6.9 # 7114 - it lives !

[CraigS]

Or, as mine is, a European Delivery on the Overseas Delivery Program.

If you do not have a solenoid, you will find they are not available. This is what I bought as a replacement.

http://www.woodauto.com/Component.aspx?Ref=SND1169

The original Bosch number was 0 001 312 103.

 

[CraigS]

Another update. The heads off the spare motor had too much corrosion, so the decision was made to remove my heads and see if they were any better. I duly removed mine at home a couple of weekends ago - not a fun job, but I got it done without breaking anything ! My heads had 2 burnt exhaust valves on the right bank, and some others showing signs of going the same way. The head itself however was in much better shape. It will need new valve guides, which I have already sourced, and some welding to fix some valve seat recession in the couple of valves that were burnt. All going well, they should be finished this week or next and the car can be taken to MB Classic Star where we will put it all back together.

Starter motor is out and the new solenoid will be installed and generally checked out to make sure all is well.

I bought a new steering coupling some time ago, but I have put it in a safe place and now cannot find it, so had to buy a new one, so that will also be done before the heads go back on.

Aside from the head job, which always gives pleasure, I was cruising eBay a couple of weeks ago and spotted some velour which appeared to be the same as mine. The seller had bought it for his W123 but never used it. After an exchange of photos, colour codes, etc., I determined it was the same as mine and duly bid on it. I was the only bidder and bought it for $150 plus postage. The seller told me afterwards that he had paid $1,350 originally. It arrived today, and it is very close to the original - bearing in mind that what is in the car has been exposed to the sun and light for 35 years, so it looks like my brother is going to have a job in his hands in the future.

 

[Styria]

When all done, Craig, you should really have a lovely car on your hands. You know, I have been driving Gleaming Beauty for the last fortnight, or thereabouts, and honestly, it is an absolute buzz each and every time. Love the sound on acceleration, and honestly, pulling back to second at 2K. rpm and hitting it up to 3K. rpm, and it becomes a real Adrenalin rush. Acceleration and pick-up are quite staggering, surprising and blinding - plus that exhaust snarl - a bit like an Aston Martin DB5. You really have something to look forward to. Regards Styria

 

[Oversize]

So my question is this... With the trick sodium filled valves, why are they burning out with such regularity?

 

[CraigS]

Regularity ? I don't understand the question. There are a number of factors. First, there was a small leak in the head gasket, which allowed water into the valve seats, eroding them. Without a proper seal, they are going to burn. Secondly, and possibly as a result of irregular servicing in the past, the valve rotators get gummed up, with the result that they no longer rotate the valve, which would normally prevent, or minimise, the sort of problem encountered.

 

[WGB]

Great to hear that your enthusiasm continues and it looks a great car.

Bill

 

[CraigS]

The enthusiasm never wanes Bill - just the cash !

 

[Styria]

The enthusiasm never wanes Bill - just the cash !

Craig, is it cash you need ? How much ? I will sell it to you at a discount price.

N.B. That's got to be the 'funny' of the month - anyone agree ?

 

[abl567]

No

 

[CraigS]

OK. Give me $1,000 and I'll give you $500. Deal done !

 

[Styria]

OK. Give me $1,000 and I'll give you $500. Deal done !

Just spent the last $1000.00 earlier on today - also, still waiting to get the $500.00. Anyhow, I got the equation back to front ! Horror. What's new. Regards Styria

 

[Styria]

No

Yes.

......I really hate single words.

 

[Oversize]

I've heard of a few cars that've burnt valves and maybe that's due to a lack of regular maintenance by POs that's caused rotator issues and leaking headgaskets?

 

[CraigS]

I thought that was what I said.

 

[Styria]

Mark, let me disagree with you on the lack of maintenance theory by previous owners - the way I see it, other than lack of oil and filter changes, and not changing the coolant, there is very little else that can be carried out by way of maintenance. As you know, hydraulic lifters are self adjusting, a worn timing chain will not cause head gasket leaks, nor will valves burn out.

Perhaps unbeknown to most, 6.9 head gaskets will burn a small passage right at the very back of the right hand cylinder gead, allowing coolant into the valve and combustion area. I have seen this on two heads now, although it was only with 'Gleaming Beauty' that there was actually a small piece of head gasket missing. It is one area where there is not a lot of 'meat', and it is susceptible - in my opinion anyway.

I can also let you in on a little secret - it has to be that way, as I am unable to prove my suspicions. It all goes back about six years. I had a 6.9 with a 'dodgy' No. 4 compression reading on the right hand side - there you are, right hand side.......previous paragraph....Anyway, I passed the job onto an Engineering firm, well known in Club circles, in the outer west so to speak. I instructed them to carry out a valve grind and de-coke as I reckoned that the low compression was a matter of valve problems. You know the wet and dry test......it did not indicate a rings problem. Anyway, next thing I know I get a call from the engine shop...''hey, you have four bent valves on the left hand cylinder head".

In those days, I was not a wake-up to various problems that can arise when the valve timing is out and you have pistons and valves touching each other. So, it is my educated guess that the shop got the valve timing all wrong, and when they turned/started the engine, that's when the valves got damaged. Luckily enough, I had some spare ones, and I passed them on FREE OF CHARGE, simply because I didn't know any better. It'd be different today.....Anyway, the valve grind and de-coke restored the compression on that No. 4 cylinder...and I sold the car. Regards Styria

 

[Oversize]

I thought that was what I said.

Yes in hindsight I repeated what you said to some degree. What I was trying to say was that it seems to be a more-than-occasional problem with the M100 6.9.

Styria there's been lots of 6.9s that haven't received regular oil changes and that alone might contribute to the burnt valves. Or could it be poor design or bad fuel?

 

[CraigS]

There is probably a bit of truth in all of it - poor maintenance, poor design, wear - it can all contribute to the scenario I, and undoubtedly others, have faced. You have to remember that these cars are 35 years old and nothing lasts forever. Combined with that, they are a high performance motor, and probably received their share of exuberant driving over the years. Fortunately, they are not a Ferrari motor, so longevity is not such a problem. One issue that can arise, despite Mercedes claim that it is not necessary to re-torque the head, is that some of the head bolts will work themselves loose, so it is prudent to check, and if necessary, re-torque the head periodically. This is obviously more relevant after work has been performed, but still necessary on an untouched motor. The difficulty in doing this is that the most likely ones to work themselves loose are those at the back, and of course, the most difficult to reach, so this is probably reason enough why they seldom, if ever, get checked.

 

[Afro107]

I was told that too lean mixture reduces consumption (and power) but has severe and adverse effects on valves/seats causing them to burn-overheat.

 

[CraigS]

The heads have now been cleaned up and ready to go back on the car. Some photos of the head and the worst of the burnt valves. For those interested, the cost was $1800 for the head work, which included welding of the valve seats as explained previously, and valve guides which I supplied, which were $200. When you combine this with the head/manifold gaskets, it has come very quickly to $3,000 - and that was using another set of good second hand valves, which I was given. If I had to buy the valves, that would have added another $1400 plus freight.

Hopefully we will re-install the heads in a couple of weeks.

 

[260ebenz]

Sorry Craig can not see the photos.