Spitfire Engine and gearbox out. Now what?

[Banksy82]

Hello All, 

I have spent the last weekend removing the engine and gearbox from my recently acquired spitfire to address a couple of known faults.

1. Crankshaft end float excessive
2. Throwout bearing noise (or so I thought - turns out locating pin for the bearing assembly is completely missing and the whole carrier was just flapping in the breeze!)
3. Mystery loud tapping at idle that doesn't go away with speed - first thought it was valve train but now not so sure - I'll investigate.
4. Sort oil leak from sump.

Now I have the lump out the whole gearbox and Overdrive is covered in oil and I am contemplating renewing gaskets and seals while I have convenient access.

Question is are there any seals / gaskets that are best left alone unless they are known to have failed or can I merrily strip them all out and replace with new from Moss / Paddocks? Equally is there any that definitely should be replaced regardless?

Also looking at removing flywheel and back plate to mount block on engine stand - any concerns with doing this?

Karl.

[RobPearce]

If it's a 3-rail gearbox (up to MkIV) then don't bother changing the O-rings on the remote shaft where it passes into the gearbox top cover housing part. They very rarely fail and are a nightmare to do.

If you think there's oil getting past the input shaft seal, and if it's a 3-rail, then there is no seal, just a scroll. It's probably not worth even trying to make that one not leak.

The gasket between the gearbox and overdrive or rear extension is a fair bit of effort to change and not likely to be leaking.

Generally, I would clean it up and look for any signs of problems, rather than assuming you'll change everything. They do get filthy because all the minor leaks and spillages your car has had in the past will have been atomised, vapourised and sprayed everywhere. Replacing gaskets and seals will not make a Triumph leak-free so it's not worth trying.

[glang]

yes I think a lot of the time its the various bolts coming loose that gives rise to leaks. Mine can always be tightened a bit more and next time I'll replace all the spring washers to see if that helps....  

[Banksy82]

@RobPearcePerfect. Thank you. 

Sorry I should have mentioned - yes it is a Late MKIV with a 3 rail box and a D-type OD.

Biggest sign of leak is around the sump, the whole area is swimming in oil/filth soup! 

I can't really tell if it is coming from the sump itself or from the cam cover gasket / oil seal so I was going to clean and change those 3 for certain and then wondered where else is likely to be in need.

 

[Banksy82]

3 minutes ago, glang said:

yes I think a lot of the time its the various bolts coming loose that gives rise to leaks. Mine can always be tightened a bit more and next time I'll replace all the spring washers to see if that helps....  

This is an excellent idea - thanks!

[Clive]

Sump off, dress the bolt holes so the sump face is flat. 

Check teh threads in the front and rear ali blocks. If poor, helicoil, and remember to use the correct size bolts. 

Endfloat is hopefully just worn thrusts, if they have fallen out it is bad news. New thrusts usually sorts te issue, kipping would suggest adding 5 thou, or I used to order a std, +5 and +10 (assuming std were fitted) and see what I could squeeze in. 

Check big ends and mains, may or may not need replacing. Clean the sump out, and yu are golden for a long time. 

To trace leaks it is best to clean the engine while still in the car, so you can find the source. Bit late now.

New gaskets tend to be very thin, so a smear of hylomar blue (don't go beserk with it) on both faces is a wise precaution. 

[Banksy82]

27 minutes ago, Clive said:

Check big ends and mains, may or may not need replacing.

Thanks for the input. What is the best way to assess the bearings?

Assuming there is no obvious play I was thinking of removing the crank to measure journals against the book to prove the crank and then plastigauge to measure clearances? 

 

[RobPearce]

16 minutes ago, Banksy82 said:

What is the best way to assess the bearings?

A visual inspection generally gives a pretty good clue. When new, the bearing surface is smooth, flat, and a dull silver colour. If it still looks like that then it's still good. If there are patches of copper colour then it's a decent bearing but a bit worn through age - reasonable odds that a replacement bearing will be all you need. If there are scratches in the bearing surface, or pitting, then you're probably looking at the crank needing a regrind. If the bearing's no longer a clearly defined shape, then you've got trouble, and the crank may well be scrap.

