Strange top end rattle?

[TVR Beaver]

fastandcurious said:

It went in for a cam change, but because the centre cam bearing had slipped round in the block, the sump had to be dropped. At that point I thought "In for a penny in for a pound". Best get it sorted. Crankshaft reground, Block line honed. Pistons were ok so bores were honed and new rings fitted, new oil pump, timing chain and sprockets, new mains and ends, new cam (TVR Power 885)new followers, heads off, cleaned up with new exhaust valves and stem seals. Followed by a removal of pre cats and a general tidy up under the bonnet.

Interesting.. Rob at V8D says it's the small ends (pins to piston).. do you know if they checked these?..
obviously Rob has loads of experiance with these things...
But to me.. it sounds more like hard metal... like I said before... ball bearings and not the tap of a hard pin on a softer piston?...

[TVR Beaver]

No comments on the noise... does anyone think it could be the issue (for thoes who have been in there and done this job??)

http://www.youtube.com/watch?v=XbCEYmtLPoQ

[TVR Beaver]

haircutmike said:

Just to add another to the list.

Mine made that noise and did for quite a while, even with new cam and followers.

Bit the bullet and took the engine out. Checked everything and all was OK .

I think it is a touch of tads and that a few of us are curious/paranoid!

Peter.. did you check your small ends when you had the engine in bits... Or pin to piston... Rob says its this but it sounds to come from all over the top end and not just one cylinder... may be a bit mor front'ish...

Would it do it when pumped up?.. Not sure... they do have a lot of movement... and I'm also thinking the cap may get lifted to release the oil pressure on overrun.. so the cap floats a bit and chatters?...

[TVR Beaver]

haircutmike said:

John, yeh checked the small ends, twas my thoughts at the time but all sound.

Only thing I found was a slight exhaust leak at the manifold and a slight leak on the welds to the o/s manifold.

So is it still doing it now?.. or has it stoped?...

I think it could be floating caps on the hydraulic adjusters.. I think everyone who has this issue has aftermarket followers?...

[TVR Beaver]

looking good there... does it rattle on over-run ....

Just getting back to Chatter.... Chris52 did his cam and fitter genuine Land-Rover ones... and his is a quiet as a mouse... Just goes to show... But he did also machine his pedastals to get a bit more pre-load... I may try this over winter

Was suggested last night (in the pub).. that synthetic oil can glaze bores... and then you can get piston slap on the 500's due to the shorter skirt?....
But in my mind it's a hard metal noise... I sticking with the lifters I think.
.
Only problem is.. to get new lifters will mean another new cam as I'm sure putting new lifters onto a bedded cam will be a no-no..

[TVR Beaver]

''500's don't have a shorter skirt?''... Another expert up in smoke ... I knew they had some work done to them for clearance but was not sure what... so it's just a bit of fettling is it...

I agree with the bore bit and pressures.. but also think the 5 or 6 bits that go to make up the lifter could be better for sure... don't understand why the cap bit is so loose?.. there must be a reason for it?... I think the noise is from the lifter only though.. not lifter in bore slap... it's a hard metal sound like I said before... ball bearings hitting eack other... (I'm assuming the bores are not lined?).. as if it was lifter in bore it would be hard metal against Ali.. so would sound duller.. and not as pingy...

You need your cam designed for solids don't you?

Something to keep us entertained whilst it's raining anyway..

Edited by TVR Beaver on Sunday 7th August 10:36

[TVR Beaver]

spend said:

Does make me wonder if some of this could be the weird dislike your motor took to Robs cam?

Okay.. get you now.. and bleed down on differant makes etc.. the original TVR ones were fine.. .but the ones I had with the Stealth did it.. and the Power ones I have now do it a tad more...

I'm not sure how it could tie in with the cam bit?.. it ran the 435 before great.. and the 885 I have in now is very good (just needs re-maping at some point as it's running the Stealth map so very rich)... how could the two be linked in any way?..

[TVR Beaver]

I had issues up to about 3 1/2 to 4 K where it was lower torque than it should be... but get your point... you could be right but guess we'll never know... it's long gone...

solids do sound the best option if you don't mind a bit of setting once a year...

food for thought....

[TVR Beaver]

You hear of people using double springs etc.. so I'm supprised 0.9mm made any diferance at all...
Are you tempted to up it at all and try again?

[TVR Beaver]

By putting the washer in, you will have compressed the spring more... so have indeed increased the force now needed to move it (but only a little)....
.
Are we sure it's more pressure we need at this RPM on overrun... I'd like to get mine on a mechanical gauge and reduce the pressure as much as I can and see what that does.. .I still think the caps may be floating on pressure in the system on over run... although with mine its temperature related (not a sound when cold)... so may be does point more to blead down as the oil gets thinner or things expand?
.


Tell you what.. It was 24 deg the other day and it was quite noisey... just been out in it today at 14 deg and its much less?... Suppose that could point to two things... Oil temp lower (so would an oil cooler help)... although sat on my drive reving it would have increased the temp... but then the fan's kick in... so could this cool it down again??...

