LOST JEEPS :: View topic - CRD Head Bolt Research Request: We need your data!

The latest one I took apart was botched by a dealer 2 or 3 times. I didn't bother to get torque readings because I was sure that they didn't follow the procedure. Anyhow, the bolts were bone dry after only lasting a small number of miles for the PO, no oil had been added to them...

Mountainman wrote:

For what it's worth, I believe the directions for the factory bolts also states that they have a manufacturing oil on them in the package and are not to be modified with any additional lubricant during installation.

I will shortly have at least one new head gasket on the way to me, and those fresh factory bolts will of course not be getting used anywhere near an engine. If one or more is desired for destructive testing of an unused bolt, they will happily be provided.

The measurements are for the average, so if you are following the measuring procedure outlined in the service manual (and I would compare both manuals to be certain there weren't any changes) and the measurements are calling for a no-hole, then that is the one I would select.

The problem is that there isn't a "spec value" as such because these are TTY bolts and the factory process says "turn x degrees after reaching 60lbs torque" or something like that, and then turn the bolts another x degrees - So what is the final torque of the TTY bolt? Impossible to know.

What we are seeing (and the point of this research thread) is that the #3 bolt seems to be affected by the heat from the cylinders and the exhaust, and loosens. Whether this is from stretch or rotation - I think it is from stretch - is somewhat irrelevant. The studs won't do either when they are properly installed.

I am not knocking the ARP studs but I am surprised on the number of users that are putting the blame down to the TTY bolts for head gasket problems. The reason for the difference in release torques on the bolts is down to the engine overheating especially around the exhaust bolts and either stretching the bolts beyond there yield and/or deforming the aluminium head. Its a bit like closing the stable door after the horse has run out. Keep the cooling system in good order = no head gasket problems.

Geordi,

Yes, I have access to hardness, tensile, and metallographic equipment. A couple of really low torque reading bolts would be interesting to look at.

My guess is that the alloy of steel used is very low and simple. It was probably heat treated just fine, but the allow itself was a poor choice for the heating cycles that these engines produce. They temper back to the point of being too soft over time.

Another possibility is that they fatigue over time like cheap springs do and get microfractures within the structure. All to save a few cents per bolt on alloy cost.

A look at the crystal structure should answer the question.

Jeremy

Just seems strange barring in mind we have 10 times more of these diesel engines here in Europe that we have not recorded as many head gasket problems as what your experiencing in the states. Yes the older VM 2.5 and 3.1 tdi installed in the 1994 on XJ Cherokee here suffered badly with head gasket problems that was caused by overheating. Like I said yes I would install ARP studs if i felt that will lock down the head better but I feel its the alloy head that's letting go?
I torqued new factory TTY bolts several times up to 120lbft rather than using the FSM way. That was around 3000 miles ago with no issues as yet. I did a test run first on an old CRD head and @ 130lbft the head started to deform and started to crush on several areas especially around the outer exhaust bolts and caused the hydraulic lifters/adjusters to stick in there bores.

Finally installed ARP studs one-by-one. Unlubed coarse block thread. Lubed washer, fine threads and nut. Inner rows 130 ft-lb and outer row 120 ft-lb. Here is the data from factory TTY bolt breakout torque.

CRD YEAR: 2006
MILEAGE: 93,000
BOLT TORQUE CENTER ROWS:
01:155
02:137
03:160
04:168
05:163
06:137
07:167
08:131
09:131
10:113

BOLT TORQUE OUTER ROWS:
11:135
12:146
13:156
14:127
15:147
16:142
17:136
18:136

While not definitive, these numbers show lower values on the inner row *intake* side, especially #10.
LMW

Mine did leak again after ARP studs. After having it machined it finally sealed it up.

Author:	farbedo [ Mon Jul 06, 2015 11:49 am ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Geordi, Yes, I have access to hardness, tensile, and metallographic equipment. A couple of really low torque reading bolts would be interesting to look at. My guess is that the alloy of steel used is very low and simple. It was probably heat treated just fine, but the allow itself was a poor choice for the heating cycles that these engines produce. They temper back to the point of being too soft over time. Another possibility is that they fatigue over time like cheap springs do and get microfractures within the structure. All to save a few cents per bolt on alloy cost. A look at the crystal structure should answer the question. Jeremy

Author:	geordi [ Tue Jul 07, 2015 4:45 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Mountainman wrote: The latest one I took apart was botched by a dealer 2 or 3 times. I didn't bother to get torque readings because I was sure that they didn't follow the procedure. Anyhow, the bolts were bone dry after only lasting a small number of miles for the PO, no oil had been added to them... For what it's worth, I believe the directions for the factory bolts also states that they have a manufacturing oil on them in the package and are not to be modified with any additional lubricant during installation. I will shortly have at least one new head gasket on the way to me, and those fresh factory bolts will of course not be getting used anywhere near an engine. If one or more is desired for destructive testing of an unused bolt, they will happily be provided.