[glang]

Yes and the out of round limit for the journals is 0.5 thou which is impossible to measure accurately without the correct expensive micrometer so you can either give it to a machine shop to check everything or as Rob says make your own judgement and proceed on that basis... 

[Banksy82]

24 minutes ago, RobPearce said:

If there are patches of copper colour then it's a decent bearing but a bit worn through age - reasonable odds that a replacement bearing will be all you need. If there are scratches in the bearing surface, or pitting, then you're probably looking at the crank needing a regrind. If the bearing's no longer a clearly defined shape, then you've got trouble, and the crank may well be scrap.

This is golden info thank you - I'll visually assess and probably post photos here for a second opinion.

I have mics and slip gauges that I would trust to be accurate to a couple or three tenths and are repeatable to 1 tenth but it appears that a visual inspection may tell me all I need to know.

[glang]

If you got a good 1" - 2" mic then certainly interesting to check the journals👍

[Clive]

Yes, i have always just used the No1 eyeball. It tells you a lot. 

Radial scratches don't wory me too much if only one or 2 per bearing, on the journal anything that catches a fingernail is worth worrying about. remember, you have choices. Either go all out for a perfect, as good as new engine that will be good to be thrashed for 80k, or if you are just intending to use the car as most owners do, a refresh with new bearings will probably last at least 10 years, probably a lot more. 

And yes, if unsure, post pics on here.

Please do check that all bearing caps are marked. Many already are numbered, if not use a punch to add dots. This is incredibly important. (and I apologise if you already know this)

[Banksy82]

10 minutes ago, Clive said:

Either go all out for a perfect, as good as new engine that will be good to be thrashed for 80k, or if you are just intending to use the car as most owners do, a refresh with new bearings will probably last at least 10 years, probably a lot more. 

Thanks for the info! I'm looking for a 'refreshed' engine I think. It is as much about finding out where things are and deciding on the best course of action for each part. At least that way I won't be wondering what the state of x is all the time! 

On that note I have just checked the tension on the timing chain and the slack is currently at 11/32 (.344) and the book limit for renewal is 0.4. I am minded to call it 'in tolerance' and just replace the tensioner which is reasonably badly scored.

18 minutes ago, Clive said:

Please do check that all bearing caps are marked. Many already are numbered, if not use a punch to add dots. This is incredibly important. (and I apologise if you already know this)

no apology necessary - I do know this but that doesn't mean I wouldn't have forgotten! - I'd rather be reminded of something than be looking at a pile of parts on the bench with that sick feeling!

[Banksy82]

30 minutes ago, glang said:

If you got a good 1" - 2" mic then certainly interesting to check the journals👍

I will probably do a visual check and then when it all looks beyond salvage mic up the journals to try and convince myself that I don't need a regrind! 😁

[glang]

If it wasnt knocking or rumbling before you took it apart theres a very good chance that all you need is change of bearings. You can check out the oil pump tolerances at the same time as theyre essential for making the new bearings last as long as possible.... 

[Banksy82]

9 minutes ago, glang said:

If it wasnt knocking or rumbling before you took it apart

There was - unfortunately - an undiagnosed noise that is partly the reason the lump is on my workshop floor. I was convinced it was cam / tappet / rocker related but the more I listened to it the more worried I got! 😁 I'm picking up an engine stand on Thursday so should be able to get the sump off and investigate my fate...

[Clive]

Beware new timing chain tensioners. Many (most? all?) are not properly hardened. So your old one may be the safest bet. Others may have more recent experience. 

[Banksy82]

45 minutes ago, Clive said:

Beware new timing chain tensioners. Many (most? all?) are not properly hardened. So your old one may be the safest bet. Others may have more recent experience. 

Duly noted! I’ll post a picture when I get back in the workshop to see what the knowledgeable folks here think of the state of my original one!

[standardthread]

13 hours ago, Banksy82 said:

Duly noted! I’ll post a picture when I get back in the workshop to see what the knowledgeable folks here think of the state of my original one!

