Misfire / knocking noise

[Graehamlost]

Hello again!

I was driving my 1993 HDJ80 home last night, got up to approximately 60mph with no issues. Drove to work this morning and friend mentioned it appeared to have developed a misfire. Started up again and it sounded like this…

Can anyone of you knowledgeable chaps help identify the issue. Truck is my daily driver.

Cheers!

 

[frank rabbets]

Sounds like it's on one cylinder only. Sounds exactly like a bad big end knock or broken piston. Possibly piston hitting valves/cylinder head as well.

 

[Towpack]

It does sound like a top end/cylinder head problem but, given the big end issue some 1HD-T's suffered you have to suspect those. Fortunately they're (relatively) easy to check/replace with the engine insitu.

 

[Shayne]

Ouch .
I'd still check for a blocked injector first just because easy start or egr cleaner spray can cause a hell of a rattle in a perfectly healthy engine .

 

[Graehamlost]

Ouch .
I'd still check for a blocked injector first just because easy start or egr cleaner spray can cause a hell of a rattle in a perfectly healthy engine .

Thanks

Sounds like it's on one cylinder only. Sounds exactly like a bad big end knock or broken piston. Possibly piston hitting valves/cylinder head as well.

It does sound like a top end/cylinder head problem but, given the big end issue some 1HD-T's suffered you have to suspect those. Fortunately they're (relatively) easy to check/replace with the engine insitu.

Thanks for the replies! Where would you start or is there a specific method that i can use to identify and fix the problem?
Im not shy on the spanners but i'll admit that i've never done this before and at a bit of a loss where to begin.
Any advice on how to proceed would be greatly appreciated.

 

[essexpete]

It sounds to me like a piston is hitting the top end. Might have spun a BE and allowed slop. I am no expert but a fuel issue would likely cause a miss fire not a knock like that. Although we did have a tractor engine that over fueled due to a leaking heat pilot and that did cause knocking. We didn't grasp why and a tip of an injector broke off, presumably because of the misfire and embedded in the crown of the piston. That knocked like bailiff. I would not run it anymore without having a proper look.

 

[Grimbo]

To rule out a leaking or faulty injector do the following ....
With the engine running just loosen the injector pipe at each injector in turn .... if you slacken one off and the noise stops then you have found both which cylinder and which injector is at fault .
Take that injector out and get it tested at your local diesel specialist....
If slackening off each injector in turn doesn't stop the noise then it is most likely a mechanical interference noise and would require engine strip to repair.... you could take the rocker cover off and run the engine and observe if all the valve train is operating correctly .

 

[chapel gate]

That's a heavy knock. Along with the other things mentioned it could be a piece of broken ring on top of the piston.

You shouldn't be running it, but put your finger over the breather pipe that goes to the air Intake and remove the oil filler cap. See if the vapours "chug".

 

[frank rabbets]

Easiest approach, though not that easy, is to take off the sump and check the play in the bottom ends of the connecting rods. If it is a worn bearing with that amount of noise play will be very noticeable. First drain the oil and check for metal swarf. But sump has to come off whatever.

 

[Towpack]

I think the most important takeaway here is run it as little as possible until you find the cause. If it is bottom end it could rapidly turn into a catastrophic failure and huge expense.

 

[Ciderman]

Sounds too slow a knock to be piston/crank pin related.
It sounds more like cam or tappet speed, but certainly a catastrophe if not dealt with immediately!

 

[Graehamlost]

Sounds too slow a knock to be piston/crank pin related.
It sounds more like cam or tappet speed, but certainly a catastrophe if not dealt with immediately!

I managed to get it recovered to my mates unit this morning. Going to crack on this weekend and start eliminating potentials one by one. Managed to eliminate an injector fault on the car park last weekend. Thanks for the advice, everyone on here has been really helpful.

 

[essexpete]

Keep us posted!

 

[Graehamlost]

Keep us posted!

Took valve cover off and turned engine over by hand. Everything looks ok up top and rotated crank with no interference. Dropped oil and checked for swarf. See pic. Just wrestling with removing the sump at present. Does anyone have any tips on how to get it off?

 

[frank rabbets]

I got a solid stainless steel kitchen knife and hammered it into the gap at right angles. Then I used the hammer to hammer it round the sump thus cutting through the sealer. Of course other implements are available.

 

[essexpete]

Don't forget eye protection

 

[frank rabbets]

And Valium. (Diazepam).

 

[Graehamlost]

Haha! Will I need to take any parts off to get the sump off the block and onto the floor?

 

[Dave]

Jack it up so you get full suspension droop.

 

[Grimbo]

And get an old bit of carpet ....leave it under the engine and let her drip overnight.... your eyes and head will thank you .