[v12-engine] Cam Cover Bolts & Gaskets / Intake Manifold Gaskets

Hello All,

I’m replacing intake and cam cover gaskets on my '88. I have a couple
of questions regarding the cam cover bolts:

  1. Is it common practice to toss the original bolts and replace them?
    What’s the downside of reusing the originals?

  2. If I replace them, is 6mm x 30mm with one flat and one lock washer a
    suitable replacement? Are these just normal bolts that can be found
    anywhere? (I’m not interested in anything fancy; just something easy to
    find locally.)

I also have questions about gasket sealants / dressings:

  1. What should I use for the intake manifold gaskets?

  2. What should I use for the cam cover gaskets w/Ron Kelnhofer’s
    aluminum 1/2 moon seals?

Regards,
Odysseus
'88 xj-s v-12
Bucks County, Pa USA

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Odysseus Marcopolus wrote:

I’m replacing intake and cam cover gaskets on my '88. I have a couple
of questions regarding the cam cover bolts:

  1. Is it common practice to toss the original bolts and replace them?
    What’s the downside of reusing the originals?

The threads are triangular, so they tend to booger up the threaded
holes a little bit each time they are screwed in and out.

  1. If I replace them, is 6mm x 30mm with one flat and one lock washer
    a suitable replacement?

Since your car is an '88, yes.

Are these just normal bolts that can be found
anywhere? (I’m not interested in anything fancy; just something easy
to find locally.)

I think you can use normal bolts with 10mm hex heads, but I’d
suggest you look for socket head screws. It’s easier to tighten them
with an allen wrench than to try to fit a socket in the little recess
in the cam cover.

What I used are called “alloy socket head screws”. The alloy doesn’t
mean aluminum, as you might think. It means a really strong steel.
They were black, and amazingly inexpensive.

I also have questions about gasket sealants / dressings:

  1. What should I use for the intake manifold gaskets?

Hylomar is good, but regular Permatex #2 dressing would also work.
Remember to retorque the nuts a couple of weeks later.

  1. What should I use for the cam cover gaskets w/Ron Kelnhofer’s
    aluminum 1/2 moon seals?

Nothing on the cam cover gaskets, presuming they are the gortex type.
If they’re the paper type, use postage on them to send them back to
the outfit that sent them to you. On the curved side of the aluminum
1/2 moons, Loctite 518.

– Kirbert

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Kirbert wrote:

Odysseus Marcopolus wrote:

  1. Is it common practice to toss the original bolts and replace them?
    What’s the downside of reusing the originals?

The threads are triangular, so they tend to booger up the threaded
holes a little bit each time they are screwed in and out.

Ok so, if they’ve never been out and the likelihood that I’m going to do
this again is low, any harm in reusing them 1 time?

I also have questions about gasket sealants / dressings:

  1. What should I use for the intake manifold gaskets?

Hylomar is good, but regular Permatex #2 dressing would also work.
Remember to retorque the nuts a couple of weeks later.

  1. What should I use for the cam cover gaskets w/Ron Kelnhofer’s
    aluminum 1/2 moon seals?

If they’re the paper type, use postage on them to send them back to
the outfit that sent them to you.

Yes well, I didn’t do my homework first and that’s what I’ve got. Since
I picked them up locally, I’ll see if they can get the gortex. OTOH, I
seem to recall some folks discussing not using gaskets at all on the cam
covers. Has anyone done this and what kind of sealer would you use then?

Regards,
Odysseus

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Odysseus Marcopolus wrote:

Ok so, if they’ve never been out and the likelihood that I’m going to
do this again is low, any harm in reusing them 1 time?

Perhaps not. But most owners are more interested in ensuring there
are no leaks after reassembly than saving a few bucks on screws.

OTOH, I seem to recall some folks discussing not using gaskets at all
on the cam covers.

Not with the aluminum half moon seals! If you go the gasketless
route, you should use the OEM rubber half moons. Then seal the metal-
to-metal contact area with Loctite 518.

