Valve Grind & De-coke on 6.9

[s class]

Camshafts and camshaft bearings are still in good condition after some 370k. kilometers, and there is no discernable lip in the cylinder bores.

That is certainly encouraging to hear. I have heard similar stories about lack of bore wear from other sources. I am hoping my luck holds out in this respect with trusty rusty.

 

[Styria]

Hi S-Class, whilst it is encouraging that there is no discernable lip in the bores, it may not be the "be all and end all" as far as engine condition is concerned. A fellow 6.9 owner in Sydney has a spare engine with no wear in the bores, yet the rings were totally unserviceable.

We priced a set of rings the other day - close enough to $A2000.00 - "get that up you Charlie" - at least, that's how I feel one would be addressed when ascertaining some prices, including the 6.9 rings from Mercedes Benz- and that is not the OZ price I might add.

Whilst I do not expect anyone to rush me, we have worked out a way of overcoming the price slug by Daimler Benz. So, anyone that wants to fit new rings to a standard size bore, Styria should be able to supply the goods. However, you will need to have the Benz pistons machined. Anyway, this is just toying with ideas and finding ways of overcoming MB spare parts prices. Regards Styria

 

[BenzBoy]

Stop complaining Stryia.
Try $30,000 for a Phantom head.
Regards,
BenzBoy

 

[abl567]

Ah, that's why I didn't get it before - here in South Africa they are 10"

Priceless !!!

 

[WGB]

Without wishing to be a Glass of cold water at a pissup what are your bearings like.

I know with Porsche experience that if a watercooled Porsche mixes water and oil you are expected to change the big-end bearings.

They make no mention of the mains because it is a much bigger job and in a 6.9 it would really need engine removal for both mains and bigends so it is not really likely to happen.

It is a reason to get the car fixed at the first sign of water in the oil.

Bill

 

[John S]

A much bigger job on a 6.9 than I realised - and I am staggered at the time you needed to get each head off, a big difference!. If you need another pair of hands to help speed up the job give me a call.

 

[s class]

Hi S-Class, whilst it is encouraging that there is no discernable lip in the bores, it may not be the "be all and end all" as far as engine condition is concerned. A fellow 6.9 owner in Sydney has a spare engine with no wear in the bores, yet the rings were totally unserviceable.

Rings may be very expensive, but ring wear is still preferable to bore wear in my books. This may indeed be trusty rusty's case. I have not had the heads off to see the tops of the bores, but from the bottom (sump off) it all looks very good. Compression is weak and uneven across cylinders though. Wet compression tests suggest that valves are main culprits for the weak compression.

 

[Styria]

WGB - I know where you're coming from as far as engine damage is concerned when relating to the quality of the oil, or lack thereof. I guess I am the perpetual optimist who looks at things on the bright side and hopes for the best by trusting his judgement.

As some of you may know, the oil pressure gauge on 'Gleaming Beauty' has been inoperative from the time I purchased her thirteen years ago this coming August. Once or twice I have had the opportunity to fit another oil line, but it always seemed to be the last job, and by that time I seemed to have enough and just wanted to finish the job - removal of the dash comes to mind. One could also say that maybe, just maybe, I did not really want to know about a working gauge - it may have been too much of a shock.

Anyway, this time I am going to bite the bullet and get the gauge working. Keep fingers crossed. Regards Styria

 

[Styria]

Hi S-Class, I was under the impression that 'trusty rusty' was the star performer in your fleet, although I seem to recall that your red AMG model has been really transformed since you sorted out the valve timing. It seems at odds that you should experience such uneven running characteristics.

The strange part with 'Gleaming Beauty' is the fact that performance wise one would have thought that there were absolutely no problems. The puff-puff on No. 6 seemed to virtually disappear as soon as the revs built up, and even economy wasn't all that bad. It will indeed be interesting to see what improvements, if any (!) will be evident once this job is completed.

I have also previously mentioned that the timing chain had been changed some three years ago and referred to the fact that there seemed to be no difference performance wise, and this had been a small source of disappointment at the time. When dismantling the top end, we looked in vain for a connecting link to split the chain so I wonder...(?) I had also asked that valve stem seals should be changed but this mechanic was of the opinion that they did not need doing..if anyone in Sydney would like to know who I am referring to, I would be pleased to give him a reference.....

Hi JohnS - thanks heaps for the offer. Look, most of the onerous and dirt tasks have been completed. Presently, the heads are being set up with the correct adjustment shims for the valve lash compensating elements on a spare 6.9 engine block and I am waiting for a new, good quality timing chain plus some other parts. Regards Styria

 

[s class]

Hi styria,

you are correct that my red AMG has improved a lot with the new timing chain. Trusty rusty has always had a very different character though, and subjectively performed better than the AMG, though the gap may have been closed since the AMG's new chain. (I haven't driven trusty rusty in some 4 months so comparisons are difficult). Anyway, the point is that trusty rusty has always pulled solidly, seemingly at odds with the compression results. Trusty rusty idles pretty well all things considered, but there is some exhaust smoke under acceleration, which to me means rings/bore issues - though the compression tests suggest valves are the biggest issues.

OK I have some ignorant questions for you :

1) you talk of another Sydney engine having good bores, but unserviceable rings - what about them makes them unserviceable - wear? loss of temper?

2) you talk of setting up your new heads with shims to correct the valve lash - I'm unfamiliar with this - what is involved, and what is the goal?

Thanks for all your insights in this most interesting thread.

