Blow by kills motor unless oil cap off

[Hillboy700]

Daughter was driving home car died I towed it home would not start , finally started with loud screaming noise and died. Opened oil fill started it and it runs but blows a column of white smoke to begin then it clears up but blows it really hard. Put the cap back on and it dies. Took off plastic vent hose and it blows really hard out that but does not run well pull cap runs fine while off.
What the heck no venting out oil dip stick.

Has egr delete kit and new cam and followers 20,000 miles ago.
Ran fine except bad bottom end which is probably plugged intake but this happened within 1 minute of freeway driving after a daily 100 mile commute then parked started to come home and quit.

Any help for a starving college brat would be appreciated .

 

[325_Guy]

Bad bottom end?

BRM engines don't suffer from the plugged intake problems the older TDIs had.

 

[joewilhite]

could be a loose injector causing blow by

 

[whitedog]

could be a loose injector causing blow by

But it runs fine with the oil cap off. it's worth the few minutes to remove the valve cover.

 

[GetMore]

No real answer, but it seems to me that whatever it is blowing out is not good for combustion. With the cap on those gasses go into the intake (After the MAF.)

I don't know what the MAF reading does for idle, but if the engine does want to see the airflow this would be a problem.

I was going to ask about a plugged air filter, but that would mean that it would suck air in through the cap, not blow anything out.

Similar for the exhaust: If it was plugged you might get excessive blowby, but I would think the car just wouldn't want to run at all. I was also thinking EGR would allow more exhaust into the intake if the exhaust was plugged, but yours is blocked.

 

[Hillboy700]

Ok I'm going to pull the valve cover

 

[JETaah]

Look to see if the turbo blew or the exhaust is plugged.
I just did one like that and it wound up being that the turbine wheel blew off and was blocking the exhaust exit on the turbo.The exhaust was backing up through the oil return and where ever else, pressuring the crankcase, venting through the CCV and into the intake. Cough, cough!!!

 

[whitedog]

I am betting that Marty is right. Assuming everything is fine under the VC, drop the down pipe and see what's happening over there.

 

[James & Son]

This does not seem good but I don't think it is cam related. A combination of flat lobes and dished followers hold the intake open during exhaust stroke and cause the burp out the exhaust pipe.

This is described as positive pressure coming from the oil cap or crankcase. It idles normal when the oil cap is removed allowing the positive pressure gasses to escape with out going through the PVC valve which when it does causes the engine to run rough or not at all.

The only two things that generate this much pressure is compression and the turbo charger. The turbo has no connection to the crankcase even if the PCV valve completely malfunctioned. As GetMore was getting at the amount of gasses coming from the crankcase is affecting the function of the MAF sensor and only when the oil cap is removed does the engine start and idle. If the intake was plugged to would get a slight additional suction through the PCV valve. A plugged exhaust can not exit through the crankcase, their is no connection.

I hope I am wrong but this leaves only one thing, blow by the rings of probably all cylinders, with still enough compression to run but enough blow by now to overwhelm the intake through the PVC.

Ok, Jetaah just probably pointed out the connection, the turbo charger oil return. The OP mentioned a screech when he started the car after initial failure.