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Head with leaky valves advice needed #5007135
02/10/19 04:48 PM
02/10/19 04:48 PM
Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
rshaw125 Offline OP
rshaw125  Offline OP

Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
A buddy of mine had persistent misfires on his Taurus. Compression test showed two weak cylinders. He pulled the head and laid it on it's side. Filled the ports with water after a few minutes a tiny dribble out of one valve. 1 of 6 intake valves. DOHC Ford. Then exhaust side . Two valves with little dribbles after a few minutes. Are these little dribbles enough to cause the misfire and low compression? The engine has around 150,000 miles. Is this just normal wear??


2012 Porsche Carrera S
2016 Ford Edge 2.0
2002 Taurus Vulcan SOLD
2006 Explorer SOLD
Re: Head with leaky valves advice needed [Re: rshaw125] #5007142
02/10/19 04:56 PM
02/10/19 04:56 PM
Joined: Jan 2012
Posts: 435
hawthorne, Ca.
46Harry Offline
46Harry  Offline

Joined: Jan 2012
Posts: 435
hawthorne, Ca.
Since the head is off and there is leakage from the valves, now would be a good time to get the head reconditioned especially since the engine has 150,000 miles on it.

Re: Head with leaky valves advice needed [Re: rshaw125] #5007153
02/10/19 05:02 PM
02/10/19 05:02 PM
Joined: Nov 2017
Posts: 471
North of you Idaho
KneeGrinder Offline
KneeGrinder  Offline

Joined: Nov 2017
Posts: 471
North of you Idaho
Pouring water in the combustion chamber now? Yes it will show the leaking valve seats if they a fairly bad. Will cause lower compression, yes, but he really should have done a comp test before removal. compression is often lost thru rings or valves. At this point he is in no man's land till he has a valve job done and mounts heads back on motor. Yes, seems like fairly normal wear for a Taurus....

As for valves causing misfire? IDK, If its the intake, and they leak bad enough, yes. The ECU should show a code for misfire if its OBD2, and its the ignition system. Atleast it should...If its back firing thru an intake valve, probably is not going to log a code.

O'pps my bad, he did a comp test, sorry! Nice German car you have by the way! I approve...

Last edited by KneeGrinder; 02/10/19 05:05 PM.

08 Tribeca 86k PUP 5w30 wix
06 Accord Hybrid 134k PPHM 0w20 wix
02 Chevy k3500 99k Delvac 1 esp 5w40 wix
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Re: Head with leaky valves advice needed [Re: rshaw125] #5007170
02/10/19 05:12 PM
02/10/19 05:12 PM
Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
rshaw125 Offline OP
rshaw125  Offline OP

Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
Thanks for the replies. Yes a compression test revealed the weak cylinders. Wet and dry. Rings are tight. After codes for misfires. The leakages are just dribbles. i was expecting a flow of water. No obviously burned valves.


2012 Porsche Carrera S
2016 Ford Edge 2.0
2002 Taurus Vulcan SOLD
2006 Explorer SOLD
Re: Head with leaky valves advice needed [Re: rshaw125] #5007212
02/10/19 05:53 PM
02/10/19 05:53 PM
Joined: Aug 2008
Posts: 23,385
ON, Canada eh?
StevieC Offline
StevieC  Offline

Joined: Aug 2008
Posts: 23,385
ON, Canada eh?
There could be different reasons. Slightly bent valve, weak valve springs, worn seats.
Best to take the head in and have it rebuilt and put it back on.


'18 Dodge Grand Caravan GT - 21k KM - AMSOIL SS 0w30
'06 Hyundai Santa Fe - 535k KM (Dead) - AMSOIL SS 0w30
Re: Head with leaky valves advice needed [Re: StevieC] #5007259
02/10/19 06:22 PM
02/10/19 06:22 PM
Joined: Oct 2010
Posts: 768
RI
mattd Offline
mattd  Offline

Joined: Oct 2010
Posts: 768
RI
What exactly were the compression test results? Valve leakage can certainly cause misfires


2007 Ford F-350 4x4 6.0 PSD

ASE Master, L1
Re: Head with leaky valves advice needed [Re: rshaw125] #5007275
02/10/19 06:32 PM
02/10/19 06:32 PM
Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
rshaw125 Offline OP
rshaw125  Offline OP

Joined: Aug 2004
Posts: 3,371
Raleigh ,NC CSA
The two bad cylinders were 55 and 65 PSI. The good cylinders were 145 - 155.


2012 Porsche Carrera S
2016 Ford Edge 2.0
2002 Taurus Vulcan SOLD
2006 Explorer SOLD
Re: Head with leaky valves advice needed [Re: rshaw125] #5007300
02/10/19 06:54 PM
02/10/19 06:54 PM
Joined: May 2016
Posts: 267
WA
DeafBrad Offline
DeafBrad  Offline

Joined: May 2016
Posts: 267
WA
I don't claim to be a professional mechanic or anything. But what is a dribble with water should be significant when the air is under compression.


