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M4A4 restoration

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Inspired by GWTs excellent blog, I thought I would start one on my Sherman.Some of you will have seen it about and may be interested in seeing the full restoration story.


My Sherman, M4A4 serial number 5271, was built in September 1942 by Chrysler at the Detroit Tank Arsenal. It was the 467th built out of a total production run of 7499 M4A4s. Issued to the US Army with Reg. No. USA W-3057081, it was transfered to the British Army and given a census number of T-146309.In British use, it was known as a Sherman V. I will tell more of its history later, not that I know much, but eventually it ended up on Salisbury Plain, along with about 25 other M4A4s and other assorted vehicles to be used as survey targets for the Royal Artillery.


This is how she was when I first saw her. More parts were removed before I got her but she was substantially complete.


This picture was taken on June 6th 1991, the day I collected her. In the intervening years, she had lost a track, some wheels, bogies an idler and various smaller parts.

The loading was performed with a Cat and this did some damage to the engine when the corner of the blade went through the open rear doors.



It was not easy to load with only a few wheels on but it went fairly smoothly and we were soon on our way home. BTW, that's not me in the picture! Apart from a puncture from a shell fragment, we had a good run back.


In my yard.

Edited by Adrian Barrell
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I spent about 9 years gathering parts for the restoration including a spare engine but I did remove the engine straight away to see just what I was faced with.




This is the view into the engine bay showing just how tight a fit it is.




This is the engine out, with the empty engine bay below. It's possible to see some of the damage i.e. the cracked bulkhead.




The vehicle had received some damage, not surprising really! The main problem was a hit on the lower right hand side that had removed two bogies, bent the side plate and sponson floor in, cracked the bulkhead as well as damaging the engine and floor.




This is a view of the rear rh fighting compartment showing the cracked joint in the lower side.


Internally, she was fairly complete, though everything below about 4" from the floor was rusted away and due to a shell having exploded inside, there was a lot of damage to the turret basket.




Drivers area.








Looking back toward the engine with the fan being clearly visible. The turret basket is completely gone at this point.




Looking forward under the gun.

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The aforementioned fan was the only casualty in the recovery as a blade broke off as we unloaded in my yard. Due to the size of the engine, the fan sticks through the floor and is normally protected by a large armoured casting but that was missing.




I did keep the broken blade and it later welded back on with no problems.


There were other little annoyances. The drivers hatch and the cupola doors had been removed in the past by cutting chunks out of the hull and ring.




With the engine out, I pulled a head off for a look....it was not good. Some of the pistons had disolved!




Eventually, by May 1999, I was ready to start restoring an engine. I had decided to try an engine first as i didn't want to get the tank restored and then find I couldn't do an engine. The Multibank is not exactly easy to lay your hands on! I did have a radial to fall back on if needed.



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Yes, that is the paint tin they used to paint the turret! As it was quite near the road, it regularly got a coat which helped to preserve the outside. Later pictures will show this.


The multibank is made from 5 engines, I'll go into greater detail in the next installment. The whole project took about 4000 hours.


As to how I got it, that's a story in itself but basically it had been earmarked for recovery for a museum and the deal fell through. I was in the right place at the right time and took it on.

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I have to agree with Tim - having spent the best part of a day (at last!!) on the refueler, to come home and see this impressive stuff makes me realise my project is a "walk in the park".....


Two questions - was that Rose's dozer for the recovery, and did you get both on the trailer home?

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I won't give a detailed history of the multibank engine as the information is available elsewhere. The engine is essentially five Windsor car engines mounted together driving a common output shaft.


It came about when Chrysler were asked to develop a tank engine due to perceived shortages in the R975 radial engine which was at that time the standard medium tank engine. Ford had come up with a V8 OHV engine which was developed from a projected V12 aircraft engine and GM were using two 6-71 two stroke diesels. All but the Ford engine were developed for the M3 medium and carried over to the M4.


Over it's production, the multibank was improved for serviceabilty and reliability. The original design had five water pumps and this was replaced fairly early on in Sherman production with a single unit. Later engines also had the five carburettors mounted in a line on top rather than on each manifold.


Design improvements also resulted in sodium filled exhaust valves being used.


