Top end rattle

[briannairnshire]

This is my first posting as I have usually found answers to any problems already on the Forum.

Like many others I have a tappety rattle when engine is cold which lessens when engine is warm. Vehicle has covered approximately 36K miles from new. Oil pressure good and timing chains recently changed.
When purchased two years ago at 32K miles engine had this noise which I thought was poor shim adjustment. Although re-shimmed the problem remains and is getting worse.

Heads removed without any difficulties encountered. Bores unmarked. Compressions vary from one at 130lb and rest between 145 and 165lb. Valves to be lapped in.

Telephone diagnosis that loose valve guide likely culprit seemed good but unfortunately not the case.

Only thing I have noticed out of what I think is normal is marking from bucket seat on No2 cylinder exhaust in two places in cylinder head and all other buckets have scraped head in one place. Buckets have slight wear markings around middle of them only and no noticeable wobble.Other head has no scuff marks from buckets in head.

Is this likely to cause the noise I am getting or should I look for other causes. Valve guides OK, valve stems straight, springs not broken but I think some of them may have been installed upside down on this cylinder bank.

Help. don't know what else to try and living in the North of Scotland have no direct access to expertise.

Views from club members would be most welcome.

Cheers

Brian

[mrwriggs]

similar tapping noise for me was a valve guide fitted by a "twat" krytens words not mine but very true, fitted it upside down,,
I now have a hole that a hamster could get through,,consequently my heads are at the machine shop recieving £400+ work being done...ouch..one head is just getting a £40 skim...the other ...well you do the maths...
Have you checked the wear on te cam shaft ?

[Staggard]

Someone sometime was wrighting on the forum about this clicking around No6 being something to do with the bucket and a casting on the head ( or did I dream this ) Com'on guy's help an old fella's memory out here OH welcome to the forum by the way Brian

[Arbman Al]

There was this thread a while ago:

http://www.stag.org.uk/forum/showthread.php?5126-Cam-bucket-wear

and this one:

http://www.stag.org.uk/forum/showthread.php?12952-Clicking-tapping-from-left-bank-on-start-up&highlight=bucket

[davidhelencole]

Ouch....!

Sympathy by the gallon.............

Dave

[flying farmer]

If you are finding scuff marks on the one head and not on the other, I think you have found the problem. Certainly fitting the valve springs upside down will not help as the close wound end is very heavy. I would check the cam for tightness or free play in its bearings when all the valves have been removed. It is not unusual to find the cam has been running very tight after the head has been skimmed to remove a warp. What tends to happen after a while is that the cam reams out the bearing caps due to the upward pressure of the valve springs, and so can turn freely again, but this can leave big gaps between the oil way in the head and the cam bearing. This means the flow of oil will be reduced where the cam is tight, and this may have an adverse effect on the lubrication of the cam buckets, particularly the ones at the front of the engine. As the timing chain pulls the cam onto the bottom bearing at the front of the engine, there will be very little oil flow here, particularly if there is large clearance on the back bearings, and the fact that the engine slopes quite steeply to the back does not help either
I have not seen any figures for the cam bearing clearance, but on good ones a 1 1/2 thou feeler gauge is tight, but I have found clearances of up to 8 thou on odd bearings due to warping. Line boring is the professional way to fix it, but I have always used 600grit wet and dry on an appropriate sized socket to lower the high bearings in the head, then lapped the bottom of the bearing cap to get down to 1 1/2 to 2 thou clearance on each bearing. Cheap, and takes about the same time as the drive to the machine shop!
Neil

[briannairnshire]

Thanks for the replies received gents. First thought received mentioned checking the cam shaft and my immediate thought was that profiles seem good and sides of cams are straight and not rounded but on receiving the flying farmers reply the earlier comment may be well grounded.
I will replace the cam shaft in the head tomorrow without valves, springs etc and see what I find. The heads were apparently skimmed ten years ago after overheating - invoice shows towing recovery cost from M25 following break down. The car has only covered around 10K miles since this incident and this may well be the wear pattern following overheating and head warp. Clever chap this flying farmer - should have been a detective!
I will post my findings when check is completed
Briannairnshire

[briannairnshire]

Well, refitted cam shaft and to my surprise as I thought previous thread re mis-alignment of bearings was going to turn up trumps found that all journals show no measurable wear. Removed bearing caps and attempted to measure clearance at either side of cam shaft and jourmals and found I could not insert my thinnest feeler guage (.002 thou).
Pleased to find that I do not have problem suggested but left confused as to where noise is comming from - is it all from buckets bottoming at lowest point of travel or something else. Compared heads and found RHS is definately not a mirror immage of LHS re bucket/ valve/ spring area - much larger clearances on RHS and I thik it impossible that scuffing could ever occur on RH bank.
Any other ideas anyone?
Brian

[Moraystag]

So I can only assume, Brian, that you did not get to the bottom of your rattle after all.

Mike

[elvimto]

When you check you cam to journal bearing clearance do it with the cam in and caps torqued up. Cheak your clearance on the top of the cap to camshaft i.e. 180 from where the valve to bucket clearance would be.The last bearing the # 5, will be the one with the biggest clearance thats the last one to get oil. Also mic the journals on the cam I found that the same journal had above normal wear so I replaced the cam shaft on that head.Clearance should be about .001 to .0015 thou. you can also check this with plastic gauge. The cam should turn freely if you can feel it bind thats a clue to a bent camshaft or the head is warped. While you are at it, mic the cam buckets and the bores where they fit, you can use snap gauges to do this, if you have to much clearance then the bucket could be slapping in the bore in the head.

hope that this helps.

cheers Stuart