got a big problem - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 08-23-2007, 11:55 PM   #21
Senior Member
iTrader: (3)
 
Join Date: Apr 2007
Location: Odenton, MD
Posts: 713
Total Cats: 0
Default

'I believe when the crankshaft becomes pressurized it pushes oil past the rings? Don't quote me, but i think that's what happens. All i can tell you is it isn't good and it has caused smoking.... not necessarily the smoke screen style. It also leads to oil splattering all over the engine bay.
Dow.tom is offline   Reply With Quote
Old 08-24-2007, 12:09 AM   #22
Junior Member
Thread Starter
 
Join Date: Nov 2006
Posts: 158
Total Cats: 0
Default

i mean you get some pressure but i dont think enough to push oil all they way up . sound like you would have to have bad rings to that witch would cause alot of blow by, oil coming out of the breather, low compression test and would have shown up on the leak down. i mean ill try the pcv thing but ill put money on it that it dont work in my application.

the car smokes bad during idle and when applied gas its smokes like crazy. all under my is black.
what miata? is offline   Reply With Quote
Old 08-24-2007, 12:10 AM   #23
Senior Member
iTrader: (3)
 
Join Date: Apr 2007
Location: Odenton, MD
Posts: 713
Total Cats: 0
Default

well re routing it is a good start... im not sure what would cause that much smoke... i'd think something to do with your routing or rings cause it's under throttle.
Dow.tom is offline   Reply With Quote
Old 08-24-2007, 01:28 AM   #24
Newb
 
Join Date: Aug 2007
Location: Spokane,WA
Posts: 15
Total Cats: 0
Default

1: I'm still in the process of Turbo'ing my Miata, but I have turbo experience on other motors. In my experience I have had a lot of difficulty finding a PCV that can properly withstand the pressures of a turbo charger. Even stock units seem to allow seepage. I found that mid to late 80's Nissan's have a METAL one way check valve for there brake booster. This check valve is absolutely awesome in keeping boost from seeping past the PCV, I always put one between my intake and PCV and intake and brake booster. Be careful some of these check valves are PLASTIC and do not work as well, thus you'll need to hit up a junk yard to find the good one's since I'm certain that all aftermarket one's will be plastic.

Now, on to why you should have a PCV. The PCV is only removing crankcase pressure when your intake manifold has less pressure than the crankcase. When in boost it serves no purpose. Now, whenever the motor is running there will ALWAYS be some blow-by (combustive gas that seep past the piston rings). This blow-by WILL add pressure to the crankcase, this increase of pressure must be overcome for the piston to travel back downwards. If the pressure in the crankcase become too great you can blow things like your oil pan gasket (I've done it with a bad PCV before).

Now if the de-pressurizing of the crankcase doesn't happen when you're in boost, why is it important? Even a turbo motor doesn't spend 100% of it's running time in boost. Every time you shift there is a great surge of vacuum generated, this vacuum will evacuate the crankcase.

Okay, one more point to make, why it's not beneficial to vent the crank case to the atmosphere. Atmospheric pressure is around 14.7 psi (at sea level). Now assuming that that itty bitty hole for the old PCV valve can provide enough flow to equalize the pressure of the crankcase between shifts you still have 14.7 psi of pressure in your crank case. Having the PCV in place allows you to remove much more of this unwanted pressure in the same amount of time.

I hope that clears things up a bit.

2: Dow.tom, I can't PM yet, but I'm interested in the '94 ECU you have. I have a buddy with a Festivia with the 1.8 Escort GT motor (practically the same as the Miata, except it's in the wrong direction ) that he would love to get Miata engine management on, that is until he can afford the MegaSquirt. Can you email me so we can discuss it? I know I'm probably asking for a wealth of Junk Mail from this but my email address is fastmonkeywheels @ hotmail.com

Last edited by fastmonkeywheels; 08-24-2007 at 12:53 PM.
fastmonkeywheels is offline   Reply With Quote
Old 08-24-2007, 09:34 AM   #25
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

how about you simply put the PCV back on so you can pull a **** load of vacuum out of the crankcase at idle and cruise, helping the turbo drain it's oil better, and keeping your rings healthy.

and then reattach the breather line to the intake so there is constant vacuum in the crankcase during all conditions....

I'd like to ask, in eradicating the pcv....what did you do, block off both ports?

fwiw, reattaching the pcv is not going to fix your current issue...
Braineack is offline   Reply With Quote
Old 08-24-2007, 10:54 AM   #26
Elite Member
iTrader: (9)
 
Saml01's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 5,730
Total Cats: 2
Default

I think you should reconnect the PCV valve and also replace it with one out of a 323GTX that can handle boost. This is something that is recommended often on this forum. The crank case vent on the right side of the valve cover can either have a catch can or a little air filter. That one I wouldnt put into your intake just because it can throw oil into the turbo, and you dont want that in there.
Saml01 is offline   Reply With Quote
Old 08-24-2007, 11:03 AM   #27
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

No, it is also highly recommended here that you do route the goddamn breather line back into the intake....
Braineack is offline   Reply With Quote
Old 08-24-2007, 02:58 PM   #28
Elite Member
iTrader: (9)
 
Saml01's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 5,730
Total Cats: 2
Default

Then why do I always read threads with people saying that if you plug the breather into the intake it can throw oil into the turbo and then into your charge pipes? Is the catch can the cleaner solution?
Saml01 is offline   Reply With Quote
Old 08-24-2007, 03:27 PM   #29
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

yes, catch can isnt a bad idea. But if you have good rings, you shouldn't be getting any blow-by.

