OM617 head gasket removal/replacement

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Dweezil
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OM617 head gasket removal/replacement

Post by Dweezil » Fri 22 Apr, 2011 10:34 pm

Hi Team,

anyone got a relatively easy to follow guide on how to remove and replace a 300D head gasket?

Ta

Dweezil

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Re: OM617 head gasket removal/replacement

Post by Mercmad » Sat 23 Apr, 2011 8:42 am

it's very simple .Ist make sure you have the correct tools, the specific socket spanner for the head studs and three foot breaker bar, a pair of 14 mmm tappet spanners, the 5mm allen keys for the front bolts (inside the cam case too ) .a 17mm flare spanner for the injector lines , 27mm deep socket for removing the injectors and a deep 12mm socket for the glow plugs if it has the later small type.a torque wrench and an engine crane to lift the head .
Unless you are strong do not try and lift the heads on these engines.!!!!
Start by removing the glow plugs and injectors . Send the injectors off to be overhauled and test the glow plugs to make sure they are working. Set the engine to Number top dead center . let the coolant go .Dont keep it but dispose of it carefully .Dont dump it down the drain as it contains things which ruin water tables.
2/ undo the chain tensioner nut in the center of the tensioner .
3/ remove the manifolds and undo the top radiator hose .remove the thermostat housing.
4/remove the linkage and vacuum lines from the cam cover and remove the cam cover
5/ remove the steering pump and fuel filter
remove the steering pump bracket
6/ mark the timing chain and the tooth on the cam gear with paint so they go back in the same place.
7/
Remove the cam gear
8/ remove rockers by undoing the retaining bolts and pulling the rockers to the side.
9/ remove the cam shaft by undoing the pedestal mount bolts.
10/ Undo the earth cable at the rear of the head
11/ Loosen the head bolts ,then remove each one . including the ones inside the chain case .
12/ hook your engine crane to the rear lifting lug and to the front of the head
13/ take the weight of the head then see if it comes free.
if it doesn't ,get a block of wood and large hammer. place the wood against the ports and whack the wood with the hammer to shock the gasket free until the head lifts off the block.
Overhual the head and do the reverse to fit it back again.

measure the head bolts. Do not reuse the bolts if they do not meet specs as the gasket will blow again.

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Tue 16 Jul, 2013 1:22 pm

Ok, getting near the time to bite the bullet and do this. Coupla questions, though. Is the gasket common to Series I and Series II? Secondly, I'm paranoid about stripping or breaking the head bolts. Is there a way to minimise risk here?

Thanks

Dweezil

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Re: OM617 head gasket removal/replacement

Post by John Green » Tue 16 Jul, 2013 8:51 pm

Head studs breaking on these is very rare, I would say you are more likely to strip a manifold stud or maybe one of the banjo bolts for the water pump breather (which you always replace, never reuse them)
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OM617 head gasket removal/replacement

Post by ansteadeh » Tue 16 Jul, 2013 10:08 pm

Those head bolts are very very tight and shouldn't break. Make sure you have the star socket seated very well in the head bolt. Clean out any rubbish and gently tap the socket home.

Lots of muscles required. These are class 10 or greater bolts and very very hard.

Tightening is fun too. You think they could not go tighter, and the manual calls for them to be turned another 1/2 or 1/4 turn (I can't remember) after they have been tensioned to the spec. They are designed to stretch.

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Fri 30 Mar, 2018 11:00 pm

OK, so seven years later I'm finally getting around to this.

I bought some spray head gasket sealant which was highly recommended. Any idea how much I use, and can I use the same stuff on the manifold gasket.

Any tips on getting the chain to keep its tension while lifting the head up and out of the way?

Thanks

Dweezil

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Re: OM617 head gasket removal/replacement

Post by Mercmad » Sat 31 Mar, 2018 11:12 am

First, release the chain tensioner! . you have to take the chain wheel off anyway . set the engine to number one TDC . so when you go to reinstall the head the timing is OK. (just line the cam marks up) . I have never used any type of sealer on heads , if the block is flat and the head surface is also flat, you dont need anything. manifolds maybe as they are often misaligned after years of heating and cooling . Have you got an engine crane ready to lift the head off ? it is damn heavy and you will damage yourself trying to remove it on your own .