 

[Styria]

Stop complaining Stryia.
Try $30,000 for a Phantom head.
Regards,
BenzBoy

Hi BenzBoy, I am not complaining . Well no, I am as there is no real rhyme nor reason at times for the prices that MB charge for parts on older cars, see 6.9's. Remember, we are not comparing apples with apples, i.e. Phantom v. 6.9. Look at the values between the two cars, also bear in mind I am just quoting for rings - never mind pistons, heads etc. etc.

It was just yesterday that I received delivery of the gasket that fits between the top flange of the water pump and the thermostat housing. Guess how much?...for just an ordinary gasket..absolutely nothing special..$A40.00 ! I just couldn't take it...at that price, I just had to send it back. I made the mistake of not checking the price before I ordered as I figured..well, if it's $4.00 don't worry. It was just as well that I checked the price of the exhaust manifold nuts - sixteen of them, at $A4.00 each ! Needless to say, I did not buy them.

So BenzBoy, sometimes it's hard not to complain - really, all I ever want and expect is a "fair go", whether that be parts or, indeed,value and quality for work done. Regards Styria

 

[Styria]

Hi S-Class, Mercedes recommend that the static setting of the hydraulic lifters (valve lash compensating elements) be checked at 40K. intervals and that if the clearances do not fall between the limits applicable, different size shims are to be used.

If that is insufficient information for you, I will endeavour to scan some further details for you.

Incidentally, I have further news that I can convey, although at this stage:

1) I am ubable to supply pics as the battery of the camera had gone "kabunk", and

2) Photobucket did not allow me to choose a file for illustration purposes.

I have since re-logged and , at least, the last named problem has been rectified.

Anyway, you may recall the 'puff-puff' from the exhaust which primarily seemed to be prevalent only when idling - well, I have looked at the underside of the inlet manifold and the fuel chamber, and there are very obvious signs of petrol (brown and moist) leakage from the seal that connects the two halves. Picture to come.

Furthermore, I can also tell you that valve recession should never be a problem on 450's and 6.9's - there is ample automatic compensation provided by the hydraulic lifters. So, maybe the problem you have with your red AMG 6.9 could well be in the same area as I have referred to. Regards Styria

 

[s class]

Thanks styria,

I have read up on checking and replacing the shims in the 6.9 engine manual. It makes sense to me now. One wonders though, most likey most cars would never have had this done. How far out are things likely to be - in other words is this something us 6.9 owners should be concerned about, like replacing the chain to get the valve timing correct?

 

[Styria]

This is the picture illustrating the discolourization process that is obviously evident on No. 6 cylinder.



..and this is a refurbished component to take its place....





..

and after removal of Water Pump and the Water Pump Housing, a bit of cleaning would not go astray...



Regards Styria - Oh BTW. I personally have my doubts if too many 6.9's have had the static setting of the lifters ever checked or adjusted - in comparison with the later model 116 (380 & 420) and 117 (560), 6.9's sound distinctly agricultural and even a low mileage 97k. version hardly sounded any different to the 375k. engine in Gleaming Beauty.

 

[s class]

Very nice looking parts. How close are you to refitting the new heads?

 

[Styria]

Hi S-Class, present intentions are to commence the re-fitting of both heads either Thursday, Friday and/or Saturday/Sunday, depending on various commitments.

Presently, I have started to paint the Engine Bay in Petrol 877Met - Gleaming Beauty was on her second colour change some seven years ago, but the engine bay had remained the original Taxi (Elfenbein) White. I am using 2-pack applied by brush and I can't get a good finish. Some pics. to follow. I am hoping that spraying clear will improve matters to some extent.

It's not often that one gains fairly good access to certain parts of the Engine Bay with heads and Intake Manifolds removed, and I keep looking longingly at the Steering Box which was re-sealed some two years ago but has a slight oil leak. Same goes for the Power Steering pump, but it has never been touched - not during my time anyway - the problem is that I have no reconditioned or rebuilt units on hand at the moment. Still, that box is so inviting - it would be child's play to remove it now - comparatively so, at least.

Another item that begs to be replaced is the Water Pump - that I reconditioned probably nine years ago, and whilst it seems fine and is not leaking, now would be the time to replace it. Well, I'll just have to play it by ear. Regards Styria

 

[Styria]

For anyone that's interested - it is best to start a new thread for ease of reading and understanding the scope of the job on hand. Needless to say, the beautifying process continues. Regards Styria

 

[Ron B.]

Heres a hint for those who intend to pull the heads on the 6.9. Use a engine lifter .
It's better than ruining your back and/or dropping a head on a customers mudguard. I even lift them back in with the hoist.
I see a couple of questions regarding lesser engines such as Phantoms and Porsches,I have had to do a few 6.9 head gaskets and I figured out long ago what caused them to fail. The water in the Oil isn't a problem unless the engine has done more than 500,000. So don't worry about bearing wear,it aint gonna happen. When the oil pressure drops below 1 bar at driving speed ,then it's time for a bearing job.
In fact I just did a 6.9 here which has 300,000 + on it and hadn't had it's oil changed since 1998!. The engine is smooth quiet,and idles and runs beautifully as it should .

 

[BenzBoy]

There is no question posted regarding a Phantom engine. Similarly, there is no question posted about Laphoaig.
Regards,
BenzBoy

 

[abl567]

There is no question posted regarding a Phantom engine. Similarly, there is no question posted about Laphoaig.
Regards,
BenzBoy

Lighten up a bit bloke, a joke is a joke and trust me Ron has an unbelieveable amount of experience to contribute to this forum.