The reason I suggest keeping the breather line there is so it's harder for excess pressure to build up in the crankcase, as you keep a constant source of vacuum in the crankcase....up to 2~hg. at 10psi of boost.

This will help your turbo drain faster & keep your rings fresh.

It doesn't kill you to have a little filter on the crankcase, but it doesn't do any good either.

Removing the PCV, imho, is just silly....
Braineack is offline   Reply With Quote
Old 08-24-2007, 08:09 PM   #30
Junior Member
 
Join Date: Mar 2006
Location: Sydney Australia
Posts: 138
Total Cats: 0
Default

Quote:
Originally Posted by what miata? View Post
disconnected the drain to make sure it was flowing with the car running that was fine. im running a small enough line, with the re stricter on the turbo.
This might seem like a Captain Obvious suggestion but...

You say you disconnected the drain, was this to see flow through the turbo?

If so I'm curious to know what would happen if you put a small funnel on the drain fitting (disconnected) and pour some oil down into your crankcase. If the drain is draining slower than the rate of oil that flows through the turbo, it will back up and push past the seals in the turbo.

Maybe you have a constipated drain?
ampz is offline   Reply With Quote
Old 08-24-2007, 11:41 PM   #31
Junior Member
Thread Starter
 
Join Date: Nov 2006
Posts: 158
Total Cats: 0
Default

pertaining your question i took off the line off the pan and ran the car and it drained and still smoked. the thing is there is oil in the cylinders on the plugs, its burning before the turbo. so the turbo has been ruled out.
what miata? is offline   Reply With Quote
Old 08-24-2007, 11:54 PM   #32
Elite Member
iTrader: (5)
 
akaryrye's Avatar
 
Join Date: Jul 2006
Location: Central California
Posts: 2,526
Total Cats: 0
Default

Has nobody even mentioned the cam cover seal? I found that one to be sortof tricky to get it not leaking and it was absolutely necessary to use silicone on the 90 degree corners. if its all over your plugs, thats where it has to come from right? its not like your cylinders are filled with oil right?
akaryrye is offline   Reply With Quote
Old 08-25-2007, 10:32 AM   #33
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

I highly doubt he is pushing past his rings VTA is not the end of the world but on some cars there is significant blowbye when running and this will cause a back up in the turbo's oil drain line, forcing oil into the ocmpressor and then into the intake inturn. A poorly routed drain or simply a drain that is to small etc can cause this as well. So in short order confirm the oil drain line is unkinked and has a free path to the oil pan and into it. Try a GTX pcv if this is the case. From there i gotta ask is the turbo new? If it is old maybe a good dissassembly and cleaning of the sealing surfaces inside and a carefull reasembly, or rebuild will fix your problem. There are 3 ways to burn oil guys remember Turbo, HG, and rings. My bet is on Turbom rings might not be helping it but turbo seems very likely. OF course if the turbo is new and does not have coked oil on it's internal seals from where it ws bypassed and then left opened a smidge by residue, then i
magnamx-5 is offline   Reply With Quote
Old 08-25-2007, 10:46 AM   #34
Elite Member
iTrader: (3)
 
Join Date: May 2006
Location: Houston, TX
Posts: 2,900
Total Cats: 0
Default

pull your charge pipe off the TB and check for lots of oil there... it could still be your turbo. There is a seal on the compressor side just like the turbine side. Although MOST oil burning issues are caused by the turbine seal, the compressor seals are also known to go bad and toss oil through your intake.

Your oil drain test is meaningless... if you have that much oil on your plugs then it will take longer to burn off pre-existing oil than it would to run your car out of oil (spilling out the return). Very short tests do no good in finding the root cause of this kind of problem.

Another thing to consider is that our oil passages in the head are laid out in a strange way. I did, at one point, have severe oil burning issues (1 quart/ 150 miles). It was a head gasket problem. I was not losing coolant, I had no coolant in the oil, or vise-a-versa. If all your other tests suggest there isn't a problem try changing the head gasket. It isn't too expensive (ebay gasket sets are under $60) and it takes about 4-5 hours (for me... I've done it half a dozen times).
Arkmage is offline   Reply With Quote
Old 08-25-2007, 08:09 PM   #35
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

DUDE.

you did a compression and leakdown test...it suggests the internals are postively fine and everythign is WELL within specs.

That being said, your drain line MUST be corrected.

If you have oil on the threads of the spark plugs that only says your valve cover gasket is leaking and the oil is not in the combustion chamber.

if the electordes are full of oil then you know the rings are failing. But since your smart *** pulled the pcv valve to pressurize the crankcase, then i'd expect lots and lots and lots and lots of burning oil.
Braineack is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Need help - Stock Balancer and Fastforward overlay pulleys Frank_and_Beans Supercharger Discussion 13 09-12-2016 09:17 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
New M62 Miata owner Pist0n Meet and Greet 4 10-01-2015 09:18 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM
Odd Steering issue interestedofold Suspension, Brakes, Drivetrain 5 09-29-2015 02:42 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 11:06 PM.