Jump to content
SAU Community

Recommended Posts

Did someone say fight..........[running fast but careful not to spill or drop stubby]!!!

I usually put my hand over the rocker cap area and measure how hard it trys to blow it off, but then I'm no garage or tuning expert.....thats how bad I think its choofing and the thread starter didn't ask for any specific car, just what is blowby? Just as long as we don't start on negative crankcase pressure hey.......

  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

guilt-toy post up ur opinion mate, would be good to hear some more of the experienced guys opinions

on a side note, is it really possible to get an idea of the condition of a engine by going off the oil filler cap? and are all engines the same/similar? (elite mentioned before nissans are sealed engines). or is it better to compression/leak down test. main reason i wanna know is when your going to look at a car to buy alot of the time its hard to a full on compression test over all the cylinders, testing via the filler cap would be a much much quicker way

excessive is filling a 2L catch can after a few laps of a track with oil.. simple as that haha.

i got a question tho.. does hitting the limiter have an affect on blow by at all?

Well.....not really.

There is a difference between excessive blowby and cam cover filling. If you have a high volume oil pump, your engine can still be very healthy and fill a 2L catch can.

Fineline's R33 is a perfect example......cannot get one drop of oil to go into his primary can on the street or on the dyno but throw a high speed corner in and 2L in 3 laps of QR. That's purely because the head is hydraulic and we can't limit the oil to the top otherwise he will wear out his valvetrain components. It's also a street car so we need to consider this as well.

Excessive blowby will do things like push the dipstick out (but even that can be tricky as most of the dipsticks are old these days so they don't seal so well anyway). It can pump oil into catch cans but if it's not doing it in a straight line at high rpm then I suggest the problem may not be excessive blowby.

Yes detonation or missfiring or hitting the rev limiter will cause torsional ring twisting which does create excessive blowby but only for the duration of the missfire.

Well.....not really.

There is a difference between excessive blowby and cam cover filling. If you have a high volume oil pump, your engine can still be very healthy and fill a 2L catch can.

Fineline's R33 is a perfect example......cannot get one drop of oil to go into his primary can on the street or on the dyno but throw a high speed corner in and 2L in 3 laps of QR. That's purely because the head is hydraulic and we can't limit the oil to the top otherwise he will wear out his valvetrain components. It's also a street car so we need to consider this as well.

Excessive blowby will do things like push the dipstick out (but even that can be tricky as most of the dipsticks are old these days so they don't seal so well anyway). It can pump oil into catch cans but if it's not doing it in a straight line at high rpm then I suggest the problem may not be excessive blowby.

Yes detonation or missfiring or hitting the rev limiter will cause torsional ring twisting which does create excessive blowby but only for the duration of the missfire.

cool thanks for that.

last track day i got a tiny bit of oil in catch can but motor saw limiter a lot and was over full as well.. think they were factors.

in my CA18's case.. few laps it would empty the sump. oil everywhere, dipstick went flying and run like shit.... pretty sure that was excessive blowby :D

cool thanks for that.

last track day i got a tiny bit of oil in catch can but motor saw limiter a lot and was over full as well.. think they were factors.

in my CA18's case.. few laps it would empty the sump. oil everywhere, dipstick went flying and run like shit.... pretty sure that was excessive blowby :D

Haha yeah I think that CA was trying to tell you something.

Many of you have absolutely no idea what 'excessive' is.

If you take the oil cap off any of the nissan turbo engines, the engine should drop in idle or nearly stall. They are a sealed engine. The cylinder head is SPLASH lubricated so it is meant to throw oil around there.

Fumes coming from the rocker cover breathers or out of the oil cap means nothing. The engine has to breathe. If it doesn't, bad shit happens.

The most annoying thing to hear is ppl going on about so called 'blowby' because when the car is on the dyno, fumes were coming out of their catch can breather or from their cover breather.

I know cars drop revs. But this thing was dying, no two ways about it.

I have not seen an RB with such an issue yet. I can assure you none of my Rb25s (or mates RB20s) have come anywhere near dying when removing the cap, nor is there any real "choofing", and as for oil, one or two splatters on the cam cover only.

The S15 was in a different league, and yes, thats a different league to the other S15's I checked. A friends S15 checked the very next day seemed to have a nice choof, but would idle, and not splatter oil everywhere. The S15 I checked was litterally blowing oil out, not splattering it.

IMO thats excessive. Also noticable on shut off, the engine ran on, which I saw as a sign of low compression in the cylinders.

Everyone has different ideas on blow by and what is 'excessive', but I'm happy I walked away from that one! I won't be touching one again in that state either :happy:

I know cars drop revs. But this thing was dying, no two ways about it.

I have not seen an RB with such an issue yet. I can assure you none of my Rb25s (or mates RB20s) have come anywhere near dying when removing the cap, nor is there any real "choofing", and as for oil, one or two splatters on the cam cover only.

The S15 was in a different league, and yes, thats a different league to the other S15's I checked. A friends S15 checked the very next day seemed to have a nice choof, but would idle, and not splatter oil everywhere. The S15 I checked was litterally blowing oil out, not splattering it.

IMO thats excessive. Also noticable on shut off, the engine ran on, which I saw as a sign of low compression in the cylinders.

