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+--- Thread: Rebuilding OM617 Head (/showthread.php?tid=3330)
Rebuilding OM617 Head - Graminal95 - 02-08-2012
I have a OM617.952 what I want to put into my 240D. The engine has very little blow-by even with 330K, but the valve guides are worn out along with the valves.
I have a spare head I picked up from a yard a few years back but that was also worn out and I am thinking of rebuilding it. I don't have much money to spend, and was looking at buying all new valves, guides, seals, etc. I can get non sodium filled exhaust valves for about 22 USD, or sodium filled for 32 USD each. Will it make that much difference in the longevity of the engine?
The total with machine shop work will be 500+, which for me is a lot of money. Is there a good alternative without buying another unknown head?
RE: Rebuilding OM617 Head - serverman777 - 02-08-2012
Personally I think it would be with your time rebuilding it yourself. Should be a fun little project.
RE: Rebuilding OM617 Head - JustPassinThru - 02-08-2012
About 20 years ago I did a "kitchen table overhaul" on the head of my W123 230 gasser. Inexpensive and effective. Just the guides and seals. Had the valve faces and head seats ground to the correct angle spec by a machine shop, and lapped the seats/faces myself. Bought the Woodruff key by which timing chain stretch is compensated-for. None of my valves was bent or excessively worn, so I didn't replace any. I would recommend you stick with sodium-filled valves, because they have much better heat transfer and so less danger of burning the faces.
To pull the timing chain tensioner fastening pins, I concocted this tool: machine screw to go in the pins (they are threaded); big fender washer at the head of the machine screw, held there by a nut; gear puller to grab onto the fender washer; and a metal tripod, welded-up from an old fireplace gridiron, to give the gear puller's hooks something to grab onto. I could not bring myself to pull the pins the Mercedes dealership service department way, which was using a slide hammer.
One piece of advice not in the manual: when you remove the cylinder head bolts, and pull the head off, thoroughly swab out any coolant which falls into the bolt holes. Get those holes perfectly dry!!! Otherwise, after you reassemble and get it back on the road, the water will flash to steam, expand, and push a crack out the head gasket. I learned this the hard way.
RE: Rebuilding OM617 Head - ronnie - 02-08-2012
are you giving up on the turbo'd 616? if so why?
RE: Rebuilding OM617 Head - DeliveryValve - 02-08-2012
(02-08-2012, 09:09 AM)Graminal95 ... I can get non sodium filled exhaust valves for about 22 USD, or sodium filled for 32 USD each. Will it make that much difference in the longevity of the engine? ..
Yes they will. MB installed sodium valves in a turbo motor to keep the valves cooler. This will in turn reduces wear on the valve guides and stems.
.
RE: Rebuilding OM617 Head - ronnie - 02-08-2012
I did put sodium filled valves in my 616 rebuild. You may want to think about new valve springs too. Have not heard of any breaking but they do have a fatigue life.
RE: Rebuilding OM617 Head - Graminal95 - 02-09-2012
(02-08-2012, 08:01 PM)ronnie are you giving up on the turbo'd 616? if so why?
There are a few reasons I'm going to swap out the 616 to the 617.
First off I have a spare engine from my fathers car that is in very good shape besides the valves. So being broke and cheap, this seems like a viable swap.
Second when I bought the 616 with something like 105K on it, there was a good amount of blow by. Now with over 210K, she eats a bit of oil from the blow maybe as much as 2L per 3K miles. She still starts and runs well and the mpg's are still in the low to mid 30's, but is costing me a bit in oil and having to think about topping up can be annoying when lending the car to others.
Third and the real reason, is that the 5 speed I put in the car has a natural frequency that is excited by the 616 at around 3200-3800 rpm, making the car noisy and not very fun to drive. I have tried to make the 616 smoother at those rpms but was not successful. The 617 in my fathers car is very smooth though out the engine operating range and should clear this issue up nicely.
