[DeTomaso] Cylinder Heads leaking

Brian Dudley bd8134 at gmail.com
Wed Nov 25 22:03:26 EST 2015


Sean,
I am not sure what leak down tester you bought but running the test at
30psi is not high enough.
Most run 80 to 100 psi on the input / first gauge.
Running it at 100psi makes life easier at working out what your loss is. :-)
If you were getting a reading of 30% loss that is bad, especially if you
are burning oil.
Do a search and you will find the procedure, most testers come with
instructions.
The test is done at TDC, just put the car in gear to stop the engine
turning over from the air pressure.
Here are a couple of sites...
https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test
https://en.wikipedia.org/wiki/Leak-down_tester
Keep testing..
Brian


On Wed, Nov 25, 2015 at 5:02 PM, Larry - Ohio Time <Larry at ohiotimecorp.com>
wrote:

> That sounds like good news Sean.
>
> Should you still have a problem after you get it running you need to do a
> complete and proper compression test as was explained earlier. By placing a
> bit of oil in the cylinder (2nd part of the test) it will give you an
> indication on how well the rings are sealing (the oil temporally seals
> them).
>
> In the meantime drive the hell out of it!
>
> Larry (someday) - Cleveland
>
>
>
> -----Original Message-----
> From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of sean mundy
> Sent: Wednesday, November 25, 2015 4:36 PM
> To: jderyke at aol.com
> Cc: detomaso at poca.com
> Subject: Re: [DeTomaso] Cylinder Heads leaking
>
> I picked up a leak down tester and removed all the rocker arms so I didn't
> have to worry about getting the valves closed.  Good news is all cylinders
> were in the green part of the gauge roughly around 25-30% loss.  This is on
> a cold engine and I think you get better readings on a warm engine as
> recommended for this test.  I then hooked up the air hose at about 30psi on
> each cylinder to check for air leaks by just listening.  I listened in the
> tailpipe, intake, dipstick and watched for bubbles in the coolant.  The
> little amount of air hissing could be heard from the dipstick tube.  I
> think
> that is normal and based on my leak down results I think the heads and the
> valves are ok.???So back to the drawing board trying to figure out my rapid
> oil consumption.  Think now the best plan is to continue to install my new
> Viton valve seals and put everything back together and see how the engine
> runs.  If I'm still burning oil at that point then I will go back to the
> possibility that the intake gaskets are leaking and the oil is being sucked
> in that route.
>
> Date: Mon, 23 Nov 2015 14:59:23 -0500
> From: jderyke at aol.com
> To: seanmundy at hotmail.com
> CC: detomaso at poca.com
> Subject: Re: [DeTomaso] Cylinder Heads leaking
>
>  You're right- you do in fact need the rockers not only installed but
> adjusted close to the way you'll be running them, in order to ingest
> consistent amounts of air to compress. Further, the plugs should be all
> removed and the throttles blocked wide open during your tests to increase
> the speed of the engine turning over. More speed = more compression= more
> variance between bad cylinders & good ones so its easier to differentiate.
> Then turn the engine over with the starter at least 5 times per cylinder, &
> write down the results. If you change ANY of the above conditions, your
> results will not compare well with others'  results, some of which are
