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'76 406.145 Doka tug
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Discussion Starter #1
I can no longer ignore the signs... Layer of foam on top of the coolant in the resevoir, cracked coolant expansion tank, pressure always leaking out the crack even when it's been at op. temp for hours and sometimes just lately the thermostat has been delayed in opening.

This evening, short drive home but uphill, park truck and smell coolant. Temp is 65 on guage, coolant is seeping out the crack and the level is 2 inches higher than normal, pop the cap, level rises then drops to normal, ugh.

No noticable contaminiation in the oil. Start engine and burst of white smoke. Figures, my offroading trip with guys from my new place of work is the day after tomorrow.

Running capless and buying a bike









stay tuned, soon to be a DIY thread.
 

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'78 Mog 416.141 DoKa
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3,407 Posts
From what I've read, IF it's simply a head gasket, it's not too tough. I think it can actually be done without tilting the cab if you're careful.
 

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Piece of cake. Normal advice applies:

-Use a very mild abrasive to clean the surfaces between the head and block.

-Take care with the rocker arms, etc.

-Following the head bolt tightening instructions to the letter. Make sure you go back and do the re-torque at the specified interval.

-You might as well adjust the valves while you are in there.

-You'll need at least one new valve cover gasket as well.

-Have fun!

That head is a fairly heavy slug. Tilting the cab will make it easier to handle.



-Sean Philyaw
 

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78 416 seismic truck
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Works best if you tilt the cab and two sets of hands to pull and reset the head. Be veeeerry careful not to bump or let the head sit on the injectors.

That's my best advice.
 

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'76 406.145 Doka tug
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289 Posts
Discussion Starter #5
Nearly started, I've been held up dealing with some details of the headgasket job I was doing on my roomate's turbo supra. I need it gone before I can tie up the end of the driveway with the Mog.

Tomorrow is my day off and I hope to make some progress on my mog then.
 

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'76 406.145 Doka tug
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289 Posts
Discussion Starter #6
Smooth sailing.. only fell off the ladder once. Got to loosening the third head stud nut (#22) and found only the mysterious rusty hole behind the water pump that I vaugely remembered puzzling over last time I worked on it.

Head off and the failure in the gasket is right beside the remains of the mostly missing stud.

To busy to look into it today but my hopes are that the break pattern on the stud indicates that it broke from over-tension instead of over-torque. If so I can hold hope for a smooth removal with suficient patience.
 

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'76 406.145 Doka tug
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289 Posts
Discussion Starter #7
Well... boo. Drilled through the stud and soaked in penetrating oil for a few days. After heating and cooling the area many times I had to conclude that the remains of the head stud are not extractable. I even test snapped one of my extractors in a hole in scrap metal to measure it's breaking torque to ensure I got the most possible out of the critical attempt. I was able to remove a few of the top threads with a fine chisel and found them black and somewhat corroded. Not a good sign, I can only assume the siezure goes deep and the penetrating oil probably didn't penetrate at all.

Now I am forced to drill it out compleatly and heli-coil the hole. Not what I would prefer to do. I trust heli-coils in all the previous applications I have used them,.... but a head bolt just makes me nervous. The torque is only 110 Nm (81 ft-lb).... I guess since it's my only option at this point I will simply try not to worry.

Any encouragement or words of wisdom would go far towards relieving my stress.

Now I'm gonna go watch the new Star Wars movie to get my mind off my truck troubles.
 

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Crash, I am clearly not the mechanic you are, but I have an idea if you don't already have it out. What if you hooked up the extractor to a impact with a low torque setting and hammered it? Do you think that would be too risky of breaking it off?

Daniel
 

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Unimog_404.113_1970
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you have´nt tried welding a nut to the head bolt?

that trick has worked fine for me a couple of times, the only hard part is to only weld it to the bolt, and not to the engine block ..
 

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'76 406.145 Doka tug
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289 Posts
Discussion Starter #10
The risk of breaking an extractor would be high using impact tools. The extractors are higher carbon content then normal steel, harder so they bite well but more brittle.

I like the idea of welding on a nut, however having already drilled the stud to try extractors I have too little of it left near the surface to weld to.

I will be able to fit 1 1/2 to 2 lengths of the helicoil into the hole once tapped. This is a fairly large thread contact area and I'm feeling a little more optimistic about the repair. I still am hesitant to actually drill the hole out
 

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78 406
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Look for a set of left hand drill bits. They work really good at getting stuck bolts out. Most of the time the stud just reverses out while drilling from the heat and torque. I never tried a masonary hammer drill with one but I bet that would add some loosening power to. If you don't have a set of these bits get one. They have backed out more bolts than I can remember. And if you end up drilling and Helicoiling your not wasting any time. I have never had any luck with the easy outs that came in my set of left handed bits.
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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I have successfully drilled out a head stud on a ford v8. I rented a magnetic drill press so that it would drill square to the bore. Work your way up through the bit sizes and you should find a point where you can pick out the remaining threads with a dental pick. I recall using a small magnet taped to a length of tig welding rod also. If you are very carefull to start drilling at center, you will barely touch the threads in the block, but you will have to tip the cab to fit a mag drill. Also, lay a shirt or some heavy paper on the deck before attatching the drill, you don't want to mar that surface! Good luck, Seth
 
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