Why is my Cobra smoking in 4th gear?

[stang8762]

I just had my Heads and engine rebuilt 9.2:1 comp manley pistons and rods after i broke a ring land on my stock motor. I have a single MP T70 turbo ..

I have this weird problem where at WOT at about 5-6000 rpm in 4th gear i get this smoke screen out the tail pipes when im driving and let off and decel. Ive even tried throwing it in nuetral after and i still see alot of smoke. I can beat on it WOT in 1st-3rd gear and no smoke. Is it my motor or Turbo .. I dont think its residual oil left in the exhaust b/c i have 600 miles on it now . The only thing i can think of is its the turbo which is new.

I do have a breather can behind my pass front bumper which both my valve covers vent into. Im using a 3/8 line off each valve cover and tee-ed behind the intake then it runs down to the breather tank w/ no pcv just a straight shot. Can the lines be to small?

My turbo drain is 1/2" line and the oil feed is straight up and there is no oil restrictor in the feed line.

Any ideas

im going to pull the plugs this weekend and check for kinks in the pcv line

 

[boosted2000si]

Only in 4th when you decelerate?

I would remove the 2 lines from the valve covers and see if it changes.

I really would think its your valve seals but I would try to free up the crank case vent to eliminate that.

Can you get a video of it?

 

[stang8762]

I hope its not my valve seals i just had the heads/ engine rebuilt by a well known shop and family friend.

im going to disconnect the lines to the valve covers and run breathers see if that helps..

Its just weird that it will only do it in 4th gear when there is alot of load on the car.. I will try and get a video..

 

[Parts-is-Parts]

Do you have a restrictor in the oil feed line to the turbo?

 

[stang8762]

Do you have a restrictor in the oil feed line to the turbo?

No oil restrictor in the feed line .. Didnt know i needed one but i do see alot of posts about one on here..

 

[solidsnak3]

you could try to use a single -10 line for your drain. (bigger is better) from the picture, it looks like you have a rubber hose to a 90 degree metal bend. i have heard, that it is bed to avoid 90 degree fittings with drains. i have a 90 degree fitting at my oil pan though not before it like you do with you metal pipe.

 

[stang8762]

you could try to use a single -10 line for your drain. (bigger is better) from the picture, it looks like you have a rubber hose to a 90 degree metal bend. i have heard, that it is bed to avoid 90 degree fittings with drains. i have a 90 degree fitting at my oil pan though not before it like you do with you metal pipe.

Maybe i will try making less of a bend for the turbo drain ... Does anyone know what psi our oil pumps run at?

 

[Juiced46]

2 things. One you need a bigger drain tube. Looks like the rubber part is 1/2 which is equal to a -8, -10 or -12 would be much better, looks like the metal tube is even smaller then that. 2nd, you have way to much of a straight on that drain. I would put a 45 on that fitting coming out of the pan, then go up to the turbo at an angle. Looks like a drainage issue. Remember, the drain is only gravity fed, it very well could be backing up in there. Especially when you are getting alot of crankcase pressure in there.

Curious, Who built the motor?

 

[stang8762]

2 things. One you need a bigger drain tube. Looks like the rubber part is 1/2 which is equal to a -8, -10 or -12 would be much better, looks like the metal tube is even smaller then that. 2nd, you have way to much of a straight on that drain. I would put a 45 on that fitting coming out of the pan, then go up to the turbo at an angle. Looks like a drainage issue. Remember, the drain is only gravity fed, it very well could be backing up in there. Especially when you are getting alot of crankcase pressure in there.

Curious, Who built the motor?

Yeah i was thinking it might be the turbo drain.. I will see what i can do .

My motor was built by my friend who works for Danbury Competition Engine and tuned by efi logics

 

[whtcobra1998]

run a restricter also with your turbo, unless you have a 3an line, I had to take a set screw and drill a small hole as a restrictor and thread it into my oil feed fitting in my turbo, our cars have high oil pressure.

 

[stang8762]

Yeah im thinking i have to fix a couple of issues first i will check my plugs to make sure its not my motor then :

1) change my oil drain to 5/8 or -10an,

2) If that doesnt work maybe add a restrictor to the feed line .

3) then change my breathers to a bigger line like -10an or 5/8" .

4) Change air filter maybe it doesnt flow enough

Anyone know what size the on3 oil feed line is ? -3an or -4an?

What size restrictor do i run?

 

[thomas91169]

Id do the drain first.

Stock drain size on even my dinky 14b is 5/8" ID. A restrictor wont be necessary once you have proper means to allow drainage out of the turbo. Whats happening without proper drainage is the oil is backing up and blowing past the seals into the exhaust. Ive seen this many times with people using flex-lines for their oil drain lines and them kinking up. Luckily you are only getting it in 4th, ive seen stock cars just driving around normally and all of a sudden the driver goes "my car sounds like a boat bogging down when i try to get into boost" and you find theyre running some flex hose in lieu of the stock hardline return and its kinked up just enough to provide enough restriction to back things up.

Does anyone know what PSI the oil pressures get up to (idle, wot, etc)?

 

[stang8762]

From what i read stock oil pressure :

Cold 80-100psi
Warm cruising 50-84psi
Under boost WOT 60-100psi

If thats the case dont some turbos only need 40psi of pressure and at WOT could it be getting too much psi?

 

[on3performance]

just a heads up on the reducer, mp requires a 1/8" supply in order for them to give the 1 year warranty on their product. He has told me if a reducer is used, they do not cover the turbo under their warrany. I really dont think the drain would be causing that, you could try to shorten the metal pipe you added so its a more direct shot into the pan. I have never had issues like that with my car so Im a little uncertain

I would think though if it was the turbo, it would be doing it though all the gears. Do you have any oil on the exhaust wheel? If the turbo was bad, that should be coated with oil

 

[whtcobra1998]

some turbos need restrictors even if its draining right, I run a greddy turbo made by Mitsubishi and it only requires less than 20 psi of pressure to operate correctly, to much pressure can cause seals to leak even with the best drains. each turbo has different requirements

 

[stang8762]

I wonder if our cars flow too much oil pressure for the turbos ?

 

[stang8762]

just a heads up on the reducer, mp requires a 1/8" supply in order for them to give the 1 year warranty on their product. He has told me if a reducer is used, they do not cover the turbo under their warrany. I really dont think the drain would be causing that, you could try to shorten the metal pipe you added so its a more direct shot into the pan. I have never had issues like that with my car so Im a little uncertain

I would think though if it was the turbo, it would be doing it though all the gears. Do you have any oil on the exhaust wheel? If the turbo was bad, that should be coated with oil

Well i havent checked the turbo wheel yet but i did streighten out my drain and it still smokes . Maybe i will get a restrictor and drill it out so its 1/8" since the line and fittings are alot bigger. Im also going to change my 3/8" line from my valve covers to my breather tank to 1/2" see if that helps.

My turbo drain is 1/2" but the barb fitting that came w/ the On3 drain kit only measures .38" ID and the ID of my 1/2 tube is only .42". So maybe i will have to step up the drain to -10an ..


Also pulled the plugs and they looked perfect so it must be coming from the turbo ..

 

[stang8762]

Update i installed some 3/4" elbows on each of the valve covers and made a make shift filters and i think i got rid of 90% of the smoking. I think my 3/8" line off of each of the valve cover were 2 small since they joined together into one then into my breather tank and there was too much crank case pressure and the air couldnt escape so it was blowing out the turbo seal. So now im going to get some breathers to stick in the valve covers or run -AN line from each valve cover and seperatly into my breather tank. Anyone know what breather filters i will need to fit the valve covers?