With the gas tank re-installed on my V12, I’ve been getting
it out on the road. With more use, I’ve noticed an
increasing amount of noise coming from the B bank of the
head, near cylinders 4-6. The sound is troublesome.
The history of the car is that it is the original engine.
About 3 years ago, I had the entire engine re-sealed
because it was leaking oil from every gasket. Since then,
a series of ignition problems have prevented me from using
the car, so I have probably put on no more than five
hundred miles.
My concern is a lack of oil to the B bank. If that is the
case, how can I check it?
Anything else I should be considering? I read a lot about
dropped valve seats, but this car runs pretty cool…no
history of overheating. I would imagine a dropped seat
would be much more problematic.
Thanks in advance.–
Bill Gutierrez, '61 OTS '73 OTS
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In reply to a message from Ed Sowell sent Sun 16 Oct 2016:
Hi Ed, not sure how accurately your video portrays the noise,
but that is much louder than what I am hearing. mine is more
of a light tick (at least now). Any suggestions on how to
diagnose what I have without a full a tear down?
Thanks for the response, BTW.–
The original message included these comments:
With more use, I’ve noticed an increasing amount of noise
coming from the B bank of the head, near cylinders 4-6. The sound is
troublesome.
Not to alarm you, but take a look at my story: Ed’s 1976 XJ-S – Ed & Judy Sowell
Ed Sowell
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Hi Ed, not sure how accurately your video portrays the noise, but that
is much louder than what I am hearing. mine is more of a light tick (at
least now). Any suggestions on how to diagnose what I have without a
full a tear down?
Have you done a compression test? That’s a good place to start. Also, if possible take it to someone who knows these V12s. My tech, for example, immediately said “that’s a valve trail issue,” and we both were able to localize it with a stethoscope.
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In reply to a message from PeterCrespin sent Mon 17 Oct 2016:
Thanks Peter,
I’ll try. If there is a block at the banjo though, would
slackening tell me anything? Is there a way to test if it is
being forced into the cam?–
The original message included these comments:
The V12 is over-oiled on purpose and I can’t envisage a
scenario where B bank is under supplied if the cam feed
banjo and line are clear.
If, however, the line got pinched during installation,
then who knows? Slacken off the banjo with the engine
running and you should see lots of oil.
Pete
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In reply to a message from Lundabo sent Mon 17 Oct 2016:
If slackening the banjo results in oil spurting out, then
you coearly have oil to that point. Whether it goes any
further is highly likely but for you to decipher.
Sometimes non-standard washers or bolts result in
obstructed flow.
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In reply to a message from Lundabo sent Sat 15 Oct 2016:
Correct me if I am wrong, but I think I read somewhere that the
tappets in some cases may be slightly undersized causing a
tapping noise. In the sae article it said the noise was
harmless.–
Maynard 94 XJS V12 Coupe 91XJS(RIP) 86XJ6 78MGB 67MGB
Palatine, IL, United States
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In reply to a message from Maynard sent Tue 18 Oct 2016:
So initial diagnose should include:
(1) listen for tick at exhaust vs. tappet
(2) slacken banjo bolt to see if there is oil pressure at head
(3) compression test to see if problem at valve.
Anything else??–
The original message included these comments:
In reply to a message from Lundabo sent Sat 15 Oct 2016:
Correct me if I am wrong, but I think I read somewhere that the
tappets in some cases may be slightly undersized causing a
tapping noise. In the sae article it said the noise was
harmless.
Maynard 94 XJS V12 Coupe 91XJS(RIP) 86XJ6 78MGB 67MGB
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Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
11
So initial diagnose should include:
(1) listen for tick at exhaust vs. tappet
(2) slacken banjo bolt to see if there is oil pressure at head
(3) compression test to see if problem at valve.
Anything else??
Well, the FIRST thing to do, I think, would be to go over the engine and
tighten every bolt and nut you can get a wrench on. The intake manifold
nuts in particular, and any exhaust manifold nuts you can reach. Hey, you
might get lucky and find a few loose fasteners and tightening them up stops
the noise.
– Kirbert
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !On 18 Oct 2016 at 11:32, Lundabo wrote:
In reply to a message from Kirbert sent Tue 18 Oct 2016:
Thanks, will do.–
The original message included these comments:
So initial diagnose should include:
Anything else??
Well, the FIRST thing to do, I think, would be to go over the engine and
tighten every bolt and nut you can get a wrench on. The intake manifold
nuts in particular, and any exhaust manifold nuts you can reach. Hey, you
might get lucky and find a few loose fasteners and tightening them up stops
the noise.
– Kirbert
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In reply to a message from Lundabo sent Tue 18 Oct 2016:
Dear Bill,
If you get an insecticide sprayer, you should be able to tap it
into the oil sender port and pump oil into the cams. What you will
eventually hear is the oil oozing out and trickling down at the
front of the timing cover. I imagine that with a stethescope, you
may hear it coming out locally through the camshaft bearings aswell.
When I rebuilt parts of my engine, before reassembling the topside,
I did this with the cam covers off and was able to see how much oil
was getting through which bearing caps.
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So, before I did anything, I did something an old mechanic I know recommended: I amsoil flushed the engine to try to get rid of varnish, sludge etc. I then refilled with Royal Purple 10w-40 synthetic, rather than the thicker castrol 20W 50 oil that was in there. Car is running much smoother now. Loud ticking gone. There is still some valve noise, but I think it is more indicative that they need some adjusting than anything else. Surprised how much better it is running after the flush.
the big relief is that I did not drop a valve. The same mechanic told me that if I had dropped a valve the car would run worse, which is not something it had done. He acknowledge that it wouldn’t run worse in the way a 4 cyl would if it dropped a valve, but he said I would still notice it. In any event, happy that the flush had results. Maybe it’s time for a valve adjustment?