'93 KA24DE - Valve Cover Bolt thread pitch and size

[BadMojo]

I've got a stripped valve cover bolt hole (or two). Was wondering if anyone knew offhand what the thread pitch of the bolt and the size is?

I'm going to be getting a helicoil kit to keep those damn bolts (the ones on the edges of the valve cover, not the center) where they're supposed to be.

[InsanityInc]

I think all mine but two are stripped out. Not sure why the damn things strip so easily. I'm trying to find some permatex thread repair stuff, as it works well, but nobody seems to have it. The strangest part is if you look at where the bolts thread into, it's like they have little removable sections.

[guyaverage]

The threads strip easily because the head is aluminum, the bolts are steel and are much stronger than the threads in the head. Once it gets nicked or bent, aluminum gives up quick. It works ok if left alone, but if you overtorque the bolts or remove them frequently the threads just dont last.

If you want to save some time and expense and have almost as good a repair, get a 1/4 tap and the correct length 1/4 bolts. The 1/4 inch tap will go right into the existing stripped hole without being re-drilled, is cheap, and readily available at any hardware store. I tapped the 3 center and 2 front holes in about 2 minutes. I dont think I spend $5 on the entire repair and was done in no time.

I'm not trying to talk you out of doing the helicoil, because that would be the stronger and 'better' repair, but its not really necessary in this case. These bolts arent (or SHOULDNT be) torqued to more than a few ft/lbs, so unless you take off the valve cover every other week, retapping the head will be plenty strong.

[BadMojo]

If you want to save some time and expense and have almost as good a repair, get a 1/4 tap and the correct length 1/4 bolts. The 1/4 inch tap will go right into the existing stripped hole without being re-drilled, is cheap, and readily available at any hardware store. I tapped the 3 center and 2 front holes in about 2 minutes. I dont think I spend $5 on the entire repair and was done in no time.

I'm not trying to talk you out of doing the helicoil, because that would be the stronger and 'better' repair, but its not really necessary in this case. These bolts arent (or SHOULDNT be) torqued to more than a few ft/lbs, so unless you take off the valve cover every other week, retapping the head will be plenty strong.

Yeah, that is a good thought. I'm always careful to follow torque specs, so the bolts were overtorqued by either the previous owner or their mechanic.

The helicoil definitely *is* overkill. I'll have to think about it for a while. Just tapping the whole sure would be a lot easier and less messy...I'm sure I have a 1/4" tap somewhere in the garage too.

[95nismo240]

i have a 96 engine in my 240..... can i tap my head with 1/4 inch tap as well?? also when i tap the holes can i use the same valve cover bolts?? or do i have to buy new ones

[deviousKA]

Dont piss off good mechanics down the road, get it fixed with the proper size.

6mm x1.0mm , retap or insert the stripped threads.

[guyaverage]

How good of a mechanic could someone be who doesnt realize 5 of the 15 bolts he is holding are different from the others? If he had half a brain he would insert he bolt back into the whole from which it came. Its not rocket science. This is a 13 year old Nissan, not a 747. Anyone who buys a decade old car and gets pissed off because someone retapped a thread probably deserves to get pissed off for nothing else than being a jerk.

i have a 96 engine in my 240..... can i tap my head with 1/4 inch tap as well?? also when i tap the holes can i use the same valve cover bolts?? or do i have to buy new ones

Use new bolts, the 1/4 inch hole is slightly larger than whats there now (not to mention one is metric, one is standard).

[deviousKA]

Hey bro, I didnt intend to insult you. Owning a japanese car or any other metric vehicle, you should have a few tools around to fix it. Theres only what?, a few thousand 6mm thread bolts on any given Nissan car, a tap and/or heli coil set just might come in useful

[guyaverage]

No offense taken at all.

On the flip side, when I worked on my friends Mustang and had 3 different size bolts, with two of them standard and one metric, holding on the same manifold, it did kind of hack me off, not because someone working on the car did it, but because it was factory! So I guess in some way we agree to an extent.

I expect (and perform) shadetree repairs on while working on older cars, but from the factory? Holy crap!

[All_Motor_KA]

While we're on the topic of valve cover bolts anyone know where to order a set? I only have 3 right now :-D.

[RACE 66]

I tend to agree with Devious, but to add a little more flexiability, in the repair, whether you use the "oem" specs or something else how about this.

"STUDS" - Yep, get yourself the right size studs (maybe a scooch longer) and thread those puppies in with antiseize and forget about them. (with repaired head threads)

So, when your working on your rip snortin' KA your only working on the "upstairs" threads not the ones in the head ! Wadea' think ?

[SSS]

I tend to agree with Devious, but to add a little more flexiability, in the repair, whether you use the "oem" specs or something else how about this.

"STUDS" - Yep, get yourself the right size studs (maybe a scooch longer) and thread those puppies in with antiseize and forget about them. (with repaired head threads)

So, when your working on your rip snortin' KA your only working on the "upstairs" threads not the ones in the head ! Wadea' think ?

That is exactly what i'm doing at the moment; my valve cover comes off every 5000kms to adjust the solid lifters.