Changing Piston Rings

[Ant 2]

Due to low compression test results i suspect my 2.0 turbo needs new pistons rings.

 

I've read Toms interesting thread about how he rebuilt his bottom end, but could do with a few pointers.

 

Does the engine need to be removed, or can i swap the rings with the lump still fitted. Its not an issue having to remove the lump and i'd prefere to do this if it saves time ( and my skin lol ) in the long run.

 

How am i best accessing the old rings. I am removing the head anyway, so is it possible to do from the top of the engine ?or do i need to access via the sump ?

 

Also, any other special tools? I saw Tom used a piston ring compressor. I can buy one of these off ebay. Do i need anything else?

 

And finally, anyone recommend a good place for the rings ? My local motor factors dont stock them. Cheers

[Miles 331 1 Cars]

To cut a long story short, Dont do it

 

Reason being is the Iron blocks suffer from bad bore wear compared to the alloy blocked engine's, The engine would need a full strip down, Block honed to suit the new ring's.

This then show's up the bore wear which 90% of the block's I've come across has this problem and I see allot of these engine's, so unless you re-bore them the block is then U/S

[Cameron 16]

QEP or Peugeot for the rings, not worth getting the cheap ones. You'll also need to get your liners honed or get new liners, depending on the condition of them. As for tools you'll need a piston ring compressor and a torque wrench, otherwise just normal tools.

 

You'll need to have the head and sump off to do all this, so its probably best to just take the engine out.

 

Edit: Ah, just noticed Miles' post an its an iron block. So yeah, what he said.

Edited January 11, 2009 by Cameron

[iamjackiechan 0]

dont bother buying the ring compresser, its alot easier by hand

[welshpug 1,651]

buy the ring compressor, rings are bloody sharp and fragile!

[Ant 2]

Cheers Gents,

 

Although im still not sure its the rings. Ive done all this becuase of Oil forced from the breathers. Engine is relitebly low Millage ( 70k now ) but had a Full service history.

 

Took the head off this weekend and looked at the pistons. There is hardly any wear at all on the top part of the liners and i can barley feel any lip once i gently wiped th greese away. A lot less than an old 1.6 lump i had in the garage.

 

So im at a loss. No Smoke, no rattles, pulls nice and strongly, but spits oil out

[Alteran 1]

If it doesn't smoke when revved up and the oil doesn't smell fuelly then it's doubtful it's piston rings. You say you now have the head off so 70% of the work is done for changing the rings. If you want to go ahead then just remove the sump and loosen the big end bearing bolts. Then carefully push the pistons upwards which pop out the top. A honer on a drill will scratch the liner surfaces up which is essential as the new rings will not bed in. ALWAYS use a ring compressor, they are delicate and you risk breaking them as welshpug states. You say you had low compression so lap your valves in on your head as it could be a valve seat problem. With the head still on it would've been easier to check if a valve was leaking by doing a cylinder leak test. But as you have it off then lapping them in is the only way to go really. Good luck mate! Soz for the essay!

[yorkshirekowboy 19 1 Cars]

I've read Toms interesting thread about how he rebuilt his bottom end, but could do with a few pointers.

 

 

so to butt into your thread mate but toms thread about his rebuilt bottom end, where is it in the forum?

 

thanks

 

d

[dcc 855]

Im not sure if you need to undo the big end bearings? i certainly didnt haveto on mine, undo the mains to allow the rod to come up through the bore, but i took the liners out on my 1.9 block. when you take them out, be care not to let the rod hit the side of the bore, wouldnt have thought it would do much damage, but you never know ;')

[Cameron 16]

Don't change the rings just for the sake of it. You will have to get the bores honed too otherwise the new rings will not bed in. You'll just end up down on power and with horrendous blow-by.

Have you checked all the breathers? Incorrectly routed or blocked breathers will cause oil to be chucked all over everywhere.

Edited January 28, 2009 by Cameron

[Alteran 1]

Main bearings are what the crank spin on, big end bearings are between the con rod and cap. But i agree with Cameron, if replacing the rings are not necessary then don't do them. So do you have a engine thats breathing heavy or low compression?

[Anthony 1,002]

Did you do a wet compression test? If it was ring issues causing low dry compression test, you'd expect it to increase considerably with a wet test, whereas things like a failing headgasket or valve seats wouldn't.

[Ant 2]

surferkid - This is toms thread. Very good read with loads of pics

 

http://forum.205gtidrivers.com/index.php?s...c=87784&hl=

 

Compression test result was about 130-135 psi across all 4 cylinders. Added some oil and was getting 145 ish, so not a massive increase.

 

Its not the head, as ive this totally rebuilt - Wondering if it is just a breather issue ?

 

I thought 130 - 135 was low , but it is a low compression engine, so can anyone tell me if this is an okay figure ?

 

cheers for the replies folks

[Anthony 1,002]

If you've equal compression across all four cylinders and it doesn't increase much if you add some oil, I'd be doubtful that it's rings, especially given the mileage.

[Ant 2]

Well i purchased a new head set this weekend, cleaned off the reminants’ of the old gasket and then was about to put the head on.

 

The head was skimmed about 12 months ago. Then i noticed the slight reses that are no longer much of a reses. You can feel very little of the reses when i run my finger over.

 

 

 

 

 

 

I had a spare 2.0 head and checked that. There are deeper reses on this head. I’m presuming this indicates it hasn’t been skimmed.

 

Could this skimming account for any of these issues. Below is a pic of the spare head. The lip on here is noticeable when you run a finger over.

 

 

 

Would this make a difference ?

 

The other thing i’m wondering ( but doubtful ) is the actual turbo. Could worn seals be causing oil to pressurise ?

 

Heres a pic of the turbo. There is “VERY” slightly play, but i do mean very and its side to side. I read somewhere that this is normal anyway, and this is reduced when oil is circulated...

 

 

 

Oh and finally, for the heck of its heres the block.

 

As i mentioned before, there is a slight lip at the top.. But hardly noticeable at all.

 

 

Thoughts folks ?

 

Cheers

[Tom Fenton 1,539]

Your skimmed head looks perfectly OK to me. Those "recesses" make no difference.

 

I've never head of the turbo doing as you describe either.

 

I'd get a proper bore gauge and measure the worn area and unworn properly.