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best head gasket for 90 EX 16V



 
 
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  #1  
Old July 16th 05, 05:27 AM
Ryan Underwood
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Default best head gasket for 90 EX 16V

Hi,
We are getting a new rebuilt head and head bolts for the 90 Accord EX (16V
SOHC) with 200k as soon as we confirm a burned valve on the old one. What is
the recommended head gasket for this application, aftermarket or OEM? And
what, if anything, should be done to the (aluminum) block to ensure a good seal
besides thoroughly cleaning the old gasket off? The head rebuilder has
recommended NOT to retorque the head bolts after 500mi or sand any surface
pattern into the deck, as seem to be common wisdom depending on who you talk
to.

Is there anything else important to replace along with the head besides the
timing belt, water pump, and all associated gaskets that would be hard to get
to later? Example: any known problems with the front crank seal, oil pump, or
timing belt tensioner?

History: The Accord always ran great, with some valve noise when cold due to
owner neglecting oil changes, until one day there was zero compression in #1.
No noise at all, just has no power. The car overheated once about five years
ago due to a leaking hose, but nothing bad seems to have come of that luckily.
Since it is aluminum, the deck will be checked for true before proceeding.

Appreciate any comments good or bad. Don't want to let a $400+weekend job get
out of hand.

Thanks.


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  #2  
Old July 16th 05, 08:07 AM
Ted Mittelstaedt
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Default


"Ryan Underwood" > wrote in message
...
> Hi,
> We are getting a new rebuilt head and head bolts for the 90 Accord EX (16V
> SOHC) with 200k as soon as we confirm a burned valve on the old one. What

is
> the recommended head gasket for this application, aftermarket or OEM? And
> what, if anything, should be done to the (aluminum) block to ensure a good

seal
> besides thoroughly cleaning the old gasket off? The head rebuilder has
> recommended NOT to retorque the head bolts after 500mi or sand any surface
> pattern into the deck, as seem to be common wisdom depending on who you

talk
> to.
>


Mostly, retorquing isn't needed these days, hasn't been for a couple decades
now. For starters many head gaskets are the "no retorque" kind. Also, if
you have "torque to yield" head bolts, as many engines do, to do a retorque
means removing the head bolts and throwing them all out and putting new
ones in.

For the aluminum block, you can use a wire brush but be careful with it -
don't use a
wire brush on a drill, use a hand brush and stop brushing when aluminum
starts to
appear under the old gasket material.. There are chemical products out there
that are designed to clean off old gaskets you might try those. For a
scraper, use
a plastic ice scraper, not a metal one.

Don't sand, wire brush, or steel wool directly on the aluminum.

I would also recommend chasing the threads in the block with a tap. Some
people just drill all of them out and replace them with HeliCoils.

> Is there anything else important to replace along with the head besides

the
> timing belt, water pump, and all associated gaskets that would be hard to

get
> to later? Example: any known problems with the front crank seal, oil

pump, or
> timing belt tensioner?
>


Yes, if the head bolts are torque-to-yield you must replace all of them.

> History: The Accord always ran great, with some valve noise when cold due

to
> owner neglecting oil changes, until one day there was zero compression in

#1.
> No noise at all, just has no power. The car overheated once about five

years
> ago due to a leaking hose, but nothing bad seems to have come of that

luckily.
> Since it is aluminum, the deck will be checked for true before proceeding.
>


How many miles on this? Frankly, an engine that was owned by an owner
who neglected oil changes is a poor candidate for new heads. Your better
off just rebuilding the entire thing.

Ted


  #3  
Old July 16th 05, 07:11 PM
Ryan Underwood
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Default

"Ted Mittelstaedt" > writes:

>For the aluminum block, you can use a wire brush but be careful with it -
>don't use a wire brush on a drill, use a hand brush and stop brushing when
>aluminum starts to appear under the old gasket material.. There are chemical
>products out there that are designed to clean off old gaskets you might try
>those. For a scraper, use a plastic ice scraper, not a metal one.


I was going to use brake cleaner and a plastic scraper as a start and save the
aggressive stuff for later.

>I would also recommend chasing the threads in the block with a tap. Some
>people just drill all of them out and replace them with HeliCoils.


