Hello all, I have been using this site for a few years to get general guidance and advice and now have a problem that I can't find the answer to. I have an 01 disco II with 168k and am replacing a blown head gasket. Everything came off the truck just fine and with no major issues. I took my heads into a local LR shop that does a one for one swap and got back a complete set that had been machined/cleaned/new rockers and valves. Passenger side went in no issues but now on the drivers side I have two exhaust manifold bolts that are giving me a major issue. One of them simply will not thread. I've literally tried everything that I can think to get it to go, I've even tried to fit the bolt with the manifold off and still it will not take. The other seems to have miss threaded. I stopped ratcheting the bolt when I felt something wasn't right but when I brought the bolt back out the first three threads or so had already been worn smooth.

So, my question is should I start by getting a tap and going at the holes that way and hoping that I can re-thread them or am I at a point where I need to start looking at replacing the head it self? If I can get even one of the bolts to go are there options to make sure that I don't end up with an exhaust leak leading to CEL, O2 sensor issues, etc etc? Thanks guys/gals for any and all input. I really feel like I'm at a standstill here, not really sure which route would be the most effective/efficient.

 

Forget about running the manifolds with a few bolts missing. That won't work. You need to have every bolt installed or you will be listening to a tick until you destroy the truck bcause you can't take it anymore.

You could try chasing the threads with a tap, but you need to make sure that the tap is threading in correctly so you don't waste the head.

I'd be more concerned about why a set of rebuilt heads won't take a bolt. I hope the machine shop didn't skip any other steps. You should contact the shop that sold them to you and have them give you a solution.

 

I would chase the holes with a tap . Vary important to any thing you torq that the threads are cleen so you don't get a false torquing ! DON'T BREAK THE TAP ! make sure it is square and not cutting new threads just cleaning the old ones .

 

if possible try to locate a bottoming tap, it will be almost flat instead of a point. that will allow you to chase the thread to the very bottom of the hole.

 

I would be willing to bet the hole is deeper then the bolt check depth with small screw driver.

 

I'd try a thread chaser before a tap. With a tap it's really easy to get the threads wrong.

For future reference I always use a thread chaser in all threaded holes on components before reinstalling them.

 

Thanks for all the help guys, I'll be calling the shop when they open. They do so many of these they actually always have them in stock. They're a really good LR shop so I can't imagine that they wouldn't have done the threads but hey crazier things have happened.

Thanks antichrist I'll start with thread chaser and move up to the tap if need be. These bolt hole are the "m8x1.25" is that correct? My auto store here sell a "8x1.25" will this be the same thing?

Also if I want to use two new bolts can I use automotive bolts the same size or do you recommend going through AB/Lucky8/PT?

 

another quick question- one of the threads I read said that the exhaust bolts he's seen have all be SAE 3/8 x 16, what is the consensus on replacing the two screwed up bolts with these vs 8x1.25??

 

I don't remember what threads the bolts are take one to the place where you are going to get your thread chaser if your heads are torqued do it on the car , pt is a great sorce for parts tell Collin blamo sent you .

 

Thanks blamo, will do, I think that the chase is going to work seems to be taking the bolts now.

Thanks all.