Kooks 4.2L I6 Header

[HARDTRAILZ]

All your positives match up directly with positives of a tune.


Anyone have experience with header that had time prior for actual results of install?

 

[seanpooh]

Well I had the original PCM tune for ~3 years which was great. Then installed the headers which improved just a little, nothing much to notice and no codes.

Then with the tune to compensate for the headers, the engine opened up much more. A tune is needed.

Again, if you have the money hanging around, go for it. Especially if you drive around Times Square the day after New Years in 2nd gear 1am in the morning, it makes tourist turn heads.

Also with the note about the 02 sensor extension cable, it's true that it's complete reverse.
I took a blow torch to my Coast Knife and heated it cherry red. The I just made the correct notch on the male end to correspond the colors and position of each wire by resting the cherry read blade in the correct spot.

 

[HARDTRAILZ]

Well I had the original PCM tune for ~3 years which was great. Then installed the headers which improved just a little, nothing much to notice and no codes.

Then with the tune to compensate for the headers, the engine opened up much more. A tune is needed.

Thats exactly what I was looking for. Thanks.

Also with the note about the 02 sensor extension cable, it's true that it's complete reverse.
I took a blow torch to my Coast Knife and heated it cherry red. The I just made the correct notch on the male end to correspond the colors and position of each wire by resting the cherry read blade in the correct spot.

Do they know of this issue? For the cost I would not expect to have to modify anything.

 

[seanpooh]

There was a comment about the O2 sensor cable being wrong earlier in the thread. I don't think anyone has told Kooks, I haven't since it wasn't that big of a deal.

Just one downfall is the bolts they supply also, they are 8.8 (IIRC) grade but the originals were 10.9. Even the originals were stronger grade and still the heads broke off. I don't know how long the Kook supplied one will hang on for.

I was reading a racing magazine and seen these special header bolts Stage 8, which are only good for not backing out themselves but we have a problem with bolt heads breaking off. Thats also something Kooks should look into and add with the headers package.

 

[ddgm]

The 8.8 and 10.9 refers to size, not grade.

 

[FlyingFischer]

The 8.8 and 10.9 refers to size, not grade.

Actually it is grade not size. 8.8 is equivalent to grade 5, and 10.9 is grade 8.

 

[seanpooh]

Oh, now I learned something new. I thought a 10.9 was a stronger bolt than lower numbers. I recant my complaint then. Thanks guys.

 

[IllogicTC]

Actually it is grade not size. 8.8 is equivalent to grade 5, and 10.9 is grade 8.

Then why did my wrench set come with 8.8mm and 10.9mm sizes?

 

[HARDTRAILZ]

Oh, now I learned something new. I thought a 10.9 was a stronger bolt than lower numbers. I recant my complaint then. Thanks guys.

It is stronger....

10.9 is = to Grade 8 which is stronger than Grade 5 which is = to 8.8

You have weaker bolts now than before. Complaint valid.

 

[IllogicTC]

It is stronger....

10.9 is = to Grade 8 which is stronger than Grade 5 which is = to 8.8

You have weaker bolts now than before. Complaint valid.

For further reference: Bolt Depot - Bolt Grade Markings and Strength Chart

The metric bolt's limits are measured in MPa rather than PSI like SAE, but each MPa is about 145 PSI according to the bottom of the chart, so you can do the math and cross reference between two bolt standards. What HARDTRAILZ said is true though.

 

[seanpooh]

I guess if any of you guys go ahead a purchase the headers and do not want to use the bolts supplied by Kooks which are presumably weaker, then stop by the dealer to pick up a set of exhaust manifold bolts.

The factory bolts lasted ~11 years for me before I noticed the heads started to break off which a good life span. But I don't think the dealership would have a supply of brand new ones.

Every time I needed a specific bolt for example a wheel hub assembly bolt and a caliper bracket to steering knuckle bolt which both are marked 10.9, I got a used one both times. The caliper bracket one still had locktite on it.

I went to rock auto and Dorman is the only exhaust manifold bolts they supply.

I wouldn't reuse my old ones though, they have seen enough exhaust time.

I did a bit of google research about the stage 8 header bolts and their grade is obviously 8 where a lot of guys with headers use them with no issue.

 

[palitoiii]

Kooks should chime in and look at the issues about the bolts and cables. For so much money it should be fixed..

 

[HARDTRAILZ]

That sure as hell makes sense to me!

Hopefully these issues have been brought to Kooks attention and not just accepted.

 

[Texan]

Just curious.
8.8 is = to Grade 5 and 10.9 is = to Grade 8. I agree with this.
I have not had a problem with my exhaust manifold yet.
If I ever do, I would consider going the header route. Could somebody
tell me the actual size of these bolts. I have had some success with
using stainless steel bolts in the past on hot parts. There are a few
hardware stores that have a good selection of SS bolts. Any thoughts/comments?

 

[Kooks Headers]

Hopefully these issues have been brought to Kooks attention and not just accepted.

We are working on these issues. I will post up more info as we get it.

Thanks

 

[palitoiii]

Yea let us know.. Im in need of an exhaust manifold anyway and wanted to get the headers. But these issues need to be fixed before I and others shell out all that money..

 

[Decembersend]

We are working on these issues. I will post up more info as we get it.

Thanks

What are the possibilities of having these issues worked out by next week? If all goes according to plan I will be buying this weekend/next week.

 

[Kooks Headers]

It appears the problem is the earlier trucks 02-03 possibly 04 with the o2 sensors. As for the question about bolts we use grade 5 bolts because in a high heat situation they tend to stretch rather than snap off. We use these type of bolts on all of our headers and have been for years so this should not be a concern.

 

[XUVFISCH]

Just wondering how your header bolts and clamps are holding up.

I've had mine in since Aug 2013 and the bolts on the headers were loose as heck. Also the clamps to the CAT and are leaking and rusty as heck.

 

[The_Roadie]

I see two in this thread:
http://gmtnation.com/forums/topic/7189-kooks-i6-header-installed/

Fishsticks used to have a set but sold his truck before he put them on. Not sure what the final outcome of that was. Hardtrailz has them IIRC.

Actually, these posts should be in the long Kooks thread in the vendor's section. Let me move them now.

 

[HARDTRAILZ]

I could not justify them. Not enough actual data to know if they would help beyond what a tune does.