Ok, I've heard that there are two kinds of taps - real taps, and thread
chasers, made out of different material, where thread chasers are made for
cleaning up existing threads. Supposedly a thread chaser runs less risk of
inadvertently doing something really bad to the threads. I was planning to get
a thread chaser, but can you shed any light on this difference?

>How many miles on this? Frankly, an engine that was owned by an owner
>who neglected oil changes is a poor candidate for new heads. Your better
>off just rebuilding the entire thing.


200k. Well, I should clarify. By neglected, I mean he usually let it get up
to 5-10k between changes. This is neglect by my standards, but may be within
reasonable tolerance. The reason I noticed it was because the valves were
noisy when cold and I asked him about it.

Looks like a crank kit is about $300 and rings another $80. Plus the motor
would have to be pulled to do the mains and the oil pump. If the compression
is good and there is no play in the pistons, could the bottom end be that bad?
What about just replacing the rod bearings from the bottom, and doing the rings
through the top after getting rid of the ridge? I also don't know if the
cylinder would need to be re-honed for the type of rings in this motor to seal
up again, or if cleaning it would suffice.

Thanks for the reply.

  #4  
Old July 16th 05, 07:37 PM
jim beam
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Posts: n/a
Default

Ryan Underwood wrote:
> Hi,
> We are getting a new rebuilt head and head bolts for the 90 Accord EX (16V
> SOHC) with 200k as soon as we confirm a burned valve on the old one. What is
> the recommended head gasket for this application, aftermarket or OEM?


oem.

> And
> what, if anything, should be done to the (aluminum) block to ensure a good seal
> besides thoroughly cleaning the old gasket off? The head rebuilder has
> recommended NOT to retorque the head bolts after 500mi or sand any surface
> pattern into the deck, as seem to be common wisdom depending on who you talk
> to.


as the head builder says, clean the surfaces only. any scratching can
lead to leakage over time. new oem heads are mirror finished.

>
> Is there anything else important to replace along with the head besides the
> timing belt, water pump, and all associated gaskets that would be hard to get
> to later? Example: any known problems with the front crank seal, oil pump, or
> timing belt tensioner?


seals & tensioners are good.

>
> History: The Accord always ran great, with some valve noise when cold due to
> owner neglecting oil changes, until one day there was zero compression in #1.
> No noise at all, just has no power. The car overheated once about five years
> ago due to a leaking hose, but nothing bad seems to have come of that luckily.
> Since it is aluminum, the deck will be checked for true before proceeding.


that noise is not due to neglect. it's just a fact of life and to some
extent, a function of the oil you're using. fortunately, a burnt valve
is /no/ reflection on the wear status of the rest of the engine.

>
> Appreciate any comments good or bad. Don't want to let a $400+weekend job get
> out of hand.
>
> Thanks.
>
>

i'd be scrupulous about cleanliness for the block. new rings and seals
are debatable at this mileage, but if it was good before and was not
burning oil, personally i'd leave them. rebuilds usually fail in 1/3 or
less time than the original build. analysis shows this is almost always
due to microscopic abrasive contamination left on the cylinder wall
after re-honing. if you can avoid doing that [and you /must/ hone if
you re-ring] you could continue to get good service from this engine.
caveat: "conventional wisdom" is strip, hone, ring, etc. but the fact
remains that rebuilds don't last and for the reasons i've stated. i
would not follow my own advice in a shop environment because i cannot be
"negligent" for following conventional practice, but if it were my own
car, and i /knew/ the block was good, sure i'd leave it as is.

  #5  
Old July 17th 05, 07:12 AM
Ryan Underwood
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Posts: n/a
Default

jim beam > writes:

>that noise is not due to neglect. it's just a fact of life and to some
>extent, a function of the oil you're using. fortunately, a burnt valve
>is /no/ reflection on the wear status of the rest of the engine.


Well, that's what I was hoping at least. The biggest concern of mine is that a
new head, being perfectly sealed, will increase the load on the compression
rings causing them to fail sooner, or at least increase blowby (fouling the oil
more quickly and perhaps overloading the PCV system). But from what I've read,
this seems to apply to older ring types and not to "moly" rings that new cars
and especially Asian cars have been using, so this is nothing to worry about.
(I'd love a correction here.) If so, that would definitely be a good thing,
because most of these cars are also using OHC aluminum head designs which seem
to invite eventual head rebuilds or gasket jobs for various reasons.

