Author Topic: Doing 6.9 head gaskets soon, please offer advice/tips/etc  (Read 7165 times)

3l33ter

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I got my 6.9 almost a year ago, but I haven't had a chance to touch it since then. It's been in my driveway while I've been finishing other projects.

It needs head gaskets so I'm planning to do that next week. I already have the new gaskets from MB. My plan is to take the heads to my machinist to be checked, and any necessary work done. Some relevant info: It has 160k miles, ran well when parked, except for the slight mixing of coolant and oil, and it needs a smog check as soon as it's running again.

Is there anything special to watch out for when doing this job? Do I need to buy any special tools? Any while-I'm-in-there things to do?

Thanks in advance!

Hopefully when it's running I can make a proper introduction thread.
'75 280S
'77 6.9
'82 300TD

oversize

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #1 on: 13 June 2014, 04:11 PM »
Consider all the other gaskets you'll need as well. Lots of the rubber hoses and connectors will be brittle and will probably break on removal.
Check the timing chain for stretch and the cam sprockets and rails for wear.
It's quite common for some of the inlet manifold bolts to break as they enter the cooling system and corrode. Valve guides and stem steals will probably need to be reconditioned or replaced.  You may need the headbolt tool so you can torque the bolts down around the cam towers. Personally I'd pull the engine to do this job but in situ you may find you have to remove the brake booster to get clearance for removal...
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

oversize

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #2 on: 13 June 2014, 04:17 PM »
Oh and you'll need cam oiler connectors and exhaust manifold nuts. Consider resealing the water pump and replacing the front crankshaft seal
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

3l33ter

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #3 on: 18 June 2014, 01:48 PM »
Thanks for the info!

What's the head bolt tool? A special socket?

What's a cam oiler connector?

I think I'd rather remove the brake booster than pull the engine, I'll go that route first.
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'77 6.9
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CraigS

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #4 on: 18 June 2014, 06:48 PM »
It's a pig of a job - especially on a right hand drive. To get the booster out, it is easier to remove the instrument cluster to get at the top nut. The other 3 are OK. You should also change the steering coupling while the exhaust manifolds are off. Get a VRS kit for the engine. This however will not include the injector seals. The special tool for the head bolts is a hook tool that goes around the cam and is all but impossible to do without. As mentioned, there is a strong possibility of breaking some of the studs that hold the intake manifold on - front left and 2 front right. Change the engine mounts at the same time and check the small dampers. Change the timing chain and make sure the chain adjustor is working properly. Replace the rubber boot that attaches the throttle body to the intake manifold and replace the two special clamps.

3l33ter

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #5 on: 20 June 2014, 12:23 PM »
Is this the tool you're talking about?

http://www.pelicanparts.com/catalog/shopcart/TOOL/POR_TOOL_MERCED_pg14.htm

I think I can make one of those. Gotta go buy a sacrificial allen wrench and some bar stock. :)

I'll wait until I'm in there, so I can measure dimensions and clearances.
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CraigS

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #6 on: 21 June 2014, 02:47 PM »
That's the one.

rob280sel

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #7 on: 22 June 2014, 04:35 PM »
While the heads are off take them to a head re-conditioner to check warp/porosity/hardness/cracks and how the valves,guides and seats are going.
Because why did the head gasket go in the first place?
No use putting the heads back on and find you have to do it all again.

3l33ter

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #8 on: 17 November 2014, 05:34 PM »
OK, it's been a while, but I finally got around to putting some more time into the 6.9. I got a valve cover off and I see why I'd need the curved allen tool for the head bolts.

But, what if I just take the camshaft off first? I need to take that off anyway, so actually I don't see the need for the special tool at all...
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'82 300TD

marku

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #9 on: 18 November 2014, 10:08 AM »
You can do it without the special tool and there really is no point in making one or at least how I tried to make it. Welded an allen key which when used actually twisted it in to a spiral. Use a key in a socket tap it firmly in first and then fit the bar extension it just works. You can take the cam off first but you will need to torque them all down when re-fitted. Machined the heads, reseated valves (MB say take the same of the seats as the head) and replaced guides and seals. Be wary of exhaust manifold studs they break really easily. Head kits come with all gaskets but not water pump. Doing the 450 in place was hard enough so don't envy you with the 6.9. Good luck.
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TJ 450

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #10 on: 19 November 2014, 07:06 AM »
The special tool is for the M117... I don't think anything is required for the M100. Cam oiler fittings are not present on this engine either... it's rock solid with no plastic fittings.

You can't buy a new water pump, or at least it's $$$$, so a recon is really the only feasible option... they're listed on eBay. Count on breaking a few bolts, as they invariably do.

Tim
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koan

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #11 on: 20 November 2014, 02:44 AM »
This is a big job that will take some time to do properly.

If you get the valves and guides done which is worth doing given the amount of work involved to do head gaskets you are going to need a spring compressor and go/no-go gauge to readjust the valve "clearances".

Have a look through koan gallery, in "Tools" you'll see my DIY bent allen key done with heat, and my DIY spring compressor design. Also under "Engine work" there's a few pictures taken during the job.

Also in my gallery in "Misc" on the second page is "M100_head_bolt_caution" which is about the spacer on front head bolt of LHS head.

One problem I encountered was getting the inlet manifold off, the EGR pipe gets stuck under the cylinder head overhang, it's a pain.

I seem to remember having to undo engine mounts and jack the engine up to get exhaust manifolds off.

As I said it's a big job and there's lots of other things that may be worth replacing along the way, timing chain, chain guides, tensioner rail, previously mentioned crank seal... it goes on and on...

Good luck.

Ken
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3l33ter

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #12 on: 24 November 2014, 05:06 PM »
Did you have to take off the brake booster to get the driver side head off?

I was doing great not breaking any bolts until the front left bolt on the upper intake. That sucker is seized badly. I drilled the head off, and I can't pull the intake off. Next, I will drill a pilot hole into the bolt shank and try a bolt extractor.

I still need to pull the exhaust manifolds, entire intake, cams/chain, and then the heads go to my machinist.

I was quoted about $500 for all the valve guides from my local dealer. Does that sound right? Also, I bought the head gaskets from them for $150 each after begging for a discount, but that's just the head gaskets alone.
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'77 6.9
'82 300TD

koan

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #13 on: 24 November 2014, 10:45 PM »
Did you have to take off the brake booster to get the driver side head off?

On RHD you do.
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CraigS

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Re: Doing 6.9 head gaskets soon, please offer advice/tips/etc
« Reply #14 on: 25 November 2014, 02:15 PM »


I was doing great not breaking any bolts until the front left bolt on the upper intake. That sucker is seized badly. I drilled the head off, and I can't pull the intake off. Next, I will drill a pilot hole into the bolt shank and try a bolt extractor.



Unless you have the bolts off both sides, you will never get it off. They are angled at about 45 degrees to each other so you are pulling against the tension on the opposite side. If you can get one of the two out, you have a chance. It is very easy to damage either the intake or the head if you get it wrong. Might be better to get someone to drill out the broken studs before trying to remove the intake.