Everyone has different ideas on blow by and what is 'excessive', but I'm happy I walked away from that one! I won't be touching one again in that state either :happy:

Yes certainly if there is a noticeable difference between two cars the same, you can use that to gauge what is excessive or not. Only using your post as an example because the revs will drop and oil will come out if you take the cap off. Some ppl will read about the revs dropping and soon everyone will be stressing about buggered engines lol.

Engine dying is not a good sign, unless the idle was a little too low already. But yeah, referring to your better judgement is always best. My main point in all of this is basically that not everyone should stress out about oil in a catch can or fumes coming from breathers.

Hopefully the ppl who read from top to bottom of this thread will be able to use the information to be able to gauge it for themselves when they inspect a car. But when in doubt, get a leakdown test done.....they don't lie when done properly

The revs dropping and/or stalling is due to the PCV and exh cam cover -> turbo inlet breather correct? And the fact they are drawing in a small amount of un-metered air?

Assuming that the car still has the factory AFM setup that is.

The revs dropping and/or stalling is due to the PCV and exh cam cover -> turbo inlet breather correct? And the fact they are drawing in a small amount of un-metered air?

Assuming that the car still has the factory AFM setup that is.

Yes that is correct.

However, it's not like introducing a direct leak to an intercooler pipe, it's more of an in-direct addition of unmetered air through the ventilation system into the intake

The more boost I run the more hydrocarbon liquid stuff ends up in the can, 11 psi I get nothing but at 15 psi after a track day I get 100-200 mils, no oil though, Im running R compound tyres but I don't think my balls and skills are up to pushing to many G,s.

Think I need to go faster through corners but someone keeps staying on the brake for to long.....................

The more boost I run the more hydrocarbon liquid stuff ends up in the can, 11 psi I get nothing but at 15 psi after a track day I get 100-200 mils, no oil though, Im running R compound tyres but I don't think my balls and skills are up to pushing to many G,s.

Think I need to go faster through corners but someone keeps staying on the brake for to long.....................

Easier said ten done, but commitent is the key! go into a corner half arsed and its all over from the start. Commitment to the terrain seperates the man from the sheep!

What about white smoke out of the tail pipe. I just noticed some more than normal blowby after installing this turbo. Im thinking its blowby from the piston rings b/c at idle im seeing smoke from the cacth can and the oil dipstick when removed. It could be the turbo but doubt it. The dipstick hasnt popped out after hard acceleration yet..

What about white smoke out of the tail pipe. I just noticed some more than normal blowby after installing this turbo. Im thinking its blowby from the piston rings b/c at idle im seeing smoke from the cacth can and the oil dipstick when removed. It could be the turbo but doubt it. The dipstick hasnt popped out after hard acceleration yet..

You'll see some smoke in any and all cases, just differing amounts.

A compression test + leakdown test will answer your question properly.

Ask any decent mechanic who is wearing his mechanics uniform in the mechanics workshop.

Not the internet mechanics with propeller hats. Try and imagine every post ITT coming from the same person. lol..

(I am an internet mechanic with a propeller hat as well so you know.)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers) Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose). Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom. For the pan, the workshop manual states the following order: Again, the torque is 8Nm only.
    • One other thing to mention from my car before we reassemble and refill. Per that earlier diagram,   There should be 2x B length (40mm) and 6x C length (54mm). So I had incorrectly removed one extra bolt, which I assume was 40mm, but even so I have 4x B and 5x C.  Either, the factory made an assembly error (very unlikely), or someone had been in there before me. I vote for the latter because the TCM part number doesn't match my build date, I suspect the TCM was changed under warranty. This indeed led to much unbolting, rebolting, checking, measuring and swearing under the car.... In the end I left out 1x B bolt and put in a 54mm M6 bolt I already had to make sure it was all correct
    • A couple of notes about the TCM. Firstly, it is integrated into the valve body. If you need to replace the TCM for any reason you are following the procedure above The seppos say these fail all the time. I haven't seen or heard of one on here or locally, but that doesn't mean it can't happen. Finally, Ecutek are now offering tuning for the 7 speed TCM. It is basically like ECU tuning in that you have to buy a license for the computer, and then known parameters can be reset. This is all very new and at the moment they are focussing on more aggressive gear holding in sports or sports+ mode, 2 gear launches for drag racing etc. It doesn't seem to affect shift speed like you can on some transmissions. Importantly for me, by having controllable shift points you can now raise the shift point as well as the ECU rev limit, together allowing it to rev a little higher when that is useful. In manual mode, my car shifts up automatically regardless of what I do which is good (because I don't have to worry about it) but bad (because I can't choose to rev a little higher when convenient).  TCMs can only be tuned from late 2016 onwards, and mine is apparently not one of those although the car build date was August 2016 (presumably a batch of ADM cars were done together, so this will probably be the situation for most ADM cars). No idea about JDM cars, and I'm looking into importing a later model valve body I can swap in. This is the top of my TCM A couple of numbers but no part number. Amayama can't find my specific car but it does say the following for Asia-RHD (interestingly, all out of stock....): So it looks like programable TCM are probably post September 2018 for "Asia RHD". When I read my part number out from Ecutek it was 31705-75X6D which did not match Amayama for my build date (Aug-2016)
×
×
  • Create New...