Aside from that issue, I'll just be on the lookout for detonation both from
improved compression from the new valves, and from the unintended rise in
compression that comes from the head being milled down.

>i'd be scrupulous about cleanliness for the block. new rings and seals
>are debatable at this mileage, but if it was good before and was not
>burning oil, personally i'd leave them. rebuilds usually fail in 1/3 or
>less time than the original build. analysis shows this is almost always
>due to microscopic abrasive contamination left on the cylinder wall
>after re-honing. if you can avoid doing that [and you /must/ hone if
>you re-ring] you could continue to get good service from this engine.
>caveat: "conventional wisdom" is strip, hone, ring, etc. but the fact
>remains that rebuilds don't last and for the reasons i've stated. i
>would not follow my own advice in a shop environment because i cannot be
>"negligent" for following conventional practice, but if it were my own
>car, and i /knew/ the block was good, sure i'd leave it as is.


So the idea is, either buy a new or rebuilt short block from a professional
rebuilder with a warranty, or leave the rings alone?

How about bearings and seals? I seem to be under the impression that unless a
bearing spun, they should be safe to replace (with a factory sized replacement)
without a hot bath or crank job. Likewise seals, unless something catastrophic
happened to the part they are sealing, just to use emery cloth or very fine
sandpaper on any shaft burrs before installing the new seal.

Of course never having done any bottom end work, I'd prefer to have my head
screwed on straight and do it right the first time or to not do it at all.
That's an area where trial and error can get expensive and inconvenient, as one
error can pile on more problems very quickly.

Thanks.

  #6  
Old July 17th 05, 03:54 PM
jim beam
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Posts: n/a
Default

Ryan Underwood wrote:
> jim beam > writes:
>
>
>>that noise is not due to neglect. it's just a fact of life and to some
>>extent, a function of the oil you're using. fortunately, a burnt valve
>>is /no/ reflection on the wear status of the rest of the engine.

>
>
> Well, that's what I was hoping at least. The biggest concern of mine is that a
> new head, being perfectly sealed, will increase the load on the compression
> rings causing them to fail sooner, or at least increase blowby (fouling the oil
> more quickly and perhaps overloading the PCV system).


doing the valve & replacing the head doesn't "improve" the compression,
merely restores it to the cylinder that had lost it.

> But from what I've read,
> this seems to apply to older ring types and not to "moly" rings that new cars
> and especially Asian cars have been using, so this is nothing to worry about.
> (I'd love a correction here.)


to be honset, don't know what honda use these days or the dates. it's
not really relevant to a valve job.

> If so, that would definitely be a good thing,
> because most of these cars are also using OHC aluminum head designs which seem
> to invite eventual head rebuilds or gasket jobs for various reasons.


detroit mythology. honda heads will happily stay on a block for 2, 3, 4
or more hundred thousand miles.

>
> Aside from that issue, I'll just be on the lookout for detonation both from
> improved compression from the new valves, and from the unintended rise in
> compression that comes from the head being milled down.


1. you don't get increased compression from new valves.
2. you have no reason to skim the head just because a valve burnt.
3. if you /do/ skim the head, you need an oversize gasket.

again, you have no reason to skim the head. alloy blocks & heads often
/do/ warp very slightly in use. but the important point most machine
shops [trying to sell you their services] never care to mention, is that
they warp in sympathy, so they still fit. unless you have a serious
distortion, such as caused by a cooling failure, do not skim the head!!!

>
>
>>i'd be scrupulous about cleanliness for the block. new rings and seals
>>are debatable at this mileage, but if it was good before and was not
>>burning oil, personally i'd leave them. rebuilds usually fail in 1/3 or
>>less time than the original build. analysis shows this is almost always
>>due to microscopic abrasive contamination left on the cylinder wall
>>after re-honing. if you can avoid doing that [and you /must/ hone if
>>you re-ring] you could continue to get good service from this engine.
>>caveat: "conventional wisdom" is strip, hone, ring, etc. but the fact
>>remains that rebuilds don't last and for the reasons i've stated. i
>>would not follow my own advice in a shop environment because i cannot be
>>"negligent" for following conventional practice, but if it were my own
>>car, and i /knew/ the block was good, sure i'd leave it as is.

