| Author | Message | ||
     Randy Roberson New User Username: randy_r Post Number: 7 Registered: 3-2007 |
Hi a technical question begs to be discussed: is the RR 6.75 l block repairable by line boring, in case of damaged main bores due to overheating? What has been tried? In our business (gas pipeline) almost everything is considered repairable, esp. if it is expensive or not available. I have seen large engines with the side torn out, have an entire new main saddle fabricated and fixed in place. Of course, the expense would be $$, but as lots of our work is only justifiable as "labor of love" anyway, what is technically possible and what has been done in the way of unique repairs to the RR 6.75L engine block? I cannot find anything on the Web describing any such repairs. | ||
| Paul Yorke Prolific User Username: paul_yorke Post Number: 105 Registered: 6-2006 |
Do you mean if the liners have been holed or the sealing ridges have been damaged? They have removable liners. These often warp when overheated, but the block is usually fine. New liners and seals are usually enough, with new pistons on the liners that have actually picked up. | ||
| Randy Roberson New User Username: randy_r Post Number: 8 Registered: 3-2007 |
Just in general; I read that the main bores tend to warp and oil pressure suffers if the engine has been overheated; would it have to be an extreme case as I imagine, or is this more common? Also, I forgot to mention earlier, have there been any attempts to repair liner fits, etc which have been damaged due to corrosion (i.e. oversize OD liners; block inserts, etc)? I understand the basic wet liner setup; it is very much like the smaller industrial engines I have experience with. What are the RR liners made of: steel, cast iron; hardened, or? How much do parts cost:pistons,liners, rings, bearings, gaskets? Gosh, I'm full of questions tonight. Thanks for your response and indulgence of a student. | ||
| Paul Yorke Prolific User Username: paul_yorke Post Number: 106 Registered: 6-2006 |
Sorry Randy, I've never had a block go on me. I believe you get corrosion build up or limescale on the water liner seal. As you pull the liner out the seal sticks and twists and cracks the seal grooves. The liners are cast iron and easily machined etc. When overheating, what seems to happen is you get a hot spot on a liner, this expands to touch the piston and metal transfers from the piston to the liner and causes a 'tocking noise'. Usually it's the A4 piston, then B4. They can run 'forever' with this hollow knock. Oil pressure shouldn't be affected by liners or overheating unless the mains have been cooked??? Really rough prices: pattern liner £100 Pistons £250 de-coke set £300 liner seal set £250 mains £300 | ||
| Randy Roberson New User Username: randy_r Post Number: 9 Registered: 3-2007 |
Thank you for the interesting information. These must be tough engines. I have see problems similar to those you described so they are pretty typical of engines in general. I grow more and more confident in these fine engines and that I can handle this. They are so interesting (and difficult to gain experience with). Merry Christmas to everyone and best regards. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1327 Registered: 4-2003 |
Randy, These are indeed incredibly tough motors. The early 6230cc motors have a design and test power output of 600HP, so it is no wonder that the production versions at about 200HP have a realistic life of 1,000,000 miles. Late single-Turbo 420HP versions of the stroked version, 6750cc, suffer no loss of life. However. York Motors told us in the 1980s that they had never found a motor in need of a full overhaul due to wear. Those badly overheated were scrap, and they never attempted to reuse an overheated block. Yorks were only fitting brand new motors back then at $35,000 for parts alone. The warpage and peripheral damage is usually too severe, so a guaranteed secondhand motor from the UK at £2,500 is the only way to go these days. Not just for that reason, our cars have regular coolant, thermostat and hose changes, using the mandatory 50% glycol (freezing at -37C) and never suffer scale or corrosion. At 275,000km (Turbo R) and 330,000km (T-Series), they run as they did the day they left the factory. Some cars are run with lower coolant concentrations, and the liners will never be removed without destroying the block on those. RT. | ||
| Randy Roberson New User Username: randy_r Post Number: 10 Registered: 3-2007 |
More excellent information, thanks for your reply. I can see the problem with liners: scale buildup on the coolant side due to poor maintenance of the coolant. I would say the liners would nave to be cut out rather than pulled in that case. I can see that, if cost is not an issue, get new parts, but for those more technically minded, and with less $$, it's more interesting to develop and execute a different, more imaginative plan of attack, this being the reason behind my questions. Also, I don't think I could put a RR block in the scrap pile (overly romantic). I guess the first one is the hardest, as they say. | ||
