1HD-FTE - something isn't right and it's getting worse.

[SMLE]

Hi folks,

I feel like I'm losing my mind on this, I'd appreciate some insights.

The car is increasingly loud, to me it sounds like it's not firing on all cylinders or there is something at play here. It just doesn't sound healthy, it sounds worse in real life than on the videos!

I bought this 100 series in September 2024, I've spent around £25K on parts and labour basically rebuilding this thing all with OEM parts. In addition to all of the suspension, rear diff, diff bushes, steering rack, brakes, handbrake all being replaced, the engine has had the following:

New Timing Belt
Water Pump etc
Injectors (brand new OEM) and associated new seals etc
injector pump hard lines
New Coolant system (radiator, pipework, T pieces)
Valve clearances checked (twice)
EGR blanked
Fuel filter assembly (with the hand priming pump)

The car has been serviced during my ownership since 234K, currently on 246K, and most recently the 15w40 oil was replaced with 10w40.

The car always smoked a bit on startup since I bought it, and was led to believe it was injectors.

I had the injectors replaced in September 2025 (along with hardlines etc mentioned above), the place that refurbed them did a bad job and MPG and power was right down. I got the refurbed injectors replaced with OEM, the fuel economy and drive was restored, however I feel like the engine is just getting louder and louder, and now on start up when the engine is cold, it will not start immediately (takes a few turns of the engine), the idle will be rough for a few seconds and it will smoke.

The turbo can be a bit loud, but apparently it doesn't have any excessive play. The large rubber hose at the front of the engine was also replaced with a new pipe recently, it had some oil in there when replacing it.

I have included some videos below:

New video · Tuesday, Oct 28, 2025 🎬

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The one showing the car smoking was a few months ago, it's now a bit worse than that (more smoke and lumpier idle for a few seconds).

I am SO far into this car now that I can't keep throwing money at it to diagnose a potentially cooked engine, so I'm trying to limit spending on it until I know the score.

I have tech stream, no EML showing, if there is anything anyone would like me to check on live data please let me know.

Any suggestions of the issue/what to check etc would be greatly appreciated.

Many thanks!

 

[Eurasiaoverland]

Is there any blow-by if you run it with the ventilation hose disconnected from the valve cover?

How much oil does it use?

 

[SMLE]

Is there any blow-by if you run it with the ventilation hose disconnected from the valve cover?

How much oil does it use?

Hi there,
I will check for blowby as suggested, I can confirm however currently it does not have any air pressure pushing out air with the oil cap unscrewed and resting on it. It doesn't have a vacuum either, just some 'air' noise.

Oil wise, I've not done massive miles since the oil change/recently, but it seems to be relatively stable on the oil front, at least not enough to drop below minimum but will check this tomorrow too.

Thanks!

 

[Ann luc]

Hi there,
I will check for blowby as suggested, I can confirm however currently it does not have any air pressure pushing out air with the oil cap unscrewed and resting on it. It doesn't have a vacuum either, just some 'air' noise.

Oil wise, I've not done massive miles since the oil change/recently, but it seems to be relatively stable on the oil front, at least not enough to drop below minimum but will check this tomorrow too.

Thanks!

Does that blue smoke and rough idle happen everytime you start or just after seating for a while or overnight?

 

[SMLE]

Does that blue smoke and rough idle happen everytime you start or just after seating for a while or overnight?

Hi there, mainly when left overnight! Thanks

 

[MUDZLLA]

Sounds normal to me.

 

[Eurasiaoverland]

You made it sound quite serious; now that I watch the videos it sounds fine. Initial roughness and delayed start may well be a bit of air getting into your fuel system. Try running a clear hose from the filter to the pump. There does not need to be an external diesel leak for there to be air getting into the fuel line.

 

[Dougal]

A family member had one that went noisy and rumbly. It was a vibration mount underneath that was worn out. About the 250,000km mark.

But it wasn't accompanied by any other engine issues.

 

[SMLE]

You made it sound quite serious; now that I watch the videos it sounds fine. Initial roughness and delayed start may well be a bit of air getting into your fuel system. Try running a clear hose from the filter to the pump. There does not need to be an external diesel leak for there to be air getting into the fuel line.

