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Bottom End Rebuild


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After a week of doing "other things" I'm now back on the TR. I have the engine of the engine stand which does make it easy to work on. My main aim was to change the front crank oil seal and also look to see how hard it would be to tackle the rear crank seal. In reality, being so far into this (with engine out the car etc) I will be doing the rear crank seal unless there is a real obstacle. So I've taken of the timing chain cover and changed the seal. I've also noted that the chain had a slack of about 12mm so needs to be changed (was going to do this anyway, along with the tensioner). This is really as far as I am, oh I've taken the sump pan off as well. 

       I do have some questions. To remove the crank I assume I can do this whilst leaving the pistons in the cylinders without and issue, is there anything I need to be aware of ...... not letting them go fully to the bottom (or top of the engine I mean as the engine will be inverted at this point.). 

      In addition, does the front engine end plate need to come off to get the crank out if this is all I'm doing. And if the end plate needs to come (or its wise to remove it) does that mean the cam needs to come out. Obviously I will be looking at a bottom end rebuild (bearings) along the way. Ideally I want to leave as much alone as I can but still want to do it right. The book isn't really that helpful on this as its more focused towards a total strip done and rebuild rather than what I need to do just to do the bottom end.   

     I know these are simple question to those of you who play with engines, this will be my first time at this level. 

Regards,

     Neil

 

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I would say that the front plate should be taken off, & that means the front camshaft bearing needs to come off. The cam can stay in place.

I assume you have already clamped the liners down to the block to prevent them moving & disturbing the FO8 seals. If so yes you can leave the pistons in the bores, just don't let them move so far that the top ring comes out.

Bob.

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Bob, 

   Thanks, I've not taken the head off and was planning to leave this on. Does it need to come off for a bottom end rebuild? I was assuming the head would hold the liners but if its not a guarantee then I'll start on that next and clap the liners down. 

  My issue is I can understand how to do a full rebuild (on paper at least) but it's just understanding which bits I can leave out just to attack a crank out job. 

   So front plate off but cam can stay in as long as I remove the bearing ..... That's some good news for me. 

Neil

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The head will hold the liners better than anything else ! & no it does not have to come off for a bottom end re-build.

If you leave the cam in, there is no need to touch the head / rockers / followers etc.

Bob.

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Thanks Bob, what about the Pistons. I'm hoping I can disconnect the big ends and then allow them to move up to the top of the cylinder (noting the engine will be the wrong way up at the time, so really gravity allowing them to slide to the top). 

   Is this acceptable or do I need to somehow suspend them from going all the way to the top?. I can pretty much see how the rest needs to be done and will use the manuals for sequence and guidance. 

Neil

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The piston rings will do an “OK” job of preventing the pistons going DONK onto the cylinder head. ( if they don’t that’s a good time to decide to change your piston rings).
You’ll have to press the pistons down the bores for clearance. Also as I remember from Technicalities the crank is removable with the front plate in place and doesn’t need removing. Otherwise it really does get a bit tedious when you are at the side of the road replacing a broken crankshaft from  underneath which is the section it’s in.

Mick Richards

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Thanks Guys, I been out after work and removed the front plate. Not as dificult as I thought it would be. I can see it might be difficult to get a good seal between the fron sealing block and the end plate if the end plate is left in position. Good to hear the Pistons and con rods can be left in place. Yes I could see that there may be enough friction to sop them falling under their own weight. 

       Might have a little more of a go tomorrow night. I'm sure I'll need some more help (support) but thanks for having the patience so far. 

Regards,

Neil

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Well, there's no going back now. The crank is out and on the desk. Everything carefully logged. Actually there is little to no wear on anything, only the timing chain was outside tolerance. Just need to order what I need now and hopefully get it all back together. Happy with what I've seen so far, no big surprises but it was running well, just leaking oil from front and back. 

Neil

Edited by NCS_TR3A
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Tangent Time....

If you are renewing the front oil seal what condition is the pulley hub that runs in the seal? 

Fitting a Speedisleeve  is the way to renew the sealing surface that will have rusted/pitted/gouged/worn since your engine was new

SKF 99175 or SKF 99174 is what I use.  99174 is 1/2" long and needs thinking about when fitting to get the new bit of the sleeve over the worn section of pulley shaft.  99175 is 3/4" long and does not need much thinking about when fitting.

https://www.ebay.com/itm/SKF-Speedi-Sleeve-99175/223480355925?hash=item3408779c55:g:MoEAAOSwPcVVqu5x

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4 hours ago, Lebro said:

Mad Marx splitseal.pdf 1.04 MB · 4 downloads

In case you did not have this.

Bastuk do a copy of this  kit which can be purchased from the TR shop.

You can also just buy the viton seal, & modify your existing scroll halves to take it.

Bob.

