| Author | Message | ||
     William H. Trovinger II Prolific User Username: bill_trovinger Post Number: 196 Registered: 8-2003 |
Hope someone can help. I am about to change out the thermostat in my ’76 SS but saw a listing on eBay that has me wondering if I should have new bolts ready before I do this. The following is a quote from that listing: “FYI YOU CANNOT REUSE YOUR THERMOSTAT HOUSING BOLTS. THE CORROSION & BOLT STRETCH WILL STRIP YOUR CYLINDER HEAD & YOU WOULD NEED TO GO THROUGH THE PAIN TO INSTALL A STEEL INSERT. BID ON THE SET OF 4 BOLTS & WASHERS NOW. YOU WOULD NEED TO REMOVE THE THERMOSTAT HOUSING IF YOU ARE DOING A COOLING SYSTEM FLUSH. DON'T SKIMP & END UP LIKE MOST SHADOW & CLOUD OWNERS WITH STRIPPED THERMOSTAT HOUSING THREADS & BE VULNERABLE! THEY LOVE TO SEE YOUR ROLLS GET TOWED IN! THE QUALITY OF THESE BOLTS IS MUCH HIGHER QUALITY THAN THE ORIGINAL ROLLS-ROYCE BOLTS. ROLLS WANTS $8 PER BOLT & IT IS LOWER GRADE MILD STEEL. SOME OWNERS THINK BY USING STAINLESS IT WOULD BE BETTER. THEY ARE WRONG BECAUSE THE NICKEL IN THE STAINLESS WILL DESTROY THE ALUMINIUM BECAUSE OF THE REACTION OF DIFFERENT METALS! STAINLESS CAN ONLY BE USED WITH STAINLESS PARTS.” Does this sound correct? Best regards, Bill SRE23726 | ||
| Gordon Norris Prolific User Username: crewes_missile Post Number: 142 Registered: 2-2005 |
Bill, The bolts on my 1990 Bentley are standard H/T steel bolts (not mild steel) .250 UNF x 875 long. Shadow probably the same (but check one first!) I don't think Crewe actually carries them anymore as they are so readily available for a couple of dollars. Can be purchased at any hardware, or if not exact size can be purchased longer and easily cut down. Often water seeps into the threads from the gasket and causes some corrosion, or people use a hard thread or gasket sealant that ruins the bolt threads. If the threads are at all suspect, use new bolts, clean the threads in the thermostat housing with a good tap if necessary, make sure there is no gunk at the bottom of the holes that could cause the bolts to "bottom-out", put a small drop of oil on each thread and then wipe to leave a fine film on the threads, and use a non-setting sealant like "hylomar" (used to be recommended by RR) sparingly on the gasket faces. Re-tighten after a few minutes settling and check again after first hot run. No need to spend alot on "special" bolts from ebay, but it is wise to have a spare set of bolts so you aren't stranded, especially if you don't know their condition. If you use the above procedure your bolts should be pretty well pristine next time around. Hope this helps, Gordon. | ||
| David Gore Moderator Username: david_gore Post Number: 435 Registered: 4-2003 |
In my opinion, the only time thermostat housing bolts cannot be reused is when they show obvious "waisting" from corrosion due to glycol coolant penetrating down the thread and setting up a galvanic reaction once it starts to break down with age. I would not use stainless steel bolts as these will accelerate corrosion ONCE it begins due to the greater voltage potential difference between stainless steel and the Aluminium block. Mild steel bolts will give satisfactory service if coolant penetration of the threads is avoided. Gordon's advice is most appropriate for this reason. Pseudo-science in a sales pitch is always a concern for me given the likelihood of acceptance by the ordinary person. | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 380 Registered: 4-2003 |
I must say that the bovine detritus in that ad which I have seen is exemplary. If you got to the point of 'stretching' the 1/4 bolts used on the thermostat you would certainly need more than new bolts. The housings were also fitted with helicoils and if you bugger one up you put in another. Personally I always use an antiseize grease which I dip the bolts in but beforehand and always run a tap down the holes and a die down the bolts. Any that are 'waisted' get the heave ho! I have always believed that this area has been a sacrificial one going back in my meagre experience to the 'B' series engines where those of you have been there will know the poor thermostat cover gets regularly eaten away. But only last weekend I ripped off the cover on an '85 SZ and the casting was as smooth as a baby's bum. Hopefully the RR coolant is doing its job. Wish I had the time and energy to rip out a liner and see what is going on down there. The lower 'O' rings however at 108K are leaking already!!! | ||
| William H. Trovinger II Prolific User Username: bill_trovinger Post Number: 197 Registered: 8-2003 |
Gordon; David and Bill; Thank you for the responses! I will forego the eBayer and just replace my thermostat this weekend. If a bolt looks bad my local hardware store will be less expensive.  Best regards, Bill | ||
| David Gore Moderator Username: david_gore Post Number: 436 Registered: 4-2003 |
Forgot to add one further piece of general information relating to rate of corrosion. The higher the relative stress levels in a material; the greater the likelihood it will corrode at a higher rate: i.e. SAE Grade 5/Grade 8 bolts will corrode much faster than mild steel bolts of the same dimensions. A fully torqued mild steel bolt will corrode somewhat faster in the same environment as a loose mild steel bolt. This is also why a high-carbon steel handsaw blade left out overnight rusts very readily [if it is not protected by grease/oil] whereas a piece of ordinary sheet steel [not galvanised or protected] only develops superficial rust spots under the same conditions. (Message edited by david_gore on April 13, 2005) | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 382 Registered: 4-2003 |
That reminds me of a facet of body repair. The car's that is. If a fender for instance has been creased and subsequently straightened out, if the paint work is really allowed to deteriorate, the first sign of rust will be along the original crease. It even happens on swage lines where the metal has been stressed. | ||
| Chip - SRX1248 Unregistered guest Posted From: 67.62.68.55 |
What a scam! Having just replaced SRX1248's thermostat I quick wire wheeled and reinstalled the original bolts. I like those Lowe's or Home Depot super hard Grade 8 bolts in the picture. Now those might strip out a questionable hole especially with their fine Taiwanese threads. YMMV, SRX1248 (Message approved by david_gore) | ||
| Gus Brogden Experienced User Username: gus Post Number: 15 Registered: 2-2008 |
Does anyone have an idea if an aftermarket lower rad hose exsists for a Shadow I? I'd rather order one from Napa than to have to pay to have one shipped from Europe.... |
