Can engine be partially seized?

[PeteWild]

I have a (possibly) strange issue with my 2002 Leon 1.8 20v t
In a nutshell, son borrowed car (first mistake I hear you say) and was on the motorway when the oil light came on, ( I did an oil change maybe 2 weeks ago and re-checked level before he left) by the time he negotiated the traffic over to the hard shoulder the car had cut out and wouldn't restart or even turn over really.
RAC brought it home, their diagnosis, low oil pressure but oil level OK so something else.
I was worried there was some internal damage so I stuck her in gear and pushed backwards to see if engine moved, and it did but then stopped, it's almost if it does 99% of one revolution then hits something, so I pushed it forwards, same thing, nearly a full revolution and then stopped.
Cam belt looks ok and tight.
Any ideas or other clever diagnostics?

 

[beastgtir]

oil light would suggest pump if the level is okay buddy,

 

[Benl172]

Was there any smoke when it happened?

 

[Ronin225]

Sounds like you've snapped a rod
Oil pressure loss is usually a result of knackered pump but more likely a blocked pick up pipe

 

[PeteWild]

Cheers guys, as for the smoke, can't say as dopey bollox driving it wouldn't notice anything other than a bird in a bikini.
I've since spoken to a mechanic mate who basically said that he was going to take the head off and see if he can see anything obvious.
If it is the snapped rod theory, is that a big bucks thing? Or is it one of those could be easy could be a bugger sort of things?
Thanks again for taking the time to reply....

 

[Ronin225]

It'd be easier to drop the sump off and have a look up through as this is much quicker and less labour than the head off
Dependant on if the rods gone it may have knackered the block, crank etc. it may have written off the bottom end

 

[traumapat]

It could be a blocked pick up pipe in the sump.. hopefully its not been too starved. A few cars have suffered with this.

 

[PeteWild]

UPDATE
Got the sump off and looking from the bottom up, everything looks pretty much as it should, at least I think it does.
Turned the engine via the pulley wheel and can see eveything move but then it hits whatever is stopping it and it wont go any futher. Turn the pulley the other way and everything moves smoothly until it hits whatever again and it stops dead.

What next? Im guess the head off and look from the top down?

Any other suggestions welcomed.......

Thanks

 

[Nath.]

I reckon you have a valve from the head hitting a piston.

Remove spark plugs and look in the hole with a torch?

Cam belt jumped a few teeth?

 

[PeteWild]

Nath, thanks

I did take a peek down the spark plug holes with a torch, although I must admit the holes were small and I wasnt 100% sure what I was looking for

Im guessing its a head off and take a proper look, I cant make things any worse.

Has anyone on here done a guide on removing the head ? Does anybody know?

Once again, thanks for taking the time to help !

 

[PeteWild]

Also, while I have some of your attention, how do I go about checking the oil pressure?

Im now leaning more and more towards the valve problem, which I hope will be obvious when I get the head off.
However, the initial problem was an oil pressure warning light on, whether or not it was caused by, or contributed to the valve issue, I will obviously need at some stage to check the pressure.

Im hoping its the simpler of the suggested possible causes, that being a blocked pick up pipe, seeing as I have the sump off, is it advisable to put a new one on?

Other than that then I guess the oil pump?

 

[Nath.]

I would be checking the cam belt timing marks. It should be quite easy to do and would give you an idea of what's going on.

Can you take the cam cover off and rotate the engine and watch the cams operate the valves. If one valve doesn't move then you know that a piston is hitting it.

 

[csd_19]

Have you tried turning the engine by hand with the spark plugs out?

The resistance you felt could've been the compression stroke on one of the cylinders.

With the plugs out you won't have that resistance, only the force from the valvetrain.

 

[PeteWild]

CSD,

Yes, tried that one, even with no plugs theres no difference, it just gets to 'that' point and wont go any more.

I dont have any garage/cover so when the weather warms up again Im going to firstly check the timing marks then take the head off.

Fortunately we have options as far as cars in the household so as much as Id like her sorted, the Leon isnt deperately needed. Not enough to get cold and wet anyway !

 

[csd_19]

Sounds like its piston/valve interference then

Lucky its not your only car going by what you said though

 

[PeteWild]

Finally got round to getting the head off, and full marks to those that diagnosed the valve / piston interference, although unfortunately the interference is very severe and Im not sure she is salvageable so may well be putting a non runner on ebay shortly.

Shame, as apart from the engine, she is in good nick, but looking at the cost of;
1. Second hand head.
2. At least one new piston
3. All the ggaskets
4. And while Im in there, the timing belt kit.

The cost is nearly what she is worth.

Ill see if anyone whos handy with the spanners fancies a project

Thanks for all your input