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Sun 01 Apr, 2018 11:27 am

Thanks, Ron.

Yes, I was going to release the chain tensioner, but I seem to have a misunderstand as to how it works.

I was expecting to see a long bolt that just screws in an out to add/release tension, but when I take off the 22mm nut on the end:
Chain_tensioner_nut.jpg
this is what I see in the 'tube':
Chain_tensioner_tube.jpg
What the hell do I do with that? How far does one pull back the guide? Are we talking inches or mm here? Where's the spring that some folks talk about?

I've also got a problem where the 'inner' exhaust pipe connection nut is in danger of rounding off. It looks accessible, but the curve of the manifold makes it almost impossible. Anyone got any tips there? Can I leave the exhaust manifold in place and move the head sideways towards the left so that the bolts clear the in-situ manifold? Does that make sense?

And yes, I've got an engine hoist with which to do the removal. I'm silly, but I'm not that silly.

Thanks again.

Dweezil
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Sun 01 Apr, 2018 12:10 pm

Oh, and I just realise the ambiguity of "Any tips on getting the chain to keep its tension while lifting the head up and out of the way?"

What I was referring to was keeping tension on the chain from the top while taking the head off so that the chain doesn't collapse downwards and skip a tooth. Here's a crappy drawing to show what I mean:
chain_tension.jpg
Once the head gets above the level of the 'hook' in this diagram it gets tricky.
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Re: OM617 head gasket removal/replacement

Post by Christo C » Sun 01 Apr, 2018 12:28 pm

Put some stiff wires or rod through the chain in the gap between block & head....
~Christo
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Sun 01 Apr, 2018 1:24 pm

Thanks, Christo.

I was thinking an old wire coat hanger should do the trick. Anyone else got a nifty suggestion?

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Sun 01 Apr, 2018 1:42 pm

Ok, another potential problem...

In loosening the chain tensioner and then rotating the cam sprocket to get it to Top Dead Centre, I may have already jumped a tooth. The timing mark is showing as about 9deg before TDC.

Is it stuffed, and if so, how do I fix it?

Thanks

Dweezil

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Re: OM617 head gasket removal/replacement

Post by Tony From West Oz » Sun 01 Apr, 2018 9:38 pm

It shouldn't have jumped a tooth if you rotated the engine in the correct direction.
Check at TDC, the IP timing mark and the cam timing mark. Both should line up with the appropriate mark on the engine.
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Re: OM617 head gasket removal/replacement

Post by Mercmad » Mon 02 Apr, 2018 7:28 am

it wont jump a tooth, all that can happen is that you dont align the crank and cam mark s correctly . it pays to do a spill test on the ijection pump too,just to make sure once the chain is re-tightened . Replace the chain after you reinstall the head by linking a new chain to the end of the old one and winding it through.

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Re: OM617 head gasket removal/replacement

Post by Simon Dove » Mon 02 Apr, 2018 7:53 am

When doing the head bolts put rags or something similar in and around the front timing chain cavity when removing and installing the two 5mm hex bolts . If you don't they may fall into the timing cavity and you may spend hrs pulling sump etc trying to find the bolt........how do I know that you ask?.... :Doh:
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Mon 02 Apr, 2018 9:08 am

Thanks, guys.

My question still is, though, why is it showing 9 deg before top dead centre? Is it indicative of another problem?

There's another angle to all this, and why I'm concerned about the timing. The IP isn't firing on the first line, and I've got another pump that's fine on another OM617. I was going to do a swap - as long as they were both on top dead centre. If they're out, I'm possibly in a world of pain there.

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Re: OM617 head gasket removal/replacement

Post by Mercmad » Mon 02 Apr, 2018 9:48 am

yes, anything higher than 5 degrees means the cam chain is worn out , time for a new one . If the teeth on the cam wheel are sharp ,you may need to replace that too, but it's rare that it ever needs changing. Dont worry about dropping stuff into the sump, it comes off easily and i usually drop them any way to clean them out. After a few hundred thousand miles there will crap sitting in there.

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Tue 10 Apr, 2018 3:51 pm

Ok, so I finally got around to removing the head today.

Disconcertingly, the gasket looked ok. There's no obvious piston slap, so what are the parameters for a good leak-down test, and what's the likelihood that I've got a cracked head. Anyone know of any good magnafluxers in Sydney?

