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W116 6.9 (6632) engine rebuild

Started by HPC, 23 January 2023, 04:39 PM

rumb


Yes the smog stuff will not find its way back into the engine bay...
[/quote]

As despicable and worthless as all that smog stuff is, you could completely kill yourself and future owners from ever being able to register or even sell the car.  CA CARB is spreading and many states just plain will never allow these cars on the road if they are missing components.

Even if your state can get by I would think heavily about removing it.  I recently sold 2 vehicles because they were missing smog components and I didnt want to get stuck with the thousands of dollars it would take to put back on them.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

Rolo

I bought +1 pistons and rings from Mahle.  I ordered directly from Germany and they only have blueprints for +1 in Euro spec.  So you'll have to switch to premium gas on US spec motors.  The F1 shop made the pistons for me.

raueda1

Quote from: Rolo on 25 January 2023, 12:47 PMI bought +1 pistons and rings from Mahle.  I ordered directly from Germany and they only have blueprints for +1 in Euro spec.  So you'll have to switch to premium gas on US spec motors.  The F1 shop made the pistons for me.
FWIW, my +1 euro pistons were supposedly 8.6:1 compression not 8.8.  I learned this from some MB rebuild manual, can't recall which.   Regardless, I use premium.  However, I have used lesser gas a couple times and never had knocking problems and my timing is advanced significantly
Quote from: rumb on 24 January 2023, 01:46 PMYes the smog stuff will not find its way back into the engine bay...

As despicable and worthless as all that smog stuff is, you could completely kill yourself and future owners from ever being able to register or even sell the car.  CA CARB is spreading and many states just plain will never allow these cars on the road if they are missing components.

Even if your state can get by I would think heavily about removing it.  I recently sold 2 vehicles because they were missing smog components and I didnt want to get stuck with the thousands of dollars it would take to put back on them.
[/quote]. Interesting point.  Does CA CARB mandate emissions testing regardless of age?  Some states just waive emissions testing altogether after a certain age.  That's the case in both Utah and Connecticut (states of relevance to ME) if 25 years old or over.  Not sure how common this is. 
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

rumb

I have seen some state that CA CARB requires all cars after 1975 to get smog tested. I think 15 or so states copy CA currently.

But to what standard I dont know. CO has same as CA, but my 6.9 was tested at the 1977 tailpipe test standard. This was 4 years ago, so I hope nothing changed.


Since I have a unmolested euro I got a federal EPA exemption. My belief is that all unmolested euro 6.9's (as well as should all other euro w116) would be able to get this. Note the car must be in original config with no smog on it.

This would be rather good news at least for 6.9 as most are euros.


You can read the prior discussion on another forum where i mention the federal form:

https://www.benzworld.org/threads/grey-market-sec-smog.3112100/page-2


In the US it is rapidly getting to the point where people decide what state to live in based on which politicians are in control.

So the question is, do you want to be the person stuck with a car you cant sell or drive 10-20 years from now? The smog stuff is ugly but it really doesnt rob that much power. Its only going to get worse, not better with our old cars.

BTW smog pumps and EGR can all be rigged to be non funtional. Ive heard of ppl gutting the inside of air pumps so they look ok but do nothing. You could do same with EGR put on blanking plate and gutted EGR on top of it.

'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

Rolo

Quote from: raueda1 on 25 January 2023, 03:22 PM
Quote from: Rolo on 25 January 2023, 12:47 PMI bought +1 pistons and rings from Mahle.  I ordered directly from Germany and they only have blueprints for +1 in Euro spec.  So you'll have to switch to premium gas on US spec motors.  The F1 shop made the pistons for me.
FWIW, my +1 euro pistons were supposedly 8.6:1 compression not 8.8.  I learned this from some MB rebuild manual, can't recall which.   Regardless, I use premium.  However, I have used lesser gas a couple times and never had knocking problems and my timing is advanced significantly
Quote from: rumb on 24 January 2023, 01:46 PMMahle only offered me one choice for +1 pistons.  Not sure what the comp ratio is, but I've tried midgrade, and it knocks.  Engine is running great according to the analyzer.  It's very strong.

HPC

Quote from: rumb on 24 January 2023, 01:46 PMYes the smog stuff will not find its way back into the engine bay...

As despicable and worthless as all that smog stuff is, you could completely kill yourself and future owners from ever being able to register or even sell the car.  CA CARB is spreading and many states just plain will never allow these cars on the road if they are missing components.

