ARP head studs

mark2m · **Posted:** Fri Mar 08, 2013 6:42 pm

LMWatBullRun thanks for taking all the time to explain what you have done. I'm about ready to go ahead and install my head with ARP studs based off what you have done. I was wondering if you have any other words of wisdom since you have completed your install.

Thanks
Mark

Valve Stem · **Posted:** Sun Mar 10, 2013 7:39 pm

Thanks for all the info this is what I am going to do for my timing belt job and replace head gasket.....The only thing I need to know is what size tap did you use to clean up the treads and if its a special size where did you get it at?

Thanks, Valve Stem

LMWatBullRun · **Posted:** Mon Mar 11, 2013 9:25 am

Valve Stem wrote:

Thanks for all the info this is what I am going to do for my timing belt job and replace head gasket.....The only thing I need to know is what size tap did you use to clean up the treads and if its a special size where did you get it at?

Thanks, Valve Stem

The tap was a 6" long tap, (pulley tap) and I got it from MSC. You also want the reamer and pilot that R2.0 sourced for removing the ridges on the head recess where the 'TTY' bolts have messed it up. I have both and will lend them in the DC area. A good torque wrench is essential, too. I would not torque the outboard nuts past 120 fp, and the inboard ones at 125. You will need a HD 6 pt 11 mm socket; a twelve point will not do the job.

Good luck!

mark2m · **Posted:** Mon Mar 11, 2013 10:04 pm

Valve Stem wrote:

Thanks for all the info this is what I am going to do for my timing belt job and replace head gasket.....The only thing I need to know is what size tap did you use to clean up the treads and if its a special size where did you get it at?

Thanks, Valve Stem

I'm not a huge fan of running a tap down since they are designed to cut new threads and if it is off just a little bit for whatever reason if could cut a whole new set of threads. The chances are slim since you should be able to tell if the tap has that much resistance but you never know and it seem like every time I have used a tap the screw / bolt is always a little sloppy. I worry about using one in a high stress environment such as a head bolt. If you can find thread chaser instead definitely use that. It is designed to be less aggressive than a tap. Now what I did since I didn't have a thread chaser in the size I needed is to take one of the old head bolts and cut a couple of flutes down the side of it and essential made a cheap thread chaser out of it.

Opinions are mixed on tap and thread chaser but that is what I did.

Valve Stem · **Posted:** Wed Mar 13, 2013 1:39 pm

OK thanks its 6" long but what is the tread size?.....yeah going to try and get a tread chaser before I look for a tap....

The question that I have is what exactly is the pilot and counterbore use for...is the counterbore the actual tap?

LMWatBullRun · **Posted:** Wed Mar 13, 2013 2:22 pm

Valve Stem wrote:

OK thanks its 6" long but what is the tread size?.....yeah going to try and get a tread chaser before I look for a tap.... The question that I have is what exactly is the pilot and counterbore use for...is the counterbore the actual tap?

A tap is not a problem and it does remove crud from the threads, see pictures on page 5. When properly threaded into the existing threads it is very easy to turn. ARP recommends using a tap to chase the threads, BTW. The size, as noted IIRC on page 5 and elsewhere in this thread, is 12mm x 1.75

WRT counterbore, this is to clean up the ridge left by the TTY bolt in the recess on the top of the head. The head was apparently designed for a 7/8 washer which was apparently omitted by some bean counter later on. It is amazing that the head recess as produced by VM Motori fits the ARP washer for the 12 mm nut as if it were designed for it. If you look on page 5 you will see a picture which shows the ridge before being crushed flat by the ARP nut and washer, and the results after the ridge has been flattened out. R2.0 has the part numbers for a good mill to remove this ridge and flatten the recess without excessive torque, which will crush the head itself. Better to mill it flat.

I had a slight problem with my glow plug holes getting very tight when things were torqued past 120 fp, and I had a problem with the front exhaust rocker hole getting deformed at 140 fp. Suggest no more than 120 fp for outside holes, and 125 to 130 fp torque for the inner holes.

Valve Stem · **Posted:** Wed Mar 13, 2013 3:43 pm

LMWatBullRun wrote:

Valve Stem wrote:

OK thanks its 6" long but what is the tread size?.....yeah going to try and get a tread chaser before I look for a tap.... The question that I have is what exactly is the pilot and counterbore use for...is the counterbore the actual tap?

