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Not starting when hot - what are the possible causes?

raffles

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tanzania
Hello,

I would really appreciate some expertise on this. My 1996 GX (HZJ80, manual) doesn't start when the engine is hot. My mechanic thought this was a problem with the starter motor, so cleaned the brushes and said that would solve it. It seemed to, but only for a bit (or maybe I didn't even get it hot enough to test it properly). I've since changed mechanics due to unrelated reasons, and my current mechanic, who I trust more (though certainly not entirely), is convinced the problem is not to do with the starter motor, but because it has "shida ya overheat" -- Swahili for an overheating-related problem.

He might be right: two years ago it overheated very badly, cracking the cylinder head. I had to buy a new one. Since then, it has been fine, until I had problems with it overheating again, which turned out to be a faulty fan belt clutch. Repaired that, then OK until a few weeks ago. The engine starts fine when cold or moderately warm. When it's hot the temperature needle is horizontal, right in the middle of the gauge, where I'm told it should be, and it doesn't go above that, but if I turn it off and then on again, it doesn't start. It sounds like the starting system is struggling, with that awful lunging sound repeatedly, but not getting to actually start. However a push-start is still possible (by the way, is this bad for the vehicle?). After waiting about 20 minutes in the shade I can also start it again without problems.

The battery is completely new. My mechanic says he might have to open up the engine and that it could well be that when it's hot, the piston(s) are unable to move up and down the sleeves properly due to metal expansion. However, before going down that avenue, I'd like to know what other diagnoses are possible. It might be worth mentioning that the fuel pump malfunctioned a few weeks ago (fuel was leaking from what appeared to be somewhere near the front left of the engine block while running) and my previous mechanic repaired it. The exhaust now emits black smoke when hard accelerating in 3rd, 4th or 5th gear, and I can smell what I assume is unburnt fuel. Current mechanic assures me this is unrelated... but after the problems I've had, I find it hard to trust Tanzanian mechanics.

Thank you in advance,

Rafael

P.S. Please forgive any errors in terminology, as you may have gathered I'm not very knowledgeable about the 1HZ... or cars in general
 
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I would try any earth points and general condition of all battery wiring including all chassis to engine connections.
I would be inclined to test the voltage at the battery during cranking and also at the starter if possible to check for voltage drop problems.
 
Hi Raffles,

Although I'm replying to this, expert I'm not :lol:

Anyway, I do own and drive a HZJ 80, one of the few on this forum as most 80 owners on here have HDJ 80s with turbos and UK specification features, making them a quite different truck.

I've made some notes in your message below, mostly questions, not sure if they help any.

My 1996 GX (HZJ80, manual) doesn't start when the engine is hot. My mechanic thought this was a problem with the starter motor, so cleaned the brushes and said that would solve it. It seemed to, but only for a bit (or maybe I didn't even get it hot enough to test it properly).

I can't imagine that a starter motor would show heat related problems, if it's turning the engine over, but sluggishly, and the batteries are good and charged, there's likely to be a connection problem, either at the motor or the solenoid. If the connections are good, then it could be the windings in the motor itself, which would mean getting a reconditioned or second hand unit.

One thing puzzles me, is your truck a 12 volt start or 24 volt start? You mentioned that the battery is is new, yet for a 24 volt starter, the truck would have 2 batteries, the starting system temporarily activates both batteries in series, providing 24 volts at the starter, but nowhere else on the truck.

I've since changed mechanics due to unrelated reasons, and my current mechanic, who I trust more (though certainly not entirely), is convinced the problem is not to do with the starter motor, but because it has "shida ya overheat" -- Swahili for an overheating-related problem.

He might be right: two years ago it overheated very badly, cracking the cylinder head. I had to buy a new one. Since then, it has been fine, until I had problems with it overheating again, which turned out to be a faulty fan belt clutch. Repaired that, then OK until a few weeks ago.

I'm wondering what caused the overheat in the first place? You say you've fixed the faulty fan belt clutch, which I take to mean the viscous fan drive (which usually lose the oil inside, so the fan stops being driven by the belt). So, if it's still overheating, have you checked/replaced the thermostat? It may be jammed closed, and in Tanzania, do you even need a thermostat? What is the lowest winter ambient temp? Other than the thermostat, have you checked the radiator? Are you using Toyota coolant, or just water in the system? It could be that there's some sludge in the bottom tank that may be blocking the free flow circulation of coolant. If regular water has been used for any length of time, the block rusts internally, and it drops to the bottom forming the sludge. I'd recommend diconnecting the hoses and flushing the radiator and the engine block with as powerful water jet as you can find. Also check the radiator cooling fins, maybe they are blocked with mud, insects or vegetation, causing a lack of airflow. Do you have Air Conditioning? Sometimes dirt gathers between the engine rad and the AC rad, they are mounted close together, but it's surprising what gets trapped between them.

