| Author | Message | ||
     Peter McCarthy Unregistered guest Posted From: 101.176.112.60 |
I have just removed the engine and gearbox from my Mk6 Special to replace the clutch plate (as the gearbox cannot be removed separately in this Special) and to address numerous oil and coolant leaks and to clean out coolant passages as per Norman's advice in KDA132. I found that the previous owner had paid $1800 only three years ago to have a line of Irontite taper plugs installed to repair an 18 inch long crack on the upper right hand side of the cylinder block, which had been smoothed and painted over. This repair has been weeping slightly. My options seem to be to look for an new block, to use some metal sealant product over the repair or to have some welding done. I have not yet measured bores etc but I expect work will be required, possibly as far as re-sleeving, new pistons etc. There has been a lot of crankcase pressure. So I wonder whether a repair can be expected to hold up. In other words, I could be throwing a lot of good money into an engine that will not last. Any advice? And has the potential supply of engine blocks in Australia dried up? (Message approved by david_gore) | ||
| Bob uk Unregistered guest Posted From: 94.197.122.74 |
That's bad news. welding is out of the qquestion because cast iron doesn't like that amount of heat and will usually crack alongside the crack. However recently I saw aluminium and steel welded together so there maybe a new process. In the UK we call it cast iron stitching. I have seen this used to good effect on even stressed components. Assuming that the stitching or irontiting is structurely sound then the seepage can be cured with a spread of epoxy metal filler. Not body filler. Then rub it down and paint over satin black. I used to run a engine recon shop and I would never consider a cracked block because I dealt we common engines that I could easily replace. Blocks that I couldn't replace I simply refused. I also had a black list of engines that I don't work on such as Triumph V8 stag and PSA V6. Ideally find a good block but it's bound to be expensive and rare. The crankcase pressure won't be enough to cause a problem. The forces developed by the engine internally can strain a repair. I understand your dilemma. (Message approved by david_gore) | ||
| Jonas TRACHSEL Frequent User Username: jonas_trachsel Post Number: 55 Registered: 2-2005 |
Peter I think you do not need a "new" block, who knows wether what you eventually find would be better or even worse than yours. I would try to save your block. There must be an economical and sucessful way to stop that slight weeping. Cast iron can be welded, however it needs to be preheated in an oven to dull red, then welded and shoved back into the oven for slow cooling down. (see www.castironwelding.co.uk). I have heard that cast iron also has been sucessfully MIG-welded, however I would ask for references of such repairs by the shop in question. Another guy proposed soft soldering the crack if the surrounding metal is sound. Hope this is of some help. Jonas | ||
| Jan Forrest Grand Master Username: got_one Post Number: 697 Registered: 1-2008 |
Jonas is pretty much correct about the right way to weld most casting iron. Heating to a 'dull red' may be a little higher than necessary, but not all casting irons are made equal. Yes, MIG might be the way to go, but if the metal was that hot I would be inclined to use stick/MMA so that my hands were further from it. Even then preparation is the key. The crack will have to be 'V' ground for better weld penetration and to prevent the crack opening up further it's usual to drill a hole at each end first to relieve the point stresses there. For more info on this kind of process go register here and ask the question again. | ||
| David Gore Moderator Username: david_gore Post Number: 1483 Registered: 4-2003 |
Welding cast iron is very much an art and not a science where experience is everything. Cast iron is very susceptible to thermal shock especially when striking an arc leading to more cracking and/or changes in microstructure that cause future cracking problems. Proper and adequate preheating and post-weld stress relieving are essential and this is best done in a temperature-controlled furnace as temperature control is critical to avoid cracking and microstructure changes. Temperatures in excess of 800+ deg C must be avoided; preheating in the range 600 to 700 deg C is usually preferred and post weld stress relieving in this temperature range [allow minimum 2 hours soaking at temperature per 25mm of maximum metal thickness before turning the furnace off and allowing the block to cool to room temperature before removing it from the furnace]. Choice of filler and welding technique should be made in consultation with a technical representative from a reputable welding consumables supplier as these will depend on the location and extent of cracking to be repaired and the welding equipment to be used. Be very sceptical about YouTube videos - what apparently worked in the video may not always be replicated successfully. Castings can vary widely in composition and quality; always assume the worst and repair accordingly. If in doubt, leave it to a recognised specialist rather than attempting a DIY reclamation. | ||
