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Post by Mabel on Oct 30, 2018 14:53:54 GMT
Mabel is unwell. The head has come off and the waterways are more or less totally blocked. That should be reasonably easy to sort out and afterwards I may even get a half-decent heater. However, the main problem is with the bores and pistons. They're totally discoloured and very wet. There's a ridge just below the top of each bore and the piston in bore four can be moved backwards and forwards with your finger. This would indicate serious wear issues. I've attached a couple of photos. One being a cleaned piston crown in bore one and how it looks in bore four. On the cleaned piston crown is the MOWOG name but there's a number 2 contained in a diamond. Does anyone know what this means? Does it indicate that a previous rebore has taken place? If that has occured is there sufficient space for further reboring to take place and indeed are there pistons and rings available for such rebores. if further rebores need to take place I can see 1489 cc being a thing of the past as it'll be nearer 1600 cc.
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Post by 2robert4 on Oct 30, 2018 19:51:55 GMT
The number in the diamond is the grade of the piston if memory serves me right there are three or four grades of standard pistons used by BMC upon assembly you should find a Diamond with a corresponding number in it on the Block face that will prove that the engine still has a standard bore with that particular grade of piston and judging by the amount of clearance(slap)the bores should be standard. You can of course measure the bore with the piston at BDC the top three eights of an inch of the bore can be measured as this should be least worn to give you the actual diameter and then use a comparator gauge to check the actual amount of wear in the bore compared to the standard diameter. You can go up to at least 50 thou oversize but if finances are tight a used engine may be the answer. I am assuming you took the head off due to a head gasket failure and subsequent overheating if this is the case you need to check each bore to see if any of the pistons have picked up but judging by the amount of slap this may not be the case. If the engine was running well before the overheating and the bores have not picked up I would be inclined to clean out the rad or recore if necessary and clean out the waterways as best you can and remove the thermostat fill with clean water only and run up to temperature and then add some kettle descaler to the water and run it some more.Let the water cool drain it out and back flush and see how much rubbish comes out be careful to wear gloves and goggles.Once the system is flushed put back a new thermostat and refill with a 50% solution of deionised water and anti freeze.You will of course burn some oil for around 500 miles or so as you have cleaned away the carbon build up around the top of the bores this will settle and you may find you can use the engine for some time before a full rebuild is required. Hope this is of some use? NP
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Post by Mabel on Oct 31, 2018 8:35:14 GMT
Thanks for taking the time to respond and for the detail supplied.
The head came off not because of overheating but I'm surprised it hadn't given that the waterways were more or less totally blocked.
Compression tests were all over the place and certainly not within 10% - 15% of each other. Oil was getting very "gungy" very quickly and the oil filled air-filter was regularly filling up. Very surprisingly, the car was not blowing out plumes of blue smoke. Yes, a puff on gear changes but not much else.
Within the receipts that came with the car was a bill from an engineering company that simply says "Engine rebuild". Given the fact that all the parts so far exposed seem to be original I'm not sure what the previous owner paid for.
The plan is to get the block out and then go for a rebore with new rings and pistons. The head will also be taken apart to see what condition it's in. Allegedly, it's had hardened valve seats fitted. Hmmm, have to wait and see if that is correct.
Owing to a lack of facilities at home a classic car chappie (that's been highly recommended from a number of different, unassociated people) is doing the work for me and he's probably lining up sometime soon the engineering workshop he uses for such things. I did consider trying to obtain a used engine but there's no guarantee that such an item would be better than what I've got. I'd also like to keep the original engine that came with the car purely for historical purposes.
The radiator is certainly past it's best so I've a trip to make to get another. They seem to go for around £235 - £250 for a re-cored example.
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Post by 2robert4 on Oct 31, 2018 19:58:49 GMT
As you have done some diagnosis work ie comp tests etc I think the course of action you are taking is the correct one going for a rebuild from a reputable source. The previous repair could have used the original pistons to keep costs down if they were serviceable but re ringed with Cord Oil Control Rings which were a common trick used in the 70's and 80's to cure excessive oil consumption but because of their construction they can cause the bore to wear excessively rather like a barrel meaning that when you do rebuild the worst case scenario could be re sleeving or at least max oversize.
Check yell.com for local radiator repair shops as they may be cheaper than £250 good luck with your rework.
NP
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Post by canuck on Nov 6, 2018 0:10:10 GMT
Hello Graham Nice to read that Mabel is getting some loving. You have received solid advice from Robert. The course you are on sounds about right. FWIW below is a picture of the mentioned diamond on the block, to match te piston to bore. and as Robert states those are Longbridge installed bits. As a precaution, you may want to measure up the oil pump to ensure it has not suffered wear. Specs; Enjoy, B
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Post by Mabel on Nov 7, 2018 13:44:13 GMT
Bruce. thanks for your input. Wise words indeed. Much appreciated.
