Rocker Steel Pads

[BeastMaster]

Just lost another steel pad on one of the aluminium rockers - started with the dreaded top end tick and on investiagation found near side bank last exhaust rocker at the back had lost its pad. Second time in 2 years had this problem, the first time offside bank last intake rocker at the back, also replaced a couple of others on this side showing hairline cracks, checked other bank which looked perfect.

Questions please - where would the pads go ? - should I drop the sump to look for it or will a simple filter change suffice ? - the pedestals have preload shims fitted but would this be a sympton of too much load ?

I know a solution would be all steel rockers, but this just seems wrong on a all aluminium engine, have an idea that I may replace the valve springs with the single type with the thought this may reduce loading on all of the valve train. The car is a 500 so not bothered about valve bounce at high rpm - no point in going over 5k.

Will from now on inspect on a yearly interval - but my main concern is what damage could done.

Many thanks

Andy

[Graham]

Might be worth having a chat with john Eales he was lamenting the poor quality of available rocker gear and may have a solution

G

[haircutmike]

It could easily have slid down the valley into the sump, hope you have a magnetic plug!

I have steel rockers so no problem there I hope!

I pprobably have a set of ally rockers complete, have you a replacement cheapy set fitted!

As for double springs, I spoke to a cam guru a while back and for use up to 6K, he advises the correct poundage single springs to reduce cam/follower wear.
He stated that the existing double springs are overkill!

[Gary11]

I need to check my clearances, what is the parts cost to change rockers and shafts retaining existing 2 spring set up? Any chance please of a picture of offending item?
Seems a weakness on 500 but am loath to change springs conversley dont want to need a new cam ...not cheap

[haircutmike]

You don't need to check clearances as you have hydraulic lifters, (unless you have been up((down?)) graded).

[PRTVR]

A few personal thoughts on this (I am no engineer and have never taken my engine apart) but just some random thoughts on the problem.

What amount of carbon would need to build up on the valve seat to produce the clicking sound we all dread,that leads to the pads coming off. ?

The wear could be located in the lifter part, oil instead of fully pressuring up and taking up the slack is passing by due to wear, a heavier oil might help.

[Gary11]

haircutmike said:

You don't need to check clearances as you have hydraulic lifters, (unless you have been up((down?)) graded).

As I understand you do there has to be some gap on the 500 the rocker posts too have shims.the springs are so (too some say) heavy its not just a matter of swopping cam and followers as per most cars with hydraulic lifters.
http://www.pistonheads.com/xforums/topic.asp?h=0&a...

Edited by Gary11 on Saturday 15th September 18:28

and here scroll down to setting tappet preloads http://www.v8engines.com/engine-4.htm

Edited by Gary11 on Saturday 15th September 18:36

[haircutmike]

Ah, see what you mean!

When the crances are set during a cam change, a measurment is made under the lifter spring, (approx 40-60 thou).

This doesn't equate to a valve clearance that you can measure at the rocker as the play is in the lifter.

Adjustments are made by taking an average and shimming the posts.

Needless to say, I haven't read your links as I am juggling a few things at home!

[BeastMaster]

Thanks for the advise / info. After replacing the offending rocker, am back to a very strong and quiet motor, so have decided to leave it alone, as to check pre load or change the valve springs will mean delving deeper into the motor and do not want to disturb anything.

For info - got the rocker ( not original part ) from a 4x4 specialist who keeps stock as it's a common problem on LR Discovery's

The symptom was a little strange - as the tick only started when oil and water came up to normal temp, and was only prolific when at idle, which was different the last time I had this problem, so was quite relieved a easy fix.

Going to add rocker pad inspection to my yearly service schedule and replace any which look suspect / cracks / or not happy with and hopefully pre-empt them becoming missing. Also looking into one of those large magnetic wraps which go around the oil filter for a little more feel good factor.

Will go to single springs / double check pre load etc as a ''while I'm there'' scenario.

Thanks again

Andy

[Gary11]

BeastMaster said:

Thanks for the advise / info. After replacing the offending rocker, am back to a very strong and quiet motor, so have decided to leave it alone, as to check pre load or change the valve springs will mean delving deeper into the motor and do not want to disturb anything.

