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  #1  
Old 04-16-2022, 01:46 PM
Echo1975 Echo1975 is offline
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Unhappy Injector thread on head cracked making engine run like garbage

Yesterday I messed up big time by removing the injectors from my car. Injector #4 had seized on the head and my dumbass removed it with a massive lever on a socket, which cracked the head on the threads of course. There is a chunk gone from the head down to the injector heat shield shim.
I drove it like that and it made it even worse. The entire engine bay is wet from fuel spraying all over and it makes a sharp loud sound every time it goes on compression stroke.

If you wonder how awful it sounds, imagine running a gas engine without a spark plug. It sounds exactly like that with an attempt at combustion.

I know I messed it up and I am wondering if I can fix the leak with TIG?

I have work on Tuesday and don't want to cause further damage to it.
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  #2  
Old 04-16-2022, 02:02 PM
v8volvo v8volvo is offline
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We have seen this once or twice before. Many of us are now careful when removing injectors to make sure we're always pulling with the force of the lever direct towards the inside of the head rather than the outside where the aluminum is very thin and can be cracked. I realize that info is not useful to you at this point though.

The only proper repairs would involve removal of the head. But given your situation I don't see why it wouldn't be worth an attempt to fix with TIG. There is no reason it shouldn't work and you don't really have anything to lose by trying. The only risk I think might be that it could make it impossible to remove that injector ever again. But that is a small price to pay if it gets the engine running again. Worst case if you ever had to get the injector out it would mean removing/replacing the whole head in the future.... but that's what you're facing right now anyway, so no difference to you.

If you try it, please share pictures and let us know how it turns out, we'll cross fingers for it to work for you.
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  #3  
Old 04-17-2022, 10:17 AM
Echo1975 Echo1975 is offline
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It turns out the sealing issue wasn't because of the thread breaking. Some previous owner had failed to properly make sure the injector seals.

The threads were black and under the heat shield it was curved and I tried to correct it but because of the piece breaking off, the threads gave up and the head is probably ruined or requires expensive treatment because I just couldn't get the mating surface straight.

So I pulled the head today and borrowed my dad's car. I'm going to part out a junkyard car and take the head from one of those next week. I will definitely make sure the injectors come out without breaking anything this time.
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Old 04-17-2022, 01:36 PM
v8volvo v8volvo is offline
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That is a bummer but it sounds like you are right, head replacement (or at least repair off the engine) is the only good option.

I think you are also right that the problems with the injector threads were not your fault, they were probably caused by the owner before you. If the injector is not sealed fully into the head (i.e. if the sealing heatshield is not replaced and/or if the injector is cross-threaded during installation and does not meet the seal flush), then just like you describe, the leaking compression will cause the threads to become packed with soot. Then it becomes very hard to unscrew the injector and could lead to destroying the head in the attempt.

I actually have a tool that someone made from the bottom half of an injector with slots cut into the threaded part, intended to be used as a thread chaser to clean up the threads in the cylinder head after soot leakage has occurred in a situation like this. But if the injector cannot be removed without damage to the head casting itself, like in your case, it doesn't help.

Good luck and hopefully at least it gives you a good opportunity to refresh some other stuff while you are in there like timing belts, etc.
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Old 04-18-2022, 11:17 AM
ngoma ngoma is offline
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Quote:
Originally Posted by Echo1975 View Post
It turns out the sealing issue wasn't because of the thread breaking. Some previous owner had failed to properly make sure the injector seals.

The threads were black and under the heat shield it was curved and I tried to correct it...
Probably too late but:::::::::::: Isn't the seat supposed to be curved? To mate with the convex shape of the heat shield? If you look at the lower surface of the heat shield it is convex along the sealing surface, with subtle ridges to bite into the aluminum head to get a good seal.
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  #6  
Old 04-20-2022, 12:54 PM
Echo1975 Echo1975 is offline
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I guess the seat is supposed to be curved in a way but this one had missing metal on it compared to the others. I obtained a used head and gave it to a machine shop to check that it's good.

The new head has the same issue with the injectors but I soaked it with rust remover and heated the injectors and got them off without breaking anything. I made sure to twist the injectors in a way which puts the force against the thick part of the head. The machine shop owner told me he can check the injector surfaces for me and correct them if they are wrong.

I actually ended buying another diesel beater so I'm not in such a hurry to get the Volvo fixed.

I would post pictures of the head damage but I am not sure what image url means.

Incase anyone reads this in the future and has the same problem.

Soak it with something like WD40 or rust off. I have heard that oil and brake fluid work with the ladder being very effective but haven't tried it.

I also recommend heating the thread part which might help it come loose. I didn't heat mine above 300 F.

The most important part is to direct the force away from the weak side of the thread like the previous answers state to avoid cracking the head.

Smacking the lever with my hand got the injector to loosen up and then I turned it back and got it out in under 30 minutes.

You don't want to try and hurry with the removal if you want to avoid a big amount of time and money down the drain.
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