Engine Knocking?

[jambo_gtir]

Hi everyone, just need some advice/help really....

I may have a buyer for my car very soon but recently i have noticed a slight knocking/tapping from the engine between certain revs. I am not the sort of person to flog the car knowing that something may be wrong; i just can't and wont do that.
The noise sounds like the noise when you first fire up the car; it sounds like the chain rattling for a second then it goes away. My engine has always done this on start-up. But when im driving along now, as i approach 3000rpm, the same rattling noise comes back. the rattle increases as the revs do and it only appears to occure under slight acceleration (i suppose i cant tell under heavy accel as all i can hear is the bloody zorst). As i back off the throttle, the rattle subdues slightly.
I originally thought it was just the tappets as this has been going on for about 6 months, but this last week or so i'm sure its getting worse. I'm thinking an engine bearing could be the cause (big end, crank bearing or what i don't know :?)
Any help or guidance would be much appreciated.
Thanks.

 

[Smo]

Certainly sounds like it James - are you around the next couple of days? I could have a listen for you.

My first R did the same, a slight rattle on cold startup for circa 1 second, and rattled on partial throttle around 3,000rpm. Does it rattle if you have your foot to the floor at any point through the revs?

 

[jambo_gtir]

yer that would be handy mate. I'll be down shanklin seafront 2morrow evening (Thursday) from about half 6 till 8ish so don't know if your in that area then?
sounds like it is the bearings then shit box.....

 

[ollydj]

Sounds like the cindrome my old engine had before the bigends properley picked up.

 

[jambo_gtir]

i think i am just going to get engine out and re-build it. May aswell get forged internals aswell while im at it.
If i order some ACL bearings do they just come as one size? This is going to be one steep learning curve i know that much lol.

 

[Dangerous Dave]

i think i am just going to get engine out and re-build it. May aswell get forged internals aswell while im at it.
If i order some ACL bearings do they just come as one size? This is going to be one steep learning curve i know that much lol.

No mate you will need to have the crank re ground and this means you will need bigger bearing i cant remember the size's but its some thing like 0.25 0.50 to 0.75 over size or something like that anyway;-)

 

[jambo_gtir]

if the crank is fine on inspection though, can't i just use again as it is?
I found a re-build kit yesterday and they e-mailed me a quote this morning: £1550 AUD
The kit is from www.spoolimports.com and comes with: SPOOL H Beam Forged Conrods, CP Forged pistons, ACL race series big end and main bearings and cometic head gasket (although i wouldn't fit that).
Does this sound a good deal?

 

[Smo]

Tonight isn't a problem bud - will you be in Sandown at all?

£890! Sounds pretty good to me mate. If your crank is unmarked you'll be alright to use it again for sure, but even if there's the tiniest scratch on there, don't be tempted to use it.

 

[campbellju]

Possibly but unecessary. Just get forged pistons, HG and all your bearings from Nissan so they are the correct size for your crank.

The con rods might be 19mm but they might be 17mm and just give you more problems? Our con rods aren't known for problems so get them checked professionaly and fit new bolts.

I don't see the attraction of ACL bearings apart from the fact they say "race".

Maybe I'm just getting old?

 

[Smo]

Just an afterthought - while it's apart you may as well fit ARP rod bolts mate.

 

[jambo_gtir]

Possibly but unecessary. Just get forged pistons, HG and all your bearings from Nissan so they are the correct size for your crank.

Yes i see your point mate; i could just get some CP forged pistons from the US for $500 all in and then get the bearings from Nissan then at least id know they are the correct size.
So with forged pistons, standard rods, standard crank and bearings id still have a stronger engine than standard right?
I'm guessing when you run more power the weakpoint is the pistons; hence the need for uprated ones. I suspect the standard rods could handle quite a lot?

Smo: Yes mate I think i will get ARP bolts; i think they actually come with the rods in that package i was on about up there ^

 

[campbellju]

The weak point on my engine was the HKS HG closely followed by the block :doh: Too much boost for too long I think.