I really like the simplicity of the 616 and all the extra room I have to work with in the engine compartment, but I need to work with what I have and that means the 617. Plus the extra ponies will be welcome, as I only have a 3.69 and 2.88 diff to work with and I have chosen the 2.88. Unless someone in the area wants to trade.
RE: Rebuilding OM617 Head - Simpler=Better - 02-09-2012
Have you tried a heavier flywheel with the 616? That might help balance things out. Maybe change your rear diff to lower/ raise the powerband?
As for rebuilding the head, It's not too hard to pull everything yourself. I just finished stripping & porting my 617's head, and dropped it off to be hot tanked / valves reseated / valves reinstalled. I think my total cost will be around $250. I'm reusing everything but the valve seals.
RE: Rebuilding OM617 Head - Graminal95 - 02-09-2012
Ronnie where did you buy your head spares? I have been looking all over to find the cheapest deal and all told the parts to rebuild the head will set me back over 350 dollars. Then there is the machining of the valve seats ~85 dollars, and guide instillation ~45 dollars.
Maybe it would be cheaper to buy a rebuilt head from adsitco for 445. The only issue is that they have some pretty bad reviews from people.
(02-09-2012, 09:11 AM)Simpler=Better Have you tried a heavier flywheel with the 616? That might help balance things out. Maybe change your rear diff to lower/ raise the powerband?
As for rebuilding the head, It's not too hard to pull everything yourself. I just finished stripping & porting my 617's head, and dropped it off to be hot tanked / valves reseated / valves reinstalled. I think my total cost will be around $250. I'm reusing everything but the valve seals.
I would have to pick up a 617 flywheel which is hard to find and very expensive if I can find one. I thought the vibes were from the IP not controlling the rack correctly at those RPMs but I added a rack damper and upper the idle compensation screw but this had no effect. At this point I think its just the nature of this tired old girl.
I have a spare head I pulled from a yard two years ago anticipating the rebuild. I stripped the head and according to MB the valves are no longer in spec and cannot be ground. The guides are shot too. I know the valves in the head on the car are shot too as they have been wearing into the head causing the clearance to become zero within a few thousand miles.
RE: Rebuilding OM617 Head - Simpler=Better - 02-09-2012
Could you take your 240 flywheel to a shop and have a plate / or/ weights welded to it and rebalanced? I'm thinking of modifying the stock 616 flywheel to make it heavier.
RE: Rebuilding OM617 Head - Graminal95 - 02-09-2012
Ya Ya, lucky you. If your at all serious and want to sell it for like 50 buck I'll send you cash now.
RE: Rebuilding OM617 Head - ronnie - 02-09-2012
I bought all my engine parts from peach parts.
exhaust valves soduim filled $35 each
intake 25 each
valve guides 7 each
valve springs 5.50 each
head gasket set with valve seals 50
I am getting a harmonic vibration about 45 if I am in fourth. Usually still in third at this speed though. All other speeds very smooth.
I wonder how much more power the stock clutch can hold though, as I plan to do an ip with larger elements.As far as power I can climb the same steep hill faster with my 240 now then the 300 turbo ever went up it. So this would say I am at more power now then the 617a had. So for me going to a 617a would be a step backwards, unless I did performance upgrades to it. But then I would lose the good handling of the 240.
RE: Rebuilding OM617 Head - ConnClark - 02-09-2012
If I were going to redo my head I would have a lot at the possibility of using titanium and/or springs.
RE: Rebuilding OM617 Head - Simpler=Better - 02-09-2012
Where would you use the titanium?
RE: Rebuilding OM617 Head - ConnClark - 02-09-2012
oops, forgot the word valves after the word titanium.
RE: Rebuilding OM617 Head - ronnie - 02-09-2012
wonder what the cost of titanium valves would be? They are used on very high performance engines, but would be way overkill for most of us.
