Smokey Piston rings??
Turbo Mini Forums

Any advice on piston rings? I have Omega pistons & rings and after 23000/4 years they need to be changed due to a bit of smoke although boost and performance great still.
Compression ok, all 4 at 162psi +-2psi Turbo New and OK, head Recently reworked and OK.

are you sure its not valve wear.... or turbo wear?

Alex

AlexF

Alex,

I Know its not the Turbo cos Even with the oil supply pipe off I get a bit of smoke (mini stationary, just a bit of throttle from idle) also this is a new Turbo from Universal.

I guess it is based on a very old T3 design now compared to whats fitted to newer cars, on boost its fine..

I had slark check the head, they found it to be very good but as it was off they replaced everything, re-ported it etc, then fitted new valve guides, stainless race valves/valve springs, new oil seals etc etc..

I have seen alot of mini turbo'd and NA smoke slightly maybe I am being too fussy?

I was running 10W40 oil for ages but have since seen the light and now use millers sport 10W50 which upped the oil pressure when very warm.

Cheers

Does it smoke on boost or vacuum?

Minis do smoke... some what anyway....

How much are you talking about?

Can you see it when driving or do you have to be behind the car?

AlexF

Guys,

Not on boost, when I am really going for it, its OK I can't see any smoke behind me, just a bit on start up and if its been idling for a while and I then pull away like in traffic I get a little puff, this could well be the Turbo just leting a bit of oil get by the seals, but It doesn't do it idling forever in the garage.
It has got drastically better since I have been using the millers oil.
I don't really notice the oil drop and a I use the car on any dry day and wet if I can't get my old pug goin, so its not using too much oil?

Sounds more like valve seals to me.

Sounds like valve guides/seals to me too.

Well, what you describe is a classic sympton.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

would you not lose a bit compression if the rings were goosed ? may be worth putting a gauge on and trying........also i have a question, would castrol R40 oil be ok in turbo engines, i use it in all my race n/a stuff, and it smells soooo nice !

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MikeRace, Mini13

before strip down i would do a leak down test first that will tell you for sure.

but sounds like normal turbo smoke to me due a bit of oil dripping down via the guides.

try jacking front of car up leave running for a while then see if it smokes if it doesnt then the problem is the guides but it seams normall to me.

always looking for them bigger bunches of bannanas

Defo guides/seals

AlexF

Did you do a full compression test?

IE wet and dry?

Alex

AlexF

Alex,

I did a warm compression test which was OK I then did a cold test the next morning that was different, can't remember the figures now but one cylinder was lower still not 10% lower from what I can remember.

I will try again at the weekend, and will do a leek down test as this seems to be a different way on checking for good compression.

Thought R40 was very thin, does smell nice in a mechanical way..

N

Ok...

you need the engine warm not cold but you need to do a few other things to...

like hold the throttle wide open...

also

DRY / WET, you've done the 1st one.

But right after that you need to tip about a teasoopn of oil down the spark plug hole. This will temporarly seal the rings and show wether the compression leaks are from the rings or the valves.

Alex

AlexF

Castrol R is a very very old oil.

Its also not very good, it was 40 years ago thou lol

In a turbo it will solidify and knock out the bearings very very rapidly. It doesn't like heat at all.

Its also a poor lubricatnt at most running temps as its a monograde!




Alex

AlexF

Alex,

I had the throttle open all the time, sorry I should have said.
I was sort of testing to see the differencr between hot and cold, hence the cold test, but it didn't rrally show anything..
Ok so dry done! I will get my oil can out and skirt a bit in to each piston (will it really get all the way round and seal?) I'm up for giving it ago anyway.
Will let you know how I get on..

On another matter I am on the look out for a twin injector throttle body, I have seen the jenvey one, awkward but good, bit expensive though..so if anyone knows of a good source anywhere (even the USA).

N

It will...

give it a wirl!

Let us know the results!

Alex

AlexF

Results were as follows

Dry with warm engine, just got home from work. Engine turned over 8 times, throttle open.

cyl 1 145psi
cyl 2 145psi
cyl 3 147psi
cyl 4 145psi

Wet with warm engine (6minutes after previous test) oiled. Engine turned over 8 times, throttle open.

cyl 1 160psi
cyl 2 160psi
cyl 3 167psi
cyl 4 160psi

Used Snap-on 250psi gauge and screw in adaptors..

I think all 4 piston rings are Knackered?????

N

Fairly conclusive, but hey I know nothing.


Alex

AlexF

Nigel, from that increase in compression when the test was done "wet", it seems that your rings have perhaps seen better days. However, I personally would not rip it to bits just yet, OK, you now know it is going to need rings at some point, but it hasn't got to a desperate state just yet, so you may as well continue to use it until it becomes a bad enough problem from oil consumption or visible smoke to demand action.

Thanks for all the advice, I think new rings are needed, I will order today but I will wait until it gets worse/xmas as I don't want to lose driving time, still more saxo's to upset..and I hate driving my pug!

On 02/11/2005 16:47:50 AlexF2003 said:

Castrol R is a very very old oil.

Its also not very good, it was 40 years ago thou lol

In a turbo it will solidify and knock out the bearings very very rapidly. It doesn't like heat at all.

Its also a poor lubricatnt at most running temps as its a monograde!




Alex

i thought it had one of the fastest recovery rates in the game, also its "hydroscopic" thinks thats the word cant remember but it keeps water/ moisture away also used to keep the engine lovely and clean, i have used it in full race n/a engines 4 years and never had problems with it just wondered about turbos tho looks like it will be a boring fully synthetic oil then...back to my old sponsors at esso

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MikeRace, Mini13

my advice is the same as toms