– Kirbert

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Kirbert wrote:

Odysseus Marcopolus wrote:

Ok so, if they’ve never been out and the likelihood that I’m going to
do this again is low, any harm in reusing them 1 time?

Perhaps not. But most owners are more interested in ensuring there
are no leaks after reassembly than saving a few bucks on screws.

Right. Actually, it’s not the few dollars - it’s the time spent trying
to get the right ones. I’m in the middle of the job now and since I use
the car as a daily driver, I don’t have the luxury of time when it comes
to tracking down parts. Not a problem if they’re readily available
locally. (My bad for not having planned this better…) Anyway, if a
one-time reuse raises the probability of leakage, I won’t do it. That’s
why I asked.

OTOH, I seem to recall some folks discussing not using gaskets at all
on the cam covers.

Not with the aluminum half moon seals! If you go the gasketless
route, you should use the OEM rubber half moons. Then seal the metal-
to-metal contact area with Loctite 518.

Why not with the aluminum half moons? Isn’t it still just metal to
metal contact there as well?

–Odysseus

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Odysseus Marcopolus wrote:

Not with the aluminum half moon seals! If you go the gasketless
route, you should use the OEM rubber half moons. Then seal the
metal- to-metal contact area with Loctite 518.

Why not with the aluminum half moons? Isn’t it still just metal to
metal contact there as well?

It might work with the aluminum half moons, but you’re asking an
awful lot from the machining tolerances. If they’re not exactly
right, the flat top of the aluminum half moon will sit a hair higher
or lower than the surrounding surface of the tappet block. If it
happens to be higher, it’ll hold the cam cover off the tappet block
and cause stress when you tighten the bolts down. If it’s lower,
it’ll leave a little gap over the half moon. With a gasket in there,
the gasket will soak up such minor variations.

The gasketless/OEM rubber half moon assembly is a ten-year no-leak
plan. It’s cheap and easy, and the thing won’t leak until the rubber
half moons rot and crumble and fall out. The gortex gasket/aluminum
half moon assembly is a lifetime no-leak plan. It’s expensive (those
gortex cam cover gaskets are stupid expensive), but once together
it’ll never leak, ever.

Don’t forget to replace the washers on the outer row of head nuts
while you’re there. Are you taking the tappet blocks off to reseal
under them?

– Kirbert

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Kirbert wrote:

The gasketless/OEM rubber half moon assembly is a ten-year no-leak
plan. It’s cheap and easy, and the thing won’t leak until the rubber
half moons rot and crumble and fall out. The gortex gasket/aluminum
half moon assembly is a lifetime no-leak plan. It’s expensive (those
gortex cam cover gaskets are stupid expensive), but once together
it’ll never leak, ever.

FTR, this project was undertaken due to my suspicion that I had an
intake manifold gasket leak. For some time, I thought I’d been hearing
a vacuum leak somewhere over the rear of the B-bank. I just couldn’t
find anything. It finally culminated in my failing emissions testing
along with a high idle and a much louder hiss. After applying some
starter spray in the area of the manifold gasket, I got some popping
and, well, here we are.

So, I got the manifolds off tonight. Removed them complete w/injectors,
air rail, etc. in one piece. As suspected, 6B intake was the culprit -
gasket was bad there. I posted a pic at
<http://home.comcast.net/~omarcopolus/jagpics/6b_port.jpg>.

Cam covers, half moons and banjo bolts had all been leaking as well.
(The final insult is that you have to move the A/C compressor to get
enough clearance to remove the A-Bank cam cover - haven’t I moved enough
junk to get this far???!!!) Anyway, I’m going to hunt down the gortex
cam cover gaskets instead of using the paper ones that I have. Are they
much thicker than the paper ones? Does that have to be figured into the
bolt length?

Don’t forget to replace the washers on the outer row of head nuts
while you’re there.

That’s a new one on me. Just pull the nuts and replace them? They go bad?