> published on line. The test is further described in all of Chilton's
> overhaul manuals & other similar places.
>
>
>
> You have a cylinder with pressurized air in it with
> valves and a gasket sealing one end & a piston & rings sealing
> (more or less) the other end. The famous compression test is a fairly crude
> test from 100 yrs ago, but it should at least point one in the direction of
> the likely cause and narrow down possibilities to one cylinder. Using a
> stethoscope with a pressurized engine (air compressor at 100 psi), I'm able
> to hear air leaking in the carb (bad intake valve), the tailpipes (bad
> exhaust valve) or the breather cap (bad rings or a bad head gasket). If TWO
> ADJACENT cylinders are low or leaking, that indicates a gasket blown
> between
> two cylinders. If you're poor, my stethoscope is an ancient two-ear airline
> sound connector; just be careful to not touch hot metal with the plastic
> tips, which melt. Better ones are at any auto parts store.
>
>
>
> You're looking first for consistent readings and second- significant
> variances in them. +- 15 psi is about normal on used non-race engines and
> should repeat 2-3 times. Variances beyond that either means the fitting is
> not being held in the sparkplug hole tightly ( i use the screw-in ones) or
> there's metal missing somewhere inside. Take the recovery tank off for
> better access to #4 plug. I cut the bracket welds and completely remove the
> whole assembly, then reinstall with a couple of sheet metal screws.
>
>
>
>
>
>
>
>
>
>
>  Worst cases are holed pistons, a cracked cylinder with a
>  piece of wall gone, a blown gasket or a chunk gone from a valve. But
> they are sort of rare and if the motor was running decently, none
> of these should apply. My best guess is a stuck ring. Several possible
> causes but the fix is replacement (with rings) especially if its a high
> mileage OEM part.
>
> Good luck, Sean- J DeRyke
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
> From: sean mundy <seanmundy at hotmail.com>
>
>
> Cc: detomaso <detomaso at poca.com>
>
>
> Sent: Sun, Nov 22, 2015 10:13 pm
>
>
> Subject: Re: [DeTomaso] Cylinder Heads leaking
>
>
>
>
>
> I was thinking the piston needs to suck in some air from the intake valve
> to
> be able to compress it so I thought I needed the rockers
>
>
>    installed.  I was only getting 30 to 40 psi on 5,6,7 cyl and on  8 I saw
> 200psi.  Those numbers dont make sense as the motor was running
>
>
>    pretty good power just burning oil
>
>
>
>
>
>
>
>
>
>
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>
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-------------- next part --------------
   Sean,
   I am not sure what leak down tester you bought but running the test at
   30psi is not high enough.
   Most run 80 to 100 psi on the input / first gauge.
   Running it at 100psi makes life easier at working out what your loss
   is. :-)
   If you were getting a reading of 30% loss that is bad, especially if
   you are burning oil.
   Do a search and you will find the procedure, most testers come with
   instructions.
   The test is done at TDC, just put the car in gear to stop the engine
   turning over from the air pressure.
   Here are a couple of sites...
   [1]https://mobiloil.com/en/article/car-maintenance/car-maintenance-arch
   ive/how-to-do-a-leakdown-test
   [2]https://en.wikipedia.org/wiki/Leak-down_tester
   Keep testing..
   Brian

