Difficult U20 head bolt removal - need advice

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doctor_evil
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Difficult U20 head bolt removal - need advice

Post by doctor_evil »

Hello all.

It's been a while since I have posted - life, you know...

So I bought a set of ARP head bolts from Dean (Ross was sold out), and had a helluva time getting out the front short (passenger side) bolt.

Most of the others audibly squeaked as I removed them with a breaker bar, but this one just wouldn't budge.

I tried Kano Kroil, and then a few days later 50-50 ATF-Acetone, but they didn't really seem to get past the washer. I let them soak in for a week, adding a little more each evening, and trying to work the bolt with a breaker bar.

After a week, I tried using the impact driver, with small bursts, and that didn't seem to work either.

So then I laid the hot air gun to the block below this bolt, and tried the impact again, every 10 minutes.

After 50 minutes, I actually got some movement! So I got out the breaker bar, and lo and behold, out it came.

But how it looked is what concerned me.

I have attached 2 photos. One of all the removed head bolts, and one closeup of the problem bolt (#7).

I'm thinking that coolant has been leaking into this area, which is what caused the bolt getting stuck.

So the next question is, what do I do next?

In case you're wondering why I replaced the head bolts, well, I have an oil leak on the passenger side rear of the head, and few of us have had success with replacing the bolts and an "italian tune-up", so I figured that I would give that a try first.

Anhyow, I'd appreciate any and all feedback and opinions - I'll probably go with the ones that I like best. :smt003
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Bwk2000
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Re: Difficult U20 head bolt removal - need advice

Post by Bwk2000 »

It should be as simple as putting in a new head gasket and an oil change. Nothing you mentioned suggests otherwise.

P.S. Glad it didn’t snap off, that would have been a nightmare.
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Re: Difficult U20 head bolt removal - need advice

Post by spl310 »

Bottom tap the holes and clean out the trash - there will be plenty. If you are reusing the head bolts, it would be advisable to clean those threads as well.
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Re: Difficult U20 head bolt removal - need advice

Post by Gregs672000 »

Agree with all, and glad it's not broken... I over torqued a head stud on my motor and broke it but was able to get it out (bad torque wrench).

The leak is a known issue as the main return passage is there. New head gaskets have added a sealing material in that spot for that reason. It's not hurting anything though.
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doctor_evil
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Re: Difficult U20 head bolt removal - need advice

Post by doctor_evil »

Thanks all.

I have ARPs, so I turned one of the old head bolts into a thread chaser with my dremel, and got a lot of crap out of there.

I greased the whole new stud down with the ARP lube (I had extra), and will take the car out for an "Italian Tuneup" once the weather improves - we still have snow on the ground up here in the great white north.

To those of you that have done it - is changing the head gasket that tough for someone with reasonable "shade tree" experience? I'm not a trained mechanic, but Ross warned me that I might want to get someone with U20 experience to change it for me if I need it done. His comment was that heads are around $6000 now, so I'm thinking that people must be breaking things when they are taking the exhaust off...
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Re: Difficult U20 head bolt removal - need advice

Post by Gregs672000 »

No, it's not technically difficult or overly physically challenging (let me tell you, it's a walk in the park next to what I did on my 2005 BMW X3 yesterday... or near anything on a modern car/BMW). The most important thing is to put the engine at top dead center, then make sure you mark your cam sprocket to the chain (I use a sharpie and a light scratch in a different place as a back up) and that you don't drop the chain down the front. If you still have the evil L you will see what it was for... holding the cam gear and chain in place while you do the head gasket. If not, then you will have to make a chain blocker/holder to pinch the chain between the guides under the cam gear before you remove the gear and set it aside. I use a a piece of a wooden paint stick about 2-3" long that's gradually shaped to a point so it slides down between the chain and then presses the chain against the guides as you tap it down below the gear, holding the chain up (same as what's done on an L-series engine). As long as you don't rotate the engine, even if you were to drop the chain down you could still line it up with your cam and chain marks. Also, be careful when removing the tensioner as there can be washers etc that fall off and down the front... I stuff a rag down the front just in case while working on it. You will need a new tensioner gasket... use no sealer and make sure the oil feed hole is not covered up. You can make your own gasket out of very thin gasket material, just copy yours and make sure you add the oil hole. Good time to check the L for chain strikes and to shim your tensioner to keep the chain tight on start up (tech wiki if you're not aware). Use light duty loctite on the tensioner bolts. Some manifold nuts and thick washers are a pain to reach, and thinner wrenches can provide just a bit more room. The cam may rotate a little due to spring pressure, but your cam gear will go back on to the same marks though you may have to turn it against the springs a little. Feel free to call me if you get stuck and I'll try to answer or call back asap... 253 230-3484. Oh, and have the manual at hand!
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doctor_evil
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Re: Difficult U20 head bolt removal - need advice

Post by doctor_evil »

Thanks for the reply Greg!

It is on the to-do list, just after 85 other work and farm projects.

Cheers!
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Re: Difficult U20 head bolt removal - need advice

Post by Gregs672000 »

doctor_evil wrote: Fri Mar 17, 2023 7:08 pm Thanks for the reply Greg!

It is on the to-do list, just after 85 other work and farm projects.

Cheers!
You Bet! Take a look at the manual and you'll have a good idea. One other thing to consider is to change out the exhaust manifold nuts from 13mm to 12mm if they are 13s... easier to get a wrench on the 12s. Run a die down the manifold studs if they're crunchy.

The leak at the back is not hurting the engine, so do it when ever you're ready... I'll be here!
:smt006
Greg Burrows
'67 2000 #588
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