Whilst the engine was essentially the side valve six used in Dodges, apart from some internals, there is very little commonality with the truck. The blocks and heads are all special, the crank rotates anti-clockwise and the cam is gear driven. Each of the five engines are also different to each other in terms of manifolds and timing gearcases.


First thing to do is remove the clutch and fan. This enables you to get the radiator off. This is, of course, the reason why the radiator was still in the vehicle as it is impossible to remove it in situ!




The radiator is a big lump and whilst it was all there, I knew it would need a new core.




The removal of the radiator shows the drive gear case and the output shaft. Also visible is the starter motor mounting which also pokes through the radiator to engage the flywheel.




Removing the gear case allows removal of the individual blocks but also shows quite clearly how the drives come together from each crankshaft.




This being the inside of the casing. Each engine drives a herringbone gear which meshes with a slightly larger centre gear to give a small reduction. The centre gear drives the clutch but also the oil and water pumps through a shaft facing back through the centre block. You can also see the broken rh mounting where the side of the tank was pushed in.


This shows the front of the blocks with the coupling sleeve on each crank.



Edited by Adrian Barrell
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Now all the individual engines can be removed. This is best achieved by rotating the assembly to allow a vertical lift for each block. No 4 is the hardest as the manifold prevents easy access to the bolts. It's bad enough when reassembling but next to impossible with non existent bolt heads. There is not enough room to get a cutting torch in but I found I could just get a gas welding torch in the gap. Heating the remains of the bolt up to yellow and then turning the acetylene off allows the oxygen to act as a cutting jet and very neatly removes the head!




No 1 off




No 2




No 3




Eventually, you are left with just the centre block. It is upside down here and you can see the oil pumps, one pressure, one scavenge that are driven via bevel gears from the centre drive.


Some of the internals were in amazing condition.




In fact, on one block I was able to slip out two of the six pistons. Others required a lot of force....


Tomorrow, I'll go through the rebuild of the blocks.

Edited by Adrian Barrell
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It could have been so much worse ! that last photo , as Odd Ball would have said what a mother wonderful beautiful sight to see , when you looked at it for the first time and not just full of rusty water and completely corroded parts.

I look foreward to the saga of getting all those pistons out one way or the other , in pieces large and small .

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Wow adrian, you always said it took you thousands of hours to restore and now I begin to comprehend what a gigantic task it was. You must have really, REALLY wanted a sherman to undertake such a project.


Thanks for posting everything up and if you agree we should find a location to preserve it on HMVF.

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Right, my wife is out showjumping and I've just put our daughter to bed so here we go!

Starting this had made me realise how many gaps there are in my photo record. All the pictures are on film and it would be much easier to do on digital. Having said that, you still need to take the pictures so forgive me if there are areas that are a bit sparse on the visual front.


Having seperated the blocks from the centre case, they became like any other engine rebuild albeit multiplied by five.


The main problem was with the general condition. As I mentioned before, some pistons slipped out with no effort but that was far from the norm. I could free them by pressing downwards but they had to come out from the top so much soaking and gentle(!) persuasion eventually had them all out.


The crank was easy but the camshaft was another matter. The valves were all stuck, some very stuck and so I had to make a tool to pry them away from the followers to allow rotation of the cam. This allowed me to remove the collets and then the valves.


Eventually, all of them were stripped and I had to pick five serviceable blocks for rebuild. Out of the ten, only five were not obviously cracked so it was a lucky thing.


Unfortunately most required re-sleeving and new valve seats. Together with pistons, this was going to cost a small fortune.


At this point, I had a bit of luck...... Whilst speaking to Jaap Rietveld, it became apparent that some 'odd Dodge blocks' he had may well be multibank. More to the point, there were six of them, they were nos and for sale! A few days later I was the proud owner of this lot.




They came with mostly new studs, the lengths of which change to suit the position of the engine, 21 nos pistons, water tubes and cam bearings.


This lucky find made a huge difference if only to my enthusiasm! I could have used my blocks but this saved money and time and I knew I had brand new blocks with no cracks and clear water passages.


I managed to salvage a full set of internals with the bulk coming from my tanks engine with just a camshaft coming from the other. There was a lot of cleaning to be done though....




The new blocks were of an intermediate production standard with the 10 bolt valve covers, the early engines only having six bolts and standard valve guides. The later sodium filled exhaust valves requiring a different guide to suit the fatter stems.




