Knocking after engine rebuild

[HHughes]

First post here, apologies if not in the correct format or place. I've often used the forums for advice for my '76 SIII 88 2.25 Diesel. So far I haven't need to post myself, I can usually get the answer I need from another post..... but I'm stumped... My engineering knowledge is too limited to diagnose my issue!

Essentially I blew the head gasket on the engine (this was actually a slowly worsening issue rather than a bang) and took it all apart and replaced all the gaskets I could, cleaned everything up, new washers etc... no new engine parts as it actually looked all okay. Cylinders, injectors all looked healthy etc.

I put it back together and flushed coolant, primed fuel etc tried to start her.... Tow start and success. The engine didn't sound healthy, but it wasn't misfiring or anything like that. I let it get warm and gave it a little revs, in neutral, there was a little pop and some white smoke and she started to hum nicely. Sounded good. I took it for a drive and it was more powerful than I've known it before and also quieter - I was fairly shocked at how seemingly well this had gone. However the champagne driving didn't last long (it never does with a series!) a sort of clapping/slapping noise developed and simultaneously the charge light came on and the battery stopped charging. The battery was extremely low anyway (hadn't been charged up after sitting a while during me messing around with the engine) so on the way home lost all the electrics. I knew I had to get the car home so I carried on, the slapping/clapping noise got louder with more revs and more frequent. I also had a lot less power from the engine.

I've investigated the issue, I've found the cables from the alternator are kaput, so that explains the charge light issue and the lack of battery... However this - to me - does not explain the noise and reduced power. I'm fairly gun ho with the car but this noise doesn't sound good, I'm really keen to work out what it is. The drive belt is okay and tight.

I'm hoping one of you Landy pros will tell me to tighten a nut and sort it - I'm not sure if I've got the energy to take the engine apart again haha - any advice is greatly appreciated - thanks in advance.

Two videos here - one of her driving back, one idling.

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[mikeau]

Ive no idea, but I wouldnt be running it too much or driving it with a noise like that until you find out what it is..!

 

[Cliff4WD]

Probably pistons hitting the valves or something equally as drastic. What on earth are you doing driving it like that? I wouldn't be at all surprised if you have now destroyed your engine altogether!

 

[HHughes]

Probably pistons hitting the valves or something equally as drastic. What on earth are you doing driving it like that? I wouldn't be at all surprised if you have now destroyed your engine altogether!

The noise started whilst I was driving, it was absolutely fine then suddenly it went, I wasn’t far so I carried on home. Whilst I was driving it I initially thought it was something to do with the fan belt because of the issue with electrics, that’s when the video was taken. Don’t worry I haven’t driven it since….

If it’s valves hitting pistons what would suddenly cause that whilst driving along? Broken timing chain?

I appreciate your help!

 

[Guitar Mick]

Welcome to the Forum @HHughes. At the very least it sounds like head off again and inspect for damage. If there is damage to a piston top, drop the sump and check the big ends and main bearings in that area. Did you notice a dramatic rise in temperature?

 

[erubus]

I'm almost willing to bet my salary on this one. I reckon when you've put the head on, one of the pushrods hasn't been seated in the cup in the bronze follower and the follower has cracked.

If you take the rocker cover off check all the rockers and you'll probably find one has a ton of clearance as the pushrod will have pushed down the side. That one valve will be opening at the wrong time making the banging noise.

I replaced my engine fairly recently and it made this exact noise. It turned out that one of the valve clearance adjusters had been massively overtightened by a PO and the thread wouldn't lock, so I'd get a few miles of good running, then this bloody banging would start.

Here it is with the noise barely audible but you can hear it as I walk towards the exhaust

And from inside

when I stripped the engine apart again for the first time (after rebuilding and fitting it) I found a broken follower and thought oh wonderful, I've found the problem. Built it all back up and then the noise started again (that's when I took the first video).

When I stripped the engine again, I didn't find any broken followers but found the stripped thread and figured out what has happened (the gap as the adjuster backed off caused the follower to break the first time). I swapped the rocker shaft and that fixed it.

If you find that it is a broken follower, pm your address and I'll send you a spare one. Oh, and welcome to the forum.

 

[HHughes]

I'm almost willing to bet my salary on this one. I reckon when you've put the head on, one of the pushrods hasn't been seated in the cup in the bronze follower and the follower has cracked.

If you take the rocker cover off check all the rockers and you'll probably find one has a ton of clearance as the pushrod will have pushed down the side. That one valve will be opening at the wrong time making the banging noise.

I replaced my engine fairly recently and it made this exact noise. It turned out that one of the valve clearance adjusters had been massively overtightened by a PO and the thread wouldn't lock, so I'd get a few miles of good running, then this bloody banging would start.

Here it is with the noise barely audible but you can hear it as I walk towards the exhaust

And from inside

when I stripped the engine apart again for the first time (after rebuilding and fitting it) I found a broken follower and thought oh wonderful, I've found the problem. Built it all back up and then the noise started again (that's when I took the first video).

When I stripped the engine again, I didn't find any broken followers but found the stripped thread and figured out what has happened (the gap as the adjuster backed off caused the follower to break the first time). I swapped the rocker shaft and that fixed it.

If you find that it is a broken follower, pm your address and I'll send you a spare one. Oh, and welcome to the forum.

This is hugely helpful and wouldn’t surprise me, I’m very handy (I’ve worked on boats etc my whole life) but it’s little bits like this that I’m bound to have messed up. I’ll look into it tomorrow. Thanks again for your advice. I’ll update you all soon!