Engine is rattling and shaking/misfiring

[Faluk]

Hello all

I am new to the forums and have a quick question.

I own a Fiesta St Mk 6. My pride and joy

However just recently while driving i changed into 2nd gear instead of 4th.
I was in high revs in 3rd gear at the time. So when i accidentally changed into 2nd instead of 4th it was in very high revs
After this the engine manigement light came on and it said oull over now and check engine
The car now struggles to pick up speed at all, go over 3 thousand revs And struggles to start.

If anyone could tell me what is wrong with the engine and how i could fix it would be greatly appreciated.

Thank you very much !

[PositronicRay]

I would have thought a compression test would have been in order, maybe bent a valve.

[Faluk]

Thats what i was thinking to. I did take the car to a mechanic who said the whole head would be needihg replacing?

[PositronicRay]

Faluk said:

Thats what i was thinking to. I did take the car to a mechanic who said the whole head would be needihg replacing?

You won't know all the damage until the head is off.
How much are second hand engines for these?

[Faluk]

Around 550+. Do you think it would be easier/cheaper to change the engine.
Or find out if it is 100% the head or a valve and change it or fix it?

[PositronicRay]

Faluk said:

Around 550+. Do you think it would be easier/cheaper to change the engine.
Or find out if it is 100% the head or a valve and change it or fix it?

Speak to a trusted garage/mechanic. If you change your engine you also need to factor in the labour.

They should be able run a compression test and peer through a borescope it's possible they find more (or if very lucky less) damage once they strip it.

[thatdude]

So what probably happened then was you over-revved the engine OP. This mostly likely caused "valve float" which means the valves were not under control of the springs, and thus not shutting. The result is a valve (or valves) is (are) still open when the piston comes up to top-dead-centre. There is some interaction which probably has resulted in a valve being bent, possibly a score on the top of the piston. The bent valve(s) is now not sealing very well, resulting in loss of compression and that low power / unwillingness to rev you describe.

It is a head-off job, but the first thing to do is a compression test (find out which of the 4 cylinders has a leak) which will point to where the damage has occurred.

Looking down the spark-lug holes with a boroscope can help with some visual inspection before taking teh head off, but I would expect it to be coming off.

[Faluk]

Yeah mate thank you for that. It was teo bent valves in the head. I had to just change the whole engine worked out cheaper.