| Trevor P Hodgkinson Experienced User Username: wm20 Post Number: 11 Registered: 11-2006 |
The first car that we bought was in a very sorry state mechanically, as we found out much latter on. When we tried to pull the liners all the front ones came out reasonably well although 2 did fracture some of the lip for the seal ( repaired with Davcon) but the back two broke the pullers and one of them started to damage the block so they were machined out. In retrospect it would have been cheaper ( and a lot faster) to buy a factory replacement but this was the first time I had pulled down one of these motors and I have learned a lot since then. The second motor was similar so we did not even bother, if the liners did not come away relatively easily then it was out with the block & off to Masters for boring straight away.On this motor nearly 1/2 the water jacket was solid cement like gunk which I was told was leak stopper, how the cylinder actually dispersed any heat I have no idea. The problem is of course that you can not be sure of the expertese & maintenance applied to the cars when you are owner 3 or 4 so I now assume the worst & treat them accordingly. The first car's last owner was a doctor who appeared to have taken good care of his Shadow, the oil was relatively clean as were all of the filters, all of the hydraulic lines had been replaced as had all of the water lines but it blew an unacceptable amount of smoke under hard acceleration and ran a little rougher than a RR should. When we finally managed to get a compression tester into the plug holes ( easy task for a contortionist) we found virtually no compression on A+B 2&3 so we assumed blown head gaskets. However with the heads off the gaskets were in good condition and relatively new but there seemed to be a lot of slop in the middle pistons. When we removed them the top rings were so worn that they fell off the pistons and the pistons complete with remaining rings would literally fall straight through the block. We guessed that someone had fitted oversized rings instead of replacing the pistons. All this was before we found this list and I can assure you that the best thing you can do is to download the entire forum including archives and the general forum as well and read them several times then do the same with the T-One Topics. The information within these pages is literally worth $ 1000's and I for one can not thank the forum originators and contributors enough. With grateful thanks Trevor | ||
| Randy Roberson Experienced User Username: randy_r Post Number: 12 Registered: 3-2007 |
Thanks for the info; I read these pages as well as Tee-One, learning all I can before I take the plunge; at least this way I am learning at a safe distance (not spending any money!). It is not easy to find a Rolls-Royce around here that one can learn from. I've sort of broken in on a 1986 S-Class Mercedes-Benz the past four years, and I haven't scared myself (much) yet. One day I'll be ready... Thanks to all of you; I value all info I have been reading, and I sense the pleasure you derive from your machines and enjoy everything you share; have a Merry Christmas and a prosperous New Year! | ||
| bob uk Unregistered guest Posted From: 80.6.170.209 |
line boring refers to the main bearing housings. not the bores or liners for pistons. The idea is open out all the main bearings housings on a single setting so that they must be in line. Overheated engines are bad news. I have overhauled thousands of engines. Best ones to overhaul are the high mileage worn out ones. Because they have been throughly "tested" and I know if the engine lasted 200,000 miles then it should last another 200,000 providing the job is done properly. I have inspected overheated engines to find a manufacturing fault such as badly cast water ways--- not R-R. If you seriously cook a R-R V8 be very careful about rebuilding it because it will never run right. I have seen engines where the block is warped and the cam and crank brgs are out of line. so much remedial machining is needed that the price goes up and up and there is only so much metal on the block. Plus oversize backs on bearings are differcult to get now. The overheat damage is never caused by one boil over is is caused by people driving the car knowing that it overheats hoping that topping up and steady driving will get them through----- it does not work the engine gets cooked. (Message approved by david_gore) | ||
| David Gore Moderator Username: david_gore Post Number: 900 Registered: 4-2003 |
Hi Bob and welcome back after a long absence - I missed your contributions from the West Country. Kind regards David | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1152 Registered: 4-2003 |
Should anyone be travelling through, around, near or over Canberra I have an engine in pieces now for a '72 Shadow and probably more interesting, a complete sub frame out and on stands. You are welcome to inspect these in my garage but let me know you are coming so that the scones will be fresh!! |