I get good oil pressure (around 55) so hopefully the oil pump, at least, is sound.
As well as no work being done on the engine despite receipts that came with the car indicating a full re-build, the head was also apparently converted to allow unleaded fuel to be used. Again, there's no evidence of any work taking place. The company that is meant to have done the work no longer seems to be trading - thank goodness.
As the head hasn't been converted, I'm in two minds whether to have it done. Maximum usage is no more than 1,000 miles a year and I'm thinking that on that level of use to spend even more money, which isn't really available, isn't cost-effective.
I'm considering using lead a replacement fuel additive including ethanol protection.
Anyone have any views on this plus recommendations for which additive to use. I'm thinking that Millers VSPe Power Plus might help.
Thanks in advance for any help, advice and suggestions.
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Post by 2robert4 on Nov 7, 2018 14:49:00 GMT
You can tell if the head has been reworked by cleaning up any one of the combustion chambers in the head you should then see a well defined ring about 3-4mm around the outside of the exhaust valve seat if this is the case then it has be converted to unleaded as that ring is the outside edge of the new valve seat insert. Note that the inlets may not have been done as they are cooled by the inlet charge and do not recede like the exhaust valves. If the head has definitely not been converted and you do not wish to have this work done then you might consider using Tetra Ethel Lead additive as used by the fuel companies in the past it is not cheap but one case lasts a long time in my case 4 years it is poisonous so correct precautions must be taken but you can say good bye to valve seat recession and pinking if you add it to Shell Max the octane can be boosted up to 110 ron.
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tjt77
Junior Member
Posts: 68
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Post by tjt77 on Nov 9, 2018 23:14:50 GMT
I note the comments on 'cords' brand piston rings.. they are an excellent solution for up to .005" of bore wear and slight ring groove wear .. but at the end of the day, its not the way to do the job properly..nor do they cause additional wear greater than any other design of ring .. they simply enable one to get back on the road with an interim 'refresh' for another 20-40k miles.. basically a 'stop gap' solution.. a proper 're-bore with oversize pistons is the long long term solution along with replacing all the other worn components.. ie..a full engine re-build....
Be aware that the 1500 B series is the bottom of the totem pole ( was superseded by the much stronger '1622 in late '61) and can be vastly improved with little effort and no extra reconditioning cost ;- since you have cylinder bore issues. consider an overbore to 1588 cc with standard MGA 1600 pistons (readily available and same price as 1500 pistons) .. the 1500 block will overbore to apporx 3" ( 76.2mm) without issues. but the 3" ( 1622cc) pistons will not fit without their con rods, due to larger gudgeon pin..the 1588 has same size pin as the 1500 and these directly interchange .. the 1.5/magntte Z camshaft is not the greatest profile (supposedly it was used to add mid range torque.. in practice it does not..and the power begins to fall off @ around 5.300rpms) .. a std MGA or 3 main MGB cam provides better overall power curve..and aftermarket grinds such as the D9 or piper BP270 are even better.. if there is bore wear . cam an lifters will also have wear ..as will the rocker shaft and rocker bushings.. The head casting has poor porting compared to later heads.. you can use the MGA 1600Mk2 head or the early MGB head('62-67) as a replacement to gain more power ..again..inexpensive and easy to find in Uk..actaully less money to recondition in Uk as the valves and hardened seats are cheaper ( you may gain some saving by ordering these from NOS locators in USA.. they have stocks of late production OEM BL valves for the early 1800 B series ..and sell a full set of 8 for +/-$55.00 US +p+p) . oil pumps rarely wear out , but the innards are cheap... what does wear are con rod and main bearings..and cam bearings.. (which will need replacing if the block is 'hot tanked' to remove the crud.. the original pressed in brass plugs for oil ways can be replaced with threaded internal hex plugs.( 1/4"pipe thread) some advice on crankshaft bearings :- be sure to go with 'tri metal' or lead copper bearings and avoid cheap substitutes marked 'SA' ( which are Bi metals, not cabable to sustaining high loads and hard on the surface to boot.. so they wear the crank journals at same time as bearing faces) when replacing the oil pressure relief valve, a 1/4 " shim will help add a slight increase in oil pressure.. depending on budget you can also balance all the rotating bits, which will make the engine run smoother and last much much longer ..I always lighten the flywheel to post '62 specs for the 1622/1800 3 main.. requires approx 8 lbs to be taken off.. OR use a std 3 main MGB flywheel which is pre drilled for both diaphragm and old style clutch.. Finally , if the water ways twixt head and block are chocked, you can be assured the radiator will also have reduced flow for same reason..so send to to a rad specialist for clean out.. it would also be wise to flush out the heater core whilst you are at it..
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