The engine starts fine when cold or moderately warm. When it's hot the temperature needle is horizontal, right in the middle of the gauge, where I'm told it should be, and it doesn't go above that, but if I turn it off and then on again, it doesn't start. It sounds like the starting system is struggling, with that awful lunging sound repeatedly, but not getting to actually start. However a push-start is still possible (by the way, is this bad for the vehicle?). After waiting about 20 minutes in the shade I can also start it again without problems.

To be honest, this sounds like fuel starvation more than a heat related problem. If the gauge does not go above half way, then it's unlikely that it's overheating.

The battery is completely new. My mechanic says he might have to open up the engine and that it could well be that when it's hot, the piston(s) are unable to move up and down the sleeves properly due to metal expansion.

This sounds to me like 100% bullsh!t
:lol:

10 out of 10 for your man's imagination, but really? There may be other reasons, but that one, unlikely.

However, before going down that avenue, I'd like to know what other diagnoses are possible. It might be worth mentioning that the fuel pump malfunctioned a few weeks ago (fuel was leaking from what appeared to be somewhere near the front left of the engine block while running) and my previous mechanic repaired it. The exhaust now emits black smoke when hard accelerating in 3rd, 4th or 5th gear, and I can smell what I assume is unburnt fuel. Current mechanic assures me this is unrelated... but after the problems I've had, I find it hard to trust Tanzanian mechanics.

It may be unrelated, but either way I imagine that to be a matter of tuning the fuel on the injector pump low down on the right hand side of the engine. (Trace the from the injectors back to the pump, you'll find it). You need a good old fashioned diesel mechanic, he'll know his stuff. Are there no trucking companies that do their own maintenance, they may be able to help.

Last questions, what makes you so sure it's overheating, is steam belching out of the expansion bottle? Is the radiator pressure cap in good order?

Thank you in advance,

Rafael

P.S. Please forgive any errors in terminology, as you may have gathered I'm not very knowledgeable about the 1HZ... or cars in general
 
Thank you both so much for your replies. Clive, here are some answers and further questions I hope you'll answer!

Hi Raffles,

Although I'm replying to this, expert I'm not :lol:

Anyway, I do own and drive a HZJ 80, one of the few on this forum as most 80 owners on here have HDJ 80s with turbos and UK specification features, making them a quite different truck.

Here the preferred version is the '95 - '98 VX Limited, which I believe is also the HDJ80, but from Japan. Pretty much every vehicle on the roads here is a Japanese second-hand import, sometimes reconditioned in Dubai.


My 1996 GX (HZJ80, manual) doesn't start when the engine is hot. My mechanic thought this was a problem with the starter motor, so cleaned the brushes and said that would solve it. It seemed to, but only for a bit (or maybe I didn't even get it hot enough to test it properly).

I can't imagine that a starter motor would show heat related problems, if it's turning the engine over, but sluggishly, and the batteries are good and charged, there's likely to be a connection problem, either at the motor or the solenoid. If the connections are good, then it could be the windings in the motor itself, which would mean getting a reconditioned or second hand unit.

From what I understand, my old mechanic also re-wound the motor, but you might be right in that I need a new motor.

One thing puzzles me, is your truck a 12 volt start or 24 volt start? You mentioned that the battery is is new, yet for a 24 volt starter, the truck would have 2 batteries, the starting system temporarily activates both batteries in series, providing 24 volts at the starter, but nowhere else on the truck

Embarrassingly, I don't know if it's 12 or 24 volt, but I've asked before whether a second battery would help and I've always been told no, so I've assumed it's 12 volt. How can I find this out by actually looking at the car?

I've since changed mechanics due to unrelated reasons, and my current mechanic, who I trust more (though certainly not entirely), is convinced the problem is not to do with the starter motor, but because it has "shida ya overheat" -- Swahili for an overheating-related problem.

He might be right: two years ago it overheated very badly, cracking the cylinder head
. I had to buy a new one. Since then, it has been fine, until I had problems with it overheating again, which turned out to be a faulty fan clutch. Repaired that, then OK until a few weeks ago.