Are you taking the tappet blocks off to reseal
under them?

Just not up for that much fun this time around…

Odysseus

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Odysseus Marcopolus wrote:

As I was removing stuff to get the intake manifolds off, I broke a
vacuum hose. It’s the large elbow located at the back of the A-Bank.
Can anyone tell me if this is just regular hose (hardened over the
years) or is it a molded piece that I need to get from a parts
supplier? I have a pic - prior to breaking it - at
<http://home.comcast.net/~omarcopolus/jagpics/manifold_elbow.jpg>

Thanks,
Odysseus

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Odysseus Marcopolus wrote:

Anyway, I’m going to hunt down the
gortex cam cover gaskets instead of using the paper ones that I have.
Are they much thicker than the paper ones? Does that have to be
figured into the bolt length?

No, the gortex cam cover gaskets are thin. The reason I suggest
going to longer bolts are A) because I suggest both a split ring lock
washer and a flat washer under the head, which is more stuff than the
OEM arrangement, and B) because there’s no reason not to. The holes
are tapped all the way through. I find it comforting to be able to
install screws into the fresh, non-boogered-up threads at the bottom
of the hole.

Don’t forget to replace the washers on the outer row of head nuts
while you’re there.

That’s a new one on me.

It’s in the book. At least, I think it’s in the book.

Just pull the nuts and replace them? They go
bad?

They were never any good. They’re too thin, so they just dish under
the tension and create little dimples in the soft aluminum head.
They also fail to maintain compression on the head gasket as a
result. So you replace those thin washers with 1/8" thick washers
that look kinda like the larger washers on the larger head nuts.

They are head nuts, so you have to remove and replace one at a time
and torque to specs. While you’re torquing to specs, you’ll easily
notice the difference; the nuts feel like they’re really seating
properly for a change.

– Kirbert

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Odysseus Marcopolus wrote:

As I was removing stuff to get the intake manifolds off, I broke a
vacuum hose. It’s the large elbow located at the back of the A-Bank.
Can anyone tell me if this is just regular hose (hardened over the
years) or is it a molded piece that I need to get from a parts
supplier? I have a pic - prior to breaking it - at
<http://home.comcast.net/~omarcopolus/jagpics/manifold_elbow.jpg>

That’s just a vacuum hose, you can replace it with generic.

It looks like there’s a check valve in the line. That doesn’t seem
right, because I think there’s supposed to be a check valve in the
barb on the intake manifold – that piece you can see the hex on.
That check valve is actually a relatively common failure point.
While you have the hose off, check it out and see if it looks like
it’s in good shape. I’m wondering if it’s been gutted and that
inline check valve was added to replace it.

BTW, that metal pipe underneath the vacuum hose heading off the top
left of the photo is the balance pipe. The hose to the MAP sensor in
the ECU in the trunk connects to the bottom of that pipe, right in
the center of the engine.

And that big flushhead screw at the left side holding the diagonal
brace is NOT a Phillips. It’s a #4 Pozidriv. Somebody’s been trying
to use a Phillips screwdriver on it; you can tell because it’s
boogered up.

– Kirbert

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Kirbert wrote:

Odysseus Marcopolus wrote:

As I was removing stuff to get the intake manifolds off, I broke a
vacuum hose. I have a pic - prior to breaking it - at
<http://home.comcast.net/~omarcopolus/jagpics/manifold_elbow.jpg>

That’s just a vacuum hose, you can replace it with generic.

It looks like there’s a check valve in the line. That doesn’t seem
right, because I think there’s supposed to be a check valve in the
barb on the intake manifold – that piece you can see the hex on.
That check valve is actually a relatively common failure point.
I’m wondering if it’s been gutted and that
inline check valve was added to replace it.

