Slight Worn Cam Shaft & Fuel Economy/efficiency

Hi Graeme,
Not being mechanically minded in LR land he was good at explaining to me what he was doing, however I'm guessing that the hydraulic lifters were not replaced as it wasn't specifically mentioned in the main lot of work that was done in phase 1 of my repairs - the reply below was from the mechanic...

"Head gaskets on a v8 engine consist of dismantling machining heads, cleaning of all components and mating surfaces and reassembly with new gaskets, bolts and seals. In doing the head gaskets the inlet manifold gasket, end seals and rocker cover gaskets are also replaced so would not require any further action on those gaskets. Also the spark plug leads can be very easily replaced at the same time at no extra labour cost. The water pump and coolant hoses are also another job that benefit from doing together as it also cuts on labour time".

From the list above, the top/bottom coolant hoses were not replaced but a new water pump went in (hoses/clamps were fine), seal on rear hub was replaced (since all ok), New serpentine belt, handbrake adjustment (from some oil leaks I need looking into still!) and exhaust flange gaskets (altho - I don't think they were replaced (but were paid for) based on a comment mentioned :( so something for me to follow up!)...

It's worth mentioning that when I do speak with the mechanic there always seems to be an emphasis on the cam shaft being worn and attributing to the problem/s and that it needs to be replaced (nothing shoved down my throat but the emphasis is there).... personally, i'm happy with how it drives and don't feel 100% about needing it to be replaced yet (new MAF/Clutch/Airfilter and soon oil/oil filter all have made a good difference)... perhaps though, if the hydraulic lifters needed doing and didn't, that may be where the emphasis is coming from by the mechanic????

I don't know what case hardening is nor the rate at which it would be wearing - time permitting... is this something that can be easily explained to me?

Cheers,
Lp

Quote:

Originally Posted by Graeme

Were the hydraulic lifters replaced when the headwork was done? Hopefully the mechanic replaced them at the same time even though the camshaft was not being changed but if not, they could be wearing through their case hardening quite quickly by now, wearing the camshaft at an increasing rate.

Hi Lp,

The lifters sit between the camshaft lobes and the valve gear that is located on top of the head. The camshaft wears because of the work done to lift the lifters which also wears the case-hardened steel on the face of the lifters. Normally lifters are replaced several times duing the life of a camshaft because when they wear, they cause the camshaft lobes to wear at a much faster rate. The lifters are cheap but require the valley cover/ inlet gasket to be removed as well as the valve gear on top of the head to access them. Hence if the valley cover is removed for any reason and the lifters haven't been replaced recently, the lifters are often replaced as at least a few are likely to have grooves from the camshaft lobes or at least have lost their slightly convex shape which keeps them spinning to prevent grooves wearing. Its a long time since I worked on a Rover V8 but years ago V8 Holden lifters were identical so were quite inexpensive compared with genuine ones.

HTH

https://www.aulro.com/afvb/images/im...012/03/660.jpg
https://www.aulro.com/afvb/images/im...012/03/661.jpg

The above is a 3.9L rover V8,, very similar to your's Lp,,
The lifters sit in the fat-round casting right at the bottom of the V
Case hardening is a very literal description,, you "case harden" your kids lunches
when you put them in a box,, in the pic below these lifters have worn through the exterior case hardening
and the softer inner material will quickly deteriorate.

https://www.aulro.com/afvb/images/im...012/03/662.jpg

The cam damage below was caused by worn lifters not rotating

https://www.aulro.com/afvb/images/im...012/03/663.jpg

This from RPi

"--these three tappets have only done 5,000 miles on the TVR engine they were fitted to. They tell a story from left to right, it's not looking good.

Comparing Cams: Top, at 35,000 miles and no sign of wear, the Morgan cam is still looking good.
Below, this cam did not take to its new tappets, so it was bad then, and worse now.
https://www.aulro.com/afvb/images/im...012/03/658.jpg https://www.aulro.com/afvb/images/im...012/03/659.jpg
The left hand tappet shows it is completely worn out and after only 5,000 miles it was the worst one on the engine. As expected, it corresponded to the camshaft lobe that was most worn (probably the one that was the cause of the tappet noise in the first instance).

The middle tappet is also quite dished and this was going to be the next one to become a major issue soon.

The right hand tappet shows the signs of wear (rounded indentation expanding from the centre) all other tappets on this engine at only 5,000 miles were showing signs of bad wear, and the three depicted above represent the extremes and average condition of what we found and what you could expect.

By coincidence, at the same time as working on this engine we started work on a Morgan +8 which was going through a stage 3 upgrade. Its engine had done only 35,000 miles and all the tappets were still in perfect order, indeed in better shape (all 16) than the best of the tappets depicted above.--"