Compression Test without a cambelt
Juan-Pierre Herboth
timing belt resently broke and Im trying to see if any valves bend
without removing the head. Ive removed the rocker arms and the sparks
plugs.My question is whether or not Ill be able to determine anything
if I do a compression test the way the engine is now?If so what
pressure whould show all is good?I cant do a leak down test(dont have
the equipment) and cant tow the car to a shop to have them do it.The
seller told be the engine was overhualed a month ago and before the
belt braking the engine ran very well,so Im not afraid of worn rings
and stuff like that.
jim beam
you don't need to compression test to see if the valves are good. put
the rockers back on and simply check the valve lash - if you have one
that's huge, the valves are bent. if not, you're good to go - just
replace the belt.
despite all the bleating you read on the net about honda engines and
"interference", it's actually unusual for there to be any damage. when
the belt breaks for normal users, it's usually at low rpm's [when cam
friction and thus belt tension is at its highest because there's no
hydrodynamic separation of the cam face and the followers], so the cam
gets time to snap into one of its four "relaxed" positions in which the
pistons can then freewheel.
when fitting a new belt, do NOT buy cheap crap. oem suppliers are
mitsuboshi and bando. if you don't buy "honda" brand, which is your
guarantee of reliability, stick to the oem suppliers if you're convinced
you need to save a buck.
--
nomina rutrum rutrum
Juan-Pierre Herboth
of the service life to make sure it will make it.About my compression
test idea?Can I go ahead a test?Im still waiting for the o-rings that
go under the rockerarm support so I have time.The o-rings are order
from honda and will take another day or 2 to arrive.
Regards
JP
jim beam
you'll not get any meaningful compression test if the valves are not
being operated - which they won't be if there are no rocker arms and no
belt.
in the mean time, you can still check the lash, so put the rockers back
on now. if any valves are bent, you'll have to take the head off to
check for more damage, so it's pointless fitting new stuff until you've
done your diagnostics.
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nomina rutrum rutrum
Juan-Pierre Herboth
online.But since Im from RSA my engine is not shown in the
manual,closest is the D15B7 and its a fi engine.Do u know where I can
find the valve lash settings.Also since,I dont trust the previous
mechanic, what kind of pressure would I expect from a cold dry
compression test if I end up putting it all back together?I dont trust
the previous mechanic when It comes to the valve lash since the belt
broke only a month after a 'overhaul'.I didnt get a owners manual with
and found one online.But since Im from RSA my engine is not shown in
the manual,closest is the D15B7 and its a fi engine.Do u know where I
can find the valve lash settings.Also since,I dont trust the previous
mechanic, what kind of pressure would I expect from a cold dry
compression test if I end up putting it all back together?I dont trust
the previous mechanic when It comes to the valve lash since the belt
broke only a month after a 'overhaul'.
Tegger
9ae5-195...@y39g2000prd.googlegroups.com:
Just temporarily put the head back on the block with a new gasket and
tighten as per spec. But WITHOUT the cams or rockers.
Now feed shop air into each spark plug hole in turn, and listen at the
intake and exhaust ports for that cylinder for any hissing noises. No hiss
out the ports, no leak at the valves, and thus no bent valves on that
cylinder.
--
Tegger
jim beam
that'll work too. if he has air...
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nomina rutrum rutrum
jim beam
clearances should be the same as the d15b7, d15b2, etc. they're usually
on the sticker that's under the hood.
but you don't need them for this. you're not looking at a couple of
thou difference, you're looking at either just a little, like normal, or
a honking great slop, which is a bent valve.
as for the compression test, frankly, it's sometimes best not to know.
as long as the motor runs, doesn't burn too much oil, and has sufficient
guts, it's irrelevant to most operation.
as for why the belt should fail so soon after "overhaul", well,
sometimes people don't do what they were paid to do, so maybe the belt
was never changed and it failed through normal old age. but there are
other potential reasons:
1. abrasives used in "overhaul". they just float about the engine and
wear the cam [and the rest of the motor]. once the cam wears through
its hard coating, the soft stuff underneath causes a DRAMATIC increase
in friction coefficient and thus belt load. particularly at idle.
2. belt was damaged while fitting. use of levers, or even just folding
can ruin a belt.
3. other mechanical stoppage. make sure the coolant pump hasn't seized
or the motor hasn't thrown a rod. for the latter, using a stick poked
down each spark plug hole, make sure each piston is still attached the
crank. [the civic d-series connecting rods are tiny little things -
i've seen a number fail.]
