I listened to it. Turned over very rapidly with none of the regular ying, ying, ying irregularity of going over compression. I'm wondering if, because it was so very cold and early in the morning so it was baltic! also it hadn't been stared for several days so it would be really cold enginewise, whether the oil could have been so thick that it was suffering from hydraulic tappet pump up. I suppose it's conceivable that very thick oil could be pumped up into the followers but be unable to exit through the bleed down holes quickly enough to avoid "jacking" up and holding the valves off their seats? That would certainly give you a lack of compression and a non starter wouldn't it?

However I think Hornswoggled quite accurately describes my thoughts on the subject. Just thought, I'd better get her to check her oil level, cold oil and low level just might be a factor? then again maybe not. - I've never seen her open the bonnet!
 
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tow starting a diesel is a bit different to tow starting a petrol and often involves "barreling" down the road at considerable speed!
I worked in a little 'village garage' at 14-17 yrs old (weekends, school holidays). The breakdown truck was an early Land Rover, series 1, 86" wheelbase, 1600cc petrol. Complete with crane on the rear deck.

We had a customer who was a one-man business, driving an 8-wheeler tipper truck, mostly working from the quarries on Portland. With a temporary cashflow issue, and needing new batteries for his truck, he resorted to two starting it each morning. After this cold start, it would start ok for the rest of the day.
The process:
Collect Land Rover, and take next door to his yard.
Attach Land Rover by solid bar to the front of the truck.
Use truck batteries to heat the glow plugs once.
Release truck brakes. (Luckily air pressure held overnight sufficient for this, and later stopping)
Back to the Land Rover, select low ratio 1st gear, move away gently, pulling the truck. Speed at tickover was much clower than normal walking pace.
With whole 'train' moving, hop out and leap into the truck.
Engage 2nd gear, turn on ign to heat glow plugs again, as soon as light went out, up with the clutch.
Truck started first time, then use truck brakes to stall teh Land Rover, before meeting the traffic on the road outside.
Leave truck ticking over, return Land Rover.
He did this every working day for about three weeks, until he had the cash for new batteries.

Mildly frightening if you put too much thought into this, but for me, a memory that will never fade.

... this homogeneous mix of air and fuel EXPLODES! long before the piston reaches the top of it's stroke.
I've seen the remains of a spark plug, blown apart by this process, with a small outwards dent in the bonnet.
... I'm wondering if, ... the oil could have been so thick that it was suffering from hydraulic tappet pump up.
I'm not sure the oil pressure will jack up the tappets. As I understand it, the tappet is held snug between cam and valve stem by a spring inside. The oil fills the tappet, and as the cam turns, the internal valve closes, so the oil, being uncompressible, keeps the tappet extended to open the valve. As wear occurs, more oil will fill the tappet.

The tappets should not drain overnight, so thick oil not refilling them should not be a problem. I wonder if valves (inlet or exhaust) were stuck open due to the cold? That would only occur if clearances were tight, or insufficient oil was there, the opposite of the jacking up theory.

I wonder how much oil is in there now.
How long ago it was last serviced, and if the invoic eshows the grade or viscosity of the oil used.

Depending on access, I'm thinking a timing check would be a good idea, and a compression test, as well as the oil check.

Don't we all just love intermittent problems.
 

StevenRB45

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the addiction thing has been around longer than ECU's though

Granted it can mask another problem but it's certainly possible to teach the ECU bad habits.

My dads Focus when new would fire without a blip on the throttle. However he was in the habit of doing so from a previous vehicle...after a year with it was an absolute bugger to start if you didn't blip the throttle.

Still is 15 years on, also loves to chuck a bit of black smoke on first start as well..almost like the fuelling map isn't right.
 
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Pugglt Auld Jock
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I worked in a little 'village garage' at 14-17 yrs old (weekends, school holidays). The breakdown truck was an early Land Rover, series 1, 86" wheelbase, 1600cc petrol. Complete with crane on the rear deck.

I wonder how much oil is in there now.
How long ago it was last serviced, and if the invoic eshows the grade or viscosity of the oil used.

When my attempt to be a car salesman came to an end and I went back into getting my hands dirty I too worked in a wee country garage. Our breakdown truck was also a petrol Mk1 Land Rover SWB (with that side/overhead valve Rover engine if I remember correctly?) with a substantial crane in the back. I had a lot of "adventures" in it as I used to earn extra money for a few years by being on call out over weekends. I remember going, on my own of course, to what I thought was going to be an easy job. An Austin Westminster with it's N/S/R wheel in the ditch. It was deepest winter and bitterly cold. When I got there the road was sheet ice but I backed up to it and put a rope to the front of it. Got back in the Landy but it wouldn't move it even in 4wd.

