Author Topic: M110 compression test.  (Read 122 times)

mrkozzy

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M110 compression test.
« on: 04 October 2020, 01:03 AM »
Hi all.  Figured my following question needs the "brainstrust" of the 116.org community.

Had reason to leave the car with my mechanic for a few days while he tinkered with the computer and Dizzy.  (280 SE D Jet with the M110 engine.)

Its came back with the following after he did a compression test:  front 3 cylinders "120", rear 3 cylinder "165".

Its running beautifully and in my mechanics mind, I should "leave well enough alone".

At present it starts, has no leaks, runs smooth, everything works.

Any thoughts on things I should maybe prepare for down the track?

Should I be saving my pennies and looking to buy parts now.?

MrKozzy

rumb

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Re: M110 compression test.
« Reply #1 on: 04 October 2020, 06:20 AM »
When testing the values are suppose to be within 10%.  Did the mechanic do a wet/dry test?  That will determine if the problem is rings or valves. However being that 3 front are low you might? have a head gasket issue.

Further testing first. 
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

mrkozzy

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Re: M110 compression test.
« Reply #2 on: 05 October 2020, 12:53 AM »
Thanks Rumb.

Don't know how he tested. I didn't ask the question.  However I will find out and respond.

Does  a head gasket issue normally come with some sort of leak also?



Thanks so far!
MrKozzy

rumb

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Re: M110 compression test.
« Reply #3 on: 05 October 2020, 02:06 PM »
I only mention head gasket as the strange being 3 in a row.  There are a variety of places and ways that head gaskets can fail. Sometimes they just leak oil externally or antifreeze internally,  while others could be combustion chamber related.

If further compression tests dont show any differences (unlikely) then the gasket may be suspect.  They most likely will show either rings or valves as the culprit.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550