Knocking noise from engine

[damojenks]

Hey folks, recently i had an engine rebuild for the second time due to crank bearings wearing down on my crank, got a new crank and acl race bearings and had them put in, ive ran the car in using running in oil as advised on here a few months ago. I did 1500 miles on running in oil changing it 4 times during this period and filters changed at same time too, but just as my car is going in on monday to have a full service ive noticed a tapping noise coming from and what sounds like the top of the block. I had my lash adjusters changed in febuary and car has been running well, this tapping noise occurs very slight at 3000 revs and stops as it gets to 4000 doesnt occur before the 3k and no power loss or drop in revs either. Im a bit worried that it may be a big end bearing thats shot again and could result in me having to get yet another crank 3rd one in 6 months. Can anyone shed any light on this for me as this car is doing my head in, pain in the a## and a money pit since i bought it over 2 years ago. Spent more time in garage than me driving it. any help would be great thanks

 

[fq-craigus]

I'll be honest buddy sounds exactly like my symptoms when my bottom end went, the tapping was so light everyone thought it was pinking or pre igniting, turned out 123 had gone, but not enough to screw the crank fully so new bearings and been good since. Only difference with mine was I lost power due to the knock sensor retarding the timing and obviously saving the crank and making the tapping lighter. You say it's a 4 I would go with a later engine mate, as rebuilt 4 engines tend to go just as easy as you now know

 

[damojenks]

Mine is an evo 5 mate, it does sound like the same noise that i had before but when it got to 3k revs last time it got a lot worse, this time round its not as noisy and it stops when it gets to 4k and sometimes you cant hear it at all, I thought it could be the lash adjusters again and maybe a performance oil will help along with a filter change and maybe flushing it before hand just incase. Struggling though, thanks for the input

 

[fq-craigus]

Yh my noise was between 3 and 4k and you could only hear it if you blipped the throttle or if the car was driving as it was loaded up, you could even increase the revs past te 3 4k mark and to redline and wouldn't hear the tapping. Best bet is don't drive the car at all, take the downpipe off and starter motor, and there will be a tin cover round the starter, that will give you access to the sump, pull all the bolts and when inside check for any play if there is play its bottom end, (make sure you dump the oil first though)

Mark my words just by doing that yourself you will save a load of hassle and money, you can start pricing parts and workin out where to go from there.

Sorry don't want to preach to a potential mechanic or anything as I know nothing about your skills with a motor just highlighting where I went wrong before I spent a fortune getting to the bottom of the problem, even though the car spent 3 or 4 weeks at an Evo specialist it still took the next garage and 200 quid to them to find the prob

 

[Phil74]

I have an E5 and the lash adjusters you usually get the ticking on start up as one being lazy but this stops as soon as oil reaches it not at 3000 rpm. I had this this before last year on my E5 and it was the big end bearing on its way out but mine stayed with the noise from 3000 rpm to 4500 rpm. Did you use semi syn to run in the engine for first 1000 miles when running it in?