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+--- Thread: OM617A valve problems... (/showthread.php?tid=7108)
OM617A valve problems... - ErikT - 03-21-2016
I have a OM617A in a G (461) which seems to eat the valves, especially exhaust valve on number 5 cyl....
It started a while ago I noticed problems with the above mentioned valved. It needed frequent adjustment until it wasnt possible to adjust it more. Noticed it initially by a minor vibration when in 4th gear between 60-80 kmt.
So I pulled the head and had it along with the valves rebuilt by a specialist shop. re-installed it. Then later I found a lack of compression was causing problems with starting in winter so I pulled the engine. Piston rings changed and other parts in the block. Also had the valve on cyl 1 replaced as it was bad.
Put it together. Adjusted valves initially plus as expected some minor adjustment after the break in of the head.
But again noticed the vibration and the exhaust valve on cylinder 5 again requires frequent adjusting...
I have an early Dieselmeken M pump in mine but its turned down by a fair margin. After the engine rebuild, it had to be turned up by 2-3 revolutions on the adjustment to get the engine to run on idle.
When starting it now with snow on the ground there is some smoke while its cold and snow gets dark. But when engine is warm its not really visible.
Could something have gone wrong in the fuel pump and caused problems with the valves (improper/uneven burning of fuel in the engine or something)?
So my question is this: After a rebuilt head and with adjusted valves is installed, what are the normal reason which will then cause the valves to being damaged and need adjustments?
RE: OM617A valve problems... - Torkey - 03-21-2016
Have you checked to injector on cylinder 5? Incorrect fuel delivery could cause problems for the exhaust valve.
RE: OM617A valve problems... - ErikT - 03-21-2016
Sorry forgot to mention that, yes.
All the injectors have been overhauled/rebuilt by Dieselmeken
I might pull the injectors to replace the seal rings, though...
What about the pre-chamber?
Edit: Also might put in the old MW pump to check to see if that makes a difference. Shouldn't but I dont know.
RE: OM617A valve problems... - barrote - 03-21-2016
that is a strange simptom ...
the valve lash shoudn´t change that much , usually manufacturers say around every 20k wish is a lot for a offroad vehicle...
i bet my coin in something like bent valve stem , eroded valve guide, or even bad valve sealing sealing, it may be reasonably to check the timing, sometimes colisions happen
the precups might also contribute to vibes, usually the ball inside breaks and the injection will be defective contributing to severe vibes...
last mont i saw a 606 with all 6 broken and one already missing....
regards
RE: OM617A valve problems... - atypicalguy - 03-21-2016
Is the compression better now that the rings are replaced?
RE: OM617A valve problems... - zeeman - 03-22-2016
It sounds like the valve head is tuliped if you have to keep adjusting the valve. This would indicate a lean condition from lack of fuel or a timing issue. It sounds like you have the injectors handled, what about plugged prechambers. Is your head specialist a diesel man? What about a plugged or semi plugged hard line? Just throwing out ideas.
RE: OM617A valve problems... - Torkey - 03-22-2016
With diesels a leaner fuel/air mix results in cooler temps, not higher. If it is a fuel issue I would expect it to be from too rich a mixture.
RE: OM617A valve problems... - zeeman - 03-22-2016
(03-22-2016, 01:32 AM)Torkey With diesels a leaner fuel/air mix results in cooler temps, not higher. If it is a fuel issue I would expect it to be from too rich a mixture.
I wonder what the shop that did the valve job found. Was the exhaust head tuliped or not. If the injectors are new it is not a fuel problem. A plugged prechamber is out if it would cause it to run cooler. And why is it just #5 all the time. What about a worn rocker arm on the valve stem side giving a phoney valve lash?
Sounds like you need to back track and find out what the machine shop that did the head found. Were there any bent valves, loose valve guides, loose seats? If not is the lash cap on the stem of the valve worn or stripped, is the lock nut stripped? When you had the head off were there any marks on the piston from a valve contacting it and was the a flame pattern from the pre chamber?
RE: OM617A valve problems... - ErikT - 03-22-2016
Thanks so far.
atypicalguy; Not measured it yet, but its better since now its starts in the cold. Previously it started until about freezing, and below that I had to use the engine heater.
Perhaps better explained:
I noticed the exhaust valve on no 5 was ruined when after constant adjustments there was nothing left to adjust. So the head was pulled of and handed of to the shop for complete rebuild (new valves, seats etc. Everything machined and fitted)
Drove it for a while but cold starts got worse. So had a dealer do a compression test and there was no compression on 1 and low on 2-5.
Pulled the engine and took things apart. New piston rings and bearings except main crankshaft bearings.
Problem on cyl 1 was exhaust valve. So the head went to the shop, where they replaced 2 valves (not sure which was the second, I wasnt the one who picked up the head), 5 guides and other small parts.
Reinstalled.
After initial valve adjustment there have been some minor adjustments to cyl 1 and one other, but no 5 exhaust is the big issue. To quantify it a bit, after driving about 350-400km the cam-rocker gap went from a little loose 0.35 to around 0.25mm
RE: OM617A valve problems... - zeeman - 03-23-2016
(03-22-2016, 05:54 PM)ErikT Thanks so far.
atypicalguy; Not measured it yet, but its better since now its starts in the cold. Previously it started until about freezing, and below that I had to use the engine heater.
Perhaps better explained:
I noticed the exhaust valve on no 5 was ruined when after constant adjustments there was nothing left to adjust. So the head was pulled of and handed of to the shop for complete rebuild (new valves, seats etc. Everything machined and fitted)
Drove it for a while but cold starts got worse. So had a dealer do a compression test and there was no compression on 1 and low on 2-5.
Pulled the engine and took things apart. New piston rings and bearings except main crankshaft bearings.
Problem on cyl 1 was exhaust valve. So the head went to the shop, where they replaced 2 valves (not sure which was the second, I wasnt the one who picked up the head), 5 guides and other small parts.
Reinstalled.
After initial valve adjustment there have been some minor adjustments to cyl 1 and one other, but no 5 exhaust is the big issue. To quantify it a bit, after driving about 350-400km the cam-rocker gap went from a little loose 0.35 to around 0.25mm
Did you replace the sleeves when you did the rings?
RE: OM617A valve problems... - ErikT - 03-23-2016
Sorry but which sleeves do you mean?
RE: OM617A valve problems... - zeeman - 03-23-2016
(03-23-2016, 10:40 AM)ErikT Sorry but which sleeves do you mean?
The piston liners.
RE: OM617A valve problems... - ErikT - 03-23-2016
Ahh..
No, didnt replace the cylinder liners.
To do that would have meant taking the block to a shop and have them install them. Liners are cheap at around $80 here, but install would be expensive. If going that far, I might also end up with needing new pistons which are around $300 each...
The cylinders looked good, still had the honing marks in them, probably from the factory.
RE: OM617A valve problems... - ErikT - 04-12-2016
Small update.
Currently wondering if the timing chain are the culprit. By using the cam/flywheel method, it looks like the chain has stretched by around 6 degrees or so.