Author:	Mountainman [ Tue Jul 07, 2015 7:06 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
geordi wrote: Mountainman wrote: The latest one I took apart was botched by a dealer 2 or 3 times. I didn't bother to get torque readings because I was sure that they didn't follow the procedure. Anyhow, the bolts were bone dry after only lasting a small number of miles for the PO, no oil had been added to them... For what it's worth, I believe the directions for the factory bolts also states that they have a manufacturing oil on them in the package and are not to be modified with any additional lubricant during installation. I will shortly have at least one new head gasket on the way to me, and those fresh factory bolts will of course not be getting used anywhere near an engine. If one or more is desired for destructive testing of an unused bolt, they will happily be provided. hmm, maybe it was just poor surface prep then, I ordered a machinist grade strait edge, and the block is very flat. Or maybe they just failed to follow the procedure multiple times in a row. From my measurements with the miller tool, this thing specs a no-hole, but there was a one-hole. But, another one I have has an even smaller measurement, and definitely calls for a no-hole, but the factory put a two-hole Now I'm scared to put anything back in except for what I know was running well:/

Author:	geordi [ Tue Jul 07, 2015 10:33 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
The measurements are for the average, so if you are following the measuring procedure outlined in the service manual (and I would compare both manuals to be certain there weren't any changes) and the measurements are calling for a no-hole, then that is the one I would select.

Author:	Mountainman [ Tue Jul 07, 2015 11:45 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
geordi wrote: The measurements are for the average, so if you are following the measuring procedure outlined in the service manual (and I would compare both manuals to be certain there weren't any changes) and the measurements are calling for a no-hole, then that is the one I would select. Thanks Geordi, I will try to summon the courage to go down two sizes from the factory

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Author:	LMWatBullRun [ Sat Aug 01, 2015 3:20 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
geordi wrote: The problem is that there isn't a "spec value" as such because these are TTY bolts and the factory process says "turn x degrees after reaching 60lbs torque" or something like that, and then turn the bolts another x degrees - So what is the final torque of the TTY bolt? Impossible to know. What we are seeing (and the point of this research thread) is that the #3 bolt seems to be affected by the heat from the cylinders and the exhaust, and loosens. Whether this is from stretch or rotation - I think it is from stretch - is somewhat irrelevant. The studs won't do either when they are properly installed. On a more general note to this topic, what we see are widely varying release torques, ranging from less than 80 FPT to over 200 FPT. That indicates that the head/headbolt system is not properly designed. More interestingly, on my CRD, the amount of take-up rotation required to reach 100 FPT with the ARP studs varied significantly, indicating that the head was slightly warped and that the ARP studs pulled the head back into alignment. In point of fact, the factory head bolts do not yield, as torquing them to the point that they yield causes head crushing. Torquing the ARP studs to the compression value required to make the factory "TTY" headbolts actually yield causes yielding of the glow plug and other head penetrations. See the ARP Stud thread for the details. The point is that the head bolts are poorly engineered for this application, and the ARP studs are a superior solution. Keep in mind that the beancounters don't care what happens after the warranty is out, which is why they took out the hardened washer under the head bolt and used a 7 mm shorter bare bolt. As long as the engine runs 100k they probably consider it a win. Factors that affect the release torque include but are not limited to (in no particular order): -smoothness and flatness of the underside of the head bolt head; -Galling of the head; -Compressive force normal to the head/head bolt bearing surface; -smoothness of the block threads; -Smoothness and uniformity of the bolt threads; -Linearity of the bolt. The ARP head stud addresses each of these issues and is distinctly superior to factory head bolts. I was convinced of this before I did the replacement, and all of the evidence I have read since reinforces that opinion. Can you make the engine run without them? Sure! Will the engine last longer and run better with them? Yes. The question you have to ask yourself is: Who benefits from a cheap solution ("TTY" head bolts)that requires regular out of warranty repairs?

Author:	lacabrera [ Sat Aug 01, 2015 5:22 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
I am not knocking the ARP studs but I am surprised on the number of users that are putting the blame down to the TTY bolts for head gasket problems. The reason for the difference in release torques on the bolts is down to the engine overheating especially around the exhaust bolts and either stretching the bolts beyond there yield and/or deforming the aluminium head. Its a bit like closing the stable door after the horse has run out. Keep the cooling system in good order = no head gasket problems.

