papaindigo wrote:
PZKW108 - what kind of useless snarky comment is that?
Mike92104 - I concur that bracket is not critical, nice to have but..., so if you can source one good but if not no problem. The HDS tstat is not all that heavy and is held to the head by 3 stout bolts which are perfectly adequate.
I actually disagree with both of you, papaindigo and Mike92104. And I am the guy that manufactures the Model 001.
Let me be clear... the Model 001 is massively strong, and it will not break. It will not break even if you are not using the little stamped steel thermostat bracket that the wing of the Model 001 bolts to. The robust machined housing of the Model 001 absolutely assures this.
However, the strength of the Model 001 is not what CRD owners should be concerned about... it is the parts the Model 001 is attached to that should give pause when considering issues like this.
This situation is one of those where unforeseen circumstances can occur when you do not replicate EXACTLY or IMPROVE upon what the engineers have done to design the thermostat assembly and all of the parts that are mated to it in the manner they have deemed appropriate. This is the reason I took so much time and trouble to design the Model 001 to replicate the form and the function of the O.E. thermostat assembly. Doing this ensures that I do not have to perform outrageously expensive laboratory testing to check out all contingencies if I wanted to cheap out on the design for the Model 001, like trying to re-use the O.E. thermostat housing.
For example, the O.E. thermostat assembly uses a thermostat valve that incorporates a spring loaded bypass valve operating on the same wax motor as the main valve controlling coolant flow to the radiator. The housing of the O.E. thermostat assembly is - by design - appropriately sized to match the flow characteristics of the valve it contains; to size it otherwise simply would not make sense. Likewise, the Model 001 uses a replaceable thermostat valve that operates the same way, in a chamber matched to the increased size of that valve. Again, to design an upgrade thermostat assembly any other way would be foolhardy. Why would I try to second guess what the engineers of the R428 engine have done, when it is easier and simpler to just match the O.E. thermostat assembly’s basic design and improve only in the areas that are recognized as being inadequate?
Taking this concept to the steel bracket mount of the O.E. thermostat assembly, it is obvious to me that the engineers who designed this felt that additional support for the thermostat assembly is required. Perhaps the engineers felt that there could be damage to the mating surfaces of the thermostat assembly and the cylinder head if the thermostat assembly were only attached by the flange mating the cylinder head.
How, you might ask? The engineers considered the following factors when considering what needed to be done to ensure long term integrity of the thermostat mounting points.
1) The weight of the part, and all other parts attached, especially on the opposite side of the mount to the engine.
2) The size of the part, and all other parts attached, especially on the opposite side of the mount to the engine.
3) The fact that the thermostat assembly is attached to the engine on one end.
4) All internal combustion engines vibrate, some more than others. Four cylinder engines tend to vibrate more than 6 and 8 cylinder engines.
5) Any weight that may be placed on the thermostat in the course of servicing the engine bay, especially when running the engine.
Imagine the weight of a heavy-set technician leaning over and laying directly on the thermostat housing while removing something else on the engine. Consider how long the O.E. part is, and the fact that you have hoses attached to the opposite side of where the thermostat is mounted to the engine. The weight of someone leaning heavily on the thermostat assembly, especially on the opposite side to the mounting flange, will create tremendous pressure on that mount. Is it enough to damage the mating surfaces and cause a leak, perhaps crack the cheap aluminum casting right at the mount, or even damage the threaded thermostat mounting holes? Quite possibly, and that is why the engineers decided another mounting bolt placed a significant distance from the thermostat to engine mounting flange is required to create a triangulation of mounting points on different planes to properly secure the thermostat assembly.
A vibrating engine can also create similar problems if the thermostat is only mounted at the thermostat to engine flange. Take a weight of about 5 lbs and hold it close to your body. Now violently shake yourself or find one of those vibration plate machines used in weight reduction clinics to strap yourself into. I am certain you will find that the weight is relatively easy to hold on to. Try doing the same exercise while holding the weight at the end of an outstretched arm, and I believe you will find that the weight is significantly more difficult to hold on to by comparison. The forces you would have to contend with in these circumstances are similar to forces that the engine would have to deal with. Therefore the more secure the mounting method - like the aforementioned triangulation of mounting bolts on different planes - the better.
Consider also the fact that the R428 engine is used in an off-road capable vehicle. Those of you who do a lot of off-roading already know that things can shake loose if extra precautions are not taken to bolt things down securely.
The case for using the steel bracket mount on the Model 001 is even stronger. Keep in mind that the O.E. part is about half the weight, (O.E. part is 580 grams or 1 lb, 4.4 oz), than the smallest version of the Model 001, (1st generation Model 001 is 1.074 kg or 2 lb, 5.9 oz; second and third generation Model 001s are slightly larger and heavier to accommodate the threaded accessory ports and the move to using a straight vertical hose barb). There is also the size and length of the O.E. part verses the Model 001 to consider, as the Model 001 is larger and longer than the O.E. part. The forces that are at play on a Model 001 could be as high as 4 times the forces placed upon an O.E. thermostat assembly. Therefore, what the engineers of the R428 deem as necessary regarding the O.E. thermostat assembly mounting points most especially applies in the case of the H.D.S. Model 001. No, you will not likely damage the Model 001 if you only use the cylinder head bolts, but there is a very good chance that you will damage the cylinder head it is attached to if you do not use all of mounting points provided to you.
I ask you; why take the chance? PZKW108 is commenting on geordi’s laissez faire attitude towards vehicle repairs. “Good enough” seems to be the mantra by which geordi conducts himself with regards to repairing vehicles, unless it suits his purpose to sell more cylinder head repair jobs. Regarding that topic, neither PZKW108 or myself have seen conclusive evidence of geordi’s claim on another thread that the torque to yield cylinder head bolts are to blame for the numerous head gasket issues experienced by CRD owners.
One of the first things you learn as a vehicle technician is that it is hazardous to second guess what the engineers who designed the vehicle have done in any given circumstance, and then try to armchair engineer a shortcut upgrade fix. geordi has done this on several occasions, including his endorsement of the in-hose thermostat valve “upgrade” to fix the cold running engine problem CRD owners face due to EPA regulation. This so-called fix makes fundamental changes to how the cooling system works in the CRD engine in ways never intended by the engineers who designed the R428, which in turn can lead to the cylinder head warping and the head gasket failing.
geordi is doing a similar thing here by stating that bolting the thermostat assembly – either the O.E. part or the Model 001 - to the steel bracket is not necessary. Mounting the thermostat assembly by only the assembly to engine bolts is also making a fundamental change to what the engineers intended with this part, and it is a foolish assumption to make for the reasons I have written above.
So I wholeheartedly endorse what PZKW108 has written here. geordi has absolutely no business commenting on the appropriateness of how the R428 is engineered/designed, or what an owner can get away with doing to his or her engine. Not only are some of his theories regarding several topics on the R428 absolutely incorrect, they show no respect to the people who actually designed and built the engine.
A general rule of thumb regarding ANY engineered product is, unless someone actually communicates with the people who designed the product to determine otherwise, then it is wrong to assume that you can simply ignore reality and do what you like. geordi not only did not contact V.M. Motori regarding this issue, he did not contact me regarding the Model 001. That is just arrogant and plain WRONG….
“That isn't that critical of a part - if you don't have it, don't sweat it. The two mounting points for the heater are more than enough to sustain it, that little bit of steel is more like a "belt and suspenders" bit of engineering.” Indeed geordi, what makes you think you know more than the V.M. Motori engineers who designed the R428, or me, who designed the Model 001?
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