W114 with M130 engine ticking hunt

[kavadarci1]

Hi guys,

I hope you can help me.
I've been trying to chase a ticking engine noise on a 1971 Mercedes
250C with M130 engine with no luck so far.
The car always starts fine, idles fine and has engine power.
The engine has 150.000km which based on the records and the condition
of the car I have all reasons to believe they are original.
The car has the original paint with all original parts and no wear anywhere.

On cold engine everything seems to be perfect but once the engine gets to normal temperature aticking starts.
It is specially noticeable on over run and on high speed. It almost
sounds like pinging but it is not.
I had a mechanic look at the car and he confirmed it is not pinging.
Timing is set properly.

I have two videos posted on youtube.
One is cold engine here:
M130 working cold no ticking - YouTube

second is hot and ticking is very noticable, specially on over run
when the engine comes to idle
M130 engine noise - YouTube


I have removed the camshaft, springs, rockers, head of the engine,
valves, everything top end and unless we are talking hundreds of mm, I
don't see any wear nor damage.
Maybe slight marks on the camshaft close to the chain but that's it.
The noise seems to be coming more from the back end of the engine.
I have few pictures attached.

I am more than willing to start replacing parts but I don't know which parts as
all look good to me..

What are your thoughts, what might be causing this ticking?
Your help is much appreciated.
Thank you very much.

[kavadarci1]

Just to add that the only play on any parts that I found was in the lower spring cover seat.

I have one sitting sideways to show you the part and on the picture it is number 18, spring cover seat.
These ones have a lot of play between the two parts combined.
Is that normal, how much play should they have?

[ansteadeh]

Did you check the pistons when you had the head off to see if they had excessive wear by trying to move them with your fingers? It could be piston slap and/or big end bearings worn.

Did it ever get low on oil on your watch?

[kavadarci1]

I did check the pistons but I am not sure how much move is good
I still have the head off
I did notice when I out cleaner on top of the pistons to clean them all the fluid sipped between the walls

I do think the oil pressure was low
On cold start will go all the way up but on hot and idle in gear will go to 5

[ansteadeh]

Ok there ought to be little/no movement in any direction of the pistons. The leak down from cleaning is a slight concern in that the rings may be either stuck in the ring lands or excessively worn. Something like petrol should not noticeable leak past a good set of rings. Low oil pressure can mean main or big end bearing wear. An M130 with a good service life and regular oil changes will show very little wear on tear down and inspection/measurement - even at high mileage. Stuck rings can indicate also a lack of regular services as vey bad oil will cause the rings to jam in the lands.

If you have the time, expertise and $, I'd be pulling the motor out since you have the head off, tear it down and inspect/replace engine parts. It really is a question of economics. Easy decision for me a few yrs ago as the car in question was an immaculate 114 250CE and worth every cent on engine parts. These coupes are rare here in Australia.

BTW by the look of the head gasket it looks like you are dealing with the later M130 motor - built after 1970/1. Some slight improvements with this motor.

[kavadarci1]

thank you
this car is in pristine condition,
original fantastic paint and everything original with no signs of wear thus my surprise on the engine ticking.

it does sound like i need to pull the block out before anything else.

[Frank Reiner]

The head gasket in your picture appears, based on the presence of a screened-on border seal, to be a replacement item.
So, why was the cylinder head removed at some time in the past? Given the apparent low mileage, the most likely cause was loss of coolant/overheating.
What happens in that situation? If, as you state, there is no noise at startup and when the engine is cold, a cracked piston is very unlikely. If, the cylinder walls are not scored, and the bores are straight, round, and on size, the source of the noise will probably be found in the head. When the M130 head is overheated there is the distinct possibility that one or more valve guides have lost their necessary press fit in the head. When cold the guides will have enough interference fit to not move, but as the head expands the guides become loose and move enough to make a clicking/ticking noise.

If you can make or obtain a mandrel that would be used to remove and install guides, then you can test the guides for tightness. A force of 100 kg should not move a guide.

By the way, the lower valve spring seats are rotators, and the parts of that device have considerable looseness.

[kavadarci1]

Thank you.

if the valve guides move up and down due to wear shouldn't i be able to see that? it should show wear somewhere or one to look different than the others, i don't see any of that.

i am starting to believe that the noise is from the block.

[vandor]

I am not intimately familiar with this engine, but in general if it makes more noise on the overrun, then it means that it is the conrod bearings. Also the sound it makes sounds a lot like loose conrod bearings. They are not that hard to replace even with the engine in the car, as long as you can take the oil pan off.
I was able to take the oil pan off my w108 (m117 engine) by loosening the engine mounts and jacking up the engine.

[kavadarci1]

I believe it is in the block as I haven't found anything significant in the head
I'm sure the head has wear after 42 years but nothing to be causing this ticking
I have removed few more components and getting ready to remove the block in the near future
I then plan to take it a part and inspect components and eventually take it to an engine shop to mic'd it and see where the issue is

Thank you