Author:	LMWatBullRun [ Sat Aug 01, 2015 10:27 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
lacabrera wrote: I am not knocking the ARP studs but I am surprised on the number of users that are putting the blame down to the TTY bolts for head gasket problems. The reason for the difference in release torques on the bolts is down to the engine overheating especially around the exhaust bolts and either stretching the bolts beyond there yield and/or deforming the aluminium head. Its a bit like closing the stable door after the horse has run out. Keep the cooling system in good order = no head gasket problems. Overheating from poor service is certainly a possible cause, but if that is the cause then there are an awful lot of poorly trained mechanics both working for dealers and working on their own. When one considers the bad design of the EGR system, the bad design of the thermostat system, the bad design of the transmission system and other miscellaneous design errors, I find it hard to blame so many HG problems on poor maintenance. The reality is that this design was never produced long enough for the manufacturer to work out all the bugs. That is what we are doing here. Also, in point of fact, I found galling at several of the head bolt recesses on my head, including at least 2 that I recall on the intake side. IIRC, others have found similar things. In short, your hypothesis WRT poor maintenance/cooling failures/bolt stretch does not stand up. It is not just the bolts proper, but the design of the bolt and head system that is flawed. If VM Motori had installed 5-7mm longer bolts with hardened and ground precision washers underneath them, torqued, loosened, and retorqued, there would be far fewer HG failures, as there would be much less variation in clamping force. In order to put the theory that overheating at the exhaust valves causes the loose gaskets to the test, we'd have to take the exhaust side outboard bolts and measure them for stretch and hardness. Even then, it could well be that for whatever reason, some CRDs have loose bolts there, and the resulting HG failures happen to appear in that location. There are enough other HG failures at other locations to make ME very wary of making any such pronouncement. My assessment of the data so far is that they are too limited to allow any sort of definitive assessment except to say that there appears to be an unacceptably large variation in the release torques of the factory head bolts. As I stated in the original thread on ARP studs, the "TTY" bolts do not yield, and the angle of rotation method used by VMM appears to result in large stochastic variation in clamping force. That is as far as I will go at present. When I next remove the intake manifold in the second Jeep to ever, as far as I know, have ARP studs installed you can be sure that I will retorque the stud nuts and measure both the release torque and the retorque rotation angles to see what I can find about how this engine has weathered the intervening mileage. I might go as far as removing a stud and sending it to ARP for testing for yield and hardness to see whether it has been overheated. The other bit of information that would be edifying would be for somebody to buy a brand new head, install factory bolts per the factory installation instructions, and check the torque as they went in. Then, run the engine for a few thousand miles and check the removal torques. Volunteers?

Author:	LMWatBullRun [ Sat Aug 01, 2015 10:30 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
farbedo wrote: Geordi, Yes, I have access to hardness, tensile, and metallographic equipment. A couple of really low torque reading bolts would be interesting to look at. My guess is that the alloy of steel used is very low and simple. It was probably heat treated just fine, but the allow itself was a poor choice for the heating cycles that these engines produce. They temper back to the point of being too soft over time. Another possibility is that they fatigue over time like cheap springs do and get microfractures within the structure. All to save a few cents per bolt on alloy cost. A look at the crystal structure should answer the question. Jeremy RacerTracer got the VM Motori assembly drawing for the factory head bolt, which included the exact steel spec. See the ARP Stud thread for the information.

Author:	lacabrera [ Sun Aug 02, 2015 11:03 am ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Just seems strange barring in mind we have 10 times more of these diesel engines here in Europe that we have not recorded as many head gasket problems as what your experiencing in the states. Yes the older VM 2.5 and 3.1 tdi installed in the 1994 on XJ Cherokee here suffered badly with head gasket problems that was caused by overheating. Like I said yes I would install ARP studs if i felt that will lock down the head better but I feel its the alloy head that's letting go? I torqued new factory TTY bolts several times up to 120lbft rather than using the FSM way. That was around 3000 miles ago with no issues as yet. I did a test run first on an old CRD head and @ 130lbft the head started to deform and started to crush on several areas especially around the outer exhaust bolts and caused the hydraulic lifters/adjusters to stick in there bores.

