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eeyoreish

Oil Pressure Oddness

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I'm sure the stuck bolts are a Rite of Passage with Esprit cam carriers.

 

We needed to drill one out when we refreshed our engine in 2012.

 

Quote

Rites of passage have three phases: separation, liminality, and incorporation. - Wikipedia

You have completed the first phase.  :hrhr:

The next is to remove the remains of the stuck bolt without damaging the threads in the head. :scared:

 

😊


Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Comforting to know it's not just me with stuck cam bolts!

Happily the remaining stud wound out no problem once there was no tension on in 🙂

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Not worth starting anything now...🍺

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Some more progress on this in the workshop today. Inlet cam tower stripped down, cleaned and rebuilt with new seals. End float is well within spec so one less thing to fix. Now ordering up some new shims (and one new torx bolt!) so it'll be on the bench until those arrive from SJ.

I also took the opportunity to repaint both cam covers while they're off the car.

image1.jpeg.9777ae325c24cdf4868fcffccd8de1cb.jpeg

image2.jpeg.35d0a61a218994151b4b5cb2a54bc154.jpeg

image3.jpeg.77299cd7fb34d5565368aaf3082f2b3c.jpeg

image4.jpeg.0d3037a11ab942f374f48edbca00cca1.jpeg


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1 minute ago, Chillidoggy said:

Might be worth considering helicoiling?

The threads in the head are still OK as I only drilled off the head of the 1 damaged torx bolt then wound out the remaining stud when the tower was off.


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Nice job on the paint.

 

I powder-coated mine.

 

I think that oil is what ruins the valve cover finish. No spills or spatters!!! 

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Atwell Haines

'88 Esprit

Succasunna, NJ USA

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12 hours ago, eeyoreish said:

The threads in the head are still OK as I only drilled off the head of the 1 damaged torx bolt then wound out the remaining stud when the tower was off.

I only say that given the age of the castings, and with the number of times the cam carriers May have been been taken off. II fear this could be a false economy. Perhaps @Sparky has an alternative view?

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Margate Exotics.

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So many 'good' threads have failed on me when replacing towers.  They get dirty, and must be meticulously cleaned, and. they're frequently overtightened by previous owners.  Go carefully and you'll probably be OK.  but if one slips, that's when I'd consider helicoiling the lot!

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British Ambassador to Florida, New York, Denmark and Newfoundland.  And Sweden.

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The Problem I have always found with well worked on engines , is the previous assemblies have done all the damage through ignorance.  When you talk to people how they do the job of re-shimming , which is where most of the torques bolts thread/head damage occurs, they all do the same error..   This is using the torques bolts to pull the cam housing down and also doing without oiling the threads..  This repeated on and off with a steel bolt in an alloy thread wares it , eventually pulling out under torque.  The other factor is few people actually use a torque wrench straight off and over torque with socket wrench first .. These are only 16 lb torque an easy limit to reach with a small spanner.      The two steel studs either end are there for a reason , That is to pull the cam housing down virtually all the way.. then you nip the torques bolts with suitable 1/4 inch drive torque wrench.  remembering to lightly oil all threads.. This also help the torque be more accurate.,.   When the shims are all in spec for final bolt down use a blob of blue lock tight , suitable for use on lightly oiled threads and the job should be  completed..  The cam cam housings have been on and off my engine more times than i can count using this method,  it has no helicoils or thread damage..   Hope this little bit of advise helps some .. 

PS..  I also see so many put it all together as in pic's , so clean with maybe light oil on the cams / followers etc..  This is very minimalist, especially when the engine stands for some time before firing.. The damage this causes on startup is about 10,000 miles worth...  Coat the lot with copious amounts of graphogen assembly compound and remove the worry on initial start up.. ..   

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Thanks for the advice guys. As far as I know, the cam towers have never been off before so I'm hopeful that it will go back with no drama. As @Sparky advises though, if one does let go I'll helicoil them all before having a second go.

It probably doesn't show in the photos but I've already used proper assembly lube on all the moving surfaces in the reassembled tower.

Fingers crossed!

