[My 220D]

Just purchased a 1972 250c, overall good shape, however engine makes a knocking sound. The previous owner said that a head job was done (doubt it), but could it be possible that the job was done incorrectly? Also, what could be the most probable cause for an engine to knock?

If so, is this particular engine hard to rebuilt?

 

[Mike D]

Depends on what they consider a "head job". It's possible they had the head surfaced and a new gasket slapped on and called it good. If so then there is a good chance the head was machined below tolerance. This can cause all kinds of problems, one which could be a loose guide causing a "rattle" sound.

 

[My 220D]

head job

Not sure what they did. Supposedly he spent 3k on the head job, but who knows what they did. If the head was indeed shaved too low, would I need a new one? Could it be possible that a valve is slapping on the top of a piston?

Thanks.

 

[Mike D]

It's possible but don't jump to conclusions. Do some investigation first. Try to narrow down the noise. One way to check individual cylinders is to pull the spark plug wires one at a time while the engine is running to try to eliminate the noise. This is merely a quick test and is not completely definitive but it can be a starting point.

 

[My 220D]

I think the previous owner did play with the distributor and points as well as carb work. But I will try what you mentioned since that is an easy and cost effective method.

Thanks.

 

[My 220D]

Tried the method you suggested, it turns out that cylinder #6 I believe...closest to firewall is the culprit. Does this mean I have to tear down entire engine or just repair that cylinder?? If so, does anyone have a good motor?

FYI, it looks like someone changed the engine to a 280c since the head is stamped 280s on the side.

 

[6punkt3]

250C motor

the 250C had an I6 sohc motor. which the early 280 C carried too.
Then came along (mid 1973) the M110 a DOHC motor and completely different.
What you may have is a cylinder head from a w108 280S (not a w116 body, which had the m110 motor).
What I know is, that the M130 motor (I think that's the internal #) ran hot, because of the smog equipment etc., so a lot of these heads have been shaved over and over.
Looks like you're in warm territory ?
It may also be that the PO or his 'mechanic' jumped timing on the timing chain or the like when reassembling it, that the distributor or the cam is off by one or two teeth....

I am in A.V. , North L A county line.

Alex

how about a video on youtube, that would be the fastest way to diagnose from afar ...

 

[My 220D]

Interesting about the timing issue. It may be that the PO played with the head and had it installed or timed wrong. I see that a lot of Mickey Mouse was performed on engine (like changing one spark wire cable instead of all of them). And yes, I live in a hot weather climate. The engine is stamped 130.923 serial and the head 1300161201 with the 280s on the side. I am not too familiar with these gas engines, but could an early w114 have a 2.8L engine from factory? And I will try to get a video on You Tube so I can show what the sound it is making.

 

[6punkt3]

maybe

but could an early w114 have a 2.8L engine from factory? And I will try to get a video on You Tube so I can show what the sound it is making.

Now that you mention it, I kind of remember reading something that the US version 250 /C might have had the 2.8 l motor to offset the lower compression.
I have to check the books on the data and the parts numbers,.
I'll see what I can find, it may take a few days, the books are buried...(in storage)

 

[My 220D]

That would be great. I would like to find out if the engine in the car is the right one.

 

[rumb]

from wiki, yes the 250C all had 2.8 M130 engine

W114
Chassis code Years Model Engine Number built[6]
Displacement Model Type
W114.015 1968–1976 230, 230.6 2.3 L M180 I6 221,783
W114.01333 1968–1972 250 2.5 L M114 I6 78,303
W114.011 1972–1976 250 2.8 2.8 L M130 I6 34,061
W114.023/022 1969–1976 250C/CE 2.8 L M130 I6 42,379
W114.060/062 1972–1976 280/E 2.8 L M110 I6 67,373
W114.073/072 1972–1976 280C/CE 2.8 L M110 I6 24,669

 

[Kitaka]

If the knock stops when you pull the plug wire it is your rod bearing that's shot. You have to pull the engine for major surgery. I too am in the same process. If it were the head you would not be getting a good valve seal or would hit the piston causing obvious damage and noises (if it would run at all).

Rebuilt engines are available but they are pricey ($9k -$11k). Check the internet for info

 

[6punkt3]

not quite

from wiki, yes the 250C all had 2.8 M130 engine

W114
Chassis code Years Model Engine Number built[6]
Displacement Model Type
W114.015 1968–1976 230, 230.6 2.3 L M180 I6 221,783
W114.010 1968–1972 250 2.5 L M114 I6 78,303
W114.011 1972–1976 250 2.8 2.8 L M130 I6 34,061
W114.021 1968-1972 250C 2.5 L M114 8,824
W114.023/022 1969–1976 250C/CE 2.8 L M130 I6 42,379
W114.060/062 1972–1976 280/E 2.8 L M110 I6 67,373
W114.073/072 1972–1976 280C/CE 2.8 L M110 I6 24,669

looks like you beat me to it, BUT
my corrections are in the above chart. (in Orange)
That is why I asked.
The 250C came originally with a 2.5 L motor and only in 1969 was also offered with a 2.8 L.
then discontinued (in the US) as the 280 C came out..

check the engine number (or if your VIN starts 114 021 or 023)

250C 1st version had the 2.5L M114.920 motor (8,824 produced)
250C 2nd version had the 2.8L M130.923 motor (and of which 10.527 series1 & 1,241 series2 were Cs)
250CE had the 2.8 L M114.980 motor and 21.787 were produced) total= 41,138 C & CEs.
The 250 sedan had the same paralell, 77,000+ produced with 2.5L motor and about 34,000 with the 2.8L M130.923 motor)

The 280S (W108) had a similar motor, but not exactly the same M130.920.
It was also in the 280SE/L with the M130.980 designation, but those were fuel injected.

How is the video coming along ?

 

[agillot]

the later 250 , 71 / 72 ??? had a 2.8 liters engine . you need to be able to tell if your engine noise is above head gasket or below [ loose piston or ??? ] head noise cause by rocker arms , cam , or just a valve cover too tight .