question Rover Mk6 Mk8 2.25 engine differences

[Cheshire Steve]

Today I learned mainly from civilian parts book that the S2 2.25 petrol was significantly different from the 2A 2.25 - for example it had an aluminium timing cover and 8-bolt water pump. But I don't have access to a military parts manual to compare the two. Up until now I thought the military 2.25 had the 7 bolt pump like I have on my 1969 lightweight engine, and the civilian had the 9-bolt, but did both civvy S2s and military Mk6 have the same engine/timing cover, and if so, when did the military models diverge?

 

Civvy part nos for the ally timing cover and water pump for the S2 are 510805 and 501041, maybe someone can look up the Mk 6 part nos for me?

 

Apols if this has been covered, I did try searching, but the search terms are tricky. Just link me to the thread if this is an old question.

 

Steve

[ruxy]

Today I learned mainly from civilian parts book that the S2 2.25 petrol was significantly different from the 2A 2.25 - for example it had an aluminium timing cover and 8-bolt water pump. But I don't have access to a military parts manual to compare the two. Up until now I thought the military 2.25 had the 7 bolt pump like I have on my 1969 lightweight engine, and the civilian had the 9-bolt, but did both civvy S2s and military Mk6 have the same engine/timing cover, and if so, when did the military models diverge?

 

Civvy part nos for the ally timing cover and water pump for the S2 are 510805 and 501041, maybe someone can look up the Mk 6 part nos for me?

 

Apols if this has been covered, I did try searching, but the search terms are tricky. Just link me to the thread if this is an old question.

 

Steve

 

There is a 8 stud water pump , BUT AFAIK - no aluminium timing case cover.

 

8 stud pump = 501041 you will only find it on a true S2 era. Solihull fitted engine (Rover 6 in 88" w.b.) - 12 volt only contracts

 

S2 Contract(s) were pure civvy based with bolt-ons (based on civvy body parts) . The S2A MOD spec. types (Rover 8 in 88" w.b.) factory fitted engine , 12 volt + 24 volt contracts , 7 and 9 stud pumps were S2A These had military spec. tubs (front spine to secure Jerry not spare as bonnet mounted, steel reinforcement rear wheel arches + front wings for antenna support mounts etc. etc.

 

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- a 8 stud timing casing = 501039

 

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7 stud = FFR & 12 volt fitted with twin belts & 8 blade fan

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Late , such as 5 mb Lightweights without oil cooler would have 9 stud pumps

Edited July 5, 2016 by ruxy
spelin

[Cheshire Steve]

Thanks for the informative response, had thought that maybe all the lightweight engines had the 7 bolt pump, same as mine. Did the lwt with 9 bolt use the civvy timing cover, or was there yet another timing cover with the filler/breather bolted on the top like the 7-bolt pump ones?

 

Turns out the S2 2.25 petrol was based closely on the 2 litre diesel, front cover pump etc have same part nos. They revised the diesel by removing the wet liners for the S2A, but they also enlarged the fan and had to move the pump spindle, so the whole front end changed, and the petrol followed. So those S2 2.25 engines are rare and unusual, and a lot of standard 2.25 parts don't fit.

 

If anyone has a parts book for the Mk 6 would be interested to know the Rover no and see if the front cover is the same as the civvy one. Now I look again at the civvy parts list I see that there was both alloy and iron front covers as the parts list has three entries for the fixing studs for the water pump - one entry for S2 with alloy type front cover - one entry for S2 with cast iron type front cover, and one entry for S2A models.

 

Its been an education this morning, I thought most 3mb 2.25s were the same, but keep turning up all sorts of differences.

 

Steve

[ruxy]

Thanks for the informative response, had thought that maybe all the lightweight engines had the 7 bolt pump, same as mine. Did the lwt with 9 bolt use the civvy timing cover, or was there yet another timing cover with the filler/breather bolted on the top like the 7-bolt pump ones?

 

Turns out the S2 2.25 petrol was based closely on the 2 litre diesel, front cover pump etc have same part nos. They revised the diesel by removing the wet liners for the S2A, but they also enlarged the fan and had to move the pump spindle, so the whole front end changed, and the petrol followed. So those S2 2.25 engines are rare and unusual, and a lot of standard 2.25 parts don't fit.

 

If anyone has a parts book for the Mk 6 would be interested to know the Rover no and see if the front cover is the same as the civvy one. Now I look again at the civvy parts list I see that there was both alloy and iron front covers as the parts list has three entries for the fixing studs for the water pump - one entry for S2 with alloy type front cover - one entry for S2 with cast iron type front cover, and one entry for S2A models.

 

Its been an education this morning, I thought most 3mb 2.25s were the same, but keep turning up all sorts of differences.

 

Steve

 

The 40A had its own bracket , later FFR genny(s) had the machined faced platform with threaded bolt holes as part of the front timing case , this is the one that uses a filler tube bolted to the top and is the cover used from S2A Lightweights onward to early S3 inc. 12 volt with twin belts / 8 blade fan / 7 stud pump.

 

There is 549735 pump for 12 volt GS and 542687 for FFR vehicles (these Nos. will be subject of supercession probably) , actually - IIRC the only difference on these 7 stud pumps is the drive hub for the belt pullies.