| Peter McCarthy Unregistered guest Posted From: 101.176.112.60 |
Since posting I have found the Block Repair thread in the 2005 archive. Thanks everyone for the information. Welding sounds daunting and the pre-heating might involve more engine stripping than I need to do, as the bore measurements are all good and there is no need for a rebore. I will research metal sealing compounds and try one of those. I will report on the outcome. (Message approved by david_gore) | ||
| Bob uk Unregistered guest Posted From: 94.197.122.86 |
On the tv show a car is reborn they repaired rust damage to the axle tube where the u bolts clamp to the leaf spring. MGB DHC. They used epoxy metal filler made by Isospon. It's dark grey in colour and sets up in about 30 mins then goes rock hard in a day. It's not expensive. St David's Isopon. Satin black in aerosols will withstand engine heat. Satin black with polished aluminum and brass bits looks very Rolls Bentley. Incidently paint on engines that discolors is an indication of overheating except near the exhaust ports. Clean engine and g/box with wire brush and paraffin. Then water soluble cleaner. Dry with heat gun. To make aluminum shine a bit wire wool. Its a messy job the engine ends up looking good but one ends up looking like a chimney sweep not matter how hard one trys to keep clean. Uses barrier cream on hands frequently while using any degreaser. (Message approved by david_gore) | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 173 Registered: 10-2008 |
Peter is the leak substantial or would one of the cooling system sealers work ? There used to be a ceramic sealer in the UK that the trade used, with some success. Mark | ||
| Peter McCarthy Unregistered guest Posted From: 101.176.112.60 |
Mark, it is a weep and not as serious as the leaks from the various cover plates, which I am now cleaning up. When I first got the car I added a sealant in the radiator which made a big difference and allowed me to run the car for a couple of years, but I knew I would have to sort it eventually.i am amazed at how much mud there is in the coolant passages, and it is coming out with bent wires and brushes. I haven't taken the front engine mount off yet so don't know how the coolant tube looks. I like the sound of the externally applied epoxy and think it will be successful on the crack. I have some special black paint which worked well went I rebuilt the rear axle and even withstood blowtorch heat so will give that a try. (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1117 Registered: 6-2009 |
Peter, To add to Bob_uk's comment about epoxy, I have used J B Weld High-Heat Epoxy Putty with great success (though not in the application that you have at hand). I used it to patch a small hole that had developed in a piece of exhaust tubing and it's held up incredibly well. Brian | ||
| Bob uk Unregistered guest Posted From: 94.197.122.72 |
JB weld is good gear. The heat that a block reaches is about 110c max. Normally the temperature of the block is the same as the water temp. I dislike sealers that are poured into the cooling system because they can block off smaller passages. Use silicon sealer on gaskets. Run a bead fit the part allow the part to stand off about 10 thou. Let the silicon go off for ten mins then torque up. To make gaskets. Using a dirty finger press the gasket against the shape. Then cut out with scissors along the dirty line. To cut the inside and holes use a ball pain hammer to tap around the shape. To make holes lay the ball in the depression in the gasket and tap with another hammer. Card board from cornflakes boxes makes good coolant gaskets. Or buy the correct stuff. The packet that the gaskets come in also makes good gaskets which amuses me no end. This is a standard way of making gaskets. Many old cars have to be done like this because gaskets are not available. When using ready made paper gaskets sometimes they shrink in storage, if so wet with water which will expand the gasket, a