compression test results

dazza · Post by **dazza** » Mon Jun 04, 2007 7:44 pm

Hi all, my ek is now registered and have found some motorvation to get her out for a spin.
She is all systems go as far as start up and idling goes, the problem is when i acelerate the engine missfires and i cant accelerate much at all, on gentle acceleration the problem is less obvious. So i have checked the plugs. dizzy, coil, all seems ok.
I did a compression test and cylinder 5 was verry low around 70psi whereas all the others were bang on 135. so im thinking it may be a ring. I was just wondering if there may be any other, eaiser to diagnose problems that may cause low compression. If not is it possible to replace one ring only,
any advice is greatly appreciated cheers!

Thommo · Post by **Thommo** » Mon Jun 04, 2007 8:18 pm

Gday Dazza
Acceleration problem could well be the fuel pump.
If any forign matter is holding the pump valves open
the pump will not create pressure. ie: deliver fuel.
Undo the 8 or so screws around the fuel pump,
Lift of the top half, check the rubber disc, 2off(pump valves) that
nothing is stopping them from sitting flat to the pump body.

Can you change one set of rings only?
you could,...but the cylinder bore might be damaged.

Cheers Jeff

FB MAD · Post by **FB MAD** » Mon Jun 04, 2007 9:34 pm

70 psi doesn't sound too good Dazza, even on a low compression grey motor.
In my day to test whether it was cracked or worn rings/bore versus burn't valve, we'd give the offending cylinder a few squirts of oil to temporarily seal up the ring to cylinder bore sealing ability then do a compression test.If the pressure increased to a major extent ( say it went from the original 70 psi reading to 100 psi ) that usualy indicated a piston/ring/bore problem but if the psi didn't increase much then it usually was a burn't out valve.
There can be other reasons for low compression however like cracked/warped head and/or blown head gasket etc but these usually result in pressure build up in the cooling system/loss of water, or water in the oil symptoms etc.

If a piston was holed or had damage to the ring lands then that wouldn't give a psi increase so the oil squirt theory wasn't always right.

Looks like whatever happens the head will have to come off and you can usually get an idea from an inspection of the valves and piston/bore condition as to how far a rebuild you will have to do.

I doubt very much whether you can buy one set of rings but you could try JP Pistons or a similar company.

Let us know the post mortem results

Hope this helps,

Terry.

P.S. Just had another thought which I should have added to the above.

Before you pull the head off,check for correct tappet clearance or sticking valve or a rocker problem as this can also give low compression readings as well, especially if the motor has been sitting around for a while

gordon · Post by **gordon** » Tue Jun 05, 2007 10:29 am

dazza,probably there is dirt in the carburettor,engine idles,but when you accelerate the dirt gets sucked into the jets causing all sorts of things to happen. When you remove the spark plugs to do a comp. test,carbon can be dislodged in the cylinder and get under the valves,causing a low reading you have to restart the engine to clear this out then recheck?

Malcolm · Post by **Malcolm** » Tue Jun 05, 2007 11:05 am

I had a simlar problem with one of my old cars years ago, it turned out to be a blocked muffler. The car would start and run but wouldn't hardly rev.

Maybe something to check, but that won't help the lack of compression.

Cheers

Mal

dazza · Post by **dazza** » Wed Jun 06, 2007 7:10 am

Thanks for the advice everyone, gonna try all of the above. The last thing I need at the moment is a full reco, getting married at the end of the year still got to pay for that, as well as the honeymoon.
Tryed the oil in the cylinder trick, and yes there was a substantial increase in comp, jumped from 70 to 100 psi, so Im certain there is a major piston issue. My next question for all you technical gurus is this, will the car be such a pig (impossible to drive) with a blown piston ring. or will it be ok if I adress all the other factors that could be making the problem more obvious.
I think Ill start looking around for a cheep second hand motor that works!
- if there is any left.
cheers Dazza

FB MAD · Post by **FB MAD** » Wed Jun 06, 2007 7:54 pm

G'day Dazza,

Addressing the other factors may make it run a bit better but if its low on compression in one cyl it will still fart and miss etc.You'd really be wasting your time I think.

You'll still be able to drive it with low compression in one cylinder but eventually you or the piston ( assuming its a piston problem ) will get the shits and give up!!

If the piston ends up disintegrating then you can end up damaging the engine block beyond repair.

If you are short of $$$ with getting hitched, honeymoon etc then I'd be looking around for a good running replacement motor and see how it goes.They take less than a day to fit.Then rebuild your old motor if you want when the budget can afford it.

There are still a reasonable amount of running grey motors around if you look around. And don't let the look of an engine frighten you either.I've got some greys in my shed that are some of the filthiest, dirtiest, greasiest motors I've ever seen and yet they still have acceptable compression that would be good enough as is to put in a car with some new seals and gaskets and some paint.

I've got hold of some running greys for free and others from $50 to $750 depending on accessories, condition etc.

