Mr FIAT - Your #1 source for vintage car parts

Technical 1.4 T-Jet Downhill breaking with engine problem

Currently reading:
Technical 1.4 T-Jet Downhill breaking with engine problem

M

marracc

New member
Joined
Nov 4, 2017
Messages
31
Points
7
Hello!
I have strange problem,and I could not find anything similar. I'm driving downhill in gear, without accelerator, only with engine breaking. After pressing clutch and full stop, car wont accelerate when I put in gear and press pedal... It is like hesitating or something, not responding on throttle for few seconds and then it goes.... Same happens after engine breaking and pressing pedal, without stop. One time there were explosions like maybe to much gasoline in cylinder. I don't know is it maybe because of oil fumes entering cylinder or what could it be... Car doesn't shout down.
 
Last edited:
Air oil segregater is more than likely the issue same thing happened to me.
Do away with that box and plumb in a catch can in place of what that box would do.the little black box is located under engine cover on top right of the engine.you could try cleaning it like I did and clean it and clean it and clean it,after that I gave up an fitted a catch can
 
Daiton said:
Air oil segregater is more than likely the issue same thing happened to me.
Do away with that box and plumb in a catch can in place of what that box would do.the little black box is located under engine cover on top right of the engine.you could try cleaning it like I did and clean it and clean it and clean it,after that I gave up an fitted a catch can
Click to expand...

I bought a new oil separator and it didn't make any change.. It seems like its bad designed system... I'm burning 1l oil on 1000km... It may be because of bad oil separator system. I will plug hose witch goes from separator to intake manifold and will see what will happen. Oil catch can is in coming, so will fit it in hose witch goes to before turbo hose.

What are symptoms of bad valve seals or guides on these T-jets?
 
marracc said:
I bought a new oil separator and it didn't make any change.. It seems like its bad designed system... I'm burning 1l oil on 1000km... It may be because of bad oil separator system. I will plug hose witch goes from separator to intake manifold and will see what will happen. Oil catch can is in coming, so will fit it in hose witch goes to before turbo hose.

What are symptoms of bad valve seals or guides on these T-jets?
Click to expand...
I tried every possible combination and nothing worked for me.
The whole pcv system is a very bad design.
After trying everything I came to the conclusion that the way the crankcase gases rise to the oil segregater it carnt seem to work fast enough because of the small chambers inside the oil segregater so the oil/gases that have risen they carnt go anywhere and leak past the valves back into the cylinders.if you take a spark plug out and see if there is oil on the thread.thats what happened on mine which was what led me to believe it was valve stem seals.
Like I said i tried everything.
The catch can I bought and fitted like you want to do,but then I thought I can use that catch can in place of the oil segregater.
So I got some hydraulic hose that fitted snug inside where the oil segregater goes into the rocker cover and fed that down to my baffled catch can then some more hose upto the intake vacuum line but fitted a check valve to connect them together,and make a bracket for a catch can and place it some where so you can empty it from time to time
This way the catch can is under vacuum pressure just like the oil segregater works.
Problem solved for me,
Sorry for the rambling but I hope this helps
 
I get your point... Pressure is to high in Oil separator so fumes are pushed down through valve oil seals... I closed hose witch is going directly into intake manifold, it didn't help a lot.... Seems like i would make same thing as you did, when my parts arrive...
 
Daiton said:
I tried every possible combination and nothing worked for me.
The whole pcv system is a very bad design.
After trying everything I came to the conclusion that the way the crankcase gases rise to the oil segregater it carnt seem to work fast enough because of the small chambers inside the oil segregater so the oil/gases that have risen they carnt go anywhere and leak past the valves back into the cylinders.if you take a spark plug out and see if there is oil on the thread.thats what happened on mine which was what led me to believe it was valve stem seals.
Like I said i tried everything.
The catch can I bought and fitted like you want to do,but then I thought I can use that catch can in place of the oil segregater.
So I got some hydraulic hose that fitted snug inside where the oil segregater goes into the rocker cover and fed that down to my baffled catch can then some more hose upto the intake vacuum line but fitted a check valve to connect them together,and make a bracket for a catch can and place it some where so you can empty it from time to time
This way the catch can is under vacuum pressure just like the oil segregater works.
Problem solved for me,
Sorry for the rambling but I hope this helps
Click to expand...


Maybe i just didn't get it from your description... but i don't think you installed it right:

It's a turbo engine, it produces much more blow-by on boost (more gases in the valve cover). if you're blocking the hose with a check-valve those gases will just have to blow out somewhere.. or will they will force some oil into the combustion chamber.

The OEM segregator works both under vacuum and under boost.


You can install a simple catch can, but you need to route the hose from it to before the turbo..... an open system ... no check-valves.
 
Last edited:
So the vacuum line from the intake I fitted a 1 way check valve like the oil segregater has,with hose from the other side of the check valve down to the catch can then more hose from catch can upto valve cover
 
Daiton said:
So the vacuum line from the intake I fitted a 1 way check valve like the oil segregater has,with hose from the other side of the check valve down to the catch can then more hose from catch can upto valve cover
Click to expand...

