Intermittent oil burn

[Aestysu]

Intermittent oil burn

Noticed past few weeks my car (r33 rb25det) has been intermittently burning oil, some days it wont lose any, others the oil level would have dropped by about 1/4 on the dipstick (this is with about 20-50kms a day driving). No leaks under the car, car doesn't blow smoke unless im under boost, after a cold start theres a slight mist but clears quickly. With a warm engine and in neutral holding at 2k theres a bit of smoke. Put a catch can in last week, havent checked to see if its caught anything but also havent really driven it enough,

Car still pulls hard no power loss from what i can feel. Smoke is a light blue sort of color.

Did a dry comp test and results were 135, 135, 120, 120, 135, 135. Put some oil down the cylinders for a wet test and results didn't really move.

 

Results arent great but im not sure my comp tester is the best either. But either way im thinking possibly valve seals? i took the pcv out and shook it but only read recently to try blow it and see if it only goes one way or something? Only mods are 3" turbo back exhaust, and a FMIC. Using penrite 10 tenths 10w40.

[KiwiRS4T]

Comps are low but car could go ok for years. Leak down test may tell you more (re valve seats e.g.)

Driving test for burning oil:   build up some speed in third, lift off for a few seconds and then floor it. Blue smoke is oil.

Oil is cheaper than a recond!!

[Aestysu]

On 3/6/2017 at 9:53 PM, KiwiRS4T said:

Comps are low but car could go ok for years. Leak down test may tell you more (re valve seats e.g.)

Driving test for burning oil:   build up some speed in third, lift off for a few seconds and then floor it. Blue smoke is oil.

Oil is cheaper than a recond!!

Yep blue smoke. I can notice it when i down shift sometimes as well. Last topped up the oil was about 50km ago, will check oil level in the morning to see how much, if any it has dropped since then. ill check my catch can as well. Im assuming if its valves, rings, anything the catch can should be picking up quite a bit? Ill have to check that on the weekend when i have more time. I have it plumbed in like this

[SkudR33]

If you blowing oil on deceleration, especially down them big ass hills it generally tends to lean towards blown turbo or valve stem seals...

 

If blowing oil on cold start it could be cracked ringlanding or bad valve stem seals...

 

If you blowing oil on hard acceleration it could be rings, ringlanding or turbo seals...

 

It's honestly such a flamin mongrel to find the issue...

 

 

Steps to resolve this:

1. Both dry and wet compression test.

2. Leakdown test.

3. Check turbo for shaft play.

 

 

From my personal experiences, I had blue smoke on cold start and under high boost/rpm application. Lasted 12 months and my engine crapped itself- turned out I had a small hairline crack in the ringlanding which developed to a catastrophic crack.

 

If you are from West Sydbey, I can refer you to the guy I used to work for - he has a fetish for jap cars!

[Aestysu]

Checked the oil. done ~80ks since i topped it up and its lost about 100ml. Cant see anything in the catch can checking window thing but i havent opened it up to see inside.

 

I changed turbo last month thinking the issue was the turbo because it was making some annoying loud whining sound. So i dont think its the turbo again but who knows could be. Turbo i put in has slight in out and back and forward shaft play, very slight.

When I say blows smoke. Cold start is very very slight and clears quick. Can't see it in rear view mirror. The only time I can notice the smoke is on a heavy down shift or boosting. 

 

But that wouldnt explain my wet compression test not bringing my numbers up, unless the kit im using is shit.

 

I want to do a leak down test but dont have a kit, gotta try see if one of my mates has one.

 

It's now blowing huge amounts of smoke. But just enough to notice if that makes sense. 

Edited March 7, 2017 by Aestysu

[SkudR33]

I'd put my dollars on valve stem seals then cause your compression numbers aren't bad enough to be blowing oil out your exhaust... also note that if results are unchanged between wet/dry compression test it generally means rings are not your problem... sometimes valve seating can cause a drop in compression. That's another whole issue to worry about but should not result in burnt oil!

 

Plus you just changed turbo and a little bit of shaft play shouldn't be causing any issues like what you're explaining...