A tap is not a problem and it does remove crud from the threads, see pictures on page 5. When properly threaded into the existing threads it is very easy to turn. ARP recommends using a tap to chase the threads, BTW. The size, as noted IIRC on page 5 and elsewhere in this thread, is 12mm x 1.75

Ok I will look and see how much it is for both a tap and thread chaser... Thanks for the size I must have read right by it

Valve Stem wrote:

WRT counterbore, this is to clean up the ridge left by the TTY bolt in the recess on the top of the head. The head was apparently designed for a 7/8 washer which was apparently omitted by some bean counter later on. It is amazing that the head recess as produced by VM Motori fits the ARP washer for the 12 mm nut as if it were designed for it. If you look on page 5 you will see a picture which shows the ridge before being crushed flat by the ARP nut and washer, and the results after the ridge has been flattened out. R2.0 has the part numbers for a good mill to remove this ridge and flatten the recess without excessive torque, which will crush the head itself. Better to mill it flat.

Well now I understand what that is for Thanks..... yeah I have the part #'s Thanks

LMWatBullRun · **Posted:** Mon Mar 18, 2013 4:12 pm

Good luck, holler if you need help. BTW ARP sells a tap for their studs if you need one.

TXriverrat · **Posted:** Tue Mar 19, 2013 1:34 am

I ordered mine from here http://www.wcpdiesel.com/engine-drivetr ... 82-02.html

It won't be long before she's tested in the Houston heat.

BC_DAVE · **Joined:** Fri Mar 18, 2011 4:34 pm **Posts:** 1

I have been following your ARP head stud thread. Do I need two of the bolt kits for the vw? Have you completed the head gasket replacement?

LMWatBullRun · **Posted:** Mon Apr 15, 2013 4:27 pm

BC_DAVE wrote:

I have been following your ARP head stud thread. Do I need two of the bolt kits for the vw? Have you completed the head gasket replacement?

You need 18 studs, nuts, and washers, and the ARP lube. All of that comes with the kit; there are 10 studs per kit, so you would need 10. Bought by the piece, the 18 individual studs are MORE expensive than 2 kits. If you want to sell me the two leftovers, I would be interested, PM me.

I did not replace the HG; I replaced the bolts with studs one by one so reused the original HG.

flman · **Posted:** Mon Apr 15, 2013 6:58 pm

LMWatBullRun wrote:

Now have about 2000 miles on it and some relatively cold starts. The 7v glow plugs work fine if you cycle the key 3 times even at 10 degrees. I am no longer using any coolant, knock wood; do not know if that was the new WP or the studs but suspect that the studs flattened out an incipient warped head.

Now on to rebuild a transmission.....then to get a manual shoehorned into this buggy.

So, it was using coolant and the ARPs fixed it for you with no head gasket replacement?

LMWatBullRun · **Posted:** Tue Apr 16, 2013 12:46 pm

flman wrote:

LMWatBullRun wrote:

Now have about 2000 miles on it and some relatively cold starts. The 7v glow plugs work fine if you cycle the key 3 times even at 10 degrees. I am no longer using any coolant, knock wood; do not know if that was the new WP or the studs but suspect that the studs flattened out an incipient warped head.

Now on to rebuild a transmission.....then to get a manual shoehorned into this buggy.

So, it was using coolant and the ARPs fixed it for you with no head gasket replacement?

I was using coolant before the WP change and stud install. I cannot say for sure what the leak was, but I could not find any external leak, and there was significant variation on the head bolt removal torque. A few bolts were so tight I really had to work to get them loose, (@250 fp) while others were very loose (<100 fp). The holes that were tight took a lot of rotation to final torque to 135 fp compared to the others. Again, I cannot say for certain what the cause was; the bolts that were tight did have the worst ridges on them.

Given, however, that the ARP studs were proven to crush the GP holes, my somewhat educated suspicion is that the head had warped slightly and was sucking slight amounts of coolant into the combustion chamber prior to the stud install. After the studs/wp install, it has not used a drop, so I suspect that the studs pulled the head back into alignment with the CI block. I have heard this happening with other AL head/CI block motors, so this makes sense.

If I knew I had a gross HG leak, I would pull the head and replace the HG. As it was, the loss was relatively small and my hope was that the WP was leaking, although the pump seemed serviceable in the event. It was only when I saw the variance in the 'TTY' head bolts as I was replacing them with studs that I suspected head warpage. At that point I elected to proceed and see whether the coolant leak stopped; by the time I realized I might have a leaky HG I had already installed most of the studs, and figured what the heck.

flman · **Posted:** Tue Apr 16, 2013 7:40 pm

I guess considering some of the bolts were loose, you could have had a warped head? I am kind of surprised it worked if it was the head?

racertracer · **Posted:** Tue Apr 16, 2013 8:07 pm

I remember Geordi testing the strength of the OEM TTY studs and they didn't give till they reached well over 300lbs of force.

I also recall a member who reused and re-torqued the heck out of the original TTY studs on his leaky HG who said that it solved his problem.

I would love to know why we can't re-use the original TTY studs in the same way as the ARP studs are used?

