Whats wrong with this picture?
Discussion
A couple of years ago, after a quite serious run round the local lanes, I had an almighty rattling sound from the engine. Stopped car and checked engine bay but nothing was out of place, and when I restarted the car the rattling had gone, so I thought no more of it.
Then a few months ago a ticking noise started up, I took the car to TVR Power for them to have a listen and the chap said the cam-shaft needs replacing. So this winter the cars been up on stands while I get round to changing the cam shaft and a few other winter jobs. Well, today I took the rocker shafts off and found this!!
The top of the valve is fine, so no major damage. I just can't believe the lifter can make up for that kind of gap, makes a mockery of setting the pre-load. I just hope the pad isn't floating around the engine somewhere, lurking, waiting to trash my engine!
On the plus side it looks like the cam-shaft doesn't need replacing, on the minus side I have already got the kit and the engine is in bits waiting for it. Or it would be if I could get the crank-shaft pulley bolt off!
It's not uncommon apparently for the rockers to lose a pad. When they do, the real problem is where it can end up. Can you drop the sump and see if its in there?
On the postive side the rockers shaft assemblies look pretty clean so the engine has almost certainly had regular oil changes or is very low mileage.
Depending on the mileage, you could do the cam anyway or stick it on E-bay if you decide not to go ahead.
Might be wort taking one of the rockers off the shaft (dead easy and just xhecking to see if there is any wear on the shaft itself. The oilways tend to block up and the shaft wears quite quickly. Any debris from this ends up in the cranshaft shells!
On the postive side the rockers shaft assemblies look pretty clean so the engine has almost certainly had regular oil changes or is very low mileage.
Depending on the mileage, you could do the cam anyway or stick it on E-bay if you decide not to go ahead.
Might be wort taking one of the rockers off the shaft (dead easy and just xhecking to see if there is any wear on the shaft itself. The oilways tend to block up and the shaft wears quite quickly. Any debris from this ends up in the cranshaft shells!
jonnyb said:
The top of the valve is fine, so no major damage. I just can't believe the lifter can make up for that kind of gap, makes a mockery of setting the pre-load. I just hope the pad isn't floating around the engine somewhere, lurking, waiting to trash my engine!
As has been said its a common malady for RV8s. As far as the preload is concerned the reason for getting this accurately set (about 0.5mm) up isnt really about quiet operation or basic function but to get the best high rev performance out of the lifters. Factory settings often tend to be over generous with as much as 2mm of preload (hence the fact that sometimes quite a bit of slack can be taken up before any noise starts). The problem with excessive preload is that it gives the lifters more propensity to pump up at high revs / high oil pressure and act as a premature rev limiter which is a pain if you are looking for high rev performance. In most normal situations the preload settings are of little importance.
I think its unlikley that the stray pad is going to cause problems, if its not visble around the valve springs then its either in that pool of oil above one of the end head bolts next to the drain channel or in the bottom of the sump. The oil strainer will prevent it from being picked up by the oil system and trashing the pump. Whether its worth the hassle of dropping the sump just to retreive it is a personal choice, maybe fit a magnetic sump plug which will probably catch it at some point.
I am rebuilding my engine at the moment with lots of performance mods including going to steel rockers for strength and reliability and experimenting with tuftrided rocker shafts to see if i can overcome the wear problems (although these are mainly associated with the soft alloy rockers picking up and becoming embedded with abrasive particles of steel which then wear the shafts). If there is any wear on the shafts there will be ovality of the rocker bores too and the whole lot will need replacing.
I am also using crane adjustable pushrods so i can set preload accurately and to allow for the fact that I have had the rocker pedestals shortened so that the rocker geometry will remain correct with the 12.5mm lift Stealth cam.
jonnyb said:
A couple of years ago, after a quite serious run round the local lanes, I had an almighty rattling sound from the engine. Stopped car and checked engine bay but nothing was out of place, and when I restarted the car the rattling had gone, so I thought no more of it.
Then a few months ago a ticking noise started up, I took the car to TVR Power for them to have a listen and the chap said the cam-shaft needs replacing. So this winter the cars been up on stands while I get round to changing the cam shaft and a few other winter jobs. Well, today I took the rocker shafts off and found this!!
The top of the valve is fine, so no major damage. I just can't believe the lifter can make up for that kind of gap, makes a mockery of setting the pre-load. I just hope the pad isn't floating around the engine somewhere, lurking, waiting to trash my engine!
On the plus side it looks like the cam-shaft doesn't need replacing, on the minus side I have already got the kit and the engine is in bits waiting for it. Or it would be if I could get the crank-shaft pulley bolt off!
whoops we got that one wrong i do apoligise,has for the hardened pads this was a major issue landrover had in 1996/7 interference shrink fit to aluminium Rockers where incorrect hence the reason steel pads randomly dropped out,Pre load has nothing to do with Pad failure,you will find steel pads sitting in the corner of your cylinder heads
Regards
Dom
Edited by Tvr Power on Tuesday 20th March 22:29
Thanks for the info guys!
I am going to replace both the shafts, if the problem has been sorted with the ally rockers then I might as well use these as it keeps the weight of the valve train down.
I am going to have a dig around to see if I can find the pad. The lifters are in quite good shape and I am quite pleased with the state of the engine (valve train anyway) for saying is a 10 year old car with 60000 on the clock. Its been well looked after, and the oil changed regularly.
As I have got this far the cams going to get changed anyway, with new lifters, rods, rocker-shafts, timing chain ect...
Then a Tornado chip or other similar to try and get the best out of it while I save up for a new ECU!
I am going to replace both the shafts, if the problem has been sorted with the ally rockers then I might as well use these as it keeps the weight of the valve train down.
I am going to have a dig around to see if I can find the pad. The lifters are in quite good shape and I am quite pleased with the state of the engine (valve train anyway) for saying is a 10 year old car with 60000 on the clock. Its been well looked after, and the oil changed regularly.
As I have got this far the cams going to get changed anyway, with new lifters, rods, rocker-shafts, timing chain ect...
Then a Tornado chip or other similar to try and get the best out of it while I save up for a new ECU!
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