Post a picture. but it sounds like the one way valve is being kept closed by boost...... (good for boost BUT bad for crank case pressure).

The oem segregator has multiple check valves (2 or 3), and a membrane with a spring (acted upon by either engine vacuum and crank case pressure).
The gases go straight to the intake on vacuum AND/OR while on boost the check-valves redirect the gas flow just before the turbo.

It's a pretty smart design, and reduces oil consumption, letting the oil drain back into the head.
They are a bit complicated the reason they go bad in time, then need replacing.
I've found generally it's good to have them replaced around the 100k km mark.... not that expensive ~50-ish euro.

They go bad even earlier if oil changes aren't done in time... crud and sludge build up in them sticking the check-valves... leading to all sorts of problems ... boost leak, oil consumption...etc.
 
Last edited:
I understand about the oil segregater,i'v cut 1 open.the part that goes into valve cover at the top of that there are 3 small holes into the first chamber then 3 more holes from that chamber that is controlled with the spring and diaphram that lead to the other chamber there is 1 check valve which is basically a flap on a hinge next to the oil drain exit and the check valve to the intake
Now you have mentioned about the check valve is good for boost but bad for crank case it's got me thinking about vacuum line upto the intake,is that not a constant vacuum
 
Last edited:
Daiton said:
is that not a constant vacuum
Click to expand...

Nope.

When the car is in boost there is positive pressure in the intake...i.e air could be pushed into the crank-case/valve cover.

So a turbo engine works in 2 ways:
- under vacuum like a NA engine at gentle throttle, cruising (at most speeds) idling..etc
- under boost ... when the engine load reaches a certain threshold, the pressure in the intake manifold will go from negative pressure (vacuum) to positive pressure (boost).

So this is the reason the OEM one also has a hose to before the turbo where pressure is atmospheric pressure.
 
I will do a compression test on my T-jet. What values are good (bar)?
 
I just measured compression:
1- 11 bar
2-10.5 bar
3-10.3 bar
4- 8.7 bar
could oil consumption be due to low compression on 4th cylinder, or is ti under acceptable criteria?
 
marracc said:
I just measured compression:
1- 11 bar
2-10.5 bar
3-10.3 bar
4- 8.7 bar
could oil consumption be due to low compression on 4th cylinder, or is ti under acceptable criteria?
Click to expand...

don't think so...
Was probably just the battery slowly dying....relates to the pressure drop over the 4 cylinders.

Compression is only a valuable tool used to determine major damage.

that ~1 bar of difference can be easily explained by battery voltage getting lower, or because of fewer revolutions when doing the test.


A slightly better way to test, is to perform a cylinder leak down test.
 
aurick86 said:
don't think so...
Was probably just the battery slowly dying....relates to the pressure drop over the 4 cylinders.

Compression is only a valuable tool used to determine major damage.

that ~1 bar of difference can be easily explained by battery voltage getting lower, or because of fewer revolutions when doing the test.


A slightly better way to test, is to perform a cylinder leak down test.
Click to expand...

Ok. Thank you.
I have installed Oil catch can in the hose going from separator up to turbo air inlet hose. After few rides I didn't find any oil inside. After leaving car over a night, when i removed turbo air inlet pipe, there was oil on turbo inlet again... same as before Oil catch can installation. What does that mean? Oil cant drain out of turbo because of clogged something? Bad turbo?
 
Last edited:
post some pictures.

Determine where the oil is coming from (turbo vs catch can)

It is a good idea to remove the turbo oil feed and oil drain and have it cleaned (brake clean spray and a wire with some rags..etc get them clean.

You could have some worn seals on the turbo..leading to oil leaks from the turbo. (a CHRA is about 150 euro)
 
aurick86 said:
post some pictures.

Determine where the oil is coming from (turbo vs catch can)

It is a good idea to remove the turbo oil feed and oil drain and have it cleaned (brake clean spray and a wire with some rags..etc get them clean.

You could have some worn seals on the turbo..leading to oil leaks from the turbo. (a CHRA is about 150 euro)
Click to expand...

100% its from turbo, not Oil catch can... I didnt took picture, but there was oil sitting in turbo inlet, with oil trail up to blades... Should oil always be in cattridge, or it drains totaly after some time?
 
Most of it drains back to the oil sump...but it's oil a drop or two will always stay behind.

1-2 drops of oil will make enough mess
 
You must log in or register to reply here.

Similar threads

N
General 1.4 t-jet bravo acceleration pedal info and q
Replies
0
Views
134
newtjetuser
N
N
Tuning Software update for 1.4 t-jet cold start problem fix
Replies
1
Views
651
newtjetuser
N
S
Technical Location of camshaft and crankshaft position sensor on a FIAT BRAVO 2008 1.4 T-Jet.
Replies
1
Views
237
electric73
E
Ryan J
Technical Cold air intake fiat bravo 1.4 t jet 120
2
Replies
23
Views
1K
Ryan J
Ryan J
H
Technical Bravo 2 1.4 tjet poor acceleration
Replies
2
Views
86
The Panda Nut
The Panda Nut
Back
Top