RE: Rebuilding OM617 Head - sassparilla_kid - 02-10-2012
Properly overkilled
RE: Rebuilding OM617 Head - Graminal95 - 02-10-2012
(02-09-2012, 07:03 PM)ronnie I bought all my engine parts from peach parts.
exhaust valves soduim filled $35 each
intake 25 each
valve guides 7 each
valve springs 5.50 each
head gasket set with valve seals 50
I am getting a harmonic vibration about 45 if I am in fourth. Usually still in third at this speed though. All other speeds very smooth.
I wonder how much more power the stock clutch can hold though, as I plan to do an ip with larger elements.As far as power I can climb the same steep hill faster with my 240 now then the 300 turbo ever went up it. So this would say I am at more power now then the 617a had. So for me going to a 617a would be a step backwards, unless I did performance upgrades to it. But then I would lose the good handling of the 240.
Thanks for the pricing info. I guess what I estimated for cost is going to be correct.
I think the stock clutch will be fine for fairly high power, but have no real way of knowing.
Are you going to dyno your 240D? I would love to see the sheet. My car according to dynolicious had something like 88hp, so not a huge improvement in power, just economy.
RE: Rebuilding OM617 Head - ConnClark - 02-10-2012
(02-09-2012, 08:47 PM)ronnie wonder what the cost of titanium valves would be? They are used on very high performance engines, but would be way overkill for most of us.
I see prices at $125+ for each one (assuming you can get them for our engines). *ouch* Yes they would be over kill but the reduction in valve train losses would be nice. It would save fuel too.
RE: Rebuilding OM617 Head - sassparilla_kid - 02-10-2012
Hmm any approximations on numbers for the gains?
RE: Rebuilding OM617 Head - ronnie - 02-10-2012
I have not found a dyno near me, so for now no. Would like to though.
RE: Rebuilding OM617 Head - ConnClark - 02-13-2012
(02-10-2012, 05:55 PM)sassparilla_kid Hmm any approximations on numbers for the gains?
The numbers are hard to quantify but valve train losses are about 6 to 10% of the engine friction. If you have a set of valves and want to get an idea of what sort of change it makes compare shaking five valves back in forth as fast as you can to shaking just three at the same speed. Now remember your engine moves one valve per cylinder for every RPM.
The reduction in force required to open the valve also results in less friction on the rocker rubbing the cam and the cam bearings. This intern reduces timing chain stretch.
RE: Rebuilding OM617 Head - larsalan - 02-13-2012
So having a lighter valve will require less force to open/close than a heavier valve?
Isn't the cam pushing against the valve spring? I'm not saying that the titanium valves wouldn't be better. However, I have a hard time equating your logic or parable to what actually happens in the motor.
RE: Rebuilding OM617 Head - ConnClark - 02-13-2012
(02-13-2012, 05:10 PM)larsalan So having a lighter valve will require less force to open/close than a heavier valve?yes, it has less inertia to overcome.
Quote:Isn't the cam pushing against the valve spring? I'm not saying that the titanium valves wouldn't be better. However, I have a hard time equating your logic or parable to what actually happens in the motor.
The valve spring still pushes against the cam. The thing is that when you open the valve the cam is fighting the force of the spring plus the inertia of the valve.
RE: Rebuilding OM617 Head - larsalan - 02-13-2012
I would assert that the inertia of either a titanium or steel valve is quite negligible compared to the force of the spring.
So inertia or momentum should be something like p=mv. p-momentum m-mass v-velocity
I guess the mass difference between the two different valves is quite small. And to read into that equation we will see that the difference in weight is most noticeable when the velocity is larger.
Now then, the velocity the valve will move at should be greater at high rpms. How much greater I couldn't say, I would imagine it's direct correlation. Like 2000rpm the valve velocity is twice what it is at 1000rpm. At least that tells you the performance gains should come more at high rpm than low.
Dig that?
RE: Rebuilding OM617 Head - ronnie - 02-13-2012
being less inertia, then maybe a lighter valve spring may work?and titanium keepers with a hardened tip. Thereby lowering energy needed even more.
If we where to go all out then we need roller rockers(followers), perhaps in a high strength aluminum. Of course if you are doing a chevy engine all this is readily available.
