Knocking and banging, low power

[itchyfeet]

Whats strange is it's happened too suddenly
A sticking or burnt valve could be the problem, worth whiping the rocker cover off and checking the rocker shaft is secure, somebody had one stud fail recently, could also reset the tappets on that cylinder and retest

did you also check the ignition timing? i'm wondering if you have a bad valve and coupled with bad ignition is making this problem if you have a timing light you can also check all leads are sparking easily with this.

[oddnumber]

I am kind of baffled by the suddenness of it too.

I've had a sticking tappet on it before that cleared after a run, but would a sticker rob that cylinder of compression? Timing is 5deg ATDC (it's a DF).

E D I T : This is a quick vid of it running tonight. You can hear two small pops back up throught the carb.

http://youtu.be/O42tTXN5kEo

[pionte]

The plot thickens ! It still doesnt sound any worse than when my tappets drain down.... If it was mine I would whip of the rocker cover to check nothing obvious amiss under there, then take it for a proper run and give it some beans ( disclaimer .... I am not suggesting that you do this, this is your engine and I dont want to be held responsible for any damage )

But thats what I would do

[BOXY]

Where is the "clunk" coming from that you can hear on the video? If you turn the engine over by hand can you feel any tight spots?
Popping back through the carb with a cold engine would point towards an inlet valve being open / not fully closed on the compression stroke. Maybe the valve seat has broken up? My van had a valve that recessed back into the head, but the van would still hit +50mph and didn't make any knocking noises. That clunk doesn't sound good.

[oddnumber]

Thanks folks.

Pionte - I took it for a run but no good, the tapping got more pronounced if anything.

Boxy - I didn't hear clunking - could it be the popping you can hear? The vid was a warm engine too.

I've checked the leads and all look good. They have metal shrouds on, so I took em off after reading they can cause issues but no different.

[NicBeeee]

Hi,

Just out of interest can I ask why you were loosening the pulley in the first place, just wondering if there might be some kind on common denominator to look at.

[oddnumber]

Hi,

Just out of interest can I ask why you were loosening the pulley in the first place, just wondering if there might be some kind on common denominator to look at.

I was hoping to investigate a coolant leak from the pipe that joins the waterpump to the right hand head.

[itchyfeet]

A valve that does not open at the correct time will result in lower compression

When you say you had a sticking tappet before what's the story?

[oddnumber]

The tappets were noisy as hell when I'd parked up and oil drained away from that cylinder (our drive is on a slope). Once it'd run for 10, 15 miles or so it'd quieten down.

This sounds and feels a bit more severe though. It's never popped through the carb previousy, nor felt underpowered.

[pionte]

well the low compression does point to a sticking valve, (or sticking piston ring,) coupled with the popping back through the carb.... if the ignition timing was way out then you could also get popping through the carb and knocking... but low compression, maybe its always been low and its a red herring . what happens if you rotate the distributor either way ? mark its position first.

[itchyfeet]

Perhaps its time to get sombody who knows about T3s to have a look

http://www.gasure.co.uk/" onclick="window.open(this.href);return false;

[oddnumber]

Yup, alas I think it's that time.

[Ian Hulley]

Time to take a rocker cover off methinks

what happens if you rotate the distributor either way ? mark its position first.

I can't help but think that if the clamp bolt isn't loose and has never been loosened then our friend needs to leave it where it was when it was last running fine.

Ian

[pionte]

yep probably wise advice Ian, It difficult to remote diagnose a problem, I have been pondering this today whilst parked up on the M25, a completely stuck open or closed valve would give a far worse compression reading than 110 I would have thought, you would have 0 if it was stuck open, so maybe a faulty tappet not allowing the valve to fully open , I think a look under the rocker cover will shed more light on this puzzle. Has someone fitted non hydraulic lifters in the past ? If this is indeed possible?

[Ian Hulley]

It reads to me like maybe a rocker end/adjuster nut breaking down ?

Has someone fitted non hydraulic lifters in the past ? If this is indeed possible?

Laurie Pettit fitted some solid lifters into a mate of mine's 1.9 DG ... for reasons best known to himself he couldn't (or be bothered to ?) replace all of them

Ian