Skip to main content

This is on my Pantera project that I received in February.  The engine is rebuilt, mostly assembled, the heads are installed, and it has not been fired.  The intake valve in cylinder #1 is not seating.  Perhaps there is some debris that is keeping it from sealing.  The engine is out of the car.  I am thinking of pulling the spring and spinning the valve with a drill in an effort to clear any debris that might be in the seat.  All of the other intake valves are sealing.  Any ideas and insight that you have about this is appreciated.

Attachments

Images (1)
  • mceclip0
Last edited by stevebuchanan
Original Post

Replies sorted oldest to newest

I made a valve removal tool out of a pry bar and was able to get the retainers and spring out.  Next, I spun the valve with a drill, and then reassembled the spring and retainers.  I then pressure tested and vacuum tested the intake runner and found that both values improved.  This is an indicator to me that the valve will likely seat once the engine is running because of the explosions pressing against it.

It looks like I will be moving forward with final engine assembly and installation into the car.

Here is a photo of the tool that I made.

Attachments

Images (1)
  • mceclip0

Risky business…

I agree with Adam!!!

AND : there are hopefully no explosions in the engine ! … it’s a burn 🔥!

there is also the possibility that the “dirt” , if it’s that , stays in the same position and just gets pounded into the seat on the head or on the valve and it will not get better! Then, you have multiple possibilities of failure!

your problem may even be a not proper installed valve seat… If that’s the case, you are actually lucky that you discovered it before you fired it up!

I would bite the bullet and open it up!

IMG_2437

There can only be two answers:

the valve seats proper

or

it doesn’t!

there is no… almost good!

Attachments

Images (1)
  • IMG_2437
Last edited by LeMans850i

I am wondering how common this problem is.  It is likely that most of us have sent cylinder heads to a shop for a valve job, installed them upon receiving them, and run the engine that way.  On the contrary, I think few of us have pressure or vacuum tested the cylinder heads after the work was done.  The only reason I did so was to test the plumbing for the EFI's MAP and IAC (Idle Air Control).  While testing that plumbing, I found leakage in the manifold gaskets and fixed such with thick gaskets and sealant.  While continuing the testing I found the leak in one valve seat.  Throughout this testing there have not been any leaks in the plumbing for the MAP and IAC.  I am somewhat reluctant to tear down a sealed manifold and cylinder head just in case one valve might not seat once the engine is running.  I am now setup to test the valve's sealing ability at any point in time.  I am inclined to run it as is, and test the valve's seal after break-in.  Over the years I have become somewhat accomplished at removing Pantera cylinder heads in the car and have a special adapter for my engine crane that handles cylinder heads nicely.  I think I will roll the dice and hope that the valve seals.  If it does not then I will pull the head in the car and lap the valve.

Thank you for your input on this.

Here are photos of the plumbing that I was testing.  It is the black tubing and push to connect fittings.





Attachments

Images (4)
  • mceclip0
  • mceclip1
  • mceclip2
  • mceclip3

I spoke with Wilkinson about this and I am going to try lapping the valve in place.  I can reach the valve through the intake runner and apply a small amount of lapping compound and spin it with the drill again.  Then try to remove the compound with a paper towel.  The photo is fuzzy but the valve seat is visible and somewhat accessible through the runner.

Attachments

Images (1)
  • mceclip0
@adam posted:

Lapping compound is a great idea, if you have any crap on or already into the seat just put that compound on and oh heck attach your drill to the valve and spin it.

Low speed, changing rotation, With a 4 inch hose connection between so you can not apply side loads!!

@stevebuchanan I’m glad you to attempt to fix the issue!!! I was surprised that you would let it go…

after you detected and fixed the intake leak so meticulously and then you would let a much worse situation slide…..

👍👍👍👍

Not sure how you keep the lapping compound out of the cylinder..😳

Last edited by LeMans850i
@panteradoug posted:

If by chance there is some type of debris under the valve and you are able to knock it loose, where does it go?

Hopefully not between the piston and the cylinder wall but hope should not be a plan.

I don't understand the apprehension in pulling the head?

Yep… My thinking as well…

Reading about sealing the intake manifold it probably takes  one day to just clean the  sealant off.. Still wouldn’t stop me pulling the head..

And lapping compound is like fine sand in a paste.. and absorbs the metal ground  off…. Rotating will sling the paste… and it will dry and fall in…

IMG_2439

Attachments

Images (1)
  • IMG_2439
Last edited by LeMans850i

lapping the valve worked.  With a screw driver, I applied a small amount of lapping compound, about half the size of a pea.  I ran the drill at low speed in both directions as Roland suggested.  Then I put a series of paper towels soaked with WD40 between the valve and the seat in an effort to collect debris.  I ran the drill between some of the cleaning cycles.  The valve spun smoothly in its seat at the end.  The combustion chamber is packed with rope through the spark plug hole to hold the valve up and it may have contained some of the debris.  There could not have been much that was causing the problem.  With the spring reinstalled, it now holds a vacuum like the other intake runners.

Attachments

Images (1)
  • mceclip0
Last edited by stevebuchanan

That sounds very good… !!

were you able to see the lapping mark on the valve? Sufficient?

I hope you don’t get me wrong. I’m rooting for you….

I am just allergic to shortcuts because my car was made out of shortcuts ….

i sure you know all the things I did and the 💩 I went through… opening can of worms seems to be my main job since last November when I bought my Pantera…

From pedal box to brakes and brake lines to cooling system to heater and A/c core and fan  to dash and center console with all the electrical problems including headlight motor , window regulators to gas filler to wheels and rusted through heater tubes to brake discs and wheel bearings, headlight switch ordeal and on and on …

I thought it’s a 4 month thing I’m doing here BUT I’m looking a whole year right in the face 😳

I drove my car today for the first since I bought it… 12 miles I did…

I came back with a few things… and the fighting continues…



IMG_2449

Attachments

Images (1)
  • IMG_2449
Last edited by LeMans850i

Thanks and it’s great that you got your car going. I think that’s the most important thing with Panteras is to have them driving. I love working on them, but it’s most important that they are drivable. Good work.

Thank you 🙏

my car got killed by 1000 shortcuts (I assume as sales prep )and then sitting in a museum for many years..

It will be my daily driver… I will beat it into submission!!!

imagejpeg_0

Resized_20240930_145526

Attachments

Images (2)
  • imagejpeg_0
  • Resized_20240930_145526
Last edited by LeMans850i

Add Reply

Post
×
×
×
×
Link copied to your clipboard.
×