I'm wondering what caused the overheat in the first place? You say you've fixed the faulty fan belt clutch, which I take to mean the viscous fan drive (which usually lose the oil inside, so the fan stops being driven by the belt). So, if it's still overheating, have you checked/replaced the thermostat? It may be jammed closed, and in Tanzania, do you even need a thermostat? What is the lowest winter ambient temp? Other than the thermostat, have you checked the radiator? Are you using Toyota coolant, or just water in the system? It could be that there's some sludge in the bottom tank that may be blocking the free flow circulation of coolant. If regular water has been used for any length of time, the block rusts internally, and it drops to the bottom forming the sludge. I'd recommend diconnecting the hoses and flushing the radiator and the engine block with as powerful water jet as you can find. Also check the radiator cooling fins, maybe they are blocked with mud, insects or vegetation, causing a lack of airflow. Do you have Air Conditioning? Sometimes dirt gathers between the engine rad and the AC rad, they are mounted close together, but it's surprising what gets trapped between them

The initial overheat was an important life-lesson for me, and will probably make users of this forum recoil in horror. I was in Ruaha National Park in southern Tanzania and, overnight, the radiator leaked all the fluid out through a leak I didn't realise had developed. In the morning, I just drove off without checking oil and water.... remarkably stupid I know, particularly considering I'd been driving hundreds of km on dirt roads. So after about 8km or so I noticed the needle was above the red temperature section. Had to be towed to a campsite and then have a mechanic brought in from Iringa with a new cylinder head. The mechanic was the one a local tobacco farmer friend used and recommended highly.

There is no thermostat, I found this out two weeks ago. And yes, it's the viscous fan drive, which my mechanic has now disabled completely so that it just spins at the same speed as the engine. The lowest temperature here can be about zero celsius, when at altitude. But generally, about 15 celsius.

After the overheating incident, I bought a new (second-hand) radiator and filled it with coolant. It has water in it at the moment until this problem is solved, but will put coolant (Total, not Toyota... that's not available here) in. I drained and refilled it last week and it wasn't even that dirty. However, being second hand, about a quarter of the tubes that go down from top to bottom are blocked off (this is the result of getting an old mechanic to buy and install it, without me checking... another life lesson). The radiator fins are quite clean, but the AC ones aren't, that's something I'll get done.


The engine starts fine when cold or moderately warm. When it's hot the temperature needle is horizontal, right in the middle of the gauge, where I'm told it should be, and it doesn't go above that, but if I turn it off and then on again, it doesn't start. It sounds like the starting system is struggling, with that awful lunging sound repeatedly, but not getting to actually start. However a push-start is still possible (by the way, is this bad for the vehicle?). After waiting about 20 minutes in the shade I can also start it again without problems.

To be honest, this sounds like fuel starvation more than a heat related problem. If the gauge does not go above half way, then it's unlikely that it's overheating

The battery is completely new. My mechanic says he might have to open up the engine and that it could well be that when it's hot, the piston(s) are unable to move up and down the sleeves properly due to metal expansion.
This sounds to me like 100% bullsh!t :lol:

10 out of 10 for your man's imagination, but really? There may be other reasons, but that one, unlikely.

I don't think the engine is overheating now, not at all. I'm very happy to hear you think the problem is fuel starvation rather than an engine problem!! Regarding my man's imagination... I might have to go to Arusha then (closer larger city) and spend the money on a proper garage having a look at it.

However, before going down that avenue, I'd like to know what other diagnoses are possible. It might be worth mentioning that the fuel pump malfunctioned a few weeks ago (fuel was leaking from what appeared to be somewhere near the front left of the engine block while running) and my previous mechanic repaired it. The exhaust now emits black smoke when hard accelerating in 3rd, 4th or 5th gear, and I can smell what I assume is unburnt fuel. Current mechanic assures me this is unrelated... but after the problems I've had, I find it hard to trust Tanzanian mechanics.
It may be unrelated, but either way I imagine that to be a matter of tuning the fuel on the injector pump low down on the right hand side of the engine. (Trace the from the injectors back to the pump, you'll find it). You need a good old fashioned diesel mechanic, he'll know his stuff. Are there no trucking companies that do their own maintenance, they may be able to help.

Thanks, I'll have the injector pump looked at. What you say makes sense; I've been told that black smoke means the fuel mixture is too fuel-rich. The thing I don't understand is why the engine being hot would cause it not to start again. All the problems mentioned seem to be things that would be an issue whether the engine was hot or cold.

what makes you so sure it's overheating, is steam belching out of the expansion bottle? Is the radiator pressure cap in good order?