Looks like the barb was gutted. If it’s that common of a failure point,
I guess the inline - non-oem - replacement was probably a reasonable and
cost effective repair? Interesting because the car only had 32k miles
when I bought it years back. So, it must have failed early in life…

And that big flushhead screw at the left side holding the diagonal
brace is NOT a Phillips. It’s a #4 Pozidriv. Somebody’s been trying
to use a Phillips screwdriver on it; you can tell because it’s
boogered up.

Yup - wasn’t me though! I was lucky enough to be the recipient of a
free PZ#4 a few years ago when lister Joe Montgomery picked up a batch
at a flea market and sent them - gratis - to several of us. A gift that
keeps on giving!

–Odysseus

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Ok, I did the unthinkable - dropped something down the timing chain
opening!!

I was trying to clean the last bits of the cam cover gasket from around
one of the studs on the a-bank and the razor slipped from my hand. It’s
flat single edge blade - the type you’d use in a utility knife. Sounded
like dropped pretty far. I’m able to get a long magnet down a ways but,
no luck.

So, how bad is this? Will a thin blade like that just settle into the
oil pan? If it gets caught in the timing chain mechanism is it likely
to just break up and fall into the pan? Do I have to get it out?

Opinions?

Thanks,.
Odysseus

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Kirbert wrote:

Nothing on the cam cover gaskets, presuming they are the gortex type.
If they’re the paper type, use postage on them to send them back to
the outfit that sent them to you. On the curved side of the aluminum
1/2 moons, Loctite 518.

I have some Permatex “High-Temp RTV Silicone Gasket Maker” here. It’s
#26B: 650F, Remains Flexible. Says it’s good for valve covers, oil
pans, etc.

Is this ok for the bottom of the aluminum 1/2 moons? I have the gortex
cam cover gaskets which I’ll install dry.

-Odysseus

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Odysseus Marcopolus wrote:

I have some Permatex “High-Temp RTV Silicone Gasket Maker” here. It’s
#26B: 650F, Remains Flexible. Says it’s good for valve covers, oil
pans, etc.

Is this ok for the bottom of the aluminum 1/2 moons?

Might be, I dunno. The one thing I’d worry about is whether or not
it will allow the aluminum half moon to be installed fully until it’s
flush. Some sealants are too stiff. The 518 works well because it’s
nearly liquid.

– Kirbert

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I was trying to clean the last bits of the cam cover gasket from
around one of the studs on the a-bank and the razor slipped from my
hand. It’s flat single edge blade - the type you’d use in a
utility knife. Sounded like dropped pretty far. I’m able to get a
long magnet down a ways but, no luck.

So, how bad is this? Will a thin blade like that just settle into
the oil pan? If it gets caught in the timing chain mechanism is it
likely to just break up and fall into the pan? Do I have to get
it out?

Opinions?

Thanks,.
Odysseus

Odysseus

Don’t worry about it.

If you were going to mess up, the timing chain opening is probably
preferably to the intake manifold port.

Chances are it will settle to the bottom of the oil pan sandwich plate.

Bernard Embden
bernardembden.com

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Well, everything’s buttoned up! Cranked it over and started right up.
Idled pretty smooth for the first time in a long while. To recap, this
project was undertaken to fix an intake manifold gasket leak.

I pulled the manifolds off complete w/injectors, air rail, etc. in one
piece. 6B intake was the culprit - gasket was bad there. I posted a
pic at <http://home.comcast.net/~omarcopolus/jagpics/6b_port.jpg>.

Cam covers, half moons and banjo bolts had all been leaking as well. I
went with Ron Kelnhofer’s aluminum 1/2 moons and banjo bolts/washers for
the cam and oil pressure sender feeds. I picked up the intake manifold
gaskets at a local parts house. They also had the cam cover gaskets but
they were the old paper ones so, I went to Jaguar for the gortex ($31
ea.) I also swapped out the original cam cover bolts for 6 x 30mm
socket head bolts that I found at Home Depot ($0.92/pr) along with flat
and lock washers.

FWIW, a couple of observations if you’re going to tackle this job:

  • Have a quality set of 1/4" drive sockets on hand - you’ll need 13mm
    deep and regular for the intake manifold bolts along with a swivel and
    extension(s).