bit. If it's still leaks then remake the joint. Never overtighten in the vain hope that the joint will seal, it won't and it damages stuff. Check around bolt holes and threads for distortion usually caused by overtightening. I have assembled many many bits on cars and rarely get leaks. Nothing worse than having leaks after assembly, because doing the job twice is annoying. I never surprised at how much mud is in coolant systems. To flush engines in situ, I like to connect a garden hose to the heater and leave for an hour. Then reverse the flow. In Dorset there are no water restrictions because if anything we have too much. If the waste water is run through a bucket that overflows the clag collects in the bucket which I show to customers so they know why they came to me rather than the agents who don't flush on services. Once every two years is good but five years is ok. Note on some set ups the thickness of the gasket is important eg Mini engine to gearbox gaskets. If to thick the lash of the primary transmission gears will be excessive. These gaskets always need wetting with water to fit. Cork floor tiles are good for gaskets, and have glue on one side, so it sticks to the part which is handy in awkward situations. Happy gaskets make for a happy engine and a clean garage floor. (Message approved by david_gore) | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 539 Registered: 5-2012 |
Bob To cut the inside and holes use a ball pain hammer to tap around the shape. To make holes lay the ball in the depression in the gasket and tap with another hammer. I have seen this demonstrated on youtube and just cannot believe it is a sensible way to make gaskets. Hammering machined surfaces with a ball pein hammer does not strike me a wise thing to do. Maybe I am wrong - I am no expert. What is the general consensus? Geoff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1118 Registered: 6-2009 |
Geoff, I, too, have seen this but elect to use a single hole punch myself. When I've seen this done, Bob's instruction tap as well as limiting that tapping to the area at the edges of the holes is critically important. In most instances the area around the holes is not really a sealing surface in any meaningful sense. I still prefer to use a pin to mark the approximate center of each hole and then punching it by hand. For cooling system gaskets I've used commercial gasket paper and absolutely no sealant. I hate trying to get old gaskets scraped off of those machined surfaces when they're being held on by ancient fixatives. I have yet to have one leak since, as Bob notes, the dry paper swells ever so slightly around the inner edge of the gasket where capillary action takes place making for a very effective seal. Brian, who's acutely aware that everyone has their favorite techniques | ||
| Bob uk Unregistered guest Posted From: 94.197.122.78 |
The hammer hits the corner of the component. Only light taps are used. It does no damage. It is a standard engineering practice used in many many disciplines. I have made many gaskets like this and sometimes it takes two attempts but I never get leaks. Also I have a selection of large ball bearings. Obviously some bits such as plastic bits may be damaged. But an aluminum inlet manifold will be fine. It would take quite hard hit to break it. A 2oz toffee hammer is not going to have the force. If you are not convinced make a gasket for some thing easy like a stat gasket on an old banger. Paint can be used as gasket gloop in an emergency. It works quite well. Not emulsion. (Message approved by david_gore) | ||
| Bob uk Unregistered guest Posted From: 94.197.122.78 |
Posting crossing each other in the Ethernet. Brian, old sealants such as red hermite are a real pain to remove, often requiring removal of studs and dowels to do a good job. I like silicone because removal is easy. I have found that providing too much is not used, any squeezed out on the inside doesn't break away. A craft knife blade is a handy gasket scraper, careful with aluminum, Sometimes when tapping a gasket out the card doesn't fully cut but shows a definite position of a feature which a hole punch or a Xacto knife quickly sorts out. use wood behind punch. or a cutting pad that heals itself. (Message approved by david_gore) | ||
| Peter McCarthy Unregistered guest Posted From: 101.176.108.58 |