For info - got the rocker ( not original part ) from a 4x4 specialist who keeps stock as it's a common problem on LR Discovery's

The symptom was a little strange - as the tick only started when oil and water came up to normal temp, and was only prolific when at idle, which was different the last time I had this problem, so was quite relieved a easy fix.

Going to add rocker pad inspection to my yearly service schedule and replace any which look suspect / cracks / or not happy with and hopefully pre-empt them becoming missing. Also looking into one of those large magnetic wraps which go around the oil filter for a little more feel good factor.

Will go to single springs / double check pre load etc as a ''while I'm there'' scenario.

Thanks again

Andy

andy did you take any pictures?

[BeastMaster]

Gary11 said:

andy did you take any pictures?

Sorry Gary I did not - it is not really a very interesting or technical part, its just a alloy rocker which has a hardened steel pad pressed into the end that operates the valve. This pad acts directly on the top of the valve stem to open a valve, but as it does so because it is an arc the pad slides across the top of the stem as it is pushing down this leaves a wear mark along the pad face.

Having inspected the rocker face, the steel pad has gone, but a portion which is pressed into the rocker is still in the recess and can see a small wear mark on the surface. This indicates to me that the pad does not drop off, but breaks up with the sliding action across it. Given time I would suspect that the valve stem would chew through what is left of the pad quite quickly as the part thats left would not be hardened. Once all steel has gone the stem would drill into the alloy to the max movement.

If you would like a pic of the offending item I will email but you should see pics of new ones on the internet or will post the thing to you if you have an interest, as I am going to try and get a better understanding of whats going on feed back is important.

Andy

[Gary11]

Thanks Andy,will get the rocker covers off I want to check as above silly not too,will let you know thanks again for reply!The 500 is definately different to the smaller engine cars but then again they are a lot more powerful there is always a price to pay.
Gary

[BeastMaster]

Gary11 said:

Thanks Andy,will get the rocker covers off I want to check as above silly not too,will let you know thanks again for reply!The 500 is definately different to the smaller engine cars but then again they are a lot more powerful there is always a price to pay.
Gary

Hi Gary

For info - if you want to eyeball the pad surface, you will need to remove the whole rocker assembly from the heads, not a difficult task but just allow yourself enough time. It will only be possible to see if the pads are in place without removal, and then a small mirror will be required to see the ones under the bulkhead at the rear.

If any of the rockers need replacing note that they are handed and need to be placed in the correct orintation on the shaft so the oilways line up, it is also handy to put the shaft in the freezer for a couple of hours so the rockers are easy to slide up the shaft.

When re fitting the assembly back on the heads note the oilways on the pedestals, if you have shims fitted be sure to keep them in order and make sure the shims do not cover the oilway in the head, mine only had one hole and could be fitted the wrong way so the oilway could be blocked.

Out of interest do you suspect the same problem.

Good luck

Andy

[Gary11]

[quote=BeastMaster]

Hi Gary

For info - if you want to eyeball the pad surface, you will need to remove the whole rocker assembly from the heads, not a difficult task but just allow yourself enough time. It will only be possible to see if the pads are in place without removal, and then a small mirror will be required to see the ones under the bulkhead at the rear.

If any of the rockers need replacing note that they are handed and need to be placed in the correct orintation on the shaft so the oilways line up, it is also handy to put the shaft in the freezer for a couple of hours so the rockers are easy to slide up the shaft.

When re fitting the assembly back on the heads note the oilways on the pedestals, if you have shims fitted be sure to keep them in order and make sure the shims do not cover the oilway in the head, mine only had one hole and could be fitted the wrong way so the oilway could be blocked.

Out of interest do you suspect the same problem.

Good luck

Andy

Hi Andy,
Its probably me however I just sold a 400 which was smooth and sweet (though had new engine) the 500 seems all it should ive has a couple of griffs so am familiar but sounds a bit "loose" across the top it is low mileage and is much improved since oil and filter last (lady) owner did short journeys only serviced once in 2years!!so oil was quite thin,the oil pressure was almost on the rest at idle when hot but changed sender and now is improved,im just mindful of the cam issues on the 500 and would rather change rockers and shafts whilst checking preload clearances than have a cam later on,thinking about changing oil pump too tbh.Thanks Andy for your help.Will let you know!