In winter we always carried grit on the back in a big bin so I put her in 4wd low range 1st gear and got out with my trusty shovel and went round feeding whichever wheel was slipping with some grit. She slowly and very surely pulled the car back onto the road with no one behind her wheel! As you say they go so slowly in low range you can outpace them without even breaking into a jog! The Austin's owner was mightily impressed and I got a good tip.

Regarding the oil? yes I'm wondering too, should have checked it whilst I had the chance. I definitely get the impression this car is run on a shoe string with as little money being spent as possible. Could be the oil is low, old and more resembling treacle than oil? Whilst we are all good friends in our street this woman is not a close friend so I don't want to make a nuisance of myself now the car is running again. Might suggest an oil change to her if our paths cross in the near future though.
 

jackwhoo

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Yes Jock series 1 land rover 1600 and then 2000 engines were inlet over exhaust engines.

Thinking about the Ibiza I'm wondering if the sprag clutch on the starter pinion was failing to engage correctly.

Hydraulic valve adjusters do not use pressurized oil from the oil pump to work, they need a good oil supply to remain immersed in oil in order to function correctly.

Cheers Jack
 
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Pugglt Auld Jock
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Yes Jock series 1 land rover 1600 and then 2000 engines were inlet over exhaust engines.

Thinking about the Ibiza I'm wondering if the sprag clutch on the starter pinion was failing to engage correctly.

Hydraulic valve adjusters do not use pressurized oil from the oil pump to work, they need a good oil supply to remain immersed in oil in order to function correctly.

Cheers Jack
Hi Jack, I remember being quite surprised the first time I saw one of those (probably a P75 or maybe a P100?). I'd worked on side valve and overhead valve engines, but here was one with both! I once did a valve job on a "Y" model Ford (a pretty car I always thought?) and, having worked on Morris 8 etc before that and then BMC "A" and "B" series I was absolutely astonished that the valve clearances were set by grinding metal off the end of the valve stems! The valves were supplied too long so you could grind them down and our valve facing machine had a jig which held the valve square to the stone as you ground it. You only got one chance though, Grind too much off and you were going to the storeman asking for another valve or brazing shimstock to the end of the valve stem - That was good fun too!

Regarding the starter, you could definitely hear the engine turning over, it wasn't just the starter spinning up.

I wondered about the lifters because when, as a young enthusiast, I was deeply into drag racing and pretty much "lived" at Santa Pod from a Friday evening to a Sunday evening I learned a lot about the big Yank V8s and one of the first things they did was to pull the hydraulic lifters and fit a "solid" valvetrain with solid lifters (cam followers) push rods and adjustable rockers. Beyond a certain RPM the hydraulic lifters would jack up and hold the valves off their seats so limiting rpm and power attainable. The problem was directly related not to the supply side but to how quickly the excess oil could bleed down as the cam lifted the follower to the point at which the cut off locked the oil inside and allowed the follower to lift the pushrod. It just occurred to me that a follower charged with a thick cold oil might suffer the same problems - supply pressure would be irrelevant, it would only need to be enough to fill the follower when it was "down".

I'm actually not at all sure this is the reason in this case though and as the car spends it's nights in the layby opposite our livingroom window I can watch out for it happening again. Almost hope it does so I can check it out again!
 
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.. one of the first things they did was to pull the hydraulic lifters and fit a "solid" valvetrain with solid lifters (cam followers) push rods and adjustable rockers. Beyond a certain RPM the hydraulic lifters would jack up and hold the valves off their seats so limiting rpm and power attainable.

The hydraulic lifter has a little valve inside it to retain the oil, so acts like a solid tappet. As the clearances increase, the lifter will take in more oil, from the pressurised gallery it sits in.

With engines that rev very high, and for prolonged periods, it is possible for the valves to not follow the camshaft as it releases. This allows the lifter to extend firther than it should, taking in oil as it does, then it is too big, holding the valves off their seats. The little valves inside are very good at what they do, so they don't bleed out easily.
Last year had to replace all the exhaust valves on brother's Peugeot 307. Had a terrible job squeezing the lifters down. Turning them on their side didn't let the oil out either. Later of course it wouldn't start until all, or most of the lifters had refilled. Then two took a week to go quiet.
In normal use the lifters can't overextend, unless valves stick in their guides, not a common problem these days.
 

DaveMcT

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My 100HP was very ticky after its first lockdown lack of use. The tappets had leaked down and took a while to reset themselves.
 
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