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1 hour ago, CHANGES said:

  The two steel studs either end are there for a reason , That is to pull the cam housing down virtually all the way.. then you nip the torques bolts with suitable 1/4 inch drive torque wrench.  remembering to lightly oil all threads.. 

So what's the best strategy here for success? Wind the tower down to position (not torqued) using the two studs/nuts at the end and then fit and torque down the torx bolts from the centre outwards? Finally torquing the nuts at the end?

I'll run a tap down the threads to clean them and make sure the bolt threads are oiled before inserting them.

16lb torque is low so is it enough/best just to nip the torx up by hand until they feel 'just' tight?


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31 minutes ago, eeyoreish said:

So what's the best strategy here for success? Wind the tower down to position (not torqued) using the two studs/nuts at the end and then fit and torque down the torx bolts from the centre outwards? Finally torquing the nuts at the end?

That's exactly it..  works a treat..  does not mater how many time you need to keep doing it ,the alloy threads in the head should not wear.

  

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I think I'd skip running a tap down the holes, for fear of removing any of the existing thread.  My experience with taps & dies is they often don't exactly match the original profile, resulting in a looser fit overall after. 

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I decided exactly the same thing today! I cleaned the threads in the head with some brake cleaner and paper towel and ran down each hole with one of the good bolts so I know the threads are clean and clear.

 


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Shims arrived this week so first 'dry' fit of the inlet cam tower today. It turns out 3 thou +3 thou = 7 thou ☹️ Who knew...

Anyway it looks like, as expected, this will take 2 or 3 goes to get right. Luckily it looks like by moving around some of the old and new shims I already have I should only need 2 more. This time I've ordered them from QED as SJ want £5 postage for 2 shims.

Hopefully next weekend I'll get this back together properly. In the meantime I've borrowed a 3/8 torque wrench as I'm beginning to get a tad paranoid about how tight is 'tight enough' for the tower bolts 🤔

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Not worth starting anything now...🍺

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Sometimes your initial readings of valve clearance are affected by worn spots on the shims. 

 

I needed 3 tries to get the clearances where I wanted them.  That is why you measure it 'dry' at first...so that you can take it apart several times.

 

Practice makes perfect as they say.😁


Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Hopeful for next weekend...

I did reuse one old shim on a different valve but turned it over to place any wear patch against the flat of the follower. I assume that's Ok to do?


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1 hour ago, eeyoreish said:

I did reuse one old shim on a different valve but turned it over to place any wear patch against the flat of the follower. I assume that's Ok to do?

Not worth the risk for the price of a shim, also don't be temped to grind a few though off a shim that's too thick, you risk going through the hardened outer casing. 


Cheers,

John W

http://jonwatkins.co.uk

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I'm definitely not grinding anything down!

What is the risk of reusing one of the original shims? Surely as long as it gives the correct clearance it will be fine?


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I'm with you Neil.

If you flipped it so that the dimple now faces the bucket, then there's a massive area to spread the load, several times the area that was in use on the end of the valve stem. So, if it took 50k to wear away and form the dimple, it will probably be 250k to wear away the rest to match. It also gives a tiny oil pocket

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I'd happily reuse a shim in this way.


British Ambassador to Florida, New York, Denmark and Newfoundland.  And Sweden.

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Yep, dimpled shims equal two sizes in one! Or at least half sizes. Flip 'em over as needed. Sometimes it's just the thing to solve the 3+3=7 problem, or get just a shade closer to a given clearance.  I recommend a good micrometer to measure the dimple vs the outer ring to be sure of what you're entering into the spreadsheet. Don't blindly trust markings on shims either, measure them all.

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Thanks guys, that was my thinking too. 

3 new shims ordered and on the way from QED but I’ll still need to relocate a couple of originals too. 

I have a good micrometer on hand and also a 3/8 torque wrench as I’m getting slightly paranoid about those cam tower bolts!


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3 shims arrived from QED today. They only took the payment yesterday so great service and only £1.95 delivery too vs £4.95 from SJ. The shims were a bit cheaper too👍


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