(already answered above). The expansion bottle stays full of water and the cap is fine. I really don't think it's overheating, it's just that it once did overheat in the past.

​Thanks again, Clive!
 
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OK, again I'm still no expert!
I didn't seem to get an answer to my question of evidence that it's overheating. There's cold start, running temperature (which you describe as "hot") yet overheating would be more than hot, it would be ejecting steam from somewhere, either the expansion bottle or otherwise through the radiator cap. I ask because a failing rad cap can display symptoms of overheating through the expansion bottle, when the engine is only hot, meaning normal running temperature.
If you only have one 12V battery, then it's likely to be a 12V starter motor, which should be checked again. Even if the engine is overheating (which I'm still not convinced) it should spin the engine over at a good starting speed, not sluggish like you say. That's connections and the motor that needs checking.
The 1HZ engine normally starts on a 1 second flip of the switch, so I suspect the problem is fuelling, especially as you have symptoms of smoke when running.
It's a process of elimination, starter motor first, then being sure whether it's overheating or not, followed by the fuelling issue.
This can be the pump, or something simple like a leak allowing air into the system which when hot causes an air lock stopping fuel coming through. It could be a blocked filter in the tank or water or other debris in the tank.
 
I don't have an 80 and i don't know your engine and i generally know less about diesel mechanics than everyone else who has replied but i will throw this out there in the hope Clive or someone with more knowledge than me can weigh it up and perhaps offer better advice . Sounds to me like the engine is struggling to breathe and so it can't burn all the fuel being delivered .
 
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The engine does not overheat. You're right, when I said "hot", I was referring to its normal operating temperature. There is no water loss from the radiator, whether liquid or as steam, so I'm pretty sure the radiator cap is fine. There is no steam coming from the expansion bottle.

The engine starts (from cold) in about a second but only if I turn the key three times, waiting each time for the coils to heat up. If it's not from cold, the same can happen with two turns.

Thank you all again for your advice, I'm going to a proper garage in Arusha on Thursday and I'll ask about all the things you've mentioned.
 
Just to throw in some terminology here raffles. When the engine is cranking, i.e. turning over with the key full turned, is it turning over fast or if you like 'comfortably'? Looking at your posts I would say the windings in the starter are suspect.

When heated it is not uncommon for the insulation in the windings to go bad, in particular when hot. To 'rewind' a starter in not something the typical mechanic would do, the contacts in the solenoid are more like the culprits.

You say it starts ok after two or three turns when cold, this could simply be a glow plug issue, not cranking when hot is more likely the starter or bad earth. I would confirm if you have a 12 volt or 24 volt system and then replace the starter after checking the connections/earths etc. Also you mention 'the' battery, i.e. singular, has your vehicle always had one (1)battery or, has it always had two (2) and you have replaced just the one?

regards

Dave
 
Shayne, that very thought crossed my mind, not that've would say it's the cause yet as there's still some grey areas but I did wonder if the air filter were blocked. Worth a look.

I'm also thinking starter contacts as these do burn out and there is a mod for them.
 
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I was thinking more along the lines of an EGR build up of soot in the intake manifold ?
 
Theres no EGR on my 80 and looking at YouTube vids not on that model either unless I'm totally wrong…which I could be. [emoji6]
 
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Just to throw in some terminology here raffles. When the engine is cranking, i.e. turning over with the key full turned, is it turning over fast or if you like 'comfortably'? Looking at your posts I would say the windings in the starter are suspect.

When heated it is not uncommon for the insulation in the windings to go bad, in particular when hot. To 'rewind' a starter in not something the typical mechanic would do, the contacts in the solenoid are more like the culprits.

You say it starts ok after two or three turns when cold, this could simply be a glow plug issue, not cranking when hot is more likely the starter or bad earth. I would confirm if you have a 12 volt or 24 volt system and then replace the starter after checking the connections/earths etc. Also you mention 'the' battery, i.e. singular, has your vehicle always had one (1)battery or, has it always had two (2) and you have replaced just the one?

The engine starts comfortably if I turn the key three times, from cold. If it's twice (waiting each time for the coil to heat up), then it makes the "starting" sound (by that I mean the loud "lunging" sound) two or three times, then starts (takes two or three seconds). If I try to start it after only one heating, then it can take several seconds, or not start at all, and then I need to heat the coil up another one or two times. I know this sounds so amateurish but I don't know the terminology.

