Number 1 cylinder is not working

Barra

Forum Member
Joined
May 11, 2016
Messages
33
Location
Brisbane
Car Year
1986
Car Model
Brumby
Transmission
4 speed manual
Hi Folks,

Just found out that my Brumby's EA81 is not firing on number 1 cylinder, idles roughly (obviously). She has spark and valve timing is OK.

I am a little worried this may be a big problem :(

Any suggestions would be appreciated.

Also, even though I like to tackle the small jobs myself, who is the best mechanic on the Northside of Brisbane for the EA81? (Just in case).

Thanks

Barra
 
well -- with a carb'd 4 cyl, if the other cylinders are firing, about the only thing that can be wrong is spark.

Plug ok? Lead ok? Dizzy contact ok for that cyl ?

You might see spark when testing it, but is marginal and fails due to a faulty insulator or dodgy lead trying to fire under compression.

Worth checking compression is ok in the cyl, too - rule out valve problems.
 
Double check you valve clearances - all you need is the exhaust valve to not seal properly and you've got a miss fire on your hands and loss of power in that cylinder.

A compression check is a must as this will show up the low compression as the issue. Or you can play around with your valve clearances and see what happens.

Have you checked the actual spark at the plug on this cylinder? It could be weak, your plug gap could be wrong or there could be an issue with a worn dizzy cap.

Do a compression check, while you've got the plug out check the gap, from memory it should be 1.1mm. Let us know how you go with it.

Cheers

Bennie
 
Hi Guys,

I'll double check the clearances and then check the compression. I'll post something this afternoon.

Barra
 
Hi Guys,
Have spark, but checked my valve clearances and have little if any compression. Didn't measure it, just rule of thumb test.
Next step - mechanic?
Please insert miracle here here:)

Barra
 
Doesn't sound good ... :(

How did you check the valve clearances?

Ditto compression?
 
What procedure are you using to check valve clearances? I'd recommend backing off the settings on cylinder #1 and run it with loose tappet settings - it'll rattle/sound like the death tick but it'll be ok. This should show that the valves are sealed as much as possible by the spring strength.

It's also a good idea to check the springs to ensure they're not snapped, rare but it can happen.

Otherwise you're looking at a compression issue that's not giving you any performance. This could be due to a blown HG or damaged rings or even a damaged piston head - hole or a crack.

Do you have any blow by when the engine is running or any bubbles in your coolant?

You might even have a bent push rod on the inlet valve. But I'd suspect you'd notice that pretty easily.

Cheers

Bennie
 
Hi Guys,

Checked/adjusted valve clearance on number one and three cyclinders, took engine to TDC and did number one, inlet at 0.010 and exhaust 0.014 (thou) and rotate the motor clockwise until I got to that straight line on the flywheel and had rotor pointing to cylinder three etc. When I did the valves I was generous with the clearances.

I don't have any bubbles in the coolant or water in the oil, no water coming out of the exhaust.

I'll take it down to the mechanics this week for a formal diagnosis.

Thanks for your help, I'll let you know how it goes :)

Barra
 
Hi Guys,

Have had the Brumby down at my trusted mechanic (it's still there). It's got even him stumped, all the basics check out, compression, valve timing spark etc. It's just that number 1 cylinder wont fire. Compression on all cylinders (including 1 is about 120-130 psi).

Are bent pushrods common? Or even worse could it be a worn cam?

Any suggestions are most welcome. Should I now look at a good second hand motor?

Barra
 
is #1 spark plug fouled? Wet or dry ? (ie: spark or fuel).

Some sort of blockage in the intake or exhaust manifold? (stretching it a bit here).

I still reckon spark is the most likely culprit -- any snappy sparkover noises in the engine bay when running on 3 cyl?

If you're getting 120psi on #1 - then the valves are not only sealing, they're also opening and letting air in.

If you're worried about valves not opening due to bent pushrods, pull off the rocker cover and turn it over by hand while looking at the valves.
 
Hi Guys,
Pushrods are straight, which is good news. I have heard the inlet manifold gasket could cause some problems?
Taking it to a guy at Beerwah (specialises in the older Subies) on Friday, hopefully he will have it going.
 
A small question. Have you tried another plug in it. If not is the plug fitted an iridium. They can snap the centre electrode insulator which allows it to fall over the gap and won't let the cyl fire. You take it out turn it so the electrode is up and the insulator falls back and looks OK. Put it back in and it vibrates back closed.
Had this problem with quite a few iridiums. May be fixed by now that was a few years ago.
 
Good thought Gregjet, but have tried that also.

Any thoughts on vacuum leaks?
 
Gidday Barra

By and large a vacuum leak will cause the entire engine to run like a pig, unless solely to that cylinder. A comprehensive compression test should show up such a single cylinder leak, and it hasn't.

I agree that this is far more likely caused by the ignition system. Tiny internal/external crack in the distributor cap; coil failure; lead/plug failure - probably others - drove to Camperdown and back for the funeral today ... a bit buggered now.
 
Two more things.
Have you checked the continuity between the inside of the dizzie cap and the top. And the end of the plug lead. A very long time ago I had a Simca that had this problem ( may not have been cyl 1) and the inside dizzaie pin had actually fallen out. Doesn't have to come out completely to reduce spark enough to not fire. Also try a new dizzie cap. Sometimes there can be tracking in a crack you just can't see.

Also did you have the car apart before the problem. ie running before, after wouldn't. If you had the manifold off the heads , did you leave a rag or plug in the head or the manifold. Or rag to protect the ports when lapping valves? That one happened to a good friend of mine. Or mud wasp nest if it was left off for a while. On that note check the exhaust for obstruction. Blocked exhaust means no flow in either.

Have you run a IR thermometer over the exhaust header when it it running to see if it is firing at all? That's how I used to check a racing motorcycle of mine that was a bit recalcitrant in firing the front cyl.
 
Hi Guys,

Just back from Beerwah and Wayne reckons it's definitely the exhaust valve on number 1. He said although it gets compression it takes time to build up?
So taking it back there Monday week for him to fix.

I will let you all know once it is actually fixed (just in case).

Cheers,

Barra;)
 
Good morning,
Got the Brumby back from Wayne up at Burpengary, nice guy. It appears the head on the driver's side must have got too hot and the exhaust spring on number 1 was weak/soft. When he took the head off he found it was warped so he put a second hand one on.
I love having all four cylinders working. :)
Have a good weekend folks,
Barra
 
Good to hear that you got it sorted out, Barra.
Not too painful compared with (say) a full engine rebuild ...
 
So only one head replaced?

Well if it works I guess all is well. I would have at least compared head thickness to the other head too with the aim of ensuring that there's equal compression across the two banks.

But I guess it's a run of the mill EA81 at the end of the day. Were both head gaskets replaced while the work was being done?

Cheers

Bennie
 
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