Even if your state can get by I would think heavily about removing it.  I recently sold 2 vehicles because they were missing smog components and I didnt want to get stuck with the thousands of dollars it would take to put back on them.
[/quote]

That makes sense!  I did not think of selling in future.

Randys01

When we last left this post I enquired about the rocker pad wear where it rubs on the camshaft.....do you have a couple of examples you can post.? I'd be interested in the rockers from Cyl 1 and 5.

HPC

Hey Randy, I have the heads back, here are pictures from Cyl 1 and 5.  they all look similar. 

You can also see the wear on the valves, out of spec on the stems.

Randys01

The original question was whether this motor was beyond repair..we've  looked at a number of what I would call "CRITICAL MARKERS" from the top of the motor. Everything IMHO looks a "go".
eg  Rocker wear seems remarkably good .

You have sent the heads out I presume to be dismantled. Now we can see the valves and they have  measured up under sized.
It's impossible to tell from a photo. how much have they worn?

But the million dollar question is how did the valve guides measure up.?

AND
what about the valve springs?  How did they measure?
 

HPC

Exhaust valve stem ~10.92  spec 10.93-10.95
Intake valve stem ~8.87  spec 8.95-8.97

Not sure about the valve guide wear amount, but the play in the old guide is much more when comparing to a new guide. Even the new guide has noticeable play.

Waiting for the new exhaust valves to arrive, still searching for new intake valves...

Springs measure about 49.40 and 45.10mm

If I can find intake valves I can have the heads rebuilt. The big question is with this much wear on the heads, wil the block need to be rebuilt as well?


Randys01

Before going any further how true are the heads?
You can't take much off these before you run into problems of camshaft timing and valley cover  machining.


Meanwhile...examining the pieces.  This is rather odd.......
the inlets are worn worse than the exhaust.?
all valves are as black as pitch.?
it doesn't look like the exhaust valves have sat on their seat (s) for a looong time.???n

You have committed to a course of substantial overhaul.
1.you have new valve guides? The old ones are clearly worn as per normal.
2 new exhaust valves  on the way
3 inlet valves which are clearly well out of spec but no new ones on the horizon.?

What are the valve seats like?. They are going to have to be recut and faced anyway.

New valve stem seals of course.

You are going to have to consider new valve lifters.

moving to the lower part of the motor....how stripped down are you prepared to go?


 

Randys01

I have a theory about this motor. I'm just puttin' it out there.
After peering into these photos for some time and taking into account what has been reported I am hily suspicious that this motor has spent a lot lot lot  of its life running rich.

I'd wager a bet ... $5.00 !... that this explains the excessive wear on the inlet valves which  have been continually  running wet and thus deprived of lubrication. The combustion chambers are far too black as are the piston tops. By the time the whole  lot is burnt off the exhaust valves are black too BUT not excessively worn.
Maybe someone fiddled with the WUR so that it ran rich to compensate for the blown head gasket. dunno

But it raises the spectre of block wear could be similarly affected.

Time to take some accurate bore measuremnets unless the pistons are coming out in which case,.all will be revealed.!

HPC

Running rich can be due to the last 8 years just starting the engine occasionally with fresh oil and no coolant to keep it going. The PO did mention having to do some work on the fuel system at some point due to not running well.

Considering the amount of wear... continue with a full rebuild (with some parts NLA), or stop here and look for a good running motor? Even if I can get the heads all new, you can't ignore the block.

I have sourced some parts for the motor already, but these may be better used on a motor in a better condition to start with.

Randys01

The next motor is going to be an unknown. At least this one you know/are getting to know. 
Do an evaluation of the bore wear..check block deck height for trueness...........a straight edge will do.
Evaluate piston crowns.
Cylinder lip wear..the usual.
Are you taking the sump off?

On balance the motor has done nominal miles......I think i'd be forging ahead with what I know. Another motor would of course require everything you've done so far.

HPC

From what I can see the block deck is straight, I am a little concerned about the gap between piston and cylinder wall.

I need to find a decent machine shop in the Dallas area. I am a little reluctant to dive deeper in to the block, but I suppose it would be best to take off the sump to inspect from underneath.  The block is still in the car.  I can get the heads redone - still searching for those intake valves..  the rest of the parts for the heads seems to be available.

You are right, another motor is another unknown, unless I find a good running one with good history.