pcv hose blew off - bad egr or pcv valve?

[tracyc]

Need some help if anyone has some ideas about this:
Yesterday I was starting my 2008 LR3 with about 160k miles and the 4.4L V8. It had a delayed start, cranking for about 10 seconds (which it has been doing intermittently maybe 1 out of every 25 starts for a few months - runs great otherwise) before it caught. Right away I heard a pop, shut it down and then some white smoke came from the engine bay. I looked and apparently the middle section of the pcv hose has been replaced with a flexible radiator type hose at some point that is attached to the original pcv hose ends. It had popped off one end and that's where the white exhaust-smelling smoke was coming from.
I replaced the pcv valve with a new genuine one a couple months ago as I had some lean codes I was troubleshooting. My lean codes did go away (whether it the valve or new injectors I'm not sure), but do you guys think the new one could be bad, or maybe the EGR valve is sticking open sometimes?
Started again a few minutes later and I could tell the pcv hose was now under vacuum as it was deforming some. New genuine hose is on the way, but I need some ideas about why there would be so much pressure in there at start. There weren't any engine codes set. Thanks!

 

[BeemerNut]

That was an explosion that blew the hose off.
Did by chance you added a little throttle or pumping the pedal while cranking this causing a lean slow burn condition and backfire in the intake tract which was common with 80's era BMW's. Owners not knowing how to PROPERLY START their engines vs carbed?
Don't confuse this with afterfire out the tailpipe of uneducated people.
BMW with their stupid wisdom added hose clamps now increasing the explosive pressures by times ten or higher now destroying the Mass Air Sensor costing way more dollars vs reinstalling the hose taking a whole three seconds to reinstall. I had to train the wifey with her new to her 86 735 BMW back in 86 when she blew off the hose several times how to reinstall it vs being stranded several times......~~=o&o>......

 

[tracyc]

No, didn't pump the throttle at all. It was definitely more like the sound of a hose popping off than an explosion. I mean there could have been a backfire as you say, but didn't sound like it...

 

[BeemerNut]

I'd be a muffled puff sound more like it with like you mentioned then vapors streaming out.

Usually a delayed ignition burn due to a leaness condition which ends up firing off the intake charge once a intake valve unseats then backfiring.
Done large enough it can bend the throttle body butterfly and shaft if large enough.

A massive crankcase explosion after cranking a lot after over spraying with starting fluid i've seel the oil pan bellied out along with valve covers with the best being the valve cover vent cap now has become a projectile and made a dent coming from under the hood.

Newer engines with cam position, crank trigger sensors along with several other position sensors aka more crap to go wrong vs the simple good old push rod engines.
Old Buicks having a tin valley cover LR pushrod engines on V-8's now lifted up and resting under the intake manifold from starting fluid used in excess.

If it isn't going to light off on gasoline rather quickly there's an issue or cause vs cranking and cranking away expecting the engine to fire up.

Broken or jumped a couple teeth the cams and valve timing out of sync can cause what you had happen. besides bending valves if not a clearance engine.
Gota love a mystery, good hunting.....~~=o&o>......

 

[tracyc]

It still runs great since this happened so I'm leaning towards an occasional stuck egr or pcv valve. Will be replacing replacing both, even though I did the pcv a couple months ago - just to be safe....

 

[tracyc]

Here's an update:

So I replaced the egr valve. Went with a dirt cheap WVE unit from Rockauto. I was quite pleased when I opened the box and it had a made in Japan Denso label on it. Came with 2 new gaskets too. Seems I got their last one as it's out of stock now.

Needed to get the torch out to get one of the EGR bolts broken free. I'm always a bit nervous using the torch in the engine compartment, but it worked, with some additional help from PB Blaster.

Replaced the pcv valve with another genuine unit to be safe. Seller Attic Market Auto on Amazon was really helpful with getting a free warranteed replacement sent out.

Replaced my broken pcv "connection" hose (the shorter one that comes off the valve) with an aftermarket one from Uro - which was not a great fit so I'll be replacing that with a genuine one when it arrives. Also replaced the longer pcv hose with another Uro product as preventative maintenance, and that one fit properly.

So far haven't had any more starting problems - it even seems to be firing up slightly quicker, but that could be my imagination.