Failed emissions test

Clean but don't looked steam cleaned.

I've found a small hole the size of a 5p in the top of the exhaust back box, would this be enough to give high emissions readings.

digi said:

Clean but don't looked steam cleaned.

I've found a small hole the size of a 5p in the top of the exhaust back box, would this be enough to give high emissions readings.

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Any hole in the exhaust system will contribute to high CO readings. One that size wouldn't be the be all and end all.....but it wont help.

6 months in the life of a K series air filter is quite a long time (For mine anyway). Surprising how filthy they get in quite a short space of time. I would re check it.

Not sure if yours is a dizzy cap engine, but if it is check the cap and arm. You need as much spark as possible to burn the mixture properly. I also have to be brutally honest with you and say the oil consumption is way above normal, and may be a real cause for concern in the long run.

I checked the air filter and it looks ok.

I think you are spot on with the oil consumption been the real problem, i removed the spark plugs to see if they were been steam cleaned as mentioned in above post, 1, 2 & 3 look ok, on cylinder 4 the spark plug thread and tip was oily, does this indicate a bad stem valve oil seal or something else.

I did a sniff test on the expansion bottle, the test liquid stayed blue so the head gasket is ok, i'm still waiting for my new compression tester to arrive to test cylinder 4.

Would you renew the stem valve oil seals to see if it makes a difference.

digi said:

on cylinder 4 the spark plug thread and tip was oily

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Was there oil in the spark plug well before you pulled the plug?

If yes = rocker/ladder gasket leak
If no = uhoh, there's your problem

digi said:

I did a sniff test on the expansion bottle, the test liquid stayed blue so the head gasket is ok, i'm still waiting for my new compression tester to arrive to test cylinder 4.

Would you renew the stem valve oil seals to see if it makes a difference.

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You need to get your compression test done - if cyl 4 is down compared to the rest it's a head gasket/piston ring issue that's the problem.

If cyl 4 = normal, I'd be suspicious of the valve stem seals.

Actually... thinking about it, it's almost impossible for oil to cross the head gasket into the cylinder - it would have to come via coolant to get there.

So it'll be a piston ring issue if it's anything to do with the bottom end - how many miles and does the engine make a ticking noise?

A problem that affects piston ring is high temperature causing considerable damage in its structure ......briefly if the engine was overheated for a period of time, likely to be damaged piston ring ....

Low compression is relatively easy to trace. First off get the engine to running temperature. Next remove all the plugs from the head. I don't use the ignition key to crank the engine over. I simply apply 12 volts to the starter trigger wire. I do this for several reasons. First off, it means I can work on my own. Second, I can hold the throttle fully open while cranking takes place. Third, there's no chance of damaging the ECU, coils, injectors or logging faults that aren't there. Once all these things are done. I'd expect to see 175 PSI on each cylinder. If one or more are low, I'd put a teaspoon of oil down each plug hole and redo the compression test. If the pressures measured improve, the cause is most likely the rings (unlikely). If there is no improvement, then the valves or seats are the likely the problem.

The compression tester came, i've redone the tests with the engine cold cylinder 1, 2 & 3 = 180psi, cylinder 4= 190psi.

I then retested with a squirt of oil in the cylinders, cylinder 1,2 &3 remained virtually the same 180psi, cylinder 4 185psi.

With these readings does this mean the pistons and rings are ok and i'm not burning oil through the rings.

But i'm still burning oil so does this indicate it to be the stem valve oil seals are there any other reasons why i'd be burning oil, would you change the seals.

That's a healthy engine, apart from the disappearing oil. 10psi ~ 5% variance so I wouldn't worry about it.

Does it smoke under load at all, if it's disappearing oil at a rate of knots, I'd expect it to be blowing blue/white smoke a bit?

I'd also expect it to chug after being left standing for a weekend then getting started.

Are you /sure/ the oil isn't getting out of the block anywhere, like in the timing case, down the back of the block or into the clutch housing? It can seep slowly from the ends of the head and look fairly innocent...

I start to see some smoke at around 3000rpm also on start up i get a burst of smoke when it's first started up then on tick over it looks clear.

digi said:

i get a burst of smoke when it's first started up

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This would have saved us a lot of guessing

Yes, your valve stem seals are no good and need replacing.

The burst of smoke isn't that great so thought it was normal as it then starts running clear, the stem valve seals are about 7 months old thats why i thought it was unlikely to be them, they could have been poor quality as they didn't look as good as the ones i took off when i did hg.

I've been to the engine shop to get a set of replacement seals, these look good quality better than the ones i put on last year.

Most of the ones included in head gasket sets aren't worth crap to be honest, they'll "sort of do for 12 months" - the bare minimum the supplier can get away with.