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nomina rutrum rutrum
Juan-Pierre Herboth
@Tegger:I spend some time going through the stuff on your site and it
was quite helpful. From what I can see finding the o-rings under the
rockerarm support is difficult in my area (Cape Town, South Africa).I
was only able to find it at the dealership. By the looks of things the
previous mechanic had a similar experience and decided to just put
liquid sealer under there and the 1st problem I found when the car
died was oil soaked spark plug. Your site helped me realise the seal
problem.However like Jim said,I cant get to a shop and dont have a
compressor.Ill check but I have a little electric compressor used for
pumping up tyres.Its not very powerful, but I see the manual talking
about 250 kPa,which is 2.5 bar, my tyres is pumped to 2 bar so that
little thing should work Ill just have a look at how to set it up.
@ Jim: I was thinking the same thing about the compression. The car
ran fine and the oil usage was good.Little oil leak, but its an old
car and my other old car also had a leak,its something I can live
with. Ill put the head and check the clearance.If Im looking for a big
gap then it should be rather easy to see.It was interesting to note
that #1 cylinder had the intake valves full open,so I think I might
have 4 valves that might be bend.Ill check and let u guys know.
Thanx again guys.e stuff on your site and it was quite helpful. From
what I can see finding the o-rings under the rockerarm support is
difficult in my area (Cape Town, South Africa).I was only able to find
it at the dealership. By the looks of things the previous mechanic had
a similar experience and decided to just put liquid sealer under there
and the 1st problem I found when the car died was oil soaked spark
plug. Your site helped me realise the seal problem.However like Jim
said,I cant get to a shop and dont have a compressor.Ill check but I
have a little electric compressor used for pumping up tyres.Its not
very powerful, but I see the manual talking about 250 kPa,which is 2.5
bar, my tyres is pumped to 2 bar so that little thing should work Ill
just have a look at how to set it up.
@ Jim: I was thinking the same thing about the compression. The car
ran fine and the oil usage was good.Little oil leak, but its an old
car and my other old car also had a leak,its something I can live
with. Ill put the head and check the clearance.If Im looking for a big
gap then it should be rather easy to see.It was interesting to note
that #1 cylinder had the intake valves full open,so I think I might
have 4 valves that might be bend.Ill check and let u guys know.
Thanx again guys.
Juan-Pierre Herboth
Tinkerer
"Juan-Pierre Herboth" <jphe...@gmail.com> wrote in message
news:d68fcb7f-57cf-40a4...@h7g2000yqm.googlegroups.com...
You appear to have hiccups or something. Not only did your message appear
twice but each copy had two copies inside. Bit like those Russian dolls.
--
Tinkerer
jim beam
> Thanx Jim and Tegger.
> @Tegger:I spend some time going through the stuff on your site and it
> was quite helpful. From what I can see finding the o-rings under the
> rockerarm support is difficult in my area (Cape Town, South Africa).I
> was only able to find it at the dealership. By the looks of things the
> previous mechanic had a similar experience and decided to just put
> liquid sealer under there and the 1st problem I found when the car
> died was oil soaked spark plug.
while that leak is annoying, it's not very important except on #3
cylinder. the rocker pillar on that cylinder has the oil riser and if
that leaks, you could oil-starve the whole rocker assembly. if you're
absolutely stuck on the o-rings, find the smaller size that fits the oil
riser, and use sealer on the rest.
re sealers, that rtv silicone stuff is next to useless. the companies
that make it have GREAT sales people, but its physical properties are
inappropriate for engine internals, particularly hot oil. [which is of
course why engine manufacturer don't use it when making the engine in
the first place! check out http://www.epm.com/material_guide.htm -
"Poor resistance to oils"]
ime, the best sealer out there is something called "hylomar". it's a
blue goo and it remains tacky - it never sets. and best of all, it's
removable with the correct solvent if you do any re-work, so you don't
scratch anything up removing silicone crap.
> Your site helped me realise the seal
> problem.However like Jim said,I cant get to a shop and dont have a
> compressor.Ill check but I have a little electric compressor used for
> pumping up tyres.Its not very powerful, but I see the manual talking
> about 250 kPa,which is 2.5 bar, my tyres is pumped to 2 bar so that
> little thing should work Ill just have a look at how to set it up.
