Restoring an old 180db Mercedes Benz (Ponton) from 1960. A barn find ?

[anyweb]

To clean the existing valves, either put them into a pillar drill, or if not available, a power drill secured to a vice, get them spinning (not too fast) and then use Emery paper to polish them.

For 'lapping' them, I have in the past used the sucker from a hand held tool placed over the head of a suitable set screw (fully threaded bolt), along with a nut wound fully up the thread, and then used an electric drill.

I was told by my mechanic to use Valve grinding paste, so i bought that (both fine and coarse), I assume i should grind them by hand with that, or do I use a tool, any idea what tool ?

 

[Ken_R]

Emery cloth for getting the old carbon deposits off the valves (and Stems). Grinding past for 'lapping' the valves to their seats. Coarse first, then fine. Once done, keep them in order.

 

[anyweb]

thanks i bought one of these today along with the fine and coarse grinding paste, just need to find a youtube video to show me what to do and when

 

[anyweb]

this is giving me ideas

 

[LostKiwi]

Apply a small amount of oil the the valve quide (for lubrication)
On the first valve apply a smear of coarse grinding paste on the valve seat area of the valve.
Carefully insert valve into head and using the sucker tool between the palms of both hands rotate the valve back and forth a few times whilst applying slight downward pressure. Lift the valve 10cm and repeat. Keep doing this till the valve develops a continuous 1.6mm grey lapped in circle. You may need to apply more grinding paste to get this completed.
Carefully remove the valve and wipe off the coarse paste. Repeat with fine. When its right the sound of the grinding will rapidly change as you lift and reseat the valve the 10cm . Be extremely careful not to get any grinding paste on the valve stem or valve guides.
Repeat for all valves.

 

[anyweb]

thanks LostKiwi, why should i "Be extremely careful not to get any grinding paste on the valve stem or valve guides." ?

 

[LostKiwi]

thanks LostKiwi, why should i "Be extremely careful not to get any grinding paste on the valve stem or valve guides." ?

Because it will cause rapid wear and problems later down the line, typically manifested as blue smoke after decelerating, coming down a hill on overrun or idling.
Before you reassemble make sure everything is spotless.

 

[anyweb]

thanks LostKiwi, I've never done this before so I will post here asking for advice before i screw up, or at least I hope I won't screw up. Thanks again for the help !

 

[LostKiwi]

Regarding your midlands pickup I'd be happy to collect it but I can't store it as I have no room in my sheds at present but if you're really stuck let me know and I'll see what I can do (might be able to put some alloys out the back of the shed to clear space).

Might be useful to know the size of it as I'll have to collect using my 129...

 

[anyweb]

thanks, regarding the valves themselves, i'm worried that i'll mix them up when removing/grinding etc, can i use a marker to mark the number on each one prior to starting that work ? or how do you guys normally do it ?

 

[Jim2]

thanks, regarding the valves themselves, i'm worried that i'll mix them up when removing/grinding etc, can i use a marker to mark the number on each one prior to starting that work ? or how do you guys normally do it ?

Anytime I was grinding valves, I used a piece of strong cardboard, and marked it 1.2.3..4.5.6.7.8. ( or more if needed ) with the outline of the cylinder head drawn on it. So simply push each valve into its corresponding position on the cardboard( make small hole or slot for each valve) as you remove them from the head, and as you grind each one, replace it on the cardboard.

 

[Jim2]

I think that maybe that

so I was chatting with my mechanic today, and he asked me if I knew what is missing from the back of the injector pump, we compared the one on the engine with the one I bought on Ebay and both have the same protruding shaft with a groove cut in, and a threads for attaching something,

here's some photos with a red arrow pointing at what we think is missing, do any of you know WHAT it's missing and whether it's needed or not, thanks in advance...

View attachment 43239 View attachment 43240 View attachment 43241

I think that this particular injection pump may have been used in other engines, and not exclusively Mercedes. And this drive does have function, just not in this case. This is quite common , especially in older engines, ( and it seems modern ones too! ) that they would buy a Bosch or Siemens or other system, rather than develop their own.

 

[anyweb]

so today I tackled cleaning the engine block, and removed the valves, next I started grinding the valves but stopped after the 4th valve as it took all day working on the engine.

Please take a look at the pitting in my final photo in my blog post here and please tell me how can i improve it ?
https://www.mb180db.com/2018/11/cleaning-the-engine-block-and-removing-and-grinding-the-valves/

 

[LostKiwi]

That's pretty bad pitting on that valve seat (and the head as well).
The only way to get rid of the pitting on the valve seat is to have it recut. It may require an insert if its too bad.
That will require a specialist to perform the work.

Well done on the rest though - they look good.

 

[anyweb]

well my budget is shot so there won't be any recut or inserts, what will the knock on effect be of leaving it as it is now ?

 

[LostKiwi]

It'll probably run but will eventually burn the valve and or seat causing poor running and requiring replacement of the valve and a new seat insert.

 

[Severnless]

Hi Niall

Great to see you back at it!! Also a nice little project to do with your lad! Just imagine his face when you start the engine for the first time after the rebuild! Priceless

For the head and lapping the valves LK advice is spot on, as for the pitted valve seat, it will seal for a short time but best practices is to get the seat replaced or at least re-cut..
Just for fun I had a dig in my shed to get to your spare engine. Found the head did a quick clean off of the red dust and these are the photos I took

As you might see no.2 has a bit of pitting on the head but the valve seat looks to be okish
The biggest problem is the hairline crack on no.3 injector seat, really don’t think it’s that bad but would need to be checked over by a specialist
Also all of the valve stem guides have been knocked out!
If you need any more info with your engine let me know, also if you want just a bit of the engine sending over, then please let me know.

 

[om613]

Looks a mixed bag of valve heads there? Something's pinged around that cylinder, I reckon.
I agree, it needs re-cutting really.

Wasn't the block painted red, so did you get another engine?
(edit: ah yes, I see you did!)

 

[anyweb]

om613, my photos show my engine, and sadly no this is the original engine Cylinder Head, i mistakingly called it the engine block, it's the cylinder head. and it's still red (the engine block...).

Serevnless, thanks for taking those photos i was wondering what condition that one was in, so I will do the remaining valves on my cylinder head this week, and will let my mechanic pressure test it, he also might get the whole cylinder head looked at by a guy who can improve the pitting (but, cost is my issue of course)

 

[anyweb]

and by the way, the 4 new pistons+piston rings are mounted in the original engine block. Will have photos of them soon...