Thanks, it does sound worse in person than the videos show typically! What would be a typical cause of air getting into the fuel system? Would that cause the engine to sound knocky too? Thanks

 

[Eurasiaoverland]

Thanks, it does sound worse in person than the videos show typically! What would be a typical cause of air getting into the fuel system? Would that cause the engine to sound knocky too? Thanks

Any split hose or corroded steel pipe from the top of the tank to the injection pump could let in air; or even an air leak in the injection pump. The fact that it's worse after the car has stood for a while (more time for air to get in) supports the idea. And yes, the coughing/spluttering is misfiring because there is no fuel getting in. If there is air in the injection line, this could delay injection (as it takes longer to build up to the injector opening pressure, which I would guess could lead to odd noises too.

 

[Squash]

Any chance of it being winter????
Cold weather changes things.....

 

[SMLE]

Any chance of it being winter????
Cold weather changes things.....

The engine is sounding less healthy since those videos but don't believe that is weather related, except for perhaps highlighting the issue more

 

[SMLE]

Any split hose or corroded steel pipe from the top of the tank to the injection pump could let in air; or even an air leak in the injection pump. The fact that it's worse after the car has stood for a while (more time for air to get in) supports the idea. And yes, the coughing/spluttering is misfiring because there is no fuel getting in. If there is air in the injection line, this could delay injection (as it takes longer to build up to the injector opening pressure, which I would guess could lead to odd noises too.

Could the air getting in cause it to run more rough when idling normally and driving too?

 

[GTSSportCoupe]

On some EGR equiped Toyota Diesels there is a throttle body with a bypass. When you disabled EGR, could this bypass also be disabled and starving the engine of air at idle? This throttle body makes vacuum which draws in exhaust gasses at idle. But the bypass allows enough air for the engine to idle as long as it's open.

 

[lelandEOD]

On some EGR equiped Toyota Diesels there is a throttle body with a bypass. When you disabled EGR, could this bypass also be disabled and starving the engine of air at idle? This throttle body makes vacuum which draws in exhaust gasses at idle. But the bypass allows enough air for the engine to idle as long as it's open.

Are you referring to the swirl flaps on the manifold or the soft shutdown valve?

 

[GTSSportCoupe]

Are you referring to the swirl flaps on the manifold or the soft shutdown valve?

I'm not familiar with 1hdfte. Just an idea to look into.

 

[Mag71k5]

Hello! Judging off the videos she sounds fine, a little puff of smoke at start up is completely normal for a cold start on 99% of diesels.

One of the more common areas where air gets into the fuel lines is your filter/primer assembly. The diaphragm breaks down, and it'll suck in air. Id replace that, it's cheap and easy to do.

Maybe then replace all the soft lines if your still concerned.

Any new videos?

 

[SMLE]

Hello! Judging off the videos she sounds fine, a little puff of smoke at start up is completely normal for a cold start on 99% of diesels.

One of the more common areas where air gets into the fuel lines is your filter/primer assembly. The diaphragm breaks down, and it'll suck in air. Id replace that, it's cheap and easy to do.

Maybe then replace all the soft lines if your still concerned.

Any new videos?

Thanks! It's the rough idle which is the concern for me, and it also sounds very loud/slightly rough when cold especially, and isn't 100% sounding when warm.

The filter/primer assembly was replaced last year with OEM.

I'll look at the soft lines too! Thanks

Will try and get a video inside the car as I feel you can hear what I mean a bit better

 

[Squash]

If it's any consolation, I currently run three diesels. 1hz, 1hdt and a 1HD-FT. Plus some diesel tractors...
Each on has its own character when cold starting.
Unless I'm missing something here, you don't have a problem.
The key is start a cold engine with at least one good glow cycle, then warm up and drive the piss out of it. Stop, park and listen.
If she purrs like a kitten, keep on driving.
The one thing to note is that you have to work a diesel engine, don't be driving like an old person....make some bloody heat.
NOTE: Only -25 C here this morning!

 

[Squash]

Still dropping.