>
>
> So the idea is, either buy a new or rebuilt short block from a professional
> rebuilder with a warranty, or leave the rings alone?


why do you want to touch the block? you burnt a valve. that does /not/
affect the block.

>
> How about bearings and seals? I seem to be under the impression that unless a
> bearing spun, they should be safe to replace (with a factory sized replacement)
> without a hot bath or crank job. Likewise seals, unless something catastrophic
> happened to the part they are sealing, just to use emery cloth or very fine
> sandpaper on any shaft burrs before installing the new seal.


there's no point stripping the block, unless you plan to replace
pistons, bearings, rings & seals, but again, i don't understand why
you're contemplating that course of action. you're turning a $500 job
into a $2500 job. maybe you want the experience, which is valid, but
it's cheaper to pick up a $200 [or cheaper] motor from a junk yard and
strip it down rather than be forced into much bigger $'s rebuilding this
motor. and you'd be robbed of most of the experience anyway because in
order to get any warranty, you'd have to let the shop do the rebuild.

>
> Of course never having done any bottom end work, I'd prefer to have my head
> screwed on straight and do it right the first time or to not do it at all.
> That's an area where trial and error can get expensive and inconvenient, as one
> error can pile on more problems very quickly.
>
> Thanks.
>


replace the valve, clean up the head & the block, put the head back on &
drive the car until you have another problem with it. /then/ figure out
what to do. for a 90, replacing the engine with a used japanese motor
is /way/ more cost effective [and probably reliable] than messing about
with extensive rebuilds for the reasons i mentioned before.

  #7  
Old July 17th 05, 06:56 PM
Steve B.
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Posts: n/a
Default

>
> Well, that's what I was hoping at least. The biggest concern of mine is that a
> new head, being perfectly sealed, will increase the load on the compression
> rings causing them to fail sooner, or at least increase blowby (fouling the oil
> more quickly and perhaps overloading the PCV system).
>


Unless your engine is just dog tired and worn out this doesn't seem to
be as big of a factor as it used to be. Were it mine I would get the
head done and slap it all back together.

Unless you have a particular reason to suspect bearing problems in the
bottom end I would leave it alone. If you start having oil pressure
problems in the future you can always do the bearing then without
having to redo the work you are doing on your heads now.

Take it from someone who doesn't know where to stop.... You have to
keep the project to a managable size and avoid all the "might as
wells" that pop up along the way. If a "might as well" is cheap and
would cause you to have to redo a massive amount of work then do it
otherwise leave it for another day.

Steve B.
  #8  
Old July 18th 05, 04:17 AM
Ryan Underwood
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Default

jim beam > writes:

>doing the valve & replacing the head doesn't "improve" the compression,
>merely restores it to the cylinder that had lost it.


Yeah, but presumably the rings have worn too. So bringing the cylinder back to
spec may cause an issue there.

>detroit mythology. honda heads will happily stay on a block for 2, 3, 4
>or more hundred thousand miles.


What I meant was that OHC/aluminum heads seem to invite regasketing/warpage
with mild overheat scenarios. Not as resilient as traditional heads. Though
aluminum blocks are probably a bigger culprit in this area.

>1. you don't get increased compression from new valves.
>2. you have no reason to skim the head just because a valve burnt.
>3. if you /do/ skim the head, you need an oversize gasket.


Sorry, I didn't mention the new head is coming from an exchange rebuilder. So
the choice whether or not to mill it down would be theirs, not mine.

>again, you have no reason to skim the head. alloy blocks & heads often
>/do/ warp very slightly in use. but the important point most machine
>shops [trying to sell you their services] never care to mention, is that
>they warp in sympathy, so they still fit. unless you have a serious
>distortion, such as caused by a cooling failure, do not skim the head!!!


Humm. Given this, is it a *bad* idea then to get an exchange head for an
aluminum block? The new one wouldn't have the same "sympathy" warp that the
block does.

>> So the idea is, either buy a new or rebuilt short block from a professional
>> rebuilder with a warranty, or leave the rings alone?


