Help, 2l Carlton loss of power - Dont Feed The Donkeys
I have a 94 Vauxhall Carlton 2L manual diplomat with 140,000 miles on the clock, full service history etc and generally in very good condition. In the last couple of weeks a nasty little problem has cropped up with is rapidly getting worse.
About a week ago I noticed the temperature gauge slightly higher than normal, usually sits just above the blue marking but now hovers around the next marker above. This is also when I noticed a slight lack of power when putting the boot down i.e. 5 up and going up a hill.
Yesterday a quick trip on the motorway revealed just how bad the problem is becoming, I was seriously struggling to reach 70mph and dropping down to 45-50 uphill.
When cruising all seems fine except the slightly high temperature gauge, push the throttle a little, nothing happens, push the throttle a little more, the exhaust note drops noticeably, car starts to slowly lose speed, foot down a little more engine rattles (pinking?) and temp gauge starts to climb.

Could the exhaust be partially blocked choking the engine? would this cause high temp / pinking ?

Fuel filter blocked ? How do you check?

There does not appear to be water in the oil or oil in the water although it has lost a little coolant lately. Does all of this stink of head gasket failure !?!

any help or suggestions ?

Help, 2l Carlton loss of power - Malcolm_L
Pinking would suggest advanced ignition timing, probably worth getting this checked before committing to changing the head gasket.

Excessive back pressure from a partially blocked exhaust would be unlikely to affect engine temps dramatically.

I certainly wouldn't rule out head gasket though.

Best of luck
Help, 2l Carlton loss of power - Railroad
Excessive back pressure from a partially blocked exhaust would be unlikely to affect engine temps dramatically.

I disagree. Hot exhaust gases are hanging around the cylinder head for longer. Some vehicles including Vauxhall Bravas use the method of temporarily partially blocking the exhaust to aid cold starting and quicker warm up.

A blocked exhaust is therefore not to be ruled out. Loosen the frontpipe on a quiet road, then drive it to see if there's any difference. If there is change the exhaust system either partly or entirely.
Help, 2l Carlton loss of power - Adam Going (Tune-Up)
Fuel filter can be checked by measuring pressure either side and flow rate, but quite honestly I wouldn't bother - unless it has been changed in the last 24K, change it anyway. Dirty underneath job, but filter only £15ish so worth doing as first move.

You have also correctly identified the next possibility - a partially blocked exhaust or Catalytic Converter. This can sometimes be picked up by measuring inlet manifold vacuum - if reading is good (20psi - 21psi) at idle, but drops away progressively as revs increase to around 3,000rpm it could be the case. Also, feel the exhaust output pressure at tailpipe - you should be able to feel a "pulsing" flow of gas, substantially increasing if you get a third party to prod the accelerator a bit. If all you get is a feeble, constant pressure blow it is another pointer.But where is it blocked ?!

If you have a sectional exhaust you may be able to remove sections progressively, starting at the rear, but noise levels make road testing risky. Sometimes an improvement is seen by loosening the flanges ahead of each box,and the Cat, in turn, but this is time consuming and not always conclusive. Unless system is very recently replaced it may just be worth renewing it regardless, and if problem is still there it could be the Cat. Has to be said that Cat is most likely anyway. But this is all a bit costly, so I would strongly advise some expert diagnostic time before commiting to anything. It would be ideal if this could be done on a rolling road as problem may not show at kerbside/in workshop.

Backpressure can certainly cause pinking, and that in turn may be cause of overheating. To check for head gasket fault have someone carry out a "cylinder block combustion" test - involves drawing gasses present in coolant (via header tank) through a blue fluid in a vacuum capsule -if it changes colour to green there is Carbon Monoxide in coolant = head gasket fault.

Regards, Adam
Help, 2l Carlton loss of power - Dont Feed The Donkeys
Suspecting the exhaust the other day I took the Carlton to my local Kwik Fit (just up the road for me) and asked then to just check the exhaust explaining briefly my problems. Within seconds they had the car in the air and looking for leaks / breaks etc. After a couple of minutes of shining a torch, waving at it and banging the cat and boxes they pronounced the exhaust as fine but strongly advised me to get the engine checked out.
This morning I paid a visit to Nationwide Auto services for diagnostic tests. After a brief stationary thrashing in the car park the technician went for a spirited run round the block, came back and confirmed that I'm not going mad but there really is a problem. Now there are three heads under the bonnet and two playing around the exhaust tail pipe and a whole fist full of revving going on. After a brief explanation that they all suspect the cat to be the problem they proceed to take the exhaust apart from the back forwards.
Cat & back box off car revs freely, cat on back box off car still revs freely. back box on problems back. Conclusion back box U/S.
Just out of interest whilst everyone though the cat was a fault I rang around few local places getting quotes for a new cat fitted.
Nationwide £294
ATS £360 !
Motorway £217
Kwickfit £195
Bannings £175
Formula 1 £170
Certainly does pay to shop about!
Anyway ran out of time (work shifts) so will have to try and source a back box tomorrow.
Help, 2l Carlton loss of power - outkast
I had the same prob with my 2.6 carlton,had everything checked out and it turned uot to be the back box on the exhaust that was blocked.So I wold start there.
Help, 2l Carlton loss of power - Dont Feed The Donkeys
New back box on and wow what a difference, the car is quiet, fast and a pleasure to drive again. Had foregotten what a great car these Carltons were. Got all the power back and some that I don't ever remeber having. No pinking, temprature still a little high but that could be more to do with the recent hot spell of weather.

Many many thanks to all to helped.

....One very happy Carlton driver....

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