Thanks Bob,  I've not used TR Shop before, I'm based in Warrington, so normally have used TR Bits and Moss (Manchester). With most things by post now it doesn't really matter. I have ordered earlier today what I need from TR Shop. Im planning on fitting the Mad Marx kit, the one that comes done rather that machine the one I have. Not that I don't think I could, although it is a consider action :)

     I was just logging on to ask a question which the attachment answers which is great. I was going to ask what sealant to use on the aluminium plate. There was nothing on the ones I took off. Didn't know if it's normal gasket sealant, something like Wellseal or my go to sealant which is silicone. Appears its silicone that's recommended. 

  Just a note, initial experience with TR Shop has been good, quick to answer phone, good knowledge and asked if I'd forgotten the timing chain Tensioner at the end, which I had. It was on my list but I skipped over it ordering. They will send a confirmation mail to check, I then pay and they send. Like that system very much. Will see what it's like when it arrives. 

Neil

 

 

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19 minutes ago, BlueTR3A-5EKT said:

Tangent Time....

If you are renewing the front oil seal what condition is the pulley hub that runs in the seal? 

Fitting a Speedisleeve  is the way to renew the sealing surface that will have rusted/pitted/gouged/worn since your engine was new

SKF 99175 or SKF 99174 is what I use.  99174 is 1/2" long and needs thinking about when fitting to get the new bit of the sleeve over the worn section of pulley shaft.  99175 is 3/4" long and does not need much thinking about when fitting.

https://www.ebay.com/itm/SKF-Speedi-Sleeve-99175/223480355925?hash=item3408779c55:g:MoEAAOSwPcVVqu5x

Hi, happy for the questions to come.... Better now than when it's all back together. To answer, it was not good. The seal was very hard (compared to the replacement). Because of this (well I assume because of this) there is a groove in the pulley hub. I have actually got a speedi drive for this. I've got 99175. I think I'd read a post from you on here saying both work but 99175 needs less thinking about (that's made for me) 

I've ended up putting a speedi sleeve on the real diff (the shaft was pretty good in reflection), the rear gearbox shaft (slightly pitted, same issue) and will do the front pulley hub (which was quite bad). I had never even heard of these before reading on here...... They seem to be a great product and I'm sure I will be using to solve other problems away from TR's. 

Thanks, 

Neil

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On 4/12/2021 at 5:12 PM, Motorsport Mickey said:

The piston rings will do an “OK” job of preventing the pistons going DONK onto the cylinder head. ( if they don’t that’s a good time to decide to change your piston rings).
You’ll have to press the pistons down the bores for clearance. Also as I remember from Technicalities the crank is removable with the front plate in place and doesn’t need removing. Otherwise it really does get a bit tedious when you are at the side of the road replacing a broken crankshaft from  underneath which is the section it’s in.

Mick Richards

Mick, you were absolutely correct. Pistons needed some help to move. I can see the crank could come out with the front plate on. Certainly easier with it off, but then it's easier with the engine on a stand upside down as well compared to roadside from underneath. I'm actually surprised how good all the parts are (except for the chain and Tensioner which were worn). Hadn't realised I had 87mm Pistons until this either. 

Neil

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Speedi sleeve is a good answer on the rear half shafts as well. I have them on most parts where there is wear from seals, bearings etc. Before I found them I was always getting oil on the rear brake shoes.

Good luck Richard & B

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  • 2 weeks later...

I've been taking my time on this but there have been a few discoverables through this rebuild and a lot of learning on my part. Main discoverables which were all new to me - 

(1). Engine has 87mm liners in it. 

(2). Camshaft is a standard TR4 item. 

(3). Conrod bolts had no locking tabs and we the non stretch type (lucky on that one) 

(4). Rear scroll seal was correctly adjusted (no wear) but hadn't been sealed to the block or each other. 

(5). Timing chain very slack

 

  I'm waiting on locking tabs for the con rods as I don't feel happy taking that chance. On changing the timing chain and lining up the marks on the gears as they where when they removed seem straight forward. On checking the valve timing (just to learn how to do it) had me messing adout for a day. Over the day I've learnt a lot on how to accurately measure but also found that if the gears are aligned as they were marked (and as they were when removed) then the timing was about 10 degrees out (inlet opening at 7 degrees instead of 17 degrees) 

  I have a quick question on valve timing, the setting for a TR4 cam is inlet starts to open at 17 degrees BTDC and closes at 57 degrees ABDC. I've got it to 17 degrees BTDC and closing at 60 degrees ABDC. So obviously my 10 thou valve gap is a little tighter than it should be. 

  How critical is this and is it better to have it opening slight earlier or closing slightly late? Or am I faffing for no real benefit. I've learnt a lot doing this, my original set up wouldnt have been accurate to 3 degrees, now I can do it in 1 degree intervals. 

Regards, 

       Neil

 

 

Edited by NCS_TR3A
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