A reputable supplier should (?) be able to supply a good tensioner. The last one I replaced (noisy tapping etc. as you experienced) didn't need replacing because the witness marks showed that someone had replaced it off centre on the pin that retains it by placing the tensioner at the wrong side of a packing washer on the pin that retains it. So effectively the tensioner was only bearing on one side of the chain so one side of the chain was flapping against the tensioner. I replaced it anyway because it was scored. I had an original boxed BL version. 

Check the profiles of the teeth on the gears, the chain may be in tolerance but the profiles of the gears could  be worn.

As above, I would mic the crank and if the shells show signs of wear I would like to know and find the cause of any scratching.

When you put the timming cover back on oil the new seal and rotate the crank before you bolt up the cover to centralise the cover/seal/crank. An 'L' shaped piece of welding rod is good for pulling the tensioner back against the case while you get the cover over the gears etc. some say an allan key but I find them too big.

[Banksy82]

@standardthread Thank you for the useful tips.

3 hours ago, standardthread said:

Check the profiles of the teeth on the gears, the chain may be in tolerance but the profiles of the gears could  be worn.

Oh the teeth are definitely worn - I wouldn't dream of trying to put a new chain on the sprockets. I'm sure I should replace them but my thoughts are that as they have worn together and within book tolerance I can put off the £60 it would cost me to replace items that can be reasonably easily accessed later with the engine in the car....

Any other thoughts on this??

 

 

[Banksy82]

This is the state of my current tensioner.

The grooves are in the order of 8 thou deep and with the leaf only 20thou or so I'm minded to replace...

Does anyone have experience of the quality of aftermarket parts from the usual suppliers?

Thanks

[glang]

Chain and sprockets should be changed together as if any component is renewed it will quickly wear to suit the older components. If the chain is within the 10mm tolerance the WS manual requires then I would leave it alone.

The tensioner is more complicated as I think its got plenty of life left in it but how long are you planning to leave it before the next inspection? If the chain is also quite worn then, bearing in mind possible quality issues of new tensioners, I would leave everything and check it again in say 15-20k miles... 

[standardthread]

1 hour ago, Banksy82 said:

This is the state of my current tensioner.

The grooves are in the order of 8 thou deep and with the leaf only 20thou or so I'm minded to replace...

Does anyone have experience of the quality of aftermarket parts from the usual suppliers?

Thanks

Looks like the tensioner, and possibly seal, are nearly new. Has someone beaten you to it and just replace the tensioner to try and quieten things down? Possibly indicating that the real issue is the worn gears? In the process of all that, not getting a good seal on the cover gasket leading to loads of oil around your sump and the excess sealer you mentioned earlier?

An offset for the cost of a complete new set of gears now is the time it would take you to do the job again plus a new seal, gasket etc. and possibly reduced efficiency of the engine (fuel costs). 

Edited September 14, 2022 by standardthread

[Banksy82]

2 minutes ago, glang said:

Chain and sprockets should be changed together as if any component is renewed it will quickly wear to suit the older components. If the chain is within the 10mm tolerance the WS manual requires then I would leave it alone.

The tensioner is more complicated as I think its got plenty of life left in it but how long are you planning to leave it before the next inspection? If the chain is also quite worn then, bearing in mind possible quality issues of new tensioners, I would leave everything and check it again in say 15-20k miles... 

Pretty much my thoughts, I am being rather frugal as I haven't had the car for all that long so I'm still going through the major components and as yet have no idea of total costs to remedy any immediate trouble. 

In terms of timescale, once drive train, suspension and brakes are checked over I can go back through and replace in tolerance but worn components in the order of most need. Given I want to drive the thing for most of next summer I would hazard a guess that the next time i would look would be in 12mths. I am unlikely to do 10k in that time.

[Banksy82]

3 minutes ago, standardthread said:

...and possibly seal, are nearly new.

I decided the seal was bad as it is very hard indeed - I would expect some flex in the lip but there really isn't any - Is this normal?