My guess would be that this would only gain a few hp at the rpm's we are running. Anyone know what the differance on a chevy v-8 would be, at a reasonable rpm like 4000? we could corilate this to ours by half. So IF the chevy makes 10 more from all the above we would make about 5 more, at least theoritically.
realistically speaking I would ream out the pc burn holes about .010 thousand. This gave me a real gain of about 10%, and lowered egt's a good bit. Known gain, not to hard to do, and no exotic hardware.
RE: Rebuilding OM617 Head - ConnClark - 02-13-2012
(02-13-2012, 06:31 PM)larsalan I would assert that the inertia of either a titanium or steel valve is quite negligible compared to the force of the spring.yes the forces are higher at higher rpms. its a second order equation however as you have to accelerate the valve to twice the speed in half the time. In the end you need 4 times the force.
So inertia or momentum should be something like p=mv. p-momentum m-mass v-velocity
I guess the mass difference between the two different valves is quite small. And to read into that equation we will see that the difference in weight is most noticeable when the velocity is larger.
Now then, the velocity the valve will move at should be greater at high rpms. How much greater I couldn't say, I would imagine it's direct correlation. Like 2000rpm the valve velocity is twice what it is at 1000rpm. At least that tells you the performance gains should come more at high rpm than low.
Dig that?
Titanium valves are about 60 to 70% percent the weight of a steel valve. If you want to calculate the force required you can adapt the method used here. (I don't have time right now but might later)
http://www.tech.plym.ac.uk/sme/desnotes/valvet1.htm
RE: Rebuilding OM617 Head - sassparilla_kid - 02-14-2012
(02-13-2012, 07:03 PM)ronnie being less inertia, then maybe a lighter valve spring may work?
Wouldn't this just cause the valves to float?
RE: Rebuilding OM617 Head - ronnie - 02-14-2012
Not sure, just thinking if the valve is lighter then then there is less mass to get moving so it would seem reasonable that less spring would do the same job.
RE: Rebuilding OM617 Head - sassparilla_kid - 02-14-2012
I guess it could work, I'm not too familiar with all of this high performance stuff lol
RE: Rebuilding OM617 Head - ConnClark - 02-14-2012
There are some obstacles to using a weaker spring on a turbo engine. Boost and back pressure can sometimes open the valves if they are too weak.
RE: Rebuilding OM617 Head - pyrojoe22 - 02-23-2012
(02-09-2012, 09:32 AM)Graminal95 I would have to pick up a 617 flywheel which is hard to find and very expensive if I can find one.
I have a flywheel from my OM617.951 from an '83 300SD that I won't be needing after I get the engine adapted to my Toyota transmission.
RE: Rebuilding OM617 Head - SurfRodder - 02-23-2012
I've got a head in the shop (been there for almost a year now, neither I nor the machinist is super motivated to get it done). The plan is to hog out the head to accept the largest aftermarket valves that will physically fit (Ferrea stainless in a common size, likely non-metric and then machined to fit). The valve my machinist was thinking about are smaller diameter shaft and should also help out a bit with valvetrain weight...the largest advantage of reducing the weight is less wear and tear on the timing system, like stated above a SB chebby may make slightly more power with the ultimate valvetrain setup, but the cost/HP ratio is quite unfavorable.
Valve seal technology has come a long way since these engines were built, let alone designed so this will be a nice upgrade as well, I will use some sort of hybrid neoprene/viton most likely. If youre gonna have all the machining done to your head anyway, I'd recommend talking to the guy doing it to see how much it would be to upgrade the seals a bit. Another cool thing about doing this is that seal replacement could be much easier if the future, if you do your homework. (read: easier to source AND easier to actually replace with head still installed)
RE: sodium valves; if youre using stockish valves, definitely use sodium filled on the exhaust. If going aftermarket, it's not really that important as the newer alloys are so far beyond whats in these from the factory.
I like the idea about fattening up the holes in the prechambers, I'll likely utilize that trick in my build as well.