Hi,

Ok, I’ve searched and can’t find a simple straightforward guide for doing a compression test on the Zed.

From what I could find out it looks to me like the best way to do it is:

 

1 - Disconnect CAS and/or take out fuel pump fuse.

2 - Take off all coil packs and remove all spark plugs (so as to allow as least resistance as possible, battery will last longer)

3 - Connect pressure gauge up to one of the cylinders (not sure if there is a preferred sequence or if it makes any difference)

4 -Turn engine over a few times (not sure how many) and push fully on accelerator (this is to open the throttle bodies to allow as much air in as possible)

 

Min 143 psi, max 184 psi (no more than 14 psi deference between any).

 

If any of the cylinders a re showing lower pressure (obviously check it a few time first and check the pressure tester connection) put a bit of oil in the cylinder, if the pressure looks better after this is would indicate the rings are leaking.

If the pressure is still low it would indicate head gasket (should have other symptoms for this as well, i.e. bubbles/CO2 in the water or possibly if bad enough mayo in water or oil), Valve stem seals (again other symptoms with this, i.e. burnt oil), or valve seats not closed flush (reduces performance and/or un-burnt fuel/ black smoke/backfiring if it’s the exhaust ones).

 

 

Can anyone pleases confirm, correct or add to this?

Cheers.

Close, but this should help

 

The first step in this is fun and all you have to do is drive your Z for about 10 minutes however you like to drive and bring it up to temp. Now that your done with this we will move on the the sucky part of this job.

 

2. Remove your coils being careful not to break the expensive connectors.

3. Remove all spark plugs and check the color of your plugs, replace if you want, but leave all out until #12.

4. Remove fuel pump fuse (by the battery)

5. While your engine is still warm to hot install the compression tester using the 14mm adapter hand tight.

6. Crank over the motor with the throttle pushed down all the way to the floor, it should take 4 to 9 revolutions for maximum compression to be reached, depending on the condition of your motor.

7. Repeat #5 and #6 for remaining cylinders and write down the numbers.

8. Now that you know what your compression numbers are compair them to the specs. I have an N/A which is 186 PSI. The low range is 140. All the cylinders should be with 14 PSI of each other. This is total not 14 to adjacent cylinders.

9. Now get a small piece of vacuum line or fuel line about 12 inches long. I use a syringe type turkey flavoring injector but anyway you can measure and insert about 1 tablespoon of oil into the cylinder will work. You can do all the cylinders at once but if you do you will shoot oil all over your engine bay so I suggest 1 cylinder at a time.

10. Repeat #7

11. Now you have new numbers I am sure. If these numbers have gone up alot you have some ring issues you may need to fix. if the numbers did not go up much or at all and you have low compression still then you have Valve issues(which is much easier to correct, IMO).

12. Put your old/new spark plugs in and reinstall fuel pump fuse.

Compression Specs

Standard, Minimum (psi)

NA - 186, 142

TT - 171, 128

Also, make sure your battery is well charged. A weak batt will effect your results.

Also you'll need to remove your balance bar to get to the back cylinders, be careful not to loose any of the three rubber O-rings underneath as they are expensive to replace

Close, but this should help

 

The first step in this is fun and all you have to do is drive your Z for about 10 minutes however you like to drive and bring it up to temp. Now that your done with this we will move on the the sucky part of this job.

 

2. Remove your coils being careful not to break the expensive connectors.

4. Remove fuel pump fuse (by the battery)

6. Crank over the motor with the throttle pushed down all the way to the floor, it should take 4 to 9 revolutions for maximum compression to be reached, depending on the condition of your motor.

 

Compression Specs

Standard, Minimum (psi)

NA - 186, 142

TT - 171, 128

 

thanks..

 

right....

 

didn't mention warm car up but knew that.... do'h

didn't mention connectors (kind of obvious)... but work putting in because they are a bit of a pain..

 

4 - fuel pump fuse near batter????? you nicked this from a us site. lol...

 

I was only doing it about 4 times... but good to know that is the minimum..

 

i knew there was a differences in compression for the NA and TT but thought that was in the 186 to 143....

so really good to know that the TT is lower... 128 - 171

 

I'll re do my list so it takes into account all the info that's relevant..

 

thanks to all.. :)

thanks..

 

right....

 

didn't mention warm car up but knew that.... do'h

didn't mention connectors (kind of obvious)... but work putting in because they are a bit of a pain..