Is the TTY stud made of malleable metal that continues to stretch over time, doesn't it eventually stop stretching...I would think that it eventually stops?

Anybody know?

LMWatBullRun · **Posted:** Tue Apr 16, 2013 10:07 pm

racertracer wrote:

I remember Geordi testing the strength of the OEM TTY studs and they didn't give till they reached well over 300lbs of force.

I also recall a member who reused and re-torqued the heck out of the original TTY studs on his leaky HG who said that it solved his problem.

I would love to know why we can't re-use the original TTY studs in the same way as the ARP studs are used?

Is the TTY stud made of malleable metal that continues to stretch over time, doesn't it eventually stop stretching...I would think that it eventually stops?

Anybody know?

The 'TTY' bolts do not, in fact, yield. I know this because the yield strength for these bolts is specified in the drawing you got from VM Motori, RT, and in order to make the bolts yield you crush the head before you get to the yield point.

The other issue is that the head was designed for a high strength washer; the 'TTY' bead bolts do not provide adequate bearing surface to prevent local distortion and galling of the head recess. Look at the picture I posted of the typical recess. There should be a hardened high strength washer to spread the load and reduce the bolt to head friction. If the bolts were about 7 mm longer, and we had a high strength washer, I think you might get good results re-using the bolts, but even so, the studs are still superior, since the nuts are more finely threaded, and the precision machining of the fine threads allows much better control of clamping force.

Sure, the studs are expensive, but next to the cost of a warped head that $350 looks pretty cheap......not to mention the PITA factor for most folks who depend on their ride.

LMWatBullRun · **Posted:** Tue Apr 16, 2013 10:28 pm

flman wrote:

I guess considering some of the bolts were loose, you could have had a warped head? I am kind of surprised it worked if it was the head?

The ARP studs are capable of crushing the head to the yield point and conforming the head to the block. VW D16-D24 diesels have similar heads, and the cure for a warped head is ARP studs; this is especially nice because unlike the CRD the cam bearings are in the head, and when the head warps you cannot simply machine it down, unless you also line-bore the cam bearings, which is a PITA. WIth studs, you simply clamp the head to the block and crush it back into shape. (Steel gasket is highly recommended for this.)

The steel ARP specified is 220,000 psi yield strength, as opposed to the 154,000 psi (IIRC) yield of the specified 'TTY' bolt. But the real issue is the low strength of the aluminum head; the warping is caused in part because the factory bolts do not have high strength washers under them, and the aluminum yields locally before the factory bolts do because there is not enough bearing area under the 'TTY' bolt head. The aluminum crushes and deforms. You can see it in the photographs. The ARP studs not only provide more strength in the fastener, they provide more bearing area for the aluminum head to push on. This is better all around.

When the head overheats locally, my thinking is that in the factory situation that the aluminum crushes before the bolt stretches. Adding a thick hardened washer would help, but then the bolt might not have enough engagement in the block. I suppose that you could source a bolt that was a little longer, but how long would it take? ARP studs are a mature technology that is race proven, and lots of other diesel heads have used them in VWs and Volvos. I could spend time trying to find a slightly cheaper solution, but why?

Once you buy a set of studs, they never need replacing. This is especially germane when you consider this is a wet sleeve commercial style engine. In 300,000 more miles, when I need to rebuild the motor, I won't have to screw around with head bolts. I expect to drive these CRDs for the rest of my life, and with the studs I do not think I will ever have to worry about head warping.

user113 · **Posted:** Thu Apr 18, 2013 9:49 pm

Your confidence in these motors makes me more optimistic, what with all the rocker arm wear issues and what not. Particularly since I just barely got an ARB bumper and a complete set of skids. I am actually thinking of replacing the timing belt (only has 77K miles, but in June will be 8 years old). I am also strongly considering the ARP studs and rocker arms. When I do, I will probably also spring for some kind of real bypass filtration. I hope I can drive mine the rest of my life, too.

LMWatBullRun · **Posted:** Thu Apr 18, 2013 9:59 pm

As posted elsewhere, there is no doubt that there are issues with the CRD, but I really like the fuel economy, the extended range, the off-road capability, the highway performance, and the ease of parking. Once the soot issues and head issues are dealt with, the motor should run for a very long time.

I am still weighing the various supplemental filtration schemes, and have not made a decision on how to proceed. I probably will try one of the remote bypass filters on one or the other of the CRDs, and I may try the centrifuge idea on the other one, but BOTH will get ARP studs for sure.

audiboy86 · **Posted:** Wed Apr 24, 2013 9:04 pm

$145.53 head stud kit

They were very fast on the shipping side of it to took them 3 days to get it to me from Sunday.

ARP head studs

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