   On Wed, Nov 25, 2015 at 5:02 PM, Larry - Ohio Time
   <[3]Larry at ohiotimecorp.com> wrote:

     That sounds like good news Sean.
     Should you still have a problem after you get it running you need to
     do a
     complete and proper compression test as was explained earlier. By
     placing a
     bit of oil in the cylinder (2nd part of the test) it will give you
     an
     indication on how well the rings are sealing (the oil temporally
     seals
     them).
     In the meantime drive the hell out of it!
     Larry (someday) - Cleveland
     -----Original Message-----
     From: DeTomaso [mailto:[4]detomaso-bounces at poca.com] On Behalf Of
     sean mundy
     Sent: Wednesday, November 25, 2015 4:36 PM
     To: [5]jderyke at aol.com
     Cc: [6]detomaso at poca.com
     Subject: Re: [DeTomaso] Cylinder Heads leaking
     I picked up a leak down tester and removed all the rocker arms so I
     didn't
     have to worry about getting the valves closed.A  Good news is all
     cylinders
     were in the green part of the gauge roughly around 25-30% loss.A
     This is on
     a cold engine and I think you get better readings on a warm engine
     as
     recommended for this test.A  I then hooked up the air hose at about
     30psi on
     each cylinder to check for air leaks by just listening.A  I listened
     in the
     tailpipe, intake, dipstick and watched for bubbles in the coolant.A
     The
     little amount of air hissing could be heard from the dipstick
     tube.A  I think
     that is normal and based on my leak down results I think the heads
     and the
     valves are ok.???So back to the drawing board trying to figure out
     my rapid
     oil consumption.A  Think now the best plan is to continue to install
     my new
     Viton valve seals and put everything back together and see how the
     engine
     runs.A  If I'm still burning oil at that point then I will go back
     to the
     possibility that the intake gaskets are leaking and the oil is being
     sucked
     in that route.
     Date: Mon, 23 Nov 2015 14:59:23 -0500
     From: [7]jderyke at aol.com
     To: [8]seanmundy at hotmail.com
     CC: [9]detomaso at poca.com
     Subject: Re: [DeTomaso] Cylinder Heads leaking
     A You're right- you do in fact need the rockers not only installed
     but
     adjusted close to the way you'll be running them, in order to ingest
     consistent amounts of air to compress. Further, the plugs should be
     all
     removed and the throttles blocked wide open during your tests to
     increase
     the speed of the engine turning over. More speed = more compression=
     more
     variance between bad cylinders & good ones so its easier to
     differentiate.
     Then turn the engine over with the starter at least 5 times per
     cylinder, &
     write down the results. If you change ANY of the above conditions,
     your
     results will not compare well with others'A  results, some of which
     are
     published on line. The test is further described in all of Chilton's
     overhaul manuals & other similar places.
     You have a cylinder with pressurized air in it with
     valves and a gasket sealing one end & a piston & rings sealing
     (more or less) the other end. The famous compression test is a
     fairly crude
     test from 100 yrs ago, but it should at least point one in the
     direction of
     the likely cause and narrow down possibilities to one cylinder.
     Using a
     stethoscope with a pressurized engine (air compressor at 100 psi),
     I'm able
     to hear air leaking in the carb (bad intake valve), the tailpipes
     (bad
     exhaust valve) or the breather cap (bad rings or a bad head gasket).
     If TWO
     ADJACENT cylinders are low or leaking, that indicates a gasket blown
     between
     two cylinders. If you're poor, my stethoscope is an ancient two-ear
     airline
     sound connector; just be careful to not touch hot metal with the
     plastic
     tips, which melt. Better ones are at any auto parts store.
     You're looking first for consistent readings and second- significant
     variances in them. +- 15 psi is about normal on used non-race
     engines and
     should repeat 2-3 times. Variances beyond that either means the
     fitting is
     not being held in the sparkplug hole tightly ( i use the screw-in
     ones) or
     there's metal missing somewhere inside. Take the recovery tank off
     for
     better access to #4 plug. I cut the bracket welds and completely
     remove the
     whole assembly, then reinstall with a couple of sheet metal screws.
     A Worst cases are holed pistons, a cracked cylinder with a
     A piece of wall gone, a blown gasket or a chunk gone from a valve.
     But
     they are sort of rare and if the motor was running decently, none
     of these should apply. My best guess is a stuck ring. Several
     possible
     causes but the fix is replacement (with rings) especially if its a
     high
     mileage OEM part.
     Good luck, Sean- J DeRyke
     -----Original Message-----
     From: sean mundy <[10]seanmundy at hotmail.com>
     Cc: detomaso <[11]detomaso at poca.com>
     Sent: Sun, Nov 22, 2015 10:13 pm
     Subject: Re: [DeTomaso] Cylinder Heads leaking
     I was thinking the piston needs to suck in some air from the intake
     valve to
     be able to compress it so I thought I needed the rockers
     A  A installed.A  I was only getting 30 to 40 psi on 5,6,7 cyl and
     onA  8 I saw
     200psi.A  Those numbers dont make sense as the motor was running
     A  A pretty good power just burning oil
     _______________________________________________
     Detomaso Forum Managed by POCA
     Posted emails must not exceed 1.5 Megabytes
     DeTomaso mailing list
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References

   1. https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test
   2. https://en.wikipedia.org/wiki/Leak-down_tester
   3. mailto:Larry at ohiotimecorp.com
   4. mailto:detomaso-bounces at poca.com
   5. mailto:jderyke at aol.com
   6. mailto:detomaso at poca.com
   7. mailto:jderyke at aol.com
   8. mailto:seanmundy at hotmail.com
   9. mailto:detomaso at poca.com
  10. mailto:seanmundy at hotmail.com
  11. mailto:detomaso at poca.com
  12. mailto:DeTomaso at poca.com
  13. http://poca.com/mailman/listinfo/detomaso_poca.com


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