This is an update on progress. I decided to seal the repaired crack with JB Weld and the result looks very good.I will be surprised if it gives any further trouble. When I removed the pistons I found number 5 had collapsed up one side from the crown to the gudgeon pin, with all three rings in small pieces and not all there. So I need to install a new set of pistons and may get away with standard pistons and a hone, or oversize in a rebore or resleave. I am removing the head studs and crankshaft so I will have a bare crankcase to take to the workshop. I just finished reading the manual and KDA132 (twice)on the harmonic balance and will strip and renew as necessary. One cam follower seems tight and requires investigation. The job keeps growing, but I am enjoying learning as I go. (Message approved by david_gore) | ||
| Bob UK Unregistered guest Posted From: 94.197.122.83 |
It is possible to hone 0.005" from liners in situ and fit 0.005 pistons. This is a machine shop job. Ask them. The pistons don't have to be specifically for a RR engine, thus taking advantage of modern pistons. Forged pistons best. I assume by tight cam follower you mean it's tight in its bore. To fix this remove follower and polish the outside. The cam follower sshould fall under it's own weight with oil and have no or very little sideways rock. Note that cam followers are off set to the cam lobe. This gives a turning action on the follower. If tight the follower won't turn. So the bottom of the follower should have swirly wear pattern. If the bottom wear pattern is in straight lines then the follower hasn't been turning. In both cases polish the bottom of the tappet or follower LIGHTLY. Tappets are case hardened. On assembly use a GL4 gear oil or a recommended cam lube on the lobes. The amount of gear oil used, 50cc is not going to mess up the engine oil. Make sure that the crank damper has the drilled holes in the outside bit so sludge doesn't build up. Also use mobile 1 oil then hopefully less sludge. Any questions or concerns just post. (Message approved by david_gore) | ||
| Peter McCarthy Unregistered guest Posted From: 119.225.135.179 |
A further update. The engine is still apart and has become a major rebuild. New pistons, all bearings including cam bearings, rebuilt camshaft, new exhaust valves and so on. Drilled the crank damper and set the slip load. Waiting on another main bearing set, Flying Spares sent the wrong ones. The wait has given my time to clean and paint the engine bay and all acillaries. Even the horn looks shiny and new. I am really looking forward to getting back on the road. (Message approved by david_gore) | ||
| Trevor pickering New User Username: commander1 Post Number: 2 Registered: 6-2012 |
How is your engine rebuild going? I have just started the rebuild of my 1953 SW engine and have just removed the head and damper etc. Did you rebuild your damper and if so what problems did you find, Thanks Trevor Pickering 1953 SW BLW66 | ||
| christopher carnley Unregistered guest Posted From: 31.51.28.246 |
They are usually manifold,and include broken drive springs, a broken and corroded spring plate,(very expensive),corroded on cotton washers, and corrosion generally. I grind shallow grooves in the wheels,to let the oil circulate and avoid the jamming sludge build up.I also buy the modern "R-R Wraith"friction washers from Will Fiennes, and soak them in engine oil for 24hrs. (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: 94.197.121.1 |
Use Mobile 1 or similar this will further prevent sludging the damper up. Wrong bits is part of the joys of rebuilding cars. These engines at first seem dauting but aren't any harder than many other engines. Except the crank damper. Once the damper is correct then the rest is like any straight six. Once overhauled the damper will last for years. I have a soft spot for straight sixes and i particularly like this engine. Local to me is 4.5 Bentley mk 6. I have never heard the engine, it's so quiet. (Message approved by david_gore) | ||
| christopher carnley Unregistered guest Posted From: 86.168.246.215 |
A constant source of complaint is the very worn camshaft,typically 60-80 thou below the case hardening. The chill cast iron tappets, particularly the inlet ones also take a beating,especially when the car has stood for a long time and rust has settle between the cam tip and the chill cast face. The silver Cloud/S1 cam is the one to use, and was rethreaded as the RE 23639. It has full width lobes,unlike the MK VI /R Type ones with the 50 degree cut back. Jack Barclay has some of these erroneously labelled the "low lift", but bear only a passing resemblance to the 1946 cam. The remanufactured R Type cam from introcar, is a nice thing, but will not do you any favours. Unlike you Bob, I have never encountered a silent 4 1/4, or a 4 1/2 litre Bentley engine, every single one is a bit noisy, or there is something wrong with the rocker/tappet settings. (Message approved by david_gore) | ||