 

4 - fuel pump fuse near batter????? you nicked this from a us site. lol...

 

I was only doing it about 4 times... but good to know that is the minimum..

 

i knew there was a differences in compression for the NA and TT but thought that was in the 186 to 143....

so really good to know that the TT is lower... 128 - 171

 

I'll re do my list so it takes into account all the info that's relevant..

 

thanks to all.. :)

 

You didnt think i was going to write that lot out again did you :winkiss:

If anyone is helping you, you will know when you have cranked enough as the gauge won't go up any further

Dont touch the CAS, or you'll have to set the timing all up again with strobe....Even if you mark it, its very sensitive.

Dont touch the CAS, or you'll have to set the timing all up again with strobe....Even if you mark it, its very sensitive.

 

LOL.. disconnect the connector... not remove the unit... :)

OK,

So here’s the revised guide…. Is this OK?

 

 

Prerequisites:

 

A good time to change spark plugs so get a new set (HGK’s PFR6B-11C).

Also a good time to check and clean coil pack connectors, so emery board & contact cleaner.

You may need some silicone gasket sealant or new O rings for the balance bar.

Make sure the batter is up to it (i.e. well charged).

Obviously the right tools to remove the balance bar coil pack brackets and spark plugs.

And again obvious, a pressure tester with 14mm thread, ensure it either has an extension of will fit down the cavity.

 

Compression test:

 

1 - warn the car up to normal running temp (should take about 10 min).

2 - remove, fuel pump fuse (and or disconnect CAS connector) RHD cars - on drivers side near firewall.

3 - remove, balance bar, ensure you do not loose the three rubber O rings/seals,

4 - undo coil pack connectors then remove coil packs and spark plugs (so as to allow as least resistance as possible, battery will last longer).

5 - connect pressure gauge up to one of the cylinders, hand tight.

6 – press fully down on the accelerator and turn engine over, 6 times should get a good reading (this is to open the throttle bodies to allow as much air in as possible).

7 - repeat point 5 & 6 for all cylinders and write down the results.

 

Info and checks:

 

NA - Min 142 psi, max 186 psi

TT - Min 128 psi, max 171 psi

(no more than 14 psi deference between any cylinders).

 

If any of the cylinders are showing lower pressure (obviously check it a few time first and check the pressure tester connection) put a bit of oil in the cylinder (method – one at a time get a small piece of vacuum line or fuel line about 12 inches long. I use a syringe type turkey flavouring injector but anyway you can measure and insert about 1 tablespoon of oil into the cylinder, do the test again and if the pressure looks better after this it would indicate the rings are leaking.

 

If the pressure is still low it would indicate:

 

1 - head gasket (should have other symptoms for this as well, i.e. bubbles/CO2 in the water or possibly if bad enough mayo in water or oil)

2 - valve stem seals (again other symptoms with this, i.e. burnt oil).

3 - valve seats not closed flush (reduces performance and/or un-burnt fuel/ black smoke/backfiring if it’s the exhaust ones).

 

 

Finish:

 

Put your old/new spark plugs in, coil packs, reconnect coil packs (check and clean connectors if needed), balance bar (check O rings) and reinstall fuel pump fuse (and/or CAS connector, check and clean).

LOL.. disconnect the connector... not remove the unit... :)

 

lol ok good, its better for me to say, just in case.

 

OK,

So here’s the revised guide…. Is this OK?

 

 

Prerequisites:

 

A good time to change spark plugs so get a new set (HGK’s PFR6B-11C).

Also a good time to check and clean coil pack connectors, so emery board & contact cleaner.

You may need some silicone gasket sealant or new O rings for the balance bar.

Make sure the batter is up to it (i.e. well charged).

Obviously the right tools to remove the balance bar coil pack brackets and spark plugs.

And again obvious, a pressure tester with 14mm thread, ensure it either has an extension of will fit down the cavity.

 

Compression test:

 

1 - warn the car up to normal running temp (should take about 10 min).

2 - remove, fuel pump fuse (and or disconnect CAS connector) RHD cars - on drivers side near firewall.

3 - remove, balance bar, ensure you do not loose the three rubber O rings/seals,

4 - undo coil pack connectors then remove coil packs and spark plugs (so as to allow as least resistance as possible, battery will last longer).

5 - connect pressure gauge up to one of the cylinders, hand tight.

