Compression Test Suggestions

1976-1985: 230T, 230E, 230TE, 230CE, 280E, 280TE, 280CE, 240D, 300D, 300CD, 300TD,
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peterac
C 111
Posts: 801
Joined: Mon 30 Jun, 2008 10:29 pm
Model you own: w123
Location: Newcastle

Compression Test Suggestions

Post by peterac » Sun 02 Jul, 2017 7:28 am

I have a rough idle that is driving me round the bend. It has gone on for too long and I need it sorted as I won't put any more money into keeping the car if compression isn't up to scratch.
Note: car is 1980 300D, valve clearances done, engine mounts and trans mount fine, filters changed, car polished. Tea pot blow by test oil cap sits still. It only has a faint light grey haze of smoke from exhaust noticeable in rear vision mirror at night in trailing car lights when I'm at higher end of revs. Car has 800,000kms on it on original motor no rebuild. One glow plug was buggered last week and starting was shocking but it did start cold, rest of the day was fine. Glow plug replaced and holes reamed out and all is good again. New injectors were put in last year by a diesel injector specialist but no difference.

So next step is the compressio test. What is the cheapest way to get this done. Buy a kit, borrow off one of you guys, advice please!
I have rust and panel work that will cost over $2000. Not worth it now if engine is not a keeper.
Thanks as always.
Peter<><
1980 300D
1979 300D (organ donor)

seventyeight
C Class
Posts: 31
Joined: Tue 05 Mar, 2013 2:41 pm
Model you own: w123
Location: Blinum Nu Zillund

Re: Compression Test Suggestions

Post by seventyeight » Wed 12 Jul, 2017 3:37 pm

I bought a diesel compression tester from Super cheap here in NZ for $100...make sure you do a valve adjustment first of course

800,000 is bloody impressive but don't be surprised if you get poor readings, I tested a couple cylinders on a '77 300D with 500,000 and were below 220 psi, didn't bother with the rest...
1977 250 parts car (drivetrain for sale!)
1977 280>300D conversion
1978 300D NA+4 speed > factory turbo + van 5 speed > NA engine back in and HX30W turbo!
1988 2.0D Corona auto "toymota"

tsharkey
C 111
Posts: 957
Joined: Sat 25 Apr, 2009 9:32 am
Model you own: w123
Location: Melbourne, Vic

Re: Compression Test Suggestions

Post by tsharkey » Wed 12 Jul, 2017 6:58 pm

Hi Peter - Didn´t you have an inexplicable diesel leak - Did you ever solve that - It looked like it could be one of the pre-chambers is not quite right and they can cause rough idle if they are leaking.

Compression test isn´t hard (just about to do one on my new toy) and the kits aren´t expensive - As the man across the ditch says, make sure the valves clearances are A-OK .
W123 1981 300TD - Family Kid mover
W202 1998 C250D Factory OM605A Turbo - Partner's daily driver
W123 1982 300CD Retro fitted OM617A Turbo - Mine
W123 1984 300TD 5 Speed Manual, to teach the kids how to drive
W123 1982 300TD Factory OM617A Turbo (Hans) - Project
W123 1985 230TE - Brother's
W123 1985 300D - Sister in Law's
1962 S-Series Valiant (Tho Daimler & Chrysler divorced, still part of the extended family)

Past benzes
W114 1969 250CE - PO put in an M110 transplant and nearly sent me around the bend
W123 1981 300TD - "Matilda" - RIP hit front side & rear but left my brother + niece A-OK

Current Projects
Coupe restoration, Turbo Wagon freshen up

peterac
C 111
Posts: 801
Joined: Mon 30 Jun, 2008 10:29 pm
Model you own: w123
Location: Newcastle

Re: Compression Test Suggestions

Post by peterac » Wed 19 Jul, 2017 7:13 pm

The leak was fixed, just removed, checked (all was fine), replaced and then no leak. Unfortunately it had no bearing on the idle. Any suggestion on what is the cheapest kit that would be ok but not dodgy?

Cheers
Peter<><
1980 300D
1979 300D (organ donor)

lockiedog
Pagoda
Posts: 155
Joined: Mon 29 Dec, 2008 6:49 pm
Model you own: w123
Region: Queensland
Location: Brisbane

Re: Compression Test Suggestions

Post by lockiedog » Mon 20 Aug, 2018 8:17 pm

Peterac did you and up sourcing a compression tester and if so what did you find? I am hoping to test one of my 300d's in the next couple weeks as I am changing the injector nozzels and thought it would be a good chance.
1984 300D Auto Manila beige
1979 240D Manual Light ivory
1976 300D Auto Mimosa yellow
1978 300D Auto Sahara yellow

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