Blown Rear Silencer

[mogsman 2]

I couldn't understand why my car kept stalling all week until today. Lots of restarting and then a very loud bang followed. Its a Klarius PG210M. I thought you might like to see the damage.

Ian

[welshpug 1,666]

not uncommon that, you might want to check the AFM and CTS with reference to the Haynes Workshop manual and a multimeter

[mogsman 2]

The engine runs fine now its removed. AFM was alright as it had been running well, could possibly be the CTS though. I have never changed it since getting the car 12 years ago.

Ian

[mogsman 2]

The MoT was last month and the gas analysis was CO 0.41% and HC 538ppm. Does this help? Could it just be the breakdown of the internals as there is alot of black bits inside? I've had a look for a new cts on gsf part no. 929BM0140. Is this the right one?

Ian

[mogsman 2]

I've done some trawling around the net and came up with http://www.ebay.co.uk/itm/BOSCH-sender-unit-coolant-temperature-0-280-130-026-/300806704089?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item46097a0bd9 Is this the one for a 1991 1.6 gti?

Ian

[pugdamo 111 2 Cars]

That's running pretty lean,CO would nearly pass a CAT test,would have expected it to be really rich if its blown the box apart like that,as Welshpug said though would check AFM and CTS just to make sure there not playing up

 

No ideas on the part numbers though im afraid

Edited December 23, 2012 by pugdamo

[mogsman 2]

I'll try the motor factors tomorrow for a cts and check on the afm. I think that it was the break up of the baffle in the box as it has lots of bits still in it, but I will still replace the cts and check the afm. The emissions values hardly change at every MoT and has been running well for a long time.

Ian

[ATK 143 1 Cars]

Mate, sorry to drag up an old thread but I had exactly the same backbox and mine blew up like yours last week! Did you find out what caused it or was it just a bad backbox? Did you try another of the same one?

[scbond 15 1 Cars]

Mate, sorry to drag up an old thread but I had exactly the same backbox and mine blew up like yours last week! Did you find out what caused it or was it just a bad backbox? Did you try another of the same one?

 

Could be a number of reasons for this happening. Too much smoke in the exhaust as a result of over fuelling can be a cause. The same issue can be caused by the exhaust being too restrictive for the engine but I doubt that's the issue here. Then again, it could also be down to the quality of the exhaust.

 

I've had this happen to me before...I had a 1.25l Fiesta which I dropped a 1.7l Puma engine into. For a couple of months I continued using the existing exhaust, which wasn't new by any stretch. Following an stupid move by myself where I left the MAF unplugged the engine was over fuelling. So I had a combination of the first two issues which resulted in a pretty mighty bang at about 7am.

 

Best thing I can suggest is checking the AFM to make sure you aren't running too rich but really I would've thought the back box would be on its last legs for pressure build-up caused by high smoke to cause it to blow.

[ATK 143 1 Cars]

AFM and backbox both brand new. Sounds like the backbox might have just been faulty...

[unariciflocos 49 1 Cars]

Unlikely. You need an awful lot of pressure to crack it open like that, pressure that can only result from an explosion inside the box from unburnt fuel.

[jackherer 543]

I agree, something has caused a lot of fuel to end up in the exhaust for that to happen. Possible causes include not just the AFM but also the CTS as mentioned and the TPS which activates the overrun fuel cut-off. An intermittent fault would be enough so it might be hard to find. Then there are timing issues to look at. I don't think you can lay the blame on the backbox itself.

[scbond 15 1 Cars]

To be honest, my Fiesta with a Puma engine did use to spit fuel a bit as they all do (nothing massive) and the MAF was unplugged at the time.