Or Air temp in the fuel / air on top of the piston... could 10 deg in out side air temp make the small ends expand / contract more..... It's certainly quieter today???

What ever it is it's very marginal if a 10 deg fluctuation makes a differance...

Edited by TVR Beaver on Monday 8th August 11:36

[TVR Beaver]

On a cold engine but high ambient... ???

ambient does make a big differance... and I've noticed how it's fueled in the past has changed it also (so guess that tie in a bit?)

So would going to 2mm hold it down further up the RPM band?... may be worth a try... are we just seeing ageing oil pump springs loosing their presure?

Wonder if Peter (haircutmike) actualy measured the small end / holes in the piston?... The pin to piston should be a tight press fit but this is where Rob says it comes from... How can something with a press fit become loose enough to rattle?... wonder how much they expand with temperature.... this area may be more prone to being affected by air / fueling temps??

[TVR Beaver]

v8 racing said:

Who is the expert that told you that?

Twas a guy in the pub who did some work for TVR at one point... not sure he worked on the Serp 500 but he obviously thought he knew his stuff

So if its pin to piston Rob... I'm assuming when you inspect them they look okay.. it just expands and get noisey at temperature? Why would this interface start to wear in the first place... Isn't the movement done on the small end to pin?

[TVR Beaver]

I wonder if someone could get a good recording of the sound (I'm stuck in China now for 2 weeks).. see if we are all actualy talking about the same thing... and also see if this is the sound Rob has experianced in the past....
As I've said before, it sounds like two hard metals making the noise to me... not a alloy piston??

[TVR Beaver]

chris52 said:

As John has already mentioned mine does not make this noise, but this is an interesting thread so I will try throw some sugestions into the pot.
From what I have heard on Johns car this noise only apears on over-run. I would have thought that if there is any play in the small end or anywhere else you would here it at other times especially under load not just over-run.
So what is different on over-run? the only thing I can think of is that the throttle is closed causing a larger vacuum in the plenum chamber and less air(lower compression) in the cylinders. So the vacuum advance on the dissy is at full pelt due to the large vacuum in the plenum also the car will be fuelling to allow Idle there will be some air in the plenum aswell, could this be some kind of detonation/pinking happening in the cyliders that is giving this noise?

Chris

Chris makes a good point here about the vac advance working at this point... I've always thought mine was front of engine and could posably be the advance weights rattling around... I suppose if the vac advance is moveing it, this too could add to the reason behind the noise?.. Worth trying it without the vac pipe attached see if that has any affect?..

[TVR Beaver]

carsy said:

I cant see the vac advance having anything to do with it. I presume when the revs are dropping your foot is off the throttle and butterfly is closed. When closed distributor wont see any vacuum as the ever so slight vacuum hole is the wrong side of the butterfly to see vacuum.

indeed... lack of sleep etc

[TVR Beaver]

Mmmm... I didn't think the serps had a retaining plate fitted?... and TBH that was one of my thoughts... if one should be fitted to help??

[TVR Beaver]

Cam walk?.. as suggested before.... I don't think mine has a plate anyway?..... noticed the other day on mine that if you hold it exactly at 1200 rpm, it does it a bit at constant rev's??.. May be it is piston related.. but the crank is off-set another few mm over 4.6 cranks.. so what increase in angular rotation does that give on the piston pin?.. very small I would have thought.. so why typicaly is it only 500's... shorter piston skirt giving a bit more piston slap?...

I'll try get a recording of mine over the next few days and post on U-tube....

Anyone any more thoughts / updates / comments on this at all?..

[TVR Beaver]

So if we did assume it was small end related.. where does the noise come from... I don't think that kind of noise could come from pin to bore slap (unless it was like a pr*ck in a buckett type fit).. people have inspected the small ends and reported them to be okay and tight.. re-fit them and the noise is still there.. .Okay, as the piston get's hot the hole will open up more than the steel pin expands so will increase the clearance... but I'm told when cold and inspected they are quite tight?.. you must have some clearance fit here or they would bind up.. so how much tighter than a good push fit can they be when new?...
Or are we talking about the noise coming from side float?.. the con-rod hitting the inside of the piston.. or the pin hitting the piston retaining clips?.. if its side movement then I don't see its much of an issue???

Edited by TVR Beaver on Friday 2nd September 21:18

[TVR Beaver]

5.0ltr said:

He has changed rattly ones before and they still can rattle after.

Hi Bob... How many miles on your car when it started?? and would you not think putting a new one on would solve it.. or at least change the noise?... chain has been suggested before.. not saying its wrong.. but don't think anyone has solved the problem by changing the chain or even cam?...
One thing is for sure... about 75% of the 500's and some 4.6 do it!!!

[TVR Beaver]

spend said:

You could always replace the chain set up with a gear drive and see if the rattle goes away.

if you can still hear it under the whine

straight cut obviously!...