T4 -99, Weird prob, sounds as if hole in manifold when startin

[swetech]

When she starts up from cold, there is a noise as if there is a hole in the exhaust manifold, however, a few minutes later, the noise goes away (quite sudden) and she sounds normal, whatever valve or similar would cause this ? It's a -99 T4 Petrol 5 cylinder, any ideas anyone ?
Tia
swetech

[Silver Caravelle]

Loose manifold bolt and/or leaking manifold gasket. It takes up when it heats up.

Regards,

Scott

[rob64981]

Yep....

Sounds like you have loose nuts

Rob

[swetech]

To be honest, I think not, it's too sudden in the quietening down, from noisy to "normal" without any in between and realistically, there would be some leaky noise even when hot. Also, the time appears to be approximately the same each time, regardless of exterior heat as well, 20 or 40 C, same time, I was thinking something like a cold start relay opening up a valve somewhere

[gregozedobe]

Just to eliminate the obvious, have you actually put a spanner (or socket) to the (possibly) offending nuts/bolts/studs ? Then you could eliminate looseness from your potential causes.

I always like try the easy/cheap fixes first, even if they seem a bit less likely (it can save lots of time and my money)

[swetech]

Yes mate, I have, that is the reason why I ask you guys if per chance anyone had ever had a similar problem, or if someone knows what relays and valves are running on a timer during cold/first start up. Because I am the same, I try to fix things first myself, I have wrenched with various cars before, big jobs and successfully, being too tight to part with my hard earned dough. This problem have me baffled.

[Golf Loon]

What size engine is it? petrol? diesel?

Does it have the warm air intake hose off the manifold into the airbox?
There is a flap in there that moves after cold startup.

[Silver Caravelle]

If it isn't a leaking manifold, it could simply be the cold start process, which would explain the sudden change after a few minutes.

When it starts up from cold, the Siemens (Siemex) injection computer retards the ignition and lifts the idle, then after a few minutes, it reverts to normal warming running cycle.

When it is in cold start cycle, it gives the impression of a leaking manifold; it is really the load on the engine in retard mode to warm up the cataylic converter quicker.

Regards,

Scott

[Silver Caravelle]

Hi Swetech,

Did you identify the reason?

Regards,

Scott

[swetech]

Yup Scott, I think (know) that you nailed it. Sorry for not getting back an the double, have been to Asia for a few jobs.

[Silver Caravelle]

That's great.

All should be fine then.

Regards,

Scott

[swetech]

Yes, learned to live with it. Truly didn't seem to be an issue with the inspector when it had to go over the pits (de registered ex ambulance) and I'm certain that he would have been quite unforgiving had there been an issue. The "noisy manifold" is only noisy whilst the choke is activated, was good for me at the auctions though, not many wanted to bid "because there was a hole in the manifold", picked her up for $1700 (plus bidding fees @ $200), not bad at all.
Thank you for your valuable conclusion.

Swetech

[Silver Caravelle]

Swetech,

Pleaure.

Nice one re the auctions I am sure all t4 2.5 petrol engines of this vintage would also do it as part of engine management to warm up the cat. My Caravelle certainly does.

Regards,

Scott