Cat

Gary_Cusdin

Now I only have 3 options left for my misfire on 1 and 4 at 3000 rpm (according to Haynes).
Leak in system (have looked and no visible signs)
Low cylinder compression (no issues before water pump change after mostly successful engine rebuild)
Blocked cat.

Now due to this occurring after the water pump change and the exhaust system has done 140000 miles now I can't help feeling that the cat converter has collapsed or maybe the gasket has failed due to removal.
When I go out in the morning and cold starting I do see loads of fumes out the back whilst driving, white, which clears once warmed.
How can I check the first cat if it is built into the manifold??
Everything else has been changed to clear the fault (fuel pump, FPR, plugs, coil) and failed to clear.
My mate works at longlife so if i popped down to him to remove can it be checked that way?

jwalker

White smoke is normal, you can check for the precat by removing either the downpipe or manifold

Gary_Cusdin

To add.
When I got back last night I popped the hood to listen and check whilst running and hot.
The back end of the engine felt very hot which I have never felt before, whilst driving there was a faint whining noise whilst accelerating..
I know it gets hot under there and the fan was running but front of engine was nice and cool. The heat seemed very strong from around the manifold, not to touch as obvious it would be hot but heat dispersing from the engine.
Should the heat not follow the exhaust gas towards the back end or could this be a sign of blocked cat?

Gary_Cusdin

jwalker said:
White smoke is normal, you can check for the precat by removing either the downpipe or manifold

Is that the second cat or the one on manifold?
It's built into the manifold no?
So u can remove manifold and look down into it yes?

guy_27

To check for blocked cat. Start car up. Walk to exhaust and put hand over it. If no gasses coming out its blocked. If it's flowing get engine to operating temperature and get someone to rev it. If it comes out burning hot it's also blocked.
Just a couple of easy diy ways to check.

Gary_Cusdin

Thanks Guy. Seems easy.
I also found a thing that says to remove oxygen sensor and put a tester in. Run engine and accelarate hard then off and see what pressure is pushing out.
If more than 4 PSI the cat is blocked.
If I get a pressure tester for the cylinders would it work on the sensor and what size would it need to be?

Sjdickso

Not sure if the Signum has a Pre cat / mini from cat but this could have failed and got stuck before the main cat?