ZX diesel,Hydraulic tappets???

terryinfrance · Unread post by **terryinfrance** » 01 Oct 2003, 17:29

What can I say but many,many thanks guys for all your advice.
It looks as though it will be head off time a.s.ap for further investigation.
Anders-many thanks for your advice,yes,the head will have to come off and further inspection needed.Will follow your reccomendations.
Dave-yes I agree with you entirely,very unusual to see probs with inlets,exhaust valves are the ones that get all the heat etc.Hard to believe that the inlet clearances have diminished,but that is what they are.I will take your advice and check for lip/ridge at bore top .
Jeremy-sound advice,head off and poss re-shim,new belt and see how it goes.Probably the only thing to do.
Terry

jeremy · Unread post by **jeremy** » 01 Oct 2003, 23:31

Terry - I was suggesting re-shim without removing the head. Cam comes off leaving head there.
There has been some postings from people who have had cambelts go on these engines. What happens is that the pistons hit the valves and the camshaft breaks, sometimes damaging the camshaft bearing caps. The camshaft is easy enough to replace but the bearing caps are not, as they are line bored in the head. I just wonder if something like this has happened to your engine and the explanation for the inlet valve clearance is the substitution of a camshaft without re-shimming?
jeremy

Dave Burns · Unread post by **Dave Burns** » 01 Oct 2003, 23:57

You know what I think has happened here Terry.
I you are calling the cambelt end no.1 cylinder (its refered to as no.4 normally), then if you look at the figures for the clearances there is a definate tapering effect, and I think the camshaft bearing journals have worn their way into the corresponding cylinder head bearing bores from the cambelt end and because of the action of the belt allways pulling on the shaft, and the reported noise is actually the camshaft rattling about in its bearings, I'd put money on it if I were a gambling type.
So Anders is probably correct in that the head is totally goosed.
Dave
Not so cotton pickin fast Burnzie, what about the unchanged exhaust valve clearances, think before yee type lest yee loose thy money[:D][:I][:o)]

terryinfrance · Unread post by **terryinfrance** » 02 Oct 2003, 00:49

Jeremy,yep you may have a point,certainly worth extracting cam first I guess,will consider that.Guess I am going to have to translate shims into French,that could be fun.
Dave,Could well be the cam rattling around as you say,the sound is very significant around rocker cover area which makes me think along those lines.
Had me somewhat puzzled though cos everything looked in good order lobes.etc.

Jonesy · Unread post by **Jonesy** » 02 Oct 2003, 02:47

I agree with Dave about it being camshaft bearings, though strange about the exhaust valve clearances. Could it possibly have suffered a minor seizure at some stage i.e. run low on oil?. Does the motor burn oil?
If it had a partial/minor seizure this would do more damage to camshaft bearing surfaces in the ally head than to the camshaft lobes in my experience.
How much are the compressions down on the two cylinders. Does it start more or less instantly from cold (after glow plugs)? If the compression on the two cylinders in particular is well down, it would not start that well and would probably run rough for a while.
Definitely needs head removal to investigate.

AndersDK · Unread post by **AndersDK** » 02 Oct 2003, 03:37

I would not take DaveBurns suggestion for sure [:)]
As Dave mentions :
"Not so cotton pickin fast Burnzie, what about the unchanged exhaust valve clearances, think before yee type lest yee loose thy money"
The unchanged exhaust clearances does'nt fit the theory - and since the exhaust valves are under the largest strain - and have the smallest head dia - these would be logic candidates for any REDUCED clearances.
BUT : IF on the other hand - Dave's theori applies - would'nt then the cam oil seal (belt end) start leaking heavily ?
Large slack causing the missing inlet valve's clearances - should then clearly feel by hand on the cam belt sprocket (cover removed).
To my experience - either a crank or cam would snap - if any large slack in the bearing journals. The axle simply starts vibrating - and then at resonance (most flexing) - it snaps.
Could the bearing (in head) journals be worn - and then the caps have been grinded down as "economy" repair last done ?
- and then carbon build up on exhaust valves explains these clearances ?
- and the carbon build up caused by the never properly closing inlet valves ?
Would be interesting to read Terry's conclusions - when head off [:p]