6 – press fully down on the accelerator and turn engine over, 6 times should get a good reading (this is to open the throttle bodies to allow as much air in as possible).

7 - repeat point 5 & 6 for all cylinders and write down the results.

 

Info and checks:

 

NA - Min 142 psi, max 186 psi

TT - Min 128 psi, max 171 psi

(no more than 14 psi deference between any cylinders).

 

If any of the cylinders are showing lower pressure (obviously check it a few time first and check the pressure tester connection) put a bit of oil in the cylinder (method – one at a time get a small piece of vacuum line or fuel line about 12 inches long. I use a syringe type turkey flavouring injector but anyway you can measure and insert about 1 tablespoon of oil into the cylinder, do the test again and if the pressure looks better after this it would indicate the rings are leaking.

 

If the pressure is still low it would indicate:

 

1 - head gasket (should have other symptoms for this as well, i.e. bubbles/CO2 in the water or possibly if bad enough mayo in water or oil)

2 - valve stem seals (again other symptoms with this, i.e. burnt oil).

3 - valve seats not closed flush (reduces performance and/or un-burnt fuel/ black smoke/backfiring if it’s the exhaust ones).

 

 

Finish:

 

Put your old/new spark plugs in, coil packs, reconnect coil packs (check and clean connectors if needed), balance bar (check O rings) and reinstall fuel pump fuse (and/or CAS connector, check and clean).

 

Yes, all looks good. Warped head, cracked/broken rings and Badly damaged pistons are other causes. The latter 2 indicated by extremely low/zero readings.

 

Overheating, losing water and over-pressurised cooling pipework are other common indications of Head gasket/warped head issues.

Edited September 17, 201213 yr by Yowser

Does your pressure gauge have a solid or rubber shaft to it? Mine had a rubber one that had set a bit bent from the packaging and was a pig to get started into the threads as they are quite deep. I had this problem and left it on a radiator to warm up and then kept bending it back on itself to get it straight again. Something else to note is you should try to get the test completed as quickly as possible after turning the engine off so they are all read at the same temp.

 

Why are you testing your compression?

thanks both... good points....

 

to answer your question... smoke... blue... one side.... almost all the time... worse some times.... :( it's embarrassing :blushing:

 

I keep telling everyone my car is like one of the red arrows.... blue smoke trail....

 

 

currently in talks with Zedworld for scenarios and costs.. :)

 

I've replaced the PVC and even made a bent pipe to see if that would reduce any oil being pushed up it.... made a small difference but the point still is what is causing the oil to be pushed up there...

To me it would suggest valve stem seals.

the fuel would have been under pressure in the rails if you warmed the car up. pressure can take overnight to drain on its own. I notice the step to release fuel pressure has been skipped.( with only the fuel fuses etc removed crank car over until its stops firing at all. then remove plugs etc))

were you pumping vapour into the air? what you wrote sounds messy.GULP!

And you do simply watch the dial on the kit.. when the needle has pumped up-up-up and then peaks at a value you can stop cranking.

Also you might like to do all cylinders then repeat the first cylinder test again- Espesh on a warm car.

Stem seals dont usually cause smoking all the time,smoke at idle and between gear changes.Sounds a deeper issue if im honest bud.

Leaky stem seals will give you smoke on start from cold and will then clear, due to oil seeping into the cylinders over night or while the car is at rest.

 

Are you sure it's not a smokey turbo, if it's piston rings your dip stick could pop out under boost / hard acceleration due to build up of crank case pressure.

 

Though does sound more like leaky turbo seal if it's doing it on idle and it's defo oil smell (light blue tinge to the smoke)

smoke sucks. currently going through this atm myself although thanks to a few members im pretty sure its the tub seal or two an the block is basically out thanks to hellraiser.

the fuel would have been under pressure in the rails if you warmed the car up. pressure can take overnight to drain on its own. I notice the step to release fuel pressure has been skipped.( with only the fuel fuses etc removed crank car over until its stops firing at all. then remove plugs etc))

were you pumping vapour into the air? what you wrote sounds messy.GULP!

And you do simply watch the dial on the kit.. when the needle has pumped up-up-up and then peaks at a value you can stop cranking.

Also you might like to do all cylinders then repeat the first cylinder test again- Espesh on a warm car.

 

Thanks, and good point, and exactly what I did when doing the test…. But brain slip when doing the guide..lol..

Couldn’t get the gauge to face the cabin on all cylinders so could only see it a few times, really need another set of eyes or a mirror..

