ive developed a strange knocking noise from the engine only at a around 3000rpm.
no change to the drive of the car and the oil temp and pressure where fine.
it was due an oil change and it was low on oil. needed a litre to get it to max. but i ended up driving it a little hard yesterday and noise just apperared.
it was sounding tappety but this always happens when the oil is low or dirty.
any ideas guys? how do i diagnose the noise. proper pissed off!

 

If it's knocking then it's knackered I'm afraid. Are you sure it's firing on all cylinders?

 

I pulled the ht leads one by one and the knocking was evident throughout. But coming to think of it one of the leads seem to make no difference to the engine note although I will need to do it again to double check. Although I would of expected the car to drive diffrently if it was firing one cylinder less?
Why is it only knocking at a certain rpm??

 

How many miles has the engine done, how bad is the piston slap when cold, I used to get bad piston slap when warm/hot but due to 200,000 miles.
tabetha

 

cant be 100% sure on the mileage as it an engine conversion car (in a bmw).
no piston slap at all. was very quiet unless it needed an oil change then it would be tappety.
not particularly smokey either.
had the head off 10000 miles ago to de-coke it and all seemed fine. had it on the rollers recently to set it up and all was fine.

 

record a video of it and post it here - by what you are saying it does not look good

is the noise louder when the engine is under load (driving it)?

 

ok il get a video up tommarow. just had another look and all cylinders are firing. if i take the leads or injectors off it does effect the idle.
it sounding very much like a diesel car at the mo.

 

if its really knocking then i'd say the bottom end is in need of a rebuild; dont drive it anymore

 

not driving it now. whats my worse and best case scenario? costs wise too.
also am better paying for a rebuild or getting another engine. what would my engibe be worth?
skint at the mo aswell

 

https://passionford.com/forum/ford-r...ottom-end.html dont know if its sold or not

otherwise it really depends on what's wrong with yours & the crank

you might get away with just a polish and a new set of shells on yours; or your crank could be scrap and you might need new pistons

you'll only know when you pull it apart for inspection

 

If it was low on oil and you've then gone out and driven it hard i wouldnt mind betting you've starved number 4 big end and made it knock, i think this as ive done it myself once, i also still had good oil pressure after and couldnt understand where the noise was coming from till i pulled it apart, crank grind and new shells etc and all was good, i have now learnt to make sure there always full of oil.

 

Sounds about right. What sort of cost would that be mate ?
Wasn't even gona drive it that day and had the oil n filter ready to change. But was pissing it down during the day and by the evening had dried up n my bro just picked up a new car and want a little cruise. Sods law

 

Well you could do one of two things depending on whether the knock is bottom end, either pull the engine out, remove the sump, pull off the big end caps and see the damage, check the shell size from previous grinds.
Then if it is that whats caused the problem depending on the extent of the damage (spun shell at worse) you could take out the crank and have it ground, new set of mains and big ends, pull the oil pump off for inspection and change if needed, replace all above and refit it to the car, then obviously dont drive it low on oil .

Or secondly pull the motor out and give it a full rebuild as thats what i did, depends on your budget and how paranoid you are in regards to swarf etc floating around after the shell let go, but if doing the above just make sure you give it a good clean out to remove what you can as if its holding good oil pressure still i wouldnt of thought it will be to bad but this is just my advice some people may dissagree.