OT: Can a camshaft just snap?

[leicesterboy15]

I've just been off the phone to my sister who has told me that the her Mitsubishi Shogun / Pajero blew up last week. She took it to an engine specialist who said the camshaft snapped

How can it just snap? She said it was driving fine when she parked it up, then when she went back and it just wouldn't start. Could a timing belt snap have caused this? They are saying it needs a new turbo as well cos there are traces of oil in it and quoting £4000 essentially for top end rebuild, turbo , water pump and a few other bits!! Sounds too much to me, I'm sure I could replace my BMW 4.0 V8 engine for less than that! Hers is a 2.8TD.

I've found a cheaper engine with turbo etc but its more of a risk I suppose as you don't know the condition of the engine. What if it happens to the replacement - unless it was caused by the cambelt snapping, I can't see a camshaft just snapping??

[Bin_jammin]

If the timing belt broke, you'd end up with bent valves and no compression on each cylinder. Cams DO break, it's not uncommon, but it's unusual. They can fail for all sorts of reasons, a valve sticking, a cam lobe that's not being oiled seizing... I've even heard stories of cams snapping because of odd harmonics from a poorly running engine. So far as the turbo goes, I'd have that checked, it's possible it's going bad, but it could be as simple as a clogged turbo oil drain line. If the oil from the turbo can't return to the pan it has to go somewhere, usually ends up in the compressor and turbine.

[whiskychaser]

I've just been off the phone to my sister who has told me that the her Mitsubishi Shogun / Pajero blew up last week. She took it to an engine specialist who said the camshaft snapped

How can it just snap? She said it was driving fine when she parked it up, then when she went back and it just wouldn't start. Could a timing belt snap have caused this? They are saying it needs a new turbo as well cos there are traces of oil in it and quoting £4000 essentially for top end rebuild, turbo , water pump and a few other bits!! Sounds too much to me, I'm sure I could replace my BMW 4.0 V8 engine for less than that! Hers is a 2.8TD.

I've found a cheaper engine with turbo etc but its more of a risk I suppose as you don't know the condition of the engine. What if it happens to the replacement - unless it was caused by the cambelt snapping, I can't see a camshaft just snapping??

No insult meant to the garage, but did it snap when they were taking the cam out? Would have thought bent valves/piston crowns or con-rod through the block more likely than a camshaft breaking

[Omega]

They can span when something stops them rotating, such as whan a valve hits a piston, striking a jacked up hydraulic lifter or through hydraulic lock of the engine.

I once saw a guy try to bump start a diesel by pulling it behind another car and dumping the clutch whilst in gear.... (do you spot the flaw in this plan yet?).. The outcome was a snapped cam belt and a *new* 4 piece camshaft. That and the well earned knowledge that you can't bump start a compression engine.

[Ferret]

That and the well earned knowledge that you can't bump start a compression engine.

We used to bump start my 205DTi all the time when its starter motor was on the way out...?

Admittedly this was only an 1800cc turbo engine though.

[winfred]

we bump started our old 240d benz a fair amount of times, **** dad use to bump it every morning when we lived on a hill (probably why the tranny went to ****, ****ing dumbass )
the belt probably broke or lost it's teeth and that broke the cam when the valves hit the pistons

[whiskychaser]

the well earned knowledge that you can't bump start a compression engine.

Er... yes you can. Pick a high gear and let the clutch out gently. But you make a good point of can happen if you get it wrong

[clindahl]

Yes - Cam shafts can snap. This is usually more common in a pushrod engine, such as an old chevy 350 V8, or Ford 302. It happens when the cam bearings are worn and one fails and locks up but the rest of the engine is still spinning. I have seen atleast one Ford 302 where 3/4 of the CAM could be removed and the last bearing was discoloured and the section of the cam couldn't be budged out with a 10 lb sledge hammer (block was trashed at that point).


Yes it is possible

[leicesterboy15]

If this was to happen is the bottom end affected or will a head off rebuild do the job (sorry about my limited engine terminology)?

[Omega]

Fair play about bumping compression engines. I've only ever seen one attempt and it was on a Vauxhall 1.8TD which the owner tried to start by letting the clutch out in first gear whilst being pulled down hill by a Mitsi Shogun....

After a god-almighty bang which involved the Vauxhall coming to a dead stop with the front wheels locked. The bumper, valence and part of the headlight/slam panel continued to travel forward, still attached to the Shoguns tow rope....

I can only say it as I saw it!

:-)