 

It is best to consult pages B2 + B3 of the MOD Lightweight parts book 61278 dated May 1975 , bit of a minefield becaause I have pencil notes on hub dims. with ref. to MOD parts manual S2A 20873 dated Oct. 1970 , this covers all Rover Mark from 6 to 9/1 (and is what you require). Front pages give Contract Numbers + Chassis Nos. ranges & you can work all sorts out. the LH column has the Contract code. you need this to zero in on the actual part Nos. for any truck. The S2 are a B Code (few only contracts) , yes - best to leave the S2 (B Code) to the rivet-counters , engine parts (diesel + petrol) are rare often and expensive. Or just fake a 2.1/4 instead.

 

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Late S3 Lightweight engines are more or less same as a civvy 5mb petrol , with a few differences. Unfortunately for some rason they use the same prefix/suffix for 12 volt and 24 volt. They can be blue/grey or red painted with black heads . Gets a bit complex - you don't always get the starting handle trumpet on crank-dog etc. Gets more complex because there are both new and old plant engines ISTR

Edited July 5, 2016 by ruxy
spelin

[Cheshire Steve]

Thanks for the extra info. The 7-bolt pump on my early lightweight engine bears the number 538693, thankfully it seems OK as they are not cheap. The engine has a S23600 prefix, and the timing cover has the machined face and filler tube. Must try and get hold of some more manuals, though my main interest is military S1, and have the manuals for that, its just that this one has the lightweight engine in it, and its needed some work lately.

 

Those old S2 2.25 petrol engines must be one of the rarest engines around - though I suppose the chances of any of the 2 litre diesels surviving without being scrapped and replaced are pretty small, but I have seen the occasional S1 diesel advertised with original engine so a few survive.

 

Steve

[ruxy]

Thanks for the extra info. The 7-bolt pump on my early lightweight engine bears the number 538693, thankfully it seems OK as they are not cheap. The engine has a S23600 prefix, and the timing cover has the machined face and filler tube. Must try and get hold of some more manuals, though my main interest is military S1, and have the manuals for that, its just that this one has the lightweight engine in it, and its needed some work lately.

 

Those old S2 2.25 petrol engines must be one of the rarest engines around - though I suppose the chances of any of the 2 litre diesels surviving without being scrapped and replaced are pretty small, but I have seen the occasional S1 diesel advertised with original engine so a few survive.

 

Steve

 

538693 , that is just the bare pump casing casting , in the L'wt Parts Book 538693 - there is no NATO part No. just NP meaning Non-provisioned , so you just select & fit the complete assembly. You can get new replacement (non-gen) spindle / impeller assemblies and bearing sets very cheap (probably Bearmach the best) to recondition up a old casing. The impellers are a shrink fit and CI so easy broken. Likewise the drive flanges. The different drive flanges for different belt pullies , a 12 Volt GS Lightweight with 8 blade fan has a twin belt set (I suppose belt & braces where you can) , , on a FFR there is just a single belt for the 8 blade fan vee belt pulley as you have a pair for the genny.

 

S236 , 236 is S2A L'wt , S = reconditioned , there is a 237 , ISTR that is a 24 volt cartridge unit , I have one crated & prefix S - it has a new block & the No. is carved in with a die-grinder , bench dyno test doc. states rocker shaft WBS & reversed , rockers faced , I will change them. Hardly a gen 236/237 BUT it had all new genny, dizzy,coil etc (that I stripped off and they worked out cheap + I still have the bare motor)

[Cheshire Steve]

Thanks for explaining the S in S236. I didn't fit the engine, and don't know if it came out of a crate or out of a lightweight, but it is +30, though no military recon plate on it, and the original Sky Blue on the block had a black paint coat over the top - which I assumed meant it had been rebored in civilian life. The other parts all had original scruffy sky blue. Its got a twin pulley on the crank, but civvy alternator and four blade fan, probably the fan being the original from the S1.

 

Having rebuilt it I still have an annoying rattle mostly when it is half warm, and having replaced so many things, what I have left is a very strong suspicion that one of the tappet guides loosens off and moves when the block warms up. I replaced the tappets and rollers and checked the play of the tappets in the guides wasn't excessive, but never thought to test the guides for tightness in the block. At least I can do that without getting the engine back out, so its back on the job list.

 

Steve

[ruxy]

IIRC all the Base Repair plates I have seen have been secured with 'splined drive rivets' , I don't like to see this done on a water jacket. All the ones that I have seen by contractor BREL (British Railways Engineering Ltd) the plates have been bonded on , can come loose & fall off. I saved one just in time , it seemed resin bond , a thick application on top of the engine laquer - not a good idea ,,

[ruxy]

btw , the pre-fix S is not just military , common civvy too - I believe it stands for 'Service Exchange'

[ruxy]

IIRC all the Base Repair plates I have seen have been secured with 'splined drive rivets' , I don't like to see this done on a water jacket. All the ones that I have seen by contractor BREL (British Railways Engineering Ltd) the plates have been bonded on , can come loose & fall off. I saved one just in time , it seemed resin bond , a thick application on top of the engine laquer - not a good idea ,,

 

 

This is a extra BREL plate they did rivet on ,,

Edited July 5, 2016 by ruxy
spelin

[Cheshire Steve]

IIRC all the Base Repair plates I have seen have been secured with 'splined drive rivets' , I don't like to see this done on a water jacket. All the ones that I have seen by contractor BREL (British Railways Engineering Ltd) the plates have been bonded on , can come loose & fall off. I saved one just in time , it seemed resin bond , a thick application on top of the engine laquer - not a good idea ,,

 

I did look for rivet holes when cleaning and repainting - didn't spot any, think I would have spotted them even though I didn't know exactly where to look.

 

It was a very coherent black paint over the Sky Blue, the block must have been thoroughly cleaned and spray painted.

 

Thanks for all the info guys. Have been educated today.