| Trevor pickering New User Username: commander1 Post Number: 4 Registered: 6-2012 |
Thank you for the replies. I have a NOS spring plate that I purchased last year! I have not pulled the damper apart yet. The engine block sans head and damper is still in the chassis and I will be removing it next week after I finish making and engine stand that will allow me to flip it over when I want to work on the crank etc. When in the stand I will do a full strip of the engine and report my findings. In the meantime I am preparing my wallet for the shock! | ||
| bob uk Unregistered guest Posted From: 94.197.121.69 |
Engine stands maybe available for hire. They aren't expensive new. On any engine there will always be some noise. The local mk 6 is quiet and I cannot hear the engine over tyre noise. Bonnet open standing next to it and the engine can be heard. But it sounds right. The tappets can just be heard. Quiet not silent. Best way to check a cam is by measuring it. (Message approved by david_gore) | ||
| christopher carnley Unregistered guest Posted From: 86.168.246.232 |
Be very careful when replacing the oil pump/distributor drive and its relationship to TDC timing, and the cam wheel. (Message approved by david_gore) | ||
| Trevor pickering New User Username: commander1 Post Number: 5 Registered: 6-2012 |
I removed the thermostat housing this AM and removed the thermostat after making a makeshift puller. I previously thought that the thermostat was a"dead duck" as it was stuck open. I gave it a soak in some Hydrochloric acid for a few minutes and it closed. Gave it a good rinse and a clean and tested it in a pan on the stove with a thermometer and it worked perfectly. Not bad after over 60 years! | ||
| Peter McCarthy Unregistered guest Posted From: 202.141.208.98 |
My engine is back in the car, but not yet started. I was going to replace the thermostat but at nearly $300 from Flying Spares I am trying to resurrect the old one. I rebuilt the damper. The plate was rusty so I sandblasted it and araldited the two discs to it as per Norman's advice in KDA 132.I had spare springs so checked and put them in, but found the internal springs very hard to locate properly and hope they all ended up on the little knobs. Set it to 24lbs slip also on Norman's advice. I had the cam refaced and ground, just caught it as the rear cam bearing had disintegrated.The crack was repaired by having a lot more plugs put along it and the surface peened. If it leaks I will cover it again with some JB Weld but looks good at present. New head and exhaust studs fitted, the exhaust studs increased to 5/16. I now have a spare set of 1/4 brass manifold nuts if anyone wants them. I had a very lucky break. Someone walked into the engine shop, saw my engine and said he had a set of pistons and rings at home for it. Brand new, with the wax on, in original boxes, and the right size. (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: 94.197.121.239 |
A bit of luck with the pistons. The stat. Try trucks or buses for an alternative. I would try a Leyland Comet engine stat. It is ok to trim the stat to fit. As long as it doesn't interfere with the operation of the stat. I like to see a 1/8 bleed hole for burping the engine. If the old stat can be made to work it will still have a question mark on it. while driving the car switching the heater on helps confirm that the system is working right. No heat means no hot water and maybe no water at all. And of course I am teaching granny to suck eggs by suggesting that both rad and heater matrix are flushed. I had a MG ZA Magnette with a bad heater and a back flush removed a large amount of dirt. The heater was nice and toasty after. The ZA was designed by Gerald Palmer and the result was a pretty car which was a contemporary of the Bentley mk6. Mine was a 1955 and was written off by a drunk driver in Park Lane London in 1980 ish. Was I annoyed or what especially when the drunk was sick all over the MG. 3 months later another drunken idiot t boned my Jag 3.4 manual with overdrive midnight blue with red leather. The insurance paid market value of £1200. Now a £25k car. I put that together with the £500 I got for the MG and wasted it on buying a bungalow in Bournemouth. I still live there. Happy days. After that I went modern and brought a Ford granada mk1 est. Now worth £3000. The bungalow is now worth 300k so I can't complian and I live rent free. Which allows me to have a Shadow which is to me the best car in the world. A banker once told me money begets money. Sorry about mission creep and a trip down memory lane. (Message approved by david_gore) |
