4.0 head bolt hole stripped, what would you do?

[RayInStl]

When putting the heads back on my 2002 explorer's block after replacing the timing chains, my mechanic reported that one of the head bolts pulled the threads out of the hole. He said everything seemed to torque down well, but when he was running it to check for leaks, it leaked at the head.

I've read that helicoils aren't great for Torque-to-yeild head bolts as it throws off the torque reading and that time-serts are recommended if you have enough "meat" around the hole.

Has anyone done this on a 4.0? Is there enough meat to do it? I've never seen the block without the head. My mechanic is recommending a different block, but I already have waaaay too much in this thing as is. I'm hoping I can salvage the block I have. It ran really well before.

I've done a lot of research, but can't find 4.0 specific information.

Thanks!
Ray

 

[gw33gp]

There are thin wall inserts that are used in the Aerospace industry which should work well for you. The problem will be finding one.
I have used a Helicoil for a head stud in a race car that I run almost 15-1 compression ratio. It worked very well. I don't use torque-to-yield bolts and don't know if they would be a problem with a Helicoil.

 

[RonD]

Mechanic would always recommend a new block, same as car salesmen would recommend a new car when ashtray is full

Both solve the problem when cost is not the issue, new engine or new car, whats not to like about that, except the cost.

4.0l SOHC is still a cast iron block as far as I know, heads are aluminum, so should be fine to use heli-coil, you do need to use a drill holder jig to make sure hole is exactly perpendicular, hand drilling would almost assure failure in the future, this requires higher ftlb so not a thermostat housing or manifold bolt.

Don't know why TTY bolt would be a problem, helicoil in block should be good for 100+ ftlb, spec on 4.0l sohc should be maybe 80ftlb after two 90deg turns, starting at 25ftlb

TTY bolts are used because they do hold well, but main reason is that during assembly auto makers no longer need calibrated torque for head installation, a machine can't do higher ftlb torque consistently unless calibrated often, but it can do 90deg all day and all night without calibration, and the starting 25ftlb is not that significant in overall result .

 

[Andy D]

I would go with a 2nd opinion or more diagnosis. Is the job preventative maintenance or did a chain fail? There may be damage from a chain break.What ever it was, the mechanic over torqued the bolt in an attempt to seal a leak. I would go with an insert of some sort. not a new block. I would also be very tempted to tow the truck home and fix it myself. I don't know how to pussy fit around it, the guy muffed the job. I know because I usually screw up the first time I do anything. Some times even the 2nd time.

 

[ericbphoto]

I agree with Ron and Andy's advice. Of course it depends on you skill and comfort level. You can find out what thread size the bolt is and look up the max torque that can be handled by the helicoil for that size bolt to verify Ron's numbers if you want.

It does need to be drilled straight and installed properly. But, since there is a straight existing hole, if it were me, I would use several intermediate drill sizes to gradually enlarge the hole carefully with a hand drill. Then be extra careful tapping it for the helicoil. As you tap the hole, stop often and use a square to make sure the tap is going in straight. Check it on 2 sides, 90 degrees from each other. During the first few revolutions of the tap, you can gently adjust it side to side to keep it straight. Patience is the key. And protect the block to make sure metal chips from drilling and tapping don't go where they don't belong.

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[adsm08]

I have a much bigger (and I feel more appropriate) question pertaining to the competency of the individual doing the job than the one raised by Andy.

Why was the head off in the first place? The heads don't need to come off to do timing chains on the SOHC.

 

[ericbphoto]

 

[RayInStl]

I have a much bigger (and I feel more appropriate) question pertaining to the competency of the individual doing the job than the one raised by Andy.

Why was the head off in the first place? The heads don't need to come off to do timing chains on the SOHC.

Sorry guys, I only gave part of the story. I bought this explorer to fix for a friend of mine. It was a running, driving truck that had been wrecked in the front. I was even able to drive it onto my trailer. The impact had pushed the radiator into the fan, so I replaced the radiator (and all the a/c stuff), the fan, fan clutch, and water pump.

After replacing all of the above, I started it up the first time and she ran really nice. But while letting it warm up, I noticed the oil was getting water in it, and fast. I shut it down and called up my brother-in-law. He is friends with Ross (the mechanic) and has had various things fixed at Ross's shop and was always treated fairly. So, since I couldn't store the truck in my yard (I live in the city and they don't like unlicensed vehicles hanging around), I called Ross up to see if he thought he could check it out.

Long story short, the water in the oil came from a crack in the water pump housing that both he and I missed. Since he had the heads off and had found the rear timing chain guide was broken, I asked him what it would cost to replace the timing chains while we were at it. I know the issues with the 4.0 chains and at this point I was going to keep the explorer for myself. So I didn't wan to have trouble down the line.

So it's my fault the heads were off. I assumed the previous owner had overheated it when the accident happened. I went into this telling Ross that the head gasket was leaking. I didn't tell him I had replaced the water pump. Honestly, if he messed up torquing the head bolt, although I'm disappointed he didn't just say that, he's been fair with me otherwise.

I normally do my own work on cars, but between the city getting on me for having a "derelict vehicle" on my property and my relative lack of experience with heads, I decided to let Ross take care of it.

Sorry for the book. I thought I should fill in the back story since everyone was curious why Ross was doing what he was. He's a good guy, I don't think he's ever touched a ford 4.0 before though. He was doing my brother-in-law a favor by taking it on. I don't think he would have done it if I had just walked in. Maybe I should have just threw it on craigslist before I was in too deep.

 

[ericbphoto]

It's not the end of the world. Just fix it.

It does help to hear the whole story.

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[85_Ranger4x4]

From the shops point of view they know they will be "guilty until proven innocent" if the thing still gets water in the oil or has any other head related issues if they put an insert in it.

They are covering their butt by saying it needs a block.

 

[RayInStl]

I might just get it back from them. My concern is the timing chains. I know you need a special tool to align everything right and if I'm not mistaken you can't remove the heads without 1) pulling the engine and 2) removing the timing chains.

Am I wrong about that? I've changed head gaskets before, so that doesn't scare me. But that was on Jeep 258 straight sixes. It's all the timing chains that I'm worried about. I've never done a timing chain and everything I've read about the 4.0 makes me think it's not the motor to learn on. lol.

I'll call him today and tell him I think we should try a helicoil and see what he says.

Thanks guys.
Ray

 

[85_Ranger4x4]

I think there are three and one is on the back.

The only timing chain I have done was on my 302 and a monkey could do it without too much training.

 

[CreepyCrawler]

broken bolt? do a v8 or diesel swap... would it take too much out to go to a bigger bolt? helicoils are nice. use them all the time on gas turbines.