Author:	LMWatBullRun [ Sun Aug 02, 2015 9:47 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
lacabrera wrote: Just seems strange barring in mind we have 10 times more of these diesel engines here in Europe that we have not recorded as many head gasket problems as what your experiencing in the states. Yes the older VM 2.5 and 3.1 tdi installed in the 1994 on XJ Cherokee here suffered badly with head gasket problems that was caused by overheating. Like I said yes I would install ARP studs if i felt that will lock down the head better but I feel its the alloy head that's letting go? I torqued new factory TTY bolts several times up to 120lbft rather than using the FSM way. That was around 3000 miles ago with no issues as yet. I did a test run first on an old CRD head and @ 130lbft the head started to deform and started to crush on several areas especially around the outer exhaust bolts and caused the hydraulic lifters/adjusters to stick in there bores. I am not at all surprised that you saw head yielding at 130 FPT PRIOR to the factory bolts yielding, which confirms my calculations. Part of the issue with the factory setup is the lack of hardened and ground washers. One of the things that you get from using ARP studs is that you use a precision made washer between the stud nut and the face of the head recess. This washer provides significantly more bearing surface on the head, allowing more clamping force without any yielding of the head.If I were going to use a bolt rather than a stud, I would definitely get a slightly longer bolt and use a hardened and ground precision washer under it. But why go to the trouble of sourcing a bolt when you can get an already engineered and tested stud that works better than any bolt you can get? This has been gone through quite a bit already on the ARP stud thread- viewtopic.php?f=5&t=65524

Author:	pjigar [ Sun Aug 09, 2015 11:33 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Finally installed ARP studs one-by-one. Unlubed coarse block thread. Lubed washer, fine threads and nut. Inner rows 130 ft-lb and outer row 120 ft-lb. Here is the data from factory TTY bolt breakout torque. CRD YEAR: 2006 MILEAGE: 93,000 BOLT TORQUE CENTER ROWS: 01:155 02:137 03:160 04:168 05:163 06:137 07:167 08:131 09:131 10:113 BOLT TORQUE OUTER ROWS: 11:135 12:146 13:156 14:127 15:147 16:142 17:136 18:136

Author:	highironcrd [ Tue Aug 11, 2015 10:22 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
got a friend coming around with a stud set and some tweaking can't wait to see the results

Author:	LMWatBullRun [ Sun Aug 16, 2015 9:38 am ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
pjigar wrote: Finally installed ARP studs one-by-one. Unlubed coarse block thread. Lubed washer, fine threads and nut. Inner rows 130 ft-lb and outer row 120 ft-lb. Here is the data from factory TTY bolt breakout torque. CRD YEAR: 2006 MILEAGE: 93,000 BOLT TORQUE CENTER ROWS: 01:155 02:137 03:160 04:168 05:163 06:137 07:167 08:131 09:131 10:113 BOLT TORQUE OUTER ROWS: 11:135 12:146 13:156 14:127 15:147 16:142 17:136 18:136 While not definitive, these numbers show lower values on the inner row intake side, especially #10. The exhaust numbers are all fairly close, #9 excepted and that one is not too bad. I'm going to look forward to seeing more data. LMW

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Author:	jwhite [ Mon Aug 17, 2015 12:24 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Hello all! new to the forum. Im desperate to find a parts supplier for the 2.5 non U.S crd. I have a 2004 Cherokee sport 5spd 4x4. Looking to rebuild engine. Thanks for any help.

Author:	pjigar [ Mon Aug 17, 2015 12:32 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
LMWatBullRun wrote: While not definitive, these numbers show lower values on the inner row intake side, especially #10. LMW The #10 bolt had sign of rust on the thread and some oily goo. That might explain the lower torque. I hope the head gasket will be fine with the ARP studs. The head gasket is not leaking right now.

Author:	geordi [ Mon Aug 17, 2015 10:42 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
To my knowledge, not a single engine that has added the ARP studs has developed a head gasket leak. You should be good.

Author:	SargeIndustries [ Tue Aug 18, 2015 1:19 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Mine did leak again after ARP studs. After having it machined it finally sealed it up.

Author:	LMWatBullRun [ Thu Aug 20, 2015 6:03 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
SargeIndustries wrote: Mine did leak again after ARP studs. After having it machined it finally sealed it up. Interesting! Did you do a one by one, or a new HG?

Author:	SargeIndustries [ Fri Aug 21, 2015 3:16 pm ]
Post subject:	Re: CRD Head Bolt Research Request: We need your data!
Did not do the one by one replacement. Had the head off and replaced the gasket using ARPs. My motto now is if you have a head gasket leak on a diesel motor with high compression, forget about taking a machined straight edge and feeler gauge to check for flatness. Mandatory head resurfacing and valves recut to recess them in a bit. It is not worth your time to have to go back buy another head gasket with all the bolts and spend 20 hours or so to do it twice. My head work cost $400 to give me peace of mind that it is flat. Hasn't leaked since.