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Full Strip down needed?


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Hi, with the goal of getting my car on the road this year I’m finally at the ‘Engine’ stage. From my other thread in projects, it’s a 912 1982 engine that is currently on the engine stand in the garage.

Looking through all of the threads I’ve picked up must-do’s and dont’s, and so far:

  • carburettors are back from refurbishment, they look great, cleaned and new seals etc all round
  • new fuel line, tank recoated inside, new fuel filter ….the fuel pump looks brand new but I’ll run petrol through it before plumbing it in
  • reconditioned and tested water pump
  • have a new timing belt to fit
  • radiator all flushed through and fins cleaned out, need to get the radiator fans tested before fitting
  • will fit new spark plugs, HT leads and clean out the distributor

Looking at the engine, I’m degreasing it bit by bit, manifolds are off and looking at the exhaust ports it looks like it was running ‘rich’ but no sign of any oil and there’s no sign of water emulsion anywhere in the cam towers or when I drained the oil. The camshaft lobes and followers look like new to me, no wear visible anywhere. No oil leaks visible at either end of the crankshaft seals. The spark plugs came out easily, except #4 which needed more gentle persuasion, but there’s no evidence of any cross threading there.

So appreciate advice, what else should I be checking out? I plan to recheck all of the valve clearances and once adjusted (if needed) should I put the engine back together as is with all of the refurbished parts above or should I go deeper into the engine? The engine last ran years ago, before I had it anyway.

thanks

Terry

 

 

 

 

Ongoing restoration photos on the Dropbox link.

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The only bit I'd want to see a bit more of is the condition of the cylinder bores - even small amounts of condensation/water can cause corrosion.  How about getting a bore scope in there to have a look?

Pete

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I would consider replacing the belt pulleys with those from Lotusbits which a have a better shaped tooth form. The tensioner and belt should also be replaced..

I suppose it boils down to this ‘do I pull the head and have to pay for a gasket and head skim at say £100 or risk it and have to pull the engine apart later?’

if you leave the head on and subsequently have to remove it, there is the cost of inlet and exhaust gaskets which will have to be replaced again.

my gut feeling is to lift the head while it is relatively easy then you can also look at valve guides and seats, update to double valve springs and clean the waterways, make sure the liners are ok etc.

I would also give the oil pump a wiz with a battery drill and check its performance.

All more work and expense but more peace of mind!

BTW did the engine turn over OK before you started and did you do a compression test?

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Do you know if the engine has been apart since 1982?  If not and you remove the head I'd be worried about the cylinder liner sealing, even with holders in place.  Personally, while the engine is out I'd strip it completely;  then you'll know it inside out.  You can then rebuild with the latest recommendations for sealants etc..  Apart from the head gasket all the other parts are cheap as chips!

Pete

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Thanks Pete (x2).

I bought a cheap Wi-Fi endoscope from ebay, close close up the focus is a bit off, but it’s good enough to have a look. From your feedback and the images below I think you’re right. Cylinders look best in #1 and 2, both 3 and 4 have some crud coming in through the inlet valves. Inlet side is about ‘11 o clock’ on the photos.

With the inlet manifold off then I can see that there is water related? corrosion on the port. And also #3 and 4 seem oily. First 4 manifold photos are inlet side.

On the exhaust side, the same, looks like #1 and 2 were firing while #3 and 4 don’t have that appearance that would indicate good/any ignition. Last 4 photos are exhaust side

This is really an untrained eye, so appreciate feedback…… but yes, I guess this engine will be coming apart.

 

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Ongoing restoration photos on the Dropbox link.

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I'd defo be wanting to clean all that up!  Looks like you've found the next part of your project Terry 😉.  If any of the valves are toast I may have some useable ones.

Pete

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Thanks Pete 🙂, yes I think so too! Do the cylinder bores look ok?

Listening to you both then is a ‘top-end’ plan?

  • fully (finally) degrease all of the engine externals
  • set pistons to be 1/2 way position in cylinders
  • measure all existing valve clearances and remove cam towers
  • look after all of the shims
  • remove head, try to keep the liners in place (are they likely to move when the head is removed?)
  • remove and clean sump, oil pick up etc

options are:

  • find local cyl. head rebuilder to clean, and as necc. replace valve guides, replace valves, reseat, (head skim?) etc
  • Or fully clean head myself, etc 
  • or…?

I read in the manual that the head gasket should be replaced with one with the same number of laminations as removed (but I haven’t seen this option on sites selling these)… are they essentially all the same?

Crank/big end bearing condition checking, is that just to look for ‘scoring’ in the shells? And I guess, if I’ve gone this far, how much more difficult is it to refurbish the bottom end?

 Thanks Terry

Ongoing restoration photos on the Dropbox link.

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Full rebuild I would say - you'll know exactly where you are then.  From what you can see the bores look reasonable - a very light hone to de-glaze may be all that is needed.  Easy to check piston ring gaps.  More difficult to check piston-to-bore clearance without further equipment (micrometer and bore gauge).  There is only one Lotus branded head gasket available now - it is the recent replacement for the Goertz gasket (which is no longer available unfortunately).  There are several head gaskets available from other suppliers - the quality seems variable.

If you dismantle the head yourself - very straightforward with a valve spring compressor - you can assess the condition of the valves/seats/guides yourself.

Check the crank for scoring - anything other than very light marks is worth getting rectified (not too expensive) - you'll probably be replacing the shells anyway.  You can check the clearances with Plastigauge (PL-A) - very easy to do.

Let us know what you find!

Pete

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Perhaps the corrosion on the piston crown is because that particular valve was open all those years and condensation got in.

When you have the head off, you must take care not to disturb the liners so male up a set of clamping bars to fit on the studs.

Measure the ‘nip’ with a straight edge across each liner with a feeler gauge, you can check head chamber volume by getting a piece of Perspex large enough to cover the chamber area, drill a small hole in it and ‘stick’ it in place over the chamber with grease, then use a hypodermic syringe to fill the chamber space with water keeping  a note of the volume of water as you go.

when you get the crank out look carefully at the upper front main shell as over tension on the drive belt can lift the crank up and wear the shell away.

keep us posted

Peter

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All rather grotty as seen in the photos, I'm in camp with those who advise a full teardown. The last of the piston pics shows what appears to be crown damage due to either severe pinking or foreign object rattling about. Such a nice thing to drive a Lotus with all in order so go the distance and get it right.

Cheers

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Started to strip the engine down…. In projects and restorations section

Ongoing restoration photos on the Dropbox link.

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