> @ Jim: I was thinking the same thing about the compression. The car
> ran fine and the oil usage was good.Little oil leak, but its an old
> car and my other old car also had a leak,its something I can live
> with. Ill put the head and check the clearance.If Im looking for a big
> gap then it should be rather easy to see.
it's not always easy to see because the valve head tends to obscure
things. but it shows up big time on the rocker arm/valve lash.
> It was interesting to note
> that #1 cylinder had the intake valves full open,
one cylinder's valves will /always/ be open if the cam and rockers are
in place. but it doesn't mean they're bent or damaged - it's normal and
what you want to see. the cam has 4 "preferred" positions due to the
springs and the cam lobes. when in any one of these 4, the pistons can
freewheel. if you replace the rockers and haven't fiddled with the
adjustment, you'll find the rockers go back on with exactly the same
adjustment as when they came off.
> so I think I might
> have 4 valves that might be bend.Ill check and let u guys know.
> Thanx again guys.
--
nomina rutrum rutrum
Juan-Pierre Herboth
and was thinking it has to do with oil supply.Interesting thing is
that some of the liquid sealer the mechanic used was actually
partially obscured the oil hole. I should be getting the o-rings from
Honda tomorrow and Ive already gotten all the other stuff.Will most
likely assemble tomorrow and update on what I found.Thats if it doesnt
rain=)Im working in the open so rain wont do.BTW what is it that you
do?I see you giving advise on multiple honda forums.Thanx again.
Juan-Pierre Herboth
little to no valve lash. Adjusted the valve lash to 0.25mm exhaust and
0.20mm intake. Its the middle of the range suggested in the manual.Now
the car starts and ideals fine and smooth.Will take it for a test run
today.Just one more question.There is a vacuum line running from the
air intake, it branches of to the vacuum advance on the distributer
and the carb(by the looks of things),but there is a third branch thats
blanked off.It seems like it should go to the distributer cap.Should I
get a new pipe and fit it to the cap or where does it go?My manual is
for fuel injected cars and only refers to the P2 and P8 connections.
Regards JP
jim beam
> Hey guys.Good news.I fitted the rockers with new seals and there was
> little to no valve lash. Adjusted the valve lash to 0.25mm exhaust and
> 0.20mm intake. Its the middle of the range suggested in the manual.Now
> the car starts and ideals fine and smooth.Will take it for a test run
> today.
good.
> Just one more question.There is a vacuum line running from the
> air intake, it branches of to the vacuum advance on the distributer
> and the carb(by the looks of things),but there is a third branch thats
> blanked off.It seems like it should go to the distributer cap.Should I
> get a new pipe and fit it to the cap or where does it go?My manual is
> for fuel injected cars and only refers to the P2 and P8 connections.
> Regards JP
if it came capped, and the cap looks as old as the rest of the system,
it's probably just a test point. i can't help with anything else in the
carbureted vehicle department - i stopped following that dead-end years ago.
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nomina rutrum rutrum
Juan-Pierre Herboth
simple is best.Especially when it comes to old cars.I believe a carb
is easier to fix and maintain for someone unskilled like me.The hose
has a screw in it so I dont think its part of the original design.Ill
see if I can find the info elsewere.Thanx again for all your help.It
was invaluable.
jim beam
you're welcome. enjoy the honda - that generation are great cars.
don't be afraid of electronic fuel injected vehicles. the reality is,
they're typically more reliable and easier to fix than carburetted
vehicles. the only thing holding most people back is the need to
acquire /new/ knowledge, and the misconception that "i know nothing
about computers or electronics, so i won't know how to fix it". reality
couldn't be much more different. everything is a unit. the computer
does most diagnostics for you. all you have to do is swap the
designated unit if it's defective. the auto repair industry has been
revolutionized and massively simplified as a result. of course, if you
want to get into the nitty gritty and repair those units and their
individual components, you'll need a little more info, but sites like
tegger's excellent tegger.com contain a wealth of accumulated honda
knowledge that'll keep most cars on the road.
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nomina rutrum rutrum
Dillon Pyron
Checking compression is, in itself, fairly useless. A leak down test
would be useful, but might also suggest you need a ring job.
Invest in a real shop manual, a high quality torque wrench, new head
gaskets, new valve cover gaskets (which I hope you already have) and
some "anti-freeze". There are also some neat little endoscopic type
tools you can get to look thorugh the plug hole, but you really have
to know what you're doing for them to be useful.
--
- dillon I am not invalid
"You idiots, it's rape, pillage,THEN BURN!!!"
--- chief of the Aggie Vikings