 

 

Stem seals dont usually cause smoking all the time, smoke at idle and between gear changes. Sounds a deeper issue if im honest bud.

 

right I see… not what I want to here.. thanks… :)

 

 

 

Leaky stem seals will give you smoke on start from cold and will then clear, due to oil seeping into the cylinders over night or while the car is at rest.

Are you sure it's not a smokey turbo, if it's piston rings your dip stick could pop out under boost / hard acceleration due to build up of crank case pressure.

Though does sound more like leaky turbo seal if it's doing it on idle and it's defo oil smell (light blue tinge to the smoke)

 

Cheers, I should have put a bit more info in the post.

Right so this is only the passengers side.

A little smoke just after it fires up, not as soon as you turn the key.

Not really any at idle, although you can smell it a bit.

Then almost none, and slowly it starters to come back.

Mostly at low revs or when hitting the throttle hard.

Hardly any visible on the motorway but I guess travelling at 70 would disperse little amounts.

If I sit and blip the throttle (not hard) it puffs out smoke.

 

I thought turbo straight away and took the TB pipe off… clean as a whistle !!!

 

The dipstick isn’t popping out and the oil pressure seems fine (not too high).

 

I went to a wedding last weekend and had clouds of the stuff out the back driving around lanes.

 

The next day I swapped out the PCV on that side and made a “U” bend pipe, that helped with the clouds on smoke but the other symptoms are exactly the same.

 

 

And thanks to all for your replies… :)

Have a look over my thread your describing near on tge same issue.

ta...

 

which one? you have quite a few... can't really tell by the heading.. :)

 

 

I hope there is a solution.. (that I'm going to like.... I don't like sad endings.. lol)

Edited September 18, 201213 yr by Medallion Man

Its tittled.

"seriously disheartened just wanna burn the car now"

Haha time will tell I want it back but if it doesnt fix it jesus im gonna be fed up.

Pop off the exhaust and turbo elbow probally passing oil. Mine looks totally healthy sadly

Ah, right you're saying the oil is going out the turbo seal to the hot side....

 

I did wonder about that but from all the stuff I could find it's very rare.... I'm running JWT 530BB's got them already on the car, can only assume their about 5 years old.

Ah, right you're saying the oil is going out the turbo seal to the hot side....

 

I did wonder about that but from all the stuff I could find it's very rare.... I'm running JWT 530BB's got them already on the car, can only assume their about 5 years old.

 

hrm yeah i spose from what i understand its the rear seal so it venting directly into the exhaust tract. wasnt aware it was rare seems to be quite common on stock tubs at least.

have you elimated everything else?

no... :(

 

can't see any oil in the intercooler pipe to the TB.

changed the PCV and it kind of reduced it a bit.

compression on the three cylinders on that side are around 140 (but really should to do it again with all plugs out and throttle open).

 

I read on the Oz forum that the X or H pipe exhaust can cure the issue with smoke due to leaky turbo (however does sound a bit like magic to me).

then again, a lot of the guys swear it works....

 

This is what one of the posts I found says:

 

Depending on your exhaust design, often an easy fix is having a H pipe fitted just behind the cats. A H pipe is just a short length of pipe which joins the two sides together. This has been very succesfull in the past with similar complaints to yours. Your exhaust guy and mechanic will both tell you it won't work, but just get it done. For the $50-100 it may cost it could very likely fix the issue.

 

The reason it works is a bit technical and I don't claim to completely understand frequencies and wavelengths etc but basically each cylinder puts out a pulse into the exhaust, the frequency and timing of these pulses can coincide with the resonant frequency of the turbine seal. That seal is exactly like a piston ring in type and operation, using the pressure in the turbine housing to force the seal into the inner edge of the groove and the bore surface of the turbo chra.

 

When that seal vibrates or more accuratley resonates, it can no longer stay in proper contact and allows oil past. Fitting the H pipe allows both sides of the engine to flow into a common chamber, with opposing pulses cancelling each other out you increase the resonant frequency to a higher level. At that higher level, you have more rpm, load and therefore exhaust pressure to over come the vibration of the seal.

I sent an email to JWT on the 13th Aug asking about the possibility of oil leaking out the hot end but didn't get a reply, I've just sent it again.

 

I'll be taking it to Zedworld to get it sorted anyway as I also need a number of other jobs doing that I would rather they sorted.

 

so have you taken the elbow/s off?