  • Have a digital camera on hand and take lots of photos and take notes
    on everything that gets disconnected.

  • After swapping Ron’s banjo bolt for the oil sender, my oil pressure
    now reads about 10 psi higher than before. I can only surmise that the
    old bolt and washers caused some misalignment with the feed and
    restricted flow into the sender.

  • I took a quick spin into town for a test drive and to get some gas.
    Mileage - according to the just reset trip computer - was easily 2-3 mpg
    better than before (w/the the intake leak).

  • No smoke and smell from oil dripping on the exhaust when I pulled in
    the garage!

Thanks to all for your help!

Regards,
Odysseus
'88 xj-s

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resurrecting an old thread, as it got most of the answers, but I still have a few questions :slight_smile:

  • re the cam cover bolts : which material should I go for ?
    steel will probably rust, but stainless in aluminium doesn’t look like a good idea
    would it be a place for aluminium bolts ? I reckon the tension is limited and they should stand it ?

  • additional washers + split washers I’ve been told adding a washer between the split washer and the cover will remove the locking feature : the bolt head will get locked to the washer, but this can rotate all together, and the bolt could loosen
    suggestion were either fitting the split ring and no washer, or use some Nord-lock washers
    https://www.nord-lock.com/nord-lock/products/washers/product-guides/
    they 're on the expensive side, but should keep the lot tight

I can’t think of anywhere I would use aluminum fasteners on this engine. I just did this work to my car and have done it to many others. Use grade 5 steel machine screws with a flat washer.

Since the screw head (steel) is harder than the object it is clamping (aluminum), a washer is necessary to protect the softer aluminum from galling.
The flat washer does two important things:

  1. it increases the clamping area under the screw head.
  2. it provides a hard bearing surface for the screw, protecting the surface of the cover.
    Without the washer, the screw head sinks into the soft aluminum and displaces material. This displacement relieves tension on the screw, decreasing the clamping force (and ruining the cover).
    Generally, if any screw(or bolt if you like) is torqued to the proper value according to grade and size, it will have enough stretch to keep it tight without locking devices. The trick is having some free length under the point of clamping and the threaded hole to provide length for stretch. Cylinder head bolts are a good example of this. Screws/bolts for covers are different because the clamped part is very thin and there is not much bolt length to stretch. A flat washer spaces the bolt head a bit farther away from the threaded hole to give room for bolt stretch. A split ring lock washer may also be used but ALWAYS with a flat washer under it, ESPECIALLY on aluminum. Never use a split ring washer on bare aluminum or even mild steel.

-Tony

thanks Tony
no aluminium but steel screws, washer + split ring to keep the tension

I was wondering about the gasket playing (partially ?) the same role as it’s soft and a few mm thick

I did not mean to say you had to use a lock washer in this application. I was referring to thin sheetmetal covers in general. The V-12 cam covers have some thickness (for bolt stretch) so I would stick with just a flat washer under the screw. Tightening the screw alone will provide tension. The gasket will not compress very much since it is flat (as opposed to an O-ring for example) and has a fairly large surface area. However, for any situation with covers or flanges, you need to tighten the screws in several stages. Make sure everything -mating surfaces, screws, threaded holes -is clean. Place the gasket and cover and insert the screws. Start from the center and run down each screw until you just start to feel some resistance. Alternate back and forth over the cover toward the ends. After the last screw, repeat the sequence, turning each screw until you feel the resistance of the compressed gasket. Go back to the middle and repeat the sequence a third time, snugging each screw down tight. Repeat once more to make sure you didn’t skip one. I use a short palm ratchet in one hand which limits the amount of torque and gives a consistent feel. Your wrist can provide more than enough torque for these small screws. As Kirby mentioned previously, you should go back after driving a couple of weeks and check that they are still tight, They might need a slight turn after some temp cycles. But the best indicator is no leaks!