Since I bought it in March 2013, it has had one battery. I will confirm whether it's supposed to, but there isn't a second tray for another battery, nor can I see where it would go. Thanks for your suggestions, Dave, I'll bring this up when I take it to the garage.

Thanks again everyone for your help, I most appreciate it!
 
To have to spin the starter on a 1HD-t engine more than 1 second from first putting the key in, I would say was excessive. The video I found on YouTube seemed to suggest the same for the non turbo engine. What you have just told me says there is something wrong. I'm sure there's others on here that will know more on this and be more helpful.

Also the same video seemed to show only one battery on the opposite side to the air filter. There being no battery on the air filter (RH) side.
 
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The 'lunging' sound I believe raffles is referring to sounds as though he has a starter problem, whether it is earth/supply or the usual solenoids/contact I do not know but, I am still concerned his mechanic rewound the starter. To lead the mechanic to take this avenue suggests the engine is turning over slowly before starting, and even slower when warm (higher compression = higher cranking load) So it comes around to the engine not being spun quick enough. Assuming all connections are good I would have to go with the starter and/or wiring to being suspect.

regards

Dave
 
I'm with you there Dave. It takes skill and special tools, tapes, insulation, wire etc to rewind such a beast. If indeed he did rewind it. Though the clue is that it started better for a while after he attended to it. It does sound like a starter motor fault.

Any chance of a short video of a starting attempt?
 
Thanks Dave. By "lunging" I meant the normal sound starting the engine produces, but for longer and less convincing sounding. I'm sorry I can't describe this sound any better, but what you say makes sense and is encouraging, so I'll bring it up tomorrow. Thanks again!
 
Rafael,

I owe you an apology for my post #5 above re quoted below. I was reading and responding on my phone which kinda juggled up your reply a bit, and I didn't see your answer.

Anyway, it's good news it's not overheating. I'm still convinced there's a starter issue. If you have access to a better mechanic, it's likely he will be able to test yours and confirm a fault. I've also heard of the solenoid contacts burning, yet that's more likely on a 24V starter (I would think). It's still worth a look, and cleaning and greasing all the main electrical cable connections (the big black and red cables) is well worthwhile.

After sorting that, you can move on to the black smoke issue. Another process of elimination, from fuel supply lines, filters, one in the tank which you can access by taking out the rear LHS middle row seat, pulling back the carpet to reveal an access cover in the floor. Once removed you can then get to the fuel scavenger pipe and gauge unit, it's all one piece, held on by 6 or 8 screws, can't remember exactly. Carefully lift it out complete with wires, and check the condition of a gauze filter that should be on the bottom of the pipe. It just pulls off to clean it if needed. There's another fuel filter under the hood, it looks like a big black oil filter can. That should be replaced with every oil change, along with the oil filter. Next on the list would be the pump, and I can tell you nothing about tuning the mixture, sorry.

OK, again I'm still no expert!
I didn't seem to get an answer to my question of evidence that it's overheating.
 
I just spent 1.8 million Tanzanian shillings (about £530) on bits for the injector pump and new nozzles, which together were causing the black smoke problem. The engine's sound is now quite different, less noisy and generally healthier sounding, and no black smoke at all. I had to buy a new head & rotor (£194), camplate (£71), rollers (4x, £24), gaskets (£16) and return washers (£3), and labour was about £35 (all minus 18% VAT). These are the names on the receipt and while I made an effort to be a good student, I don't know what all these bits do or even if you would call them the same thing! The injector pump guys (an outlet of Bosch in Arusha) told me the nozzles that were there are actually for a Pajero engine while shaking their heads and chuckling. Helped remind me why I ditched my ex-ex-mechanic.


Parts are quite expensive in Tanzania (but labour fortunately isn't); how much would doing these things cost in the UK?


Regarding the starter problem, my mechanic earthed the starter motor directly with the battery and this seems to have solved the problem. It starts in less than 1 second if it's not the first time in the day I start it. If it's in the morning, it's like in this video I took yesterday.

Unfortunately not three hours after leaving the injector pump place, thieves jammed something into the driver's side lock, got in and stole some stuff, including my jumper cables and some tools. Quite annoying.

I'm due for an oil and filter change in about 400km so that's next on the list. Thanks again for everyone's help!
 
Hey, a result!

Well done Rafael, albeit it costing you some.

Nothing's for nothing these days... :thumbup:
 
"shida ya overheat" ....shida ya fundi ya gari!

We just never learn. Hope you sort it.
 
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