free hit
counters
Esprit Turbo project car - part3 - the further continuation - Page 202 - Esprit 'Project & Restoration' Room - The Lotus Forums #ForTheOwners Jump to content


Esprit Turbo project car - part3 - the further continuation


Recommended Posts


Upgrade today to remove Google ads and support TLF.
5 hours ago, Lotusfab said:

Just put a borescope down the opposite side grub screw. Fortunately its not protruding into the oil way and the oil way narrows just beyond it. I took some pics. Thats one thing ruled out. Onto the next.

Was worth a punt,  as you say has cleared that area now.   so the plot thickens !!!

Have we got any pictures of all these damaged parts... it may help us understand a bit more on what may have caused the failure.   Its still a bit confusing on what you have said so far..  some illustrations may help..  

  • Like 1
Link to comment
Share on other sites

Fabian, I am not inclined to connect the frag'd tappet to lack of oil. For that situation to emerge the area would need to be distinctly starved of oil in which case one would expect plenty of comparable witness marks/damage nearby. Still fancy the tappet failure as your single source of the grief at this point though you must, as Dave advises, rigorously check the lot. You're not the sort to do anything in half measures as we all can see!

On lack of oil pressure I offer, not for the first time, a little saga of engine operation after proven loss of oil feed. A mate and I were packing it up after an evening out at the bar and, after an incident most peculiar by which the oil pump drive chain on his BMW 530i was thrown into the sump, the car was driven gingerly home to his residence, a distance of some 6km's. Up a moderate 1/2 km hill to start, over an expansive, arched bridge, the remainder of the journey level and no damage of consequence was found in either valvetrain or bearings in that very recently blueprint built lump. This known because the thing was torn down after as a precaution, of course. So correct oil splashing about under no pressure in a well built engine may stave off disaster for a limited time under light load, apparently. Something to ponder.

Dave, is that an unqualified endorsement for the oil feed restrictor mod?

Cheers

  • Like 1
Link to comment
Share on other sites

On the inlet all the cam follwer skirts are worn. I belive they were then wobbling whilst moving up and down and the weakest one cracked. 

The exahust side hardly any wear on the followers, but this side is much lower on the engine. Points to an oil pump issue.  If it was blast media the wear would be equal. When my oil sample comes back I will be able to rule out contamination.

My gut is the oil pump caused all the issues. I believe the PRV is not operating correctly. 

 

Link to comment
Share on other sites

🙃 My term "unqualified" was perhaps not the best choice - my intent was to ask whether there were further details  by which you would "qualify" the advice!! That has arrived with your comments just posted, thank you!

Cheers

Link to comment
Share on other sites

  • Gold FFM
39 minutes ago, Lotusfab said:

By end of March latest it will be running again and fully rebuilt.

Anyone fancy a flutter?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

Link to comment
Share on other sites

Maybe the odds just changed?  I had a spare 5 minutes so I  took it out by myself, I would suggest two people is much easier. If you take it out yourself you really need to split it and take the gearbox out first to avoid damage. The discs need to be off because its tight. Now lets get building again!

IMG_0762.thumb.JPG.b72f20885956bc4bbd9775e55c6140fa.JPG

There really isnt much to this engine. But crucial info you need for rebuild is not all in the manual! I now will start oil pump tests. 

Link to comment
Share on other sites

Still no pic's of damage cam's, cam carriers, followers , etc...    did you forget to post because we are all keen to see them .. 

6 hours ago, Lotusfab said:

Not sure if I want to fit an oil restrictor, especially when my problem seems to be lack of oil. Ill think about it.

You may be correct here ,  especially when your problem seems to be a lack of understanding..  !!!     However if you ask i am sure someone will explain.. 

Link to comment
Share on other sites

I thought the idea of the restrictor was to slow the draining of oil back to the sump keeping the cams maintaining better top end lubrication?

Well done getting the engine back out and onto the engine stand, always stressful on your own in case something moves the wrong way or slips causing damage. 

Keep going Fabian, I think March is realistic allowing for any machining.

Dave :) 

Do or do not, there is no try! 

 

Link to comment
Share on other sites

  • Gold FFM

As someone who may also be staring a rebuild in the face, I'm intrigued as to your comments about not enough significant detail being available about the oil pump. Presumably there's a service manual, and if so, what do you suggest might be missing from it? From what I can see, and what I have read so far, the main issue is initial pump priming (or the pump's inability to self-prime), following a rebuild. Can the auxiliary drive shaft pulley be spun up beforehand using a drill top work up pressure? And if so would that solve the problem? When I built small block Chevys, the advice was to fill the pump cavity with Vaseline when rebuilding. Perhaps that might also help in this case?

Margate Exotics.

Link to comment
Share on other sites

The manual doesnt have any detail on the pump apart from the specs to determine if its worn. There is no info on the PRV. You must must check it! I didnt because its not mentioned anywhere.  If only I had known about it I might still be driving my car around! Anyhow, you can spin it up with an allen key on the end of a drill. But what is supposed to happen? How much oil per minute should you get out of the turbo feed? Should the oil from the head pipe hit the ceiling or trickle out? How long should it take to build pressure in seconds? These things will be known by experienced builders, but if its the first one how do you know if its working correctly? Having done this once I already have learned so much. Flow diagrams to explain where the oil is going in the housing would help understand whats going on. Dont worry I will have done serval tests with two different pumps and housings and post the results with pictures, so hopefully you wont be rebuilding again! 