Put up a wanted post here or have a look on evilbay ( Ebay ) and see it there's any around near your area. If you can't pickup an engine yourself transport costs via a freight company can make it VERY expensive if it has to be delivered unfortunately.

Hope this advice helps,

Regards,

Terry.

FB search · Post by **FB search** » Thu Jun 07, 2007 3:57 pm

G'day Dazza,

Dunno where Bargo is vs Adelaide, but I thought I'd throw in this E bay link for you to squiz at anyway.
Good luck.

Item number: 140126124403

here

Cheers

Dominic

dazza · Post by **dazza** » Sat Jun 09, 2007 2:15 pm

cheers for the advice and help everyone!
No luck so far, finding a running grey is nearly impossible here in adelaide.
So ive pulled the head off and had a bit of look, the cylinder walls seem to be in a reasonable state from what i can tell, they arent out of round or tapered, and not scored, so i think i might be able to put a fresh set of rings in and see how it goes. Im a bit nervous as ive never done it before, has anyone got any tips or techniques that might help me out. The engine is still in the car so im off to kennards to hire a hoist and stand for the week.
while i have the head off ill clean it. is there any way to flush out the coolant galleries there seems to be quite a bit of scale in them. the valve seats seem to be in good cond, although i dont really know what im looking for. i guess i will see more once i clean the carbon off.
thanx Dazza

Thommo · Post by **Thommo** » Tue Jun 12, 2007 11:32 am

Hey Dazza
Have you seen the grey motor advertised on this forum.
click here
You could make one motor from all the best parts
of yours and his combined.

This might get you going quickly & cheaply for now.
Then later you could have whats left over,
fully recond, to swap in later when funds allow.

Cheers Jeff

dazza · Post by **dazza** » Sun Jun 24, 2007 9:49 am

ok after pulling the motor out, and putting new rings in i have run into a problem you turn the motor i can hear a slow hissing sound followed by a plunging noise i have done a compression test and all cylinders are even but low. so i thought id have a crak and start it. no go there is flames coming out the manifold and poping out the carby so the flames i guess may be timing related but the only thing i can think of is the head gasket not sealing between two cylinders thats why im getting the poping from the carby Ive torqued the head to 83nm as instructed but i think im gonna have a crack doing the nuts up tighter to see if i get better compression. Have come to far to give up now, but am getting awfully frustrated, if any one could give sugestions on how to get the old girl going it would be greatly appreciated, cheers! dazza

smooth · Post by **smooth** » Sun Jun 24, 2007 4:42 pm

Popping and backfiring out of the carby is normally an indication of the dizzy being 180 degrees out. You will need to adjust that. As a cheat you can move the leads around 180 on the dizzy cap to test the theory.

Bring #1 cylinder up to TDC on a compression stroke and check the timing mark on the flywheel. Drop the dizzy in with about 1/8th of a turn to the left (anticlockwise) from the #1 position and drop it into place so that the rotor points to the number 1 position. You will know it is in correctly because the vacuum advance line will connect quite easily and will allow the timing to be moved back and forth without tension.

Good luck, you will get there in the end.

Regards, Smooth

FB MAD · Post by **FB MAD** » Sun Jun 24, 2007 6:27 pm

"I have done a compression test and all cylinders are low"

Hmmmmmmmm........................................

Cam Timimg ??

How low is the compression results??

"Hissing sound followed by a plunging noise "

Could be just the compression "hissing " and Exhaust stroke/intake stroke "plunging noise ", but hard to say without hearing it.

Head gasket not sealing between two cylinders won't really give you a backfire through the carby unless something has really gone wrong there.

I assume you checked the head for warpage/cracks??

From what you describe it really sounds like a timing problem and the low compression indicates to me that it could be a cam timing problem and/or ignition timing problem like smooth said.

If I was placing a bet I'd back Cam Timing for a win and Ignition Timing for a place!!

Try smooths suggestion first however as it is the least time consuming of both scenarios.

Could be something completely different to what I've said but you have to start somewhere I suppose.

Any other ideas from other members??

Let us know how you get on.

Hope this helps,

Terry.

FB MAD · Post by **FB MAD** » Sun Jun 24, 2007 6:42 pm

Another thought.

Have you set the tappet clearances correctly??.
If they are too tight the engine will cough and fart all over the place.

Inlet should be set at 8 thousandths of an inch clearance and exhaust at 12 thousandths of an inch ie:- .008 inlet and .012 exhaust.

Each tappet( rocker ) pair ( inlet/exhaust )must be set with each cylinder at their respective TDC ( Top Dead Centre ) on Compression/Ignition.

These are hot engine settings.

Set at about .010 inlet and .014 exhaust for a cold engine and then to .008 inlet and .012 exhaust once engine is hot.

I remember doing tappets on a grey when I was a 14 year old kid ( long time ago now !! ) and completely got it wrong and I remember the motor was coughing and farting all over the place and flames from the carby as well.

Another less time consuming avenue to persue before you check the Cam timing theory above.

Regards,

Terry.

fbekholden.com