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exhaust manifold stud stripped thread in head


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Following my cylinder head gasket saga started to reassemble mo sign of dowel section by the way.

Fitting the exhaust manifold one of the threads in cylinder head is stripped thats probably why I got the replacement head pre skimmed cheap off ebay private seller so no comback.

All other bolts okay. Tried to wind in stud best I could using loctite 638 to secure it not much hope though.

If I can get it all back and running plan to take it to local landrover specialist see if head can be re tapped in situ and slightly larger stud fitted.

Any suggestions or recommendations greatly appreciated.

Exasperated 90 owner

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Go for the Helicoil, (or similar brand) and do all of the stud tapping's while you are at it, most kits include 10 insert threads with the correct sized drill and tap, the S/S thread is stronger than the original alloy thread.

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Thanks it gives me an option anyway weather taken turn for the worst here so unlikely I will get much done today anyway.

Landrover won't fit in the garage so stuck working outside.

I am based in the middle of Warrington Wigan and St Helens landrover is at my mothers in St Helens at the moment no garage at my house.

I work 12 hour shifts and start back on 3 day shifts Friday followed by 3 nights so only today and tomorrow to get it sorted or its another week.

Heli coils sounds best option but drilling the head makes me nervous and not much space to get drill in its front bolt next to the dip stick pipe.

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Thanks it gives me an option anyway weather taken turn for the worst here so unlikely I will get much done today anyway.

Landrover won't fit in the garage so stuck working outside.

I am based in the middle of Warrington Wigan and St Helens landrover is at my mothers in St Helens at the moment no garage at my house.

I work 12 hour shifts and start back on 3 day shifts Friday followed by 3 nights so only today and tomorrow to get it sorted or its another week.

Heli coils sounds best option but drilling the head makes me nervous and not much space to get drill in its front bolt next to the dip stick pipe.

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Thanks it gives me an option anyway weather taken turn for the worst here so unlikely I will get much done today anyway.

Landrover won't fit in the garage so stuck working outside.

I am based in the middle of Warrington Wigan and St Helens landrover is at my mothers in St Helens at the moment no garage at my house.

I work 12 hour shifts and start back on 3 day shifts Friday followed by 3 nights so only today and tomorrow to get it sorted or its another week.

Heli coils sounds best option but drilling the head makes me nervous and not much space to get drill in its front bolt next to the dip stick pipe.

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When drilling for the HeliCoil you aren't really removing much metal, mostly just the damaged thread, I've done it before using the drill bit just held in a chuck (not attached to a drill) and turning by hand, or you could use a 90 degree adapter for your drill, they're quite cheap from toolstation.

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I agree with CwazyWabbit - I've prepared damaged threads using hand turned chuck plus drill - provided that you take in slow stages no problem. You also avoid the problem of drill judder when drilling in tight places. Loctite Thread Lock is also a good idea initially, as is slightly peening over the start of the seating thread to stop the insert backing out. Be careful to use the minimum amount of Loctite and clean out any excess.

One note of caution, make sure that the helicoil sits below the surface by the equivalent of half a thread. If too close/slightly proud of the surface it can start to unravel. Don't ask - >£250k of production ruined (not to mention recall) in leaving the initial job to an unsupervised apprentice. That's when we discovered twinserts!

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The Loctite held the stud in place sufficient to get everything back together. Topped up coolant/antifreeze and turned her over eventually fired up and ran sweet as a nut, nice and quiet no tapping noises no water leaks.

Going to Scotland for a week in Feb, so will run it for next two weeks and see how I get on. If no sign of problems, I will use the Land Rover for the trip as planned.

As soon as I get back from my short break, I will crack on and sort the stud out with a heli coil as suggested. I should have a bit more time then and no pressure from the wife, who prefers to tackle Scotland in the Land Rover in this weather rather than her car.

Then its onto replacing the swivel housing seals etc on near side and finally getting around to installing some side windows I bought for it.

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Before starting the cylinder head gasket started having problems starting, its always been a good starter prior to this point. Thought it was cold weather at first or heater plug problems or combination of both.

Discounted fuel as once it fired up it didn't misfire, then thought with gasket leaking could be poor compression !

expected it to take a few turns today to get it started and eventually I did. Then ran it for 20 mins or so and took it out for a drive no problems starting with engine warm.

Went out tonight and its same as before, struggle to start but once it does runs fine. Done most of service on it oil, oil filter, air filter etc only thing not done is fuel filter could this be causing my problem ?

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Before starting the cylinder head gasket started having problems starting, its always been a good starter prior to this point. Thought it was cold weather at first or heater plug problems or combination of both.

Discounted fuel as once it fired up it didn't misfire, then thought with gasket leaking could be poor compression !

expected it to take a few turns today to get it started and eventually I did. Then ran it for 20 mins or so and took it out for a drive no problems starting with engine warm.

Went out tonight and its same as before, struggle to start but once it does runs fine. Done most of service on it oil, oil filter, air filter etc only thing not done is fuel filter could this be causing my problem ?

Check the leak-off pipes between the injectors for fraying or the banjo bolts being loose.

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If you read the Helicoil instructions it clearly states NOT to use Loctite on the Helicoil. The Helicoil will expand as its screwed into the tapping and lock in, retaining fluids are not required.

Drill the damaged thread out with the drill supplied with the kit, and to the correct depth of the coil to be inserted (this is easily measured with a smaller drill) tap out the hole with the Helicoil tap, with a small hose blow out any debris from the tapping and with the "L" shaped tool supplied screw in the insert Helicoil thread.

Once the thread is fully in, with a drift break off the tang at the end of the Helicoil and with a small magnet remove it, the Helicoil is S/S but of a type that has a small magnetic character.

When fully inserted the Helicoil should be just inside / below the face of the parent metal face.

Screw in the stud - the two nut method is best unless you have the correct stud insertion tool, at this stage you can use a small quantity of Loctite on the stud, use the Blue grade of stud retaining fluid and wait until it has almost fully air set, excessive amounts may, at a future date cause the stud, (if it is ever required to be removed) to draw the Helicoil out with it, and that you don't want!.

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I'm surprised at the advice not to use Loctite on the insert itself. In my experience it's standard in aerospace and marine industries - though part of that is admittedly extreme paranoia on galvanic corrosion and risk reduction.

Theory suggests that, for the maximum pull strength the helicoil be used without thread lock, because the insert deforms slightly under load to spread that load more evenly over more turns of the thread, whereas locking the insert makes it act more like the original thread. Perhaps that's why the advice. It shouldn't matter either way if the original thread was strong enough for the load.

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I changed the fuel filter and seems to have sorted the starting problem although following the comment I checked the re-feed pipes on the injectors they are frayed and one is split so need replacing asap.

Thanks Mo I will look into the Recoil kit you mentioned.

Now I am back on the road again I have a big grin on my face again. Although I have found another leak on my power steering one thing after another.

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Given YouTube a good bashing now feel confident I could sort the heli coil myself depends now on how much space I have to get my drill and bit in to drill out the old thread.

Suppose if push comes to shove wing has to come off.

Just hope my old rechargeable drill has enough torque to drill into the head.

Guessing I only really need to drill sufficient to take the heli coil plus bit extra so its recessed into the head.

I assume its a m8 kit I go for as the stud is m8.

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