>why do you want to touch the block? you burnt a valve. that does /not/
>affect the block.


[..]

>there's no point stripping the block, unless you plan to replace
>pistons, bearings, rings & seals, but again, i don't understand why
>you're contemplating that course of action. you're turning a $500 job
>into a $2500 job.


I asked the question for future reference.

>replace the valve, clean up the head & the block, put the head back on &
>drive the car until you have another problem with it.


That was the plan. Except now I'm not sure whether to get an exchange head or
to have this one rebuilt, given what you've mentioned above.

Thanks.

  #9  
Old July 18th 05, 04:19 AM
Ryan Underwood
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Posts: n/a
Default

Steve B. > writes:

>Take it from someone who doesn't know where to stop.... You have to
>keep the project to a managable size and avoid all the "might as
>wells" that pop up along the way. If a "might as well" is cheap and
>would cause you to have to redo a massive amount of work then do it
>otherwise leave it for another day.


Solid advice, and the "might as wells" are exactly the problem I have when
knowing where to stop. I'll try not to make a federal case of this one.

  #10  
Old July 18th 05, 05:36 AM
jim beam
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Default

Ryan Underwood wrote:
> jim beam > writes:
>
>
>>doing the valve & replacing the head doesn't "improve" the compression,
>>merely restores it to the cylinder that had lost it.

>
>
> Yeah, but presumably the rings have worn too. So bringing the cylinder back to
> spec may cause an issue there.


absolutely not. all that will happen is that your car will suddenly run
well again. pistons running without load don't wear as fast as the ones
with load, so if anything, this piston will be healthier than the rest.
valves burn because they're not seating right or because they have a
defect. it's got _nothing_ to do with what's going on 0.1" further south.

>
>
>>detroit mythology. honda heads will happily stay on a block for 2, 3, 4
>>or more hundred thousand miles.

>
>
> What I meant was that OHC/aluminum heads seem to invite regasketing/warpage
> with mild overheat scenarios. Not as resilient as traditional heads.


cast iron heads crack & warp just as effectively as aluminum.

> Though
> aluminum blocks are probably a bigger culprit in this area.


not if they're designed right.

>
>
>>1. you don't get increased compression from new valves.
>>2. you have no reason to skim the head just because a valve burnt.
>>3. if you /do/ skim the head, you need an oversize gasket.

>
>
> Sorry, I didn't mention the new head is coming from an exchange rebuilder. So
> the choice whether or not to mill it down would be theirs, not mine.
>
>
>>again, you have no reason to skim the head. alloy blocks & heads often
>>/do/ warp very slightly in use. but the important point most machine
>>shops [trying to sell you their services] never care to mention, is that
>>they warp in sympathy, so they still fit. unless you have a serious
>>distortion, such as caused by a cooling failure, do not skim the head!!!

>
>
> Humm. Given this, is it a *bad* idea then to get an exchange head for an
> aluminum block? The new one wouldn't have the same "sympathy" warp that the
> block does.


any "sympathy" warp is usually minimal. don't fret it - i just
mentioned it in case you need ammo with the head shop - but i may have
muddied the water because most places neither know nor care. but it's
still best to use your old head if you can.

>
>
>>>So the idea is, either buy a new or rebuilt short block from a professional
>>>rebuilder with a warranty, or leave the rings alone?

>
>
>>why do you want to touch the block? you burnt a valve. that does /not/
>>affect the block.

>
>
> [..]
>
>
>>there's no point stripping the block, unless you plan to replace
>>pistons, bearings, rings & seals, but again, i don't understand why
>>you're contemplating that course of action. you're turning a $500 job
>>into a $2500 job.

>
>
> I asked the question for future reference.


no problem. ask as many times as you need.

>
>
>>replace the valve, clean up the head & the block, put the head back on &
>>drive the car until you have another problem with it.

>
>
> That was the plan. Except now I'm not sure whether to get an exchange head or
> to have this one rebuilt


rebuild the old one. presumably it's just one valve. that makes the
job $13 for the valve, $165 for the gasket kit, $70 for the chilton, $20
for the valve tool rental, and one half of a weekend. suddenly, you're
back on the road. and pretty one-up on your buds too.

>, given what you've mentioned above.
>
> Thanks.
>


 




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