Push rod wear/nipple

keanej

keanej

New Member
I took the cylinder heads off the car today and on checking the parts over noticed that two push rods had worn and developed a nipple, this is the worst one.

DSC01251.JPG


The tappet doesn't look too bad, has a matching hole in the centre of the cup and has been working against the rim of the hole around the nipple, but the main area of the cup for the push rod doesn't appear worn or distorted

On the basis that I only do 3 - 4000 miles per year I don't want to go over the top with new parts but at the same time I don't want to be doing this job again in 2 years.

So should I put 2 new push rods in and hope for the best or play safe and replace all the push rods and tappets ?, I sort of favour this 2nd option, as if two rods have started to go how long will the others last.

Advice from the experienced V8 engineers awaited.

Follow up question - if I replace the push rods should I then replace the rockers or keep them - they look OK
 
Normally you get that on the top of the pushrod where it fits into the rocker arm. The nipple then blocks the oilway and it all gets "tappy". Short term fix is to take the nipple off on the grindstone.( :? :oops: ), but you'll have worn through any hardening so it won't last. Fitting followers, "tappets" as you refer to them is a waste of time without changing the camshaft as well. This is the problem you get into when dismantling them in that the list seems to always get longer.

The answer you don't want to hear is that it probably needs cam & followers (and most likely cam bearings), pushrods, rockers and shafts and a timing chain and sprockets.
 
For starters, what is the total mileage on your engine? How often do you change the engine oil in months / miles? On replacing parts,...you can if you wish just replace the pushrods with no ill effects.

If you wish to replace the tappets, then it would be strongly advised that you replace the camshaft at the same time. You will almost certainly find that withdrawing the tappets up and out of their bores is not possible in all cases, and as such removing the camshaft first is the only way that you will be able to remove them. They will drop down and if not caught in time will work their way down to the sump, and if so it too will need removal in order to collect them.

You can replace the entire rocker assemblies if you wish and fit new pushrods, but leave the tappets in place.

Ron.
 
The car has done around 69k, it did have a cam shaft a few years back but that was around 56k - so not that many miles ago.

As for oil changes I do that once a year but with my mileage thats more than adequate - don't know about previous owners, but the inside of the engine and sump are reasonable which would suggest it has been looked after in the past, they certainly spent a fortune on the base unit - I have all the receipts to show what was done so I don't think they would have missed serices.

If this was my day car and doing 20k per year then I wouldn't think twice about replacing all the bits, but as a weekender I'm not sure.

I'm tempted to go for new push rods
 
keanej said:
I'm tempted to go for new push rods
Click to expand...

If it had a cam and followers 13k ago I'd be inclined to do the same, replacing any rockers that are worn would probably end up with all new rockers and shafts if they weren't done at the same time as the cam, if they were just change any dodgy ones.

As I said before, the trouble is the more you look the more you find, and as they're mostly "hobby" cars doing limited mileages it is difficult to justify some of the larger sums that can come along.

The days of "do what needs doing, I must have it for work on Monday" are long gone, more's the pity!
 
I'm in the middle of doing the same job on mine. New cam and lifters, timing chains and sprockets, waterpump, everything cleaned (I think I need pushrods as mine have flatspots on each end) I'm also overhauling the wiper system and heater while I'm at it. More cost!
But it should be so much nicer to use! And quieter too.
 
Ah. So mine might not be worn after all. I believe it had seconhand pushrods in before I bought it. Shame they didn't do the cam and lifters too!
 
as a rule of thumb engineering wise. suggesting we only replace one part that is in fact operating with another ..is very bad practise and every frowned on. one surface will be worn and another 'new'. .
like replaced one gear out of two that runs against each other. the 'new' gear will not improve the old one but rather very soon degrade form using the 'old' gear. if we replace BOTh we get correct wear/fit balance. irrelevant if just gears ..or we can sat we are changing. cam. followers and not the cam.. that path only leads to reduction in service life and potential early component failure(s) . if we. fit a new cam we ALWAYS fir new tappets ..hence same with pushrods. Odds are ,hardened thickness will have worn away and we risk early failure. hence Harvey etc. saying it's best to bite bullet and renew as much interacting parts as we can to avoid issues and extend performance and longevity. costly I know but long term is cheaper .
 
You must log in or register to reply here.
Back
Top