VW AQY Compression

Did a compression check on my smokey bug and the 3 cylinders I could get to read 50 psi.

Seems a bit low to me but not been able to find what they should be, would have expected in the 100 psi region ?

Reply to
SteveN
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50 psi is too low to run. about 150 is about right with a minimum of 100 variation between cylinders of about ten per cent. Did you have the engine hot, throttle wide open and spinning a good few times?
Reply to
Mrcheerful

As someone who is cursed with a car which also has the AQY boat-anchor under the bonnet, you will almost certainly grow to hate this block of iron.

I don't know about the cylinder pressures, but maybe you can find the answer in one of the self-study guides?

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(apols if you already know about these.)

Reply to
David Paste

Although it's not the same engine, page 13 of this one:

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does show higher running pressures than 50psi. Check the oil filler cap - any emulsion there? My engine has had the head gasket go twice already (110k miles) and been skimmed both times. I think it's on the way out again. I hate this engine.

Reply to
David Paste

So this is dry compression what happens if you squirt oil down the cylinder and measure them wet?

Reply to
Rob

"Mrcheerful" wrote in news:d7P6r.232802$ snipped-for-privacy@newsfe28.ams:

Thanks,

Thought as much..

I'll try again with the throttle open and see what I get.

Reply to
SteveN

Rob wrote in news: snipped-for-privacy@dnews.tpgi.com.au:

Thanks, yes dry,,

I'll check again and try the oil, if I can get good access to the plugs :(

Reply to
SteveN

David Paste wrote in news: snipped-for-privacy@gr6g2000vbb.googlegroups.com:

Thanks,

Was never keen from day one :)

It's my daughters, she's been given the runaround by the local garages so offered to take a looksee..

I'm more used to GM barges where you can get lost in the engine bay. I have trouble getting to the plugs on this bug, should I remove the manifold ? Even that look difficult !

I'll check the head gasket, no apparent sludge though and I don't think there's pressure in the header tank but I'll investgate.

Symptoms is black soot from exhaust, my guess is as it's drinks so much oil she's not been able to keep up. Sure I've found it bone dry in the past.

And thanks for the links, I'm on a learning curve so no egg sucking.

Reply to
SteveN

Oh yeah, they seem to drink oil as a matter of course!

Sooty exhaust? Doesn't that indicate over-fuelling? Two things I've learnt:

  1. Check the MAF
  2. Check the engine temp. sensor which is in the block. I'll take a photo of these if you like. Check this one first, it's the cheapest to replace. Apparently the factory fitted ones (coloured with a black goo around the top) were a bit rubbish, and the replacements (sealed with a green goo around the top) are much better in terms of longevity.

Good luck with it!

Reply to
David Paste

David Paste wrote in news: snipped-for-privacy@gr6g2000vbb.googlegroups.com:

I agree re the fuel, garages have been there, lamba/MAF/cats, that's if you can belive anything they say or do, tryed to get a list off her but you must know what it's like.

Latest being compression, two of them were adamant they were down, #3 in particular, hence me getting involved. That's why I wanted to get this compression out of the way and start looking for the real cause

Did squirt the MAF with carb cleaner the other day.. These things are so expensive to swap on spec :(

Reply to
SteveN

On the dash, does the temperature get up to what it should be when running? I suppose that would rule out the temp. sensor.

The MAF, as far as I understand it, is a complete bugger. Other MAFs have a self-cleaning ability which kicks in each time the car is used, but the MAFs on the AQY don't have this feature, so they are liable to fail, and cleaning them - according to the guides I've seen on the web

- is a bit more involved than squirting solvent down them. I can't claim this as gospel though...

If the Check Engine Light is also on on the dash, you might try checking the exhaust sensors before and after the cat. AIUI, the oil consumption and over-fuelling doesn't do much for the cat and can break it. I'd torch the car if I were you!

Reply to
David Paste

Don't spray carby cleaner down the MAF's if you don't know what your doing.

The solution is to wipe it out with cleaner on a rag.

Reply to
Rob

David Paste wrote in news: snipped-for-privacy@hv2g2000vbb.googlegroups.com:

Goes out when up to temp.

I don't think the MAF has been changed and we're at 120k miles so maybe worth replacing.

No check light but I'm sure it has come on in the past. Maybe if I took it for a run, it's sat on the drive and not legal.

Think I should check the lambas and compression, then torch it :)

What you recon to this..

As it's burning so much oil, must be worn pistons ?, the cat plugs and lambas are getting chocked up which causes the management to think it's running lean, hence forcing more fuel through. Change whatever, over a period gets clogged, back to square one.

Does your use a stupid amount of oil without smoke ?

Been reading a lot about these smoky AQY's and folk seem to go around in circles..

Reply to
SteveN

Rob wrote in news:4f5d3b95$ snipped-for-privacy@dnews.tpgi.com.au:

You're right, I should know better :(

Reply to
SteveN

The normal VAG answer, VAG-COM

or valve stem seals.

Reply to
Duncan Wood

Did you have the throttle wide open - and how many turns of the engine?

Reply to
Dave Plowman (News)

Maybe, but... Someone else has just mentioned valve stem seals, which reminded me that apparently one symptom of this is smokey exhaust on overrun. Now this IS a problem with mine - find a big hill, roll down with your foot off the throttle and apparently when you get back on the throttle, if it smokes, it's indicative of the valve stem seals (what I've been told)

Possibly, but try the overrun thing first.

Yup! Oil consumption is high, and no smoke, as you say. Except on overrun.

10th circle of hell!
Reply to
David Paste

Ah ha! You are a very good memory aid! Cheers, I'd forgotten about this bit.

Reply to
David Paste

I had an audi A6 in that used a lot of oil, but did not smoke when hot, cold it produced a fog, but once the cat was up to temp. it just burnt it off. generally valve stem seals will not use up an awful lot of oil, while worn rings and bore will.

Reply to
Mrcheerful

Good to know, cheers.

Reply to
David Paste

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