Problem with cam bearing caps, helicoils didn't work

[99 E-klips gs]

I got my head fixed ( couple valves replaced and had it resurfaced) but anyway, put it back on and when I got to the cam cap bolts, the threaded hole stripped out. I know this a pretty common problem but after searching, everyone says use helicoils. I noticed after trying to drill the hole some old helicoils came out. So I just figured they went bad over time (guessing last owner already did this). But I drilled the hole, tapped it, put new helicoils in and only some of them worked. I bought some new bolts and put some new helicoils back in and they still didn't work. The bolt will just spin and spin. And once pulling the bolt back out the helicoils are wrapped around the bolt in between the threads. I figured I would also try the outer bolts, the bigger ones, but I'm scared to drill a 1/4 hole into the one that has the rod sticking out. Any more advice you guys have?

 

[Diamond Star Werks]

Take it to a good welder and have the holes filled in, then just drill and tap for regular bolts. The cap bolts only take 15ft/lbs, if you have trouble knowing how much is too much, I suggest using a torque wrench or a shorter ratchet to reduce the leverage.

 

[99 E-klips gs]

In my Chilton it says 107 inch lbs which is 8.9 foot lbs. But I had a inch torque wrench and I couldn't get it past 70 before it would bust loose

 

[WES_393]

Yeah, it sounds like a bad helicoil job. You could try going the next size up and drilling through the alignment dowel. I've had luck doing that in the past. Just make sure you have enough meat between the hole and the outer edge of the journal.

Either that or have the hole professionally welded and rethreaded like MJ said. Any machine shop could do it for pretty cheap.

 

[BogusSVO]

When you drilled out the old heli coil, the hole got messed up, and will not allow for new threads to be tapped, or support the coil.

It will be hard for a welder to get to the bottom of the small hole and weld up. Then the head will stand a good chance of being distorted in the cam bores from the heat., so the cam journals could distort, and grab the cam.

Also add that if the welder comes above the bolt hole the top of the head will need surfaced. Thact will change the shape of the cam bores, so the cam bores would need aligned bored.

Next, if you drill and tap the bolt holes and get them off, that can shift the cam cap, that will cause the bores to need aligned honed.

The best repair I can see to do, now that heli-coils have failed, is to stud the holes, not all just the ones the threads have pulled.

Find a stud, good chance it will have to be 3/8 (10 mm is slightly larger)
If you look around, you may find 3/8 one end and 5/16 on the other.

Install the cams with out the Followers or HLAs, install the cam caps, and torque any good holes to spec.

( on the bad holes, you may have to remove the alignment dowels)

Drill thu the cam caps, and into the head.

Remove the caps, install the studs, now replace the cams and caps, torque to spec.

If the cam will spin by hand, you should be good to install the head.

If the cam will not spin by hand, the bores need align honed.

 

[99 E-klips gs]

Stud the holes? Sorry not familiar with this. Such as a wooden dowel ?

 

[BogusSVO]

Like the studs on the exhaust side of the head

Sorry I was thinking 4g head, you are a 420A, cam cap bolts are diffrent sizes.


Most of your cam cap bolts are a 6mm X1.00

If you drilled for a 6mm heli-coil, you went .250 or 1/4 inch

You should be able to tap for a 5/16 hole.

These are the specs on the studs I would use to fix your issue.
http://catalog.automotivefasteners.com/item/threaded-fasteners-rods-and-studs/studs-2075/675-092?

Most of the 420a cam bolts measure appox 1.600
so a 1.750 should work with little or no top trimming.

 

[99 E-klips gs]

So you are saying put these studs in? And screw a nut onto it? How do you install studs? Am I up sizing the hole to 5/16? Putting more helicoils in? The screw stud in?

 

[BogusSVO]

No Heli-coils.

Just tap the bolts holes to 5/16. Then install the studs.

All this will still apply.

The best repair I can see to do, now that heli-coils have failed, is to stud the holes, not all just the ones the threads have pulled.

Install the cams with out the Followers or HLAs, install the cam caps, and torque any good holes to spec.

( on the bad holes, you may have to remove the alignment dowels)

Drill thu the cam caps, and into the head.

Remove the caps, install the studs, now replace the cams and caps, torque to spec.

If the cam will spin by hand, you should be good to install the head.

If the cam will not spin by hand, the bores need align honed.

 

[okm12346]

Use a solid insert instead of helicoil and then stud it.

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[99 E-klips gs]

Oh okay I understand now. Will try that when I get off work, thanks

 

[99 E-klips gs]

Wow, the studs I'm finding are all over 100$

 

[okm12346]

Get some automotive studs from pepboys. They have both metric and standard sizes

 

[99 E-klips gs]

Get some automotive studs from pepboys. They have both metric and standard sizes

None around here within at least 100 miles.

 

[okm12346]

Try hardware store - they should have grade 7 studs.

 

[99 E-klips gs]

What about inserts?

 

[okm12346]

wjat size?

 

[gprix1]

I know that Time-Sert makes an oversized insert called the BIG-SERT that is specifically for failed heli-coil jobs. Thing about Time-Serts though is it requires their special tools to install. Even their taps are non-standard sizes so typically home mechanics will use heli-coils. Most machine shops do carry Tine-Serts and can easily fix this for you.
When I had my head done the machine shop replace all my outer valve cover holes with time-serts as most had pretty bad threads.
Here are the BIG-SERT sizes:
++ BIG-SERT Oversized thread repair kits ++ thread repair kits for oversized holes, previously repaired threads oversized holes

 

[BogusSVO]

99 E-klips.... Before you go spend money on studs and insert kits and such.

Do you think you have the skill set needed to do this repair? Keeping the caps aligned to the bore?

If you anwser No. Go buy another head, and install any good parts in that head.

From reading this thread, and the questions you have asked, I do not see you having the skills to do this with out more damage to the head and maybe the engine.

 

[99 E-klips gs]

Ya I have never really had to mess with any threading besides tapping. So yes I am kind of inexperienced with this field. But I have already put so much money in my car just because my idler pulley exploded. Wasn't getting spark so changed a lot of stuff. And I have never messed with timing before on any of my cars, but my timing lined up fine, until I spun the crank twice, then it was off. When I checked timing I did not know to check this. So I ended up spending money on new battery, ecu, cps, cas, etc etc. Once I figured out it was timing and bought all of this out of my stupidity, I took the head to a shop and they replaced 3 valved, all the seals, cleaned all of it and resurfaced my head. Then after buying new head bolts and gaskets I was sitting at $900 and then bought helicoils for $50 which failed anyways. A lot of this money I have spent is because of my stupidity and not paying attention to directions carefully enough. But really I just got my head redone and put a lot of money into it. I can't spend anymore on it. Getting very frustrated about these damn cam caps, because I am so damn close to my car running and can't stand to pay someone to take me to work every morning, like I have been for the last month

 

[BogusSVO]

I understand how fustrating all this is.

The margin of error of getting this right is about .0005 or less.

Get this wrong, and you will be doing all over again, along with getting a new head and cams.

 

[99 E-klips gs]

I got 6 more to do out of the 25. I bought some new helicoils. Off brand that are about half the price, but the coils were way thicker. The only problem I'm running across now is the 3 hollow studs that stick out of the head that the caps sit on. The coils are the same size as the stud. Any suggestions

 

[Bryanhash]

What are the bigger bolts on cam caps size/specs new build first time building my self stripped 2 bolts one the 6mm and the other one is the slightly bigger one by the cam sensor