Toyota Echo 250,000 + miles
Geo XFI 50+ mpg
Honda CBR250r 65+ mpg
Re: Head with leaky valves advice needed [Re: DeafBrad] #5007332
02/10/19 07:19 PM
02/10/19 07:19 PM
Joined: Jun 2003
Posts: 18,208
Deplorable in apple valley, ca
Chris142 Offline
Chris142  Offline

Joined: Jun 2003
Posts: 18,208
Deplorable in apple valley, ca
Originally Posted by DeafBrad
I don't claim to be a professional mechanic or anything. But what is a dribble with water should be significant when the air is under compression.

Yep. If liquid will pass air will really leak past.


02 Wrangler carlube 5w30
87 F250 traveler 15w40
07 fjcruiser Chevron 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: Head with leaky valves advice needed [Re: rshaw125] #5007363
02/10/19 07:50 PM
02/10/19 07:50 PM
Joined: Dec 2016
Posts: 7,750
Waco, TX
Linctex Offline
Linctex  Offline

Joined: Dec 2016
Posts: 7,750
Waco, TX
Originally Posted by rshaw125
Are these little dribbles enough to cause the misfire and low compression?


Little dribbles after several minutes?

No - - Those will not affect the way the engine runs.

I have seen heads where liquid would almost run out as fast as it poured in - - STILL, no misfires!

But you could SURE hear the whistle in the exhaust when cranking it to start it!!!!!!


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Head with leaky valves advice needed [Re: rshaw125] #5007366
02/10/19 07:51 PM
02/10/19 07:51 PM
Joined: Dec 2016
Posts: 7,750
Waco, TX
Linctex Offline
Linctex  Offline

Joined: Dec 2016
Posts: 7,750
Waco, TX
Originally Posted by rshaw125
The two bad cylinders were 55 and 65 PSI. The good cylinders were 145 - 155.


You should have done a "DRY" test followed by a "WET" test.

I honestly do not think the head is your problem, if you got "Just a tiny dribble" after several minutes.


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Head with leaky valves advice needed [Re: rshaw125] #5007405
02/10/19 08:18 PM
02/10/19 08:18 PM
Joined: Nov 2006
Posts: 20,998
MA, Mittelfranken.de
Trav Offline
Trav  Offline

Joined: Nov 2006
Posts: 20,998
MA, Mittelfranken.de
Sure, numbers like that can and do cause misfires, under 90 psi can cause it and the lower it goes the greater the odds. That kind of leakage is enough to cause the low compression.
Seeing as a wet and dry test was done I think you found the issue.

Edit: You should check the valve guides and cam lobe/lift also, worn guides can cause erratic seating in the running engine and worn lobes can cause low compression, a dial indicator is be the easiest way to tell on a cam in block engine.

Last edited by Trav; 02/10/19 08:28 PM.

ASE L1, Master. Deutsch Meisterbrief.
Re: Head with leaky valves advice needed [Re: DeafBrad] #5007451
02/10/19 09:14 PM
02/10/19 09:14 PM
Joined: Nov 2017
Posts: 471
North of you Idaho
KneeGrinder Offline
KneeGrinder  Offline

Joined: Nov 2017
Posts: 471
North of you Idaho
Originally Posted by DeafBrad
I don't claim to be a professional mechanic or anything.

"But what is a dribble with water should be significant when the air is under compression."


Correct!


08 Tribeca 86k PUP 5w30 wix
06 Accord Hybrid 134k PPHM 0w20 wix
02 Chevy k3500 99k Delvac 1 esp 5w40 wix
00 F350 136k Delvac 1300 15w40 wix
Re: Head with leaky valves advice needed [Re: 46Harry] #5007613
02/11/19 06:24 AM
02/11/19 06:24 AM
Joined: Jul 2005
Posts: 31,461
NY
demarpaint Offline
demarpaint  Offline

Joined: Jul 2005
Posts: 31,461
NY
Originally Posted by 46Harry
Since the head is off and there is leakage from the valves, now would be a good time to get the head reconditioned especially since the engine has 150,000 miles on it.

+1 And in all honesty if he plans on keeping the car he might as well do the other head, and check the cam.


God Bless Our Troops

Re: Head with leaky valves advice needed [Re: rshaw125] #5007617
02/11/19 06:35 AM
02/11/19 06:35 AM
Joined: Mar 2004
Posts: 21,605
Upstate NY
Donald Offline
Donald  Offline

Joined: Mar 2004
Posts: 21,605
Upstate NY
Originally Posted by rshaw125
Thanks for the replies. Yes a compression test revealed the weak cylinders. Wet and dry. Rings are tight. After codes for misfires. The leakages are just dribbles. i was expecting a flow of water. No obviously burned valves.


What was done to determine "rings were tight"?

What year Taurus?


2015 Subaru Forester 2.5 engine/CVT
2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)
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