Thanks

Dweezil
Jurgen_gasket_1_2.jpg
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Tue 10 Apr, 2018 3:53 pm

Jurgen_block_1_2.jpg
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Jurgen_block_4_5.jpg
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Re: OM617 head gasket removal/replacement

Post by merc-304 » Tue 10 Apr, 2018 4:45 pm

Post a pic of the Head/Valves
Any of the chambers look cleaner than others ?
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Re: OM617 head gasket removal/replacement

Post by Christo C » Tue 10 Apr, 2018 5:17 pm

Disconcertingly, the gasket looked ok.
What were the original symptoms which led ypu to the conclusion the head gasket needed changing?
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Tue 10 Apr, 2018 6:10 pm

Thought the gasket had gone due to failure to start and zero compression on Cyls 2 and 3.

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Re: OM617 head gasket removal/replacement

Post by Christo C » Wed 11 Apr, 2018 1:19 am

failure to start and zero compression on Cyls 2 and 3
Head gasket wouldn't have been high on my list of suspects; stuck valves or failed valve-stem springs or seals come to mind.
Anyway you have the head off now, so I would have it checked & refurbished by a professional.
Some of those holes in your block look pretty grotty.
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Re: OM617 head gasket removal/replacement

Post by Mercmad » Wed 11 Apr, 2018 6:47 am

On all of these mercedes Diesels one thing needs to be done before you remove the head. it's a tappet adjustment then a leak down test,to determine if the rings are good or the valves aren't sealing properly . The Tappets on these do not get loose with time, they tighten up . This is the usual cause of hard starting (besides bad glow plugs) . Now that you have the head off get the head rebuilt with new guides, it will then last you forever. John at MB classic in greenacre has an automotive machinist working with him and has plenty of parts on hand to rebuilt your head.

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Re: OM617 head gasket removal/replacement

Post by Dweezil » Thu 12 Apr, 2018 1:26 pm

Thanks guys. The valve clearances were indeed done before the compression test.

A few more questions:

I've never done a leak-down test before. What parameters should I be looking at?

Is there anything I can specifically check on the head before I send it away?

How much would one typically pay for (ahem) a head job?

Thanks

Dweezil

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Re: OM617 head gasket removal/replacement

Post by Christo C » Thu 12 Apr, 2018 3:49 pm

Google
cylinder leak down test diesel engine
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Fri 13 Apr, 2018 12:23 am

Christo C wrote:
Thu 12 Apr, 2018 3:49 pm
Google
cylinder leak down test diesel engine
Hi Christo,

I always thought a leak down test was a thing where you put petrol into the open cylinder and saw how long it took to go down, say, and inch. The stuff I saw was air pressure stuff, which obviously I shoulda done before I took the head off.

Is anyone au fait with the petrol method?

Thanks

David

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Re: OM617 head gasket removal/replacement

Post by Christo C » Fri 13 Apr, 2018 6:37 am

I always thought a leak down test was a thing where you put petrol into the open cylinder and saw how long it took to go down, say, and inch. The stuff I saw was air pressure stuff, which obviously I shoulda done before I took the head off.

I don't think I'd be putting Petrol anywhere near a Diesel, nor any other liquid into the pots - air will not kill you, or the sump oil should it leak down there.
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Re: OM617 head gasket removal/replacement

Post by Dweezil » Mon 23 Apr, 2018 5:37 pm

Hi Team,

so I indeed put about an inch of petrol into cylinders 2-5. The quickest to empty was #2 in about 15 minutes, the rest not too far from that.

Does this mean that the rings are shot?

I've got a spare OM617 that had a new timing chain and head work done about 30,000km ago, but the compression isn't great there, either. Does anyone know where I can get the right connector to do an air compressor leak-down test while the head is still on to see if it's looking ok?

Thanks

Dweezil

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Re: OM617 head gasket removal/replacement

Post by Christo C » Mon 23 Apr, 2018 7:23 pm

so I indeed put about an inch of petrol into cylinders 2-5. The quickest to empty was #2 in about 15 minutes, the rest not too far from that.
Petrol in a diesel engine - good move... will tell you nothing.
I wash my hands of any further comment or advice.
~Christo
1986 230E W124.023 M102.982 ~290,000km Thistle Green Saloon "Janis"

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