Topic: CLUNK!... crank locked up (Auto)

[maxstu]

Probably just a jammed starter then

Ha! If only... the engine was locked up even with the starter removed.

Worse still, after only 20miles of driving and a few uneventful starts... it's locked up solid again!! 

Did it lock up whilst driving or on an attempt to start engine from cold?

Have you check colour and condition of both engine oil and transmission red oil?

[silverbullet]

I would be checking that one of the torque convertor bolts hasn't come loose and is rattling around in the bellhousing and occasionally locking the ring gear.
This does sound like a loose foreign body problem.

[chris7ian]

It locked up after a short drive of a mile. Drove normally, parked up, then went to move it after a few minutes stationary and it spun over noisily/rattly but failed to start. On second turn of the key it wouldn't turn over (same as at the start of this thread) and the crank is solid again...

It does seem like it'd be a foreign body, but after the engine place dropped the engine and spent hours investigating they said they found nothing, not even witness marks. Presumably they'd have checked the torque converter bolts, but I wll enquire on Tuesday.

The oil and ATF were all good at the start of the 20miles, although I've not checked it since this last lock up.

I've spoken with the auto transmission place again and he's scratching his head too as there's nothing in the 'box that should cause a locked transmission, not least because it was working again albeit briefly.

Could anything in the diff be involved?



 

[chris7ian]

Right... it's been sitting for a month whilst I tried to find out where to get any parts I may potentially need. But after a quick phonecall to book it into the auto transmission specialist he suggested he could pop over to take a look before going to the effort of having the bus transported over.
So Sunday evening he came over and within 3 minutes he'd freed up the motor with a small screwdriver by rotating the fan vanes in the torque converter!!

I'm gobsmacked as it was impossible to rotate from the pulley (back) of the motor, and more so because the bus had been into an engine specialist who'd actually dropped the motor.

We still haven't found what the problem is and what's causing the lock-up, but at least I can get it moving when it inevitably happens again. He doesn't think the issue is the torque converter itself so I'm no closer to a solution. If I knew for a fact it was the torque converter I'd just have it changed, but having already spent a fortune having the engine out and looked at I can't just throw more money at it on a whim.

My gerbox guy seems think the problem is the engine, while the engine guy thinks it's the gearbox (but only because in his opinion "it isn't the engine"!!)

The only other piece of new information I have is that when it was running (smoothly) last night, there was a new, very faint tapping/rattling sound from around the front of the engine, more or less between the motor and torque converter... I'll get my stethoscope on it next time I have a chance, but any more input form anyone is welcome!

[chris7ian]

I've been away so haven't had any time to spend on this, but in the last week I've managed to start up the bus and drive it locally with the mechanical 'CLUNK' getting a little stronger, and ocassionally having to to 'free' the torque converter by rotating it via the fins through the inspection hole with a screwdriver... until last night, when despite doing this the bus struggles and won't start; The engine 'drags' and turns very slowly on the starter with a lot of resistance...

If I could tell for a fact it was a duff torque converter I'd just shell out and replace it, but no-one seems able to confirm!
 

[R0B]

Very few people on here know about auto boxes. I had mine rebuilt be Lee at T2five all I can suggest is contacting him on Farcebook or Twitter. He may be able to help.
𝕤𝕒𝕧𝕚𝕟𝕘 𝕠𝕟𝕖 𝕥𝟚𝕗𝕚𝕧𝕖 𝕒𝕥 𝕒 𝕥𝕚𝕞𝕖 (@t2five) • Instagram photos and videos

[maxstu]

To narrow down the issue, how about removing the three flex plate bolts that attaches it to the torque converter. Then rotate the engine using a spanner on the crank pulley. Remove plugs
to make it easier to turn.

Then spin the torque converter as you did before. If neither lock up, then surely the problem is either the transmission or the diff (final drive).

I was also thinking of spinning over the engine using the starter at this stage too. To see if there is any slow dragging issues. Disconnect fuel injection system and earth coil lead to ground. I'll leave you decide on that approach.
When you slowly spin converter check starter teeth for any apparent damage.

As you remove flex plate bolts, mark the plate for ease of reinstalling bolts. Use tippex or a marker.

[chris7ian]

To narrow down the issue, how about removing the three flex plate bolts that attaches it to the torque converter. Then rotate the engine using a spanner on the crank pulley.....

I should point out that it's still impossible to roate from the crank pulley *E D I T* until it's been freed up front the torque converter end

The engine's been out and everything rotated freely, even when reinstalled... The other night it all started up fine with no locking up or dragging... Annoyingly it's again stuck on the driveway rather than where I normally keep it

[chris7ian]

Very few people on here know about auto boxes. I had mine rebuilt be Lee at T2five all I can suggest is contacting him on Farcebook or Twitter. He may be able to help.
𝕤𝕒𝕧𝕚𝕟𝕘 𝕠𝕟𝕖 𝕥𝟚𝕗𝕚𝕧𝕖 𝕒𝕥 𝕒 𝕥𝕚𝕞𝕖 (@t2five) • Instagram photos and videos

Funnily enough I've just started following them last week after their 'barn find' high-top

[maxstu]

To narrow down the issue, how about removing the three flex plate bolts that attaches it to the torque converter. Then rotate the engine using a spanner on the crank pulley.....

I should point out that it's still impossible to roate from the crank pulley!

The engine's been out and everything rotated freely, even when reinstalled... The other night it all started up fine with no locking up or dragging... Annoyingly it's again stuck on the driveway rather than where I normally keep it

I'm not sure l understand? Does the engine rotate or not?

The point lm making by removing the flex plate bolts, is once they are removed the engine must be free to turn. That is all there is between engine and gearbox.
If your engine does turn smoothly and freely (plugs removed) with a spanner on the pulley, then you have isolated the problem to diff or transmission.

[maxstu]

After a quick read up on the internet, the symptoms lead (perhaps) to a faulty pump in the torque converter.

There are a few tests for checking condition of a converter. A stall test, for instance. A dodgy operation, though. Look it up on internet for more details.

I do have an untested spare torque converter at your disposal, if you wish? I was assured it was in full working order when l bought it. It will need recharging with fluid. But either way, engine or final drive/tranny will need dropping once again.

Whereabouts are you?

[chris7ian]

Sorry, my post was misleading so I've edited it now:
"I should point out that it's still sometimes impossible to rotate from the crank pulley until it's been freed up front the torque converter end.
However, last night it started up fine, albeit with the loud initial 'CLUNK', without having to touch anything.

I'll have to look into the pump issue and stall test later.
Thanks for the generous offer to borrow your spare - I'll certainly keep it in mind! I'm in South London

[maxstu]

What news?
My sister lives in Mottingham. Can leave converter there for you.