I built up all five engines, including hand lapping 60 valves, and here they can be seen after painting. They are numbered 1 to 5 from left to right and are installed on the power unit numbered anti-clockwise starting from the top block. It's possible to see the different manifolds, timing gear covers and water fittings in the heads.




You can also see the old blocks I didn't use in the background.

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Having finished the blocks, I concentrated on the centre casing which joins everything together. Again, having two sets of everything helped but both sets of oil pumps had pitting on the gears and I had to use some nos pumps I just happened to have. Actually, the reason I had all these parts is because I had spent the previous nine years gathering bits from all over the place. It paid dividends many times.


The manual stresses the importance of the position of the blocks on the centre casting to achieve the correct backlash in the drive gears. This is achieved by using different thickness gaskets between the joints. There is a special tool to determine the correct thickness and I made one only to find the required thickness was stamped on each block! I did check them all and it was correct. The hardest part was finding gasket material of the correct thickness.


The blocks have to go on in the correct order to some extent and so I followed the reverse of the dismantling. It's also easier to rotate the whole assembly as you go to allow a straight drop into place. As the engine as a whole weighs 2500kg, this does have to be done carefully!


No 5 on first.




No 4 and 3




All on.




Looking at the front of the engine, the layout is clearly visible with the two lower engines undercutting the middle two.



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The next step is the gear case. The herringbone gears run on roller bearings but the gears bore is the outer race and the pin is the inner race for the bearings rather like a motorcycle big end. The problem with this is any pitting on either componant is a bad thing. Fortunately, the gears from my tanks engine were perfect.


The gear case is offered up on the studs untill it goes tight. At this point the studs increase in diameter to become dowels and it is time to 'time' the engine. There is a plug in each gear position to ensure the timing marks are all in line. The manual is a godsend in this respect as it makes it very easy to do.


The firing order is progressive throughout all the engines and whilst the firing order of each block is 142635 i.e. the reverse of normal due to the reverse rotation, the overall firing order is 1 on eng.1, 5 on eng.3, 3 on eng.5, 6 on eng.2, 2 on eng.4 and 4 on eng.1 and so on. This gives a firing impulse every 24 degrees making it very smooth.




The next thing to do was the engine wiring harness. This was quite complicated as the engine has a plethora of gauge sending units. There is a water temp. sender in every head as well as a high temp. warning switch, an oil pressure sender, an oil temp. sender and an exhaust temperature switch on each manifold. These are known as stack lights and are to give the driver a warning if one block is not firing. The lights on the dash are the same as a Dodge Hi-beam warning light.


I made a new harness using Nyvin wiring which handles the high temperatures well and wrapped it all in braided sleeving as per original. It all terminates in a 14 pin plug above the starter motor.




The cross shaft on the engine is for the choke linkage.


The next step was fitting ancilleries such as the five distributors, coils all nos and the rebuilt water pump. The pump required a lot of work as two of the outlets were broken off. I had to build five carbs from 11 as despite being nos, they had sat outside for many years. The starter motor was probably the hardest part to do as it was very corroded and the brush holders had rotted away but I found a more modern motor had the same parts and just swapped them over.




The last major bit was the radiator. I knew I had to have a new core so having stripped all the tanks off, I sent it away and Sercks made a good job of a new one. I repaired a few shrapnell holes in the header tank and assembled the new core with new bolts and gaskets.




With the radiator on and connected up, I was nearly ready for a test run. The clutch is the same as a radial engine clutch so I managed to find a new flywheel and some parts but had to reuse the pressure plate. With new springs it all functioned correctly. I welded the broken blade back on the fan and fitted it all together.




Jumping forward in time slightly, I managed with thanks to the Tank Museum, to borrow a fan cowl from their display engine. This enabled me to make a copy.




It's a complicated double skinned affair with an airfoil section and is close fitting to the fan.




Back a year or so..... I set the engine up on it's trolley and rigged up a Valentine oil tank, a jerry can and two batteries.....




It all worked!:yay:

Well almost! I checked the exhaust manifolds and one was cold but it was just a stuck carburetor float valve so that was easy to fix. I did think it was only running on 24.....:rofl:

This was Dec 31st 2000, a great day!

Edited by Adrian Barrell
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