 

Dude one other thing, make sure your pcv isn't seized up... it really assists in lowering crank case pressure when the manifold is in vacuum. It's an easy thing to look at while you wait to do a leak down test!

 

[Aestysu]

19 hours ago, SkudR33 said:

I'd put my dollars on valve stem seals then cause your compression numbers aren't bad enough to be blowing oil out your exhaust... also note that if results are unchanged between wet/dry compression test it generally means rings are not your problem... sometimes valve seating can cause a drop in compression. That's another whole issue to worry about but should not result in burnt oil!

 

Plus you just changed turbo and a little bit of shaft play shouldn't be causing any issues like what you're explaining...

 

Dude one other thing, make sure your pcv isn't seized up... it really assists in lowering crank case pressure when the manifold is in vacuum. It's an easy thing to look at while you wait to do a leak down test!

 

Leak down tomorrow most likely, ill check pcv as well.

 

Had to top up oil today again. Ive gone through about 2L in 600kms. Seems like a whole lot especially when im not smoking at all unless under load etc. Checked my catch can, bone dry. Any possibility of a leak somewhere? but nothing under the car so doesnt seem like it. If i leave the car sitting and dont drive it oil stays at the same level. I checked my intercooler piping, pretty much no blowby, throttle body clean as well as my dump. Noticed today as well sometimes when i take off at the lights, not aggressive or anything, but i can really notice the smoke the, its not insane but enough to see out the back window.

 

Anyway, lets see what this leakdown tells me.

Edited March 10, 2017 by Aestysu

[KiwiRS4T]

a litre per 300 is a bit much. Hope its just valve stem seals

[SkudR33]

a litre per 300 is a bit much. Hope its just valve stem seals

It sounds extreme right - I'd imagine they'd be smoke pouring out everywhere and it would be catastrophic!

[Aestysu]

ok boys well this weekend didnt go to plan, saturday didnt really do anything beside weld and wire up my afr gauge. went to do the leakdown today and the bloody kits end that goes to the compressor hose was a different size. so during the week i need to get an adapter or something. and as i was doing all that i left the damn ratchet on the crank bolt and turned the engine on for like 2 seconds before i realised, and it loosend it, so had to put that back in. zzzzzz

[Aestysu]

Alright finally got the leakdown done. Bad news piston 1 rings. air leaking through dipstick/oil filler cap. But compression was still alright. No idea how bad the leak is because my leakdown tester is a bit weird but definitely 1st cylinder.

 

Thinking what to do from here? do i urgently get a new engine/get a rebuild done/just drive it for a little while till the first two options happen?

[SkudR33]

Dude can I just ask did you have piston at tdc when you did the leakdown test? Did you also make sure the engine is at operating temperature. You do realise if the valves in the head are open it will give you a false reading...

If you did do the test correctly, you gotta understand no engine will have 0% leak because an engine needs to allow crank case pressure to escape. Crankcase pressure travels to your dipstick, oil filler cap, pvc and any other head drains which may be present. On average most engines leak between 5-10% of the air which is compressed into the cylinder. You really need to have a gauge that tells you how much air is leaking out. If you find you are leaking more than 10% but below 20% it just means engine has some wear on it however once you start passing mid 20's it means you got a major problem.

You need to redo the test and get the actual percentage of loss which is occurring... unfortunately if you did the test correctly and you have a 30% leak going through the cap and dipstick it means you got piston landing or ring issues...

[Aestysu]

Haha my last post sounded back but yeah was at tdc and at temp. 

My tester was just a bit weird and wouldn't go to 0 while still having air go through it. So when I was testing the needle wasnt on 0 so I don't know exactly how much it was leaking but it was moving and the air escaping was definitely more noticeable than the other cylinders. 

I found a long motor for 900$ good health 155 comp per cylinder. So I figured why not just swap it over. Either way it's burning quite a bit of oil and probably won't be able to fix it without at least taking the head off. swap them over at home with some help from a mate. Get to learn a bit as well. Also have a turbo coming this week so I'll just drop everything in at the same time. 

[SkudR33]

Yeh may aswell just swap it over... then you can also rip apart the old one and find out exactly what your problem was!

Good luck with it all.