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OM605 running rough
Petar Offline
7.5mm M pump
****


Posts: 414
Joined: Feb 2014
Location: Serbia
#1
OM605 running rough
So I have a '96 c250 with a mechanical pump from om602 non turbo.Besides from low power(the pump only fuels for a NA OM602 so i have like 90-100hp) it was running ok. Last year i noticed a slight clicking from the engine, sounded like it's coming from the head. Recently it started running rough, especially when cold but it starts ok. It will run rough until it warms up then it sounds like it has a bad injector. I can hear a chuffing sound from the intake manifold and my guess is that i'm loosing compression through the intake valve. I haven't yet taken off the manifold to check. What could the reason be ? Bad lifter ? Burnt valve ??

Oh and I'm also loosing coolant. It started with 1 liter every year and now I'm loosing 1 liter in about 2 months. No obvious leaks. Could this be related somehow ? Bad head gasket due to overheating ??
(This post was last modified: 01-07-2018, 05:13 AM by Petar.)
01-07-2018, 05:08 AM
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addi.bigg Offline
OM605; 7,5mm elements
**


Posts: 94
Joined: Aug 2016
Location: Hungary
#2
RE: OM605 running rough
(01-07-2018, 05:08 AM)Petar Wrote: So I have a '96 c250 with a mechanical pump from om602 non turbo.Besides from low power(the pump only fuels for a NA OM602 so i have like 90-100hp) it was running ok. Last year i noticed a slight clicking from the engine, sounded like it's coming from the head. Recently it started running rough, especially when cold but it starts ok. It will run rough until it warms up then it sounds like it has a bad injector. I can hear a chuffing sound from the intake manifold and my guess is that i'm loosing compression through the intake valve. I haven't yet taken off the manifold to check. What could the reason be ? Bad lifter ? Burnt valve ??

Oh and I'm also loosing coolant. It started with 1 liter every year and now I'm loosing 1 liter in about 2 months. No obvious leaks. Could this be related somehow ? Bad head gasket due to overheating ??

Do you have video of the rough running?
01-07-2018, 11:50 AM
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Petar Offline
7.5mm M pump
****


Posts: 414
Joined: Feb 2014
Location: Serbia
#3
RE: OM605 running rough
Yes

warmed up:
https://www.youtube.com/watch?v=nOhwkhPcUHk
The chuffing is louder on video than it really is.

cold start:
https://www.youtube.com/watch?v=ryv5pOgGUPw
Misfires like a bad glowplug but it does this for much longer, only when it warms past 50-60*C it will stop
I do have one bad glow plug but that had been like it since last year, and it would only misfire for about a minute after a cold start.
(This post was last modified: 01-11-2018, 12:49 PM by Petar.)
01-11-2018, 12:48 PM
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Petar Offline
7.5mm M pump
****


Posts: 414
Joined: Feb 2014
Location: Serbia
#4
RE: OM605 running rough
It ran much worse and started loosing A LOT of coolant
https://www.youtube.com/watch?v=wGIDGs7LmFU

Today we pulled the head and a gasket leak was barely visible but there was significant cavitation damage on cyl #4 water passage in the head. Also a lot of soot on intake valve on #10 (5th cylinder). Tommorow i'll take the head to a machine shop and see if it is still serviceable or needs to be replaced.

UPDATE: The head is cracked between intake and exhaust valves on cylinders #3, #4 and #5. My guess is that it was badly overheated since the fan clutch was broken when i bought it. Found a used head, had it checked and serviced at a machine shop. Just have to reinstall it.
(This post was last modified: 02-25-2018, 04:47 PM by Petar.)
02-19-2018, 03:32 PM
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