terryinfrance · Unread post by **terryinfrance** » 03 Oct 2003, 00:40

Well Guys,Watch this space.
This afternoon have made a start on head removal,rain stopped play .
Could use a tip.There seems to be conflicting methods posted regarding whether its best to remove cam pulley keeping cam belt attached,secured with cable straps presumably?or to leave pulley attached and remove belt.
Either way will I need to de-tension the belt tensioner?
Easiest method recommendations please.
If I go this route will I be able to bolt back under tension from belt tensioner.
Have taken engine to T.D.C and pegged injector pump with bolt through to hole on block.
Car is an Auto so does usual apply re. bolt/hole behind starter to lock crank at T.D.C.
Cheers.

AndersDK · Unread post by **AndersDK** » 03 Oct 2003, 03:12

Terry -
No doubt the belt has to come off - even considered the hassle of access to the belt - I'm sure this is the easiest option.
If you want a tip on how to avoid the hassle indexing engine & pump axles when refitting the belt - even allowing you to turn any axle during work - look here :
http://citroenz.com/forum/viewtopic.php?t=46
Otherwise the usual applies to locking the axles.

Dave Burns · Unread post by **Dave Burns** » 03 Oct 2003, 04:15

Terry, if the plastic timing covers are the early clip on type then the camshaft pulley has to be removed before you can take the head off, because of the sheet metal front plate that forms the rear of the timing cover, later screw on type plastic cover does not have the front plate so the camshaft pulley can stay on if you like.
You deffinately have to take the tension off to get the belt off, but worse is the fact that the offside engine mounting which houses the tensioner spring and plunger needs to be taken off, it has four bolts going through it, the lower three go into the block and the top one goes into the head, this top one near the cam pulley also has a hollow dowel in it secured to the head which is the reason the mounting is best removed alltogether and IIRC early ones have to be removed again because of the front plate.
Later types with a screw on plastic timing cover may allow removal of the head with the engine mount still attached but not sure and in any case doubt it would save anything.
The tensioner spring is quite lively so watch out for it.
Tension is relieved on the belt by loosening the roller bracket bolts (2) then using a 10mm or 3/8 square drive in the square hole in the bracket, levering the bracket so as to compress the spring, nip up the bolt to hold it there then take the belt off.
You either have to prevent the spring from getting out while the mounting is moved (very difficult) or let it come out and drill and tap into its bore so it can be reinserted off the engine and held in place by a temporary retaining screw against the plunger, which is removed when its all back in position.
Don't worry about loosing the timing position it is easey to retime.
Dave

terryinfrance · Unread post by **terryinfrance** » 04 Oct 2003, 19:10

COULD IT BE???
The head is off.All bores are clean with original honing still visible.
NEGLIGIBLE ridge at bore top.
All valves clean with reasonable seats.
On turning cam with spanner with head off cam there seemed to be a distinct rattle coming from Vacuum pump.Pump removed ,turn again ,silent!!!
Could this be the cause of my probs,has anyone experienced a noisy Vac pump.
This rides off the end of the cam as you all know.Any noise created will use the cam as a medium to amplify.
Is this theory sound/viable.
Comments please

AndersDK · Unread post by **AndersDK** » 04 Oct 2003, 22:35

OF COURSE !
Any periphals driven off the cam/crank may be suspected - and these will no doubt by time develop wear/noise - like anything else mechanical.

terryinfrance · Unread post by **terryinfrance** » 04 Oct 2003, 22:40

Cheers Anders,thanks for all you advice all the same.Im not 100per cent sure at this stage but its looking highly suspect.
Still the issue of the tight inlet valve clearances which may not be helping ,will get them attended to soon and hopefully deliver the final verdict!!