In my case the pump was packed and checked but the PRV was stuck open, so no pressure! I think malfunctioning PRV  led to the failure of my engine.

Link to comment
Share on other sites

  • Gold FFM

There’s a number of cc per set period from that turbo supply line - it’s buried in one of the manuals I’ve seen. I measured mine - you had to have at least a certain amount of oil in a time for it to be classed as good.

theres also a spec for the oil pump annulus and housing that needs to be checked

Only here once

Link to comment
Share on other sites

  • Gold FFM

I’m sure it’s in the S4 onwards manual - or one of them - I’ll try and find the section when I’m back home as I’ll need it again, and the wife’s best Perspex jug, very soon

  • Haha 2

Only here once

Link to comment
Share on other sites

Ahh that explains it,  Inwas looking in the Turbo manual. Pressumably the same pump on an S4?

With reference to the restrictor I understood that the resistrictor in the head reduced the flow to the head so the sump would run low on oil whilst turning   corners at 4 g? I wont be racing or turning quickly so would rather have the oil in the camshaft area.

Link to comment
Share on other sites

Fabian,

If I suggest any course of action it is in the best spirit of support and collaboration, and I'm confident that is true for Dave as well. Your enthusiasm is unsurpassed, inspiring to those of us plowing uphill on deep restorations. Garry Kemp is highly regarded, seems a valuable source for guidance as well as the components he distributes. No doubting your experience with absent oil pressure by any here, just cautionary words on what to take away from all this. The cam journals offer a considerable bearing area for their workload, the tappet/lobe interfaces are splash oiled as are the tappet/bore surfaces. If they have been wet they have been lubricated, for the most part. As to the oil pump, convention for checking condition is tip clearance between rotor and annulus (spelling?) and the side clearance between those and the housing in which they operate. Straightforward enough for checking, not a common point found to show wear in engines as they are lightly loaded and always operate in a lubricated state. FWIW.

Press on mate.

  • Like 1
Link to comment
Share on other sites

If the pump is within spec regarding clearances, oil spec is reasonable then flow rate will be as intended. Lotus knew bloody well what they were up to in designing this engine for the most part as the service record bears witness to. A stuck PRV is another matter and would be associated with your tardy oil supply. It is possible you had a tappet fail coincidentally with the aforementioned, not necessarily by cause of it.

  • Like 1
Link to comment
Share on other sites

5 minutes ago, CHANGES said:

No.  The none return valve in the oil filter does that , which it is why you must have the correct spec filter..  When tuning these 900 series engines many years ago it was discovered that the oil supply to the cams was excessive , flooding the cam housings with oil that would could be better distributed at the bottom end and turbo.  By fitting a restrictor you can modify your oil flow to the cams and engine as a whole .  By doing this you can better maintain oil pressure , increasing it in a well built unit.   However anyone who is not sure of what they are doing or does not fully understand the concept should avoid doing it until they are confident it is correct for their build..    To be fair the benefits far out way the avoidance which is why most of us tuning professionals do it as a matter of course.     The drain back is a completely different side of the oil flow dynamic.     

I am so sorry Fabian, i was trying to do a play on your words, but it obviously came across to strong.. Sorry.. 

 I thought you had forgot the pics because you had posted so many more since,  i was just checking as we are all so interested , a picture is worth a thousand words  . 

On the cam followers , i agree longer skirts have advantages in certain situations.   BUT..... not just any long skirt follower . The ones GK sells will do the job perfect as they are a tuning part.... However did you know the crown on the GK ones is a lot thicker so the follower sits higher on the valve, providing the required skirt clearances...   Now why you need to know this is because everything changed has an effect ..    So, to explain. With most engine rebuilds, especially when fitting new guides , you will re-cut the valve seat. this in turn will reduce the thickness of your shims when fitting the cams by .010 - .030 depending on a lot of factors.  When resetting/ matching the combustion chamber volumes further cutting back of valves is normally used as the primary method before fine fettling. ( but not many bother with the chamber matching)  .  On top of that you then fit a cam follower which is circa .020 thicker  .   When you take into account the original shim thicknesses vary from .080 to .100 , you can have a situation where the shims you will be fitting can be getting a tad on the thin size.   You want to try and keep them north of .070 to be on safe side.    I only say this as you mentioned this engine had been professionally re built before , so i expect they will have been re-cut prior and again when you did it . As a result  , especially as you are now fitting new guides another cut will be needed , this will compound the situation unless you intend to fit new valve seats at the same time ..    This is just something you may not have known or fully understood , i hope i have put this across in a way that is not condescending ....  This is not the first time we have bumped heads.  So if you wish me to stop posting observations just say, i will not be offended..

This post is already to long to go into the pump side of the flow dynamic , but i am sure someone will give a technical explanation .. etc..     

If it was easy everyone would do it.   .. keep going.. 

 

No problem Dave. You obviously know far more than I do, any help or advice is gratefully accepted. It will help me but more importantly anyone else doing a rebuild. I will have a go at labelling the housing if no one else knows. It will take a while to work it out though!

Link to comment
Share on other sites

5 minutes ago, Lotusfab said:

Thanks, you might be correct. There are other things beside the spec of the rotor, annulus and housing clerance that might have an effect. Such as the distributor seal, pick up olive.

The pick up olive and